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Okonya, Joshua, Walter Ocimati, Anastase Nduwayezu, Déo Kantungeko, Nicolas Niko, Guy Blomme, James Legg und Jürgen Kroschel. „Farmer Reported Pest and Disease Impacts on Root, Tuber, and Banana Crops and Livelihoods in Rwanda and Burundi“. Sustainability 11, Nr. 6 (15.03.2019): 1592. http://dx.doi.org/10.3390/su11061592.
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Biotic constraints cause major crop losses and, hence, food insecurity in sub-Saharan Africa. This study documented the popularity, production constraints, pests and diseases, farmers’ perceptions on the severity of biotic constraints and the impact of related crop losses on household food security for the key root, tuber and banana (RTB) crops (cassava, potato, sweetpotato and banana). Farmer interviews were conducted in 2014 covering 811 households in Rwanda and Burundi. Farmers were asked to list their RTB crop production constraints, name insect pests and diseases of RTB crops, estimate crop loss due to pests and diseases, and mention if their household experienced any form of food insecurity due to pests and diseases. Cutworms and late blight in potato, banana weevils and banana Xanthomonas wilt in banana, cassava whitefly and cassava mosaic disease in cassava, sweetpotato weevils, and sweetpotato virus disease in sweetpotato were the most predominant pests and diseases reported. Crop losses due to pests and diseases for sweetpotato, banana, potato and cassava were estimated at 26%, 29%, 33%, and 36%, respectively, in Rwanda and 37%, 48%, 38%, and 37% in Burundi. Pests and diseases reduce the profitability of RTB crops, threaten food security, and constitute a disincentive for investment. Sustainable and affordable integrated pest management packages need to be developed.
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Nesamari, R., T. A. Coutinho und J. Roux. „Diseases and pests of Encephalartos species in South Africa“. South African Journal of Botany 98 (Mai 2015): 214. http://dx.doi.org/10.1016/j.sajb.2015.03.168.
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Montemayor, S. I., P. M. Dellapé und M. C. Melo. „Predicting the potential invasion suitability of regions to cassava lacebug pests (Heteroptera: Tingidae: Vatiga spp.)“. Bulletin of Entomological Research 105, Nr. 2 (19.12.2014): 173–81. http://dx.doi.org/10.1017/s0007485314000856.
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AbstractCassava (Manihot esculenta Crantz) is one of the most important staple crops for small farmers in the tropics, feeding about 800 million people worldwide. It is currently cultivated in South and Central America, Africa and Asia. The genus Vatiga is widespread throughout the Neotropical region. Its species are sympatric and feed exclusively on cassava. The main objectives of this paper are: (1) to assess the potential distribution of Vatiga, one of the most relevant pests of cassava; (2) to project the resulting models onto the world; (3) to recognize areas with suitable and optimal climates (and thus, high probability) for future colonization, and (4) to compare this model with the harvested area of cassava analyzing the climatic variables required by both the host and the pest species. Species distribution models were built using Maxent (v3.3.3k) with bioclimatic variables from the WorldClim database in 2.5 arc min resolution across the globe. Our model shows that Vatiga has the potential to expand its current distribution into other suitable areas, and could invade other regions where cassava is already cultivated, e.g., Central Africa and Asia. Considering the results and the high host specificity of Vatiga, its recent appearance in Réunion Island (Africa) poses a serious threat, as nearby areas are potentially suitable for invasion and could serve as dispersal routes enabling Vatiga to reach the continent. The present work may help prevention or early detection of Vatiga spp. in areas where cassava is grown.
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Kwibuka, Yves, Espoir Bisimwa, Arnaud G. Blouin, Claude Bragard, Thierry Candresse, Chantal Faure, Denis Filloux et al. „Novel Ampeloviruses Infecting Cassava in Central Africa and the South-West Indian Ocean Islands“. Viruses 13, Nr. 6 (29.05.2021): 1030. http://dx.doi.org/10.3390/v13061030.
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Cassava is one of the most important staple crops in Africa and its production is seriously damaged by viral diseases. In this study, we identify for the first time and characterize the genome organization of novel ampeloviruses infecting cassava plants in diverse geographical locations using three high-throughput sequencing protocols [Virion-Associated Nucleotide Acid (VANA), dsRNA and total RNA], and we provide a first analysis of the diversity of these agents and of the evolutionary forces acting on them. Thirteen new Closteroviridae isolates were characterized in field-grown cassava plants from the Democratic Republic of Congo (DR Congo), Madagascar, Mayotte, and Reunion islands. The analysis of the sequences of the corresponding contigs (ranging between 10,417 and 13,752 nucleotides in length) revealed seven open reading frames. The replication-associated polyproteins have three expected functional domains: methyltransferase, helicase, and RNA-dependent RNA polymerase (RdRp). Additional open reading frames code for a small transmembrane protein, a heat-shock protein 70 homolog (HSP70h), a heat shock protein 90 homolog (HSP90h), and a major and a minor coat protein (CP and CPd respectively). Defective genomic variants were also identified in some cassava accessions originating from Madagascar and Reunion. The isolates were found to belong to two species tentatively named Manihot esculenta-associated virus 1 and 2 (MEaV-1 and MEaV-2). Phylogenetic analyses showed that MEaV-1 and MEaV-2 belong to the genus Ampelovirus, in particular to its subgroup II. MEaV-1 was found in all of the countries of study, while MEaV-2 was only detected in Madagascar and Mayotte. Recombination analysis provided evidence of intraspecies recombination occurring between the isolates from Madagascar and Mayotte. No clear association with visual symptoms in the cassava host could be identified.
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Boykin, Sseruwagi, Alicai, Ateka, Mohammed, Stanton, Kayuki et al. „Tree Lab: Portable genomics for Early Detection of Plant Viruses and Pests in Sub-Saharan Africa“. Genes 10, Nr. 9 (21.08.2019): 632. http://dx.doi.org/10.3390/genes10090632.
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In this case study we successfully teamed the PDQeX DNA purification technology developed by MicroGEM, New Zealand, with the MinION and MinIT mobile sequencing devices developed by Oxford Nanopore Technologies to produce an effective point-of-need field diagnostic system. The PDQeX extracts DNA using a cocktail of thermophilic proteinases and cell wall-degrading enzymes, thermo-responsive extractor cartridges and a temperature control unit. This closed system delivers purified DNA with no cross-contamination. The MinIT is a newly released data processing unit that converts MinION raw signal output into nucleotide base called data locally in real-time, removing the need for high-specification computers and large file transfers from the field. All three devices are battery powered with an exceptionally small footprint that facilitates transport and setup. To evaluate and validate capability of the system for unbiased pathogen identification by real-time sequencing in a farmer’s field setting, we analysed samples collected from cassava plants grown by subsistence farmers in three sub-Sahara African countries (Tanzania, Uganda and Kenya). A range of viral pathogens, all with similar symptoms, greatly reduce yield or destroy cassava crops. Eight hundred (800) million people worldwide depend on cassava for food and yearly income, and viral diseases are a significant constraint to its production. Early pathogen detection at a molecular level has great potential to rescue crops within a single growing season by providing results that inform decisions on disease management, use of appropriate virus-resistant or replacement planting. This case study presented conditions of working in-field with limited or no access to mains power, laboratory infrastructure, Internet connectivity and highly variable ambient temperature. An additional challenge is that, generally, plant material contains inhibitors of downstream molecular processes making effective DNA purification critical. We successfully undertook real-time on-farm genome sequencing of samples collected from cassava plants on three farms, one in each country. Cassava mosaic begomoviruses were detected by sequencing leaf, stem, tuber and insect samples. The entire process, from arrival on farm to diagnosis, including sample collection, processing and provisional sequencing results was complete in under 3 h. The need for accurate, rapid and on-site diagnosis grows as globalized human activity accelerates. This technical breakthrough has applications that are relevant to human and animal health, environmental management and conservation.
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Boykin, Laura, Ammar Ghalab, Bruno Rossitto De Marchi, Anders Savill, James M. Wainaina, Tonny Kinene, Stephen Lamb et al. „Real time portable genome sequencing for global food security“. F1000Research 7 (18.07.2018): 1101. http://dx.doi.org/10.12688/f1000research.15507.1.
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Crop losses due to viral diseases and pests are major constraints on food security and income for millions of households in sub-Saharan Africa (SSA). Such losses can be reduced if plant diseases and pests are correctly diagnosed and identified early. Currently, accurate diagnosis for definitive identification of plant viruses and their vectors in SSA mostly relies on standard PCR and next generation sequencing technologies (NGS). However, it can take up to 6 months before results generated using these approaches are available. The long time taken to detect or identify viruses impedes quick, within-season decision-making necessary for early action, crop protection advice and disease control measures by farmers. This ultimately compounds the magnitude of crop losses and food shortages suffered by farmers. The MinION portable pocket DNA sequencer was used, to our knowledge globally for the first time, to sequence whole plant virus genomes. We used this technology to identify the begomoviruses causing the devastating cassava mosaic virus, which is ravaging smallholder farmers’ crops in sub-Saharan Africa.
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Moodley, Vaneson, Augustine Gubba und Paramu L. Mafongoya. „Emergence and Full Genome Analysis of Tomato Torrado Virus in South Africa“. Viruses 12, Nr. 10 (15.10.2020): 1167. http://dx.doi.org/10.3390/v12101167.
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Emerging pests and diseases are a major threat to food production worldwide. In a recent survey, Tomato torrado virus (ToTV) was identified on tomato crops in the Limpopo province of South Africa and a first report of the disease was published. In this follow-up study, the full genome sequence of a tomato-infecting isolate of ToTV from South Africa was elucidated. High-throughput sequencing was used to generate the full genome of ToTV infecting tomato crops in South Africa. The longest contig obtained for the RNA-1 and RNA-2 genome of ToTV was comprised of 7420 and 5381 nucleotides (nt), respectively. Blast analysis of the RNA-1 sequence of ToTV from South Africa (ToT-186) matched 99% to a Spanish and Polish isolate; the RNA-2 segment of ToTV from South Africa (ToT-186) matched 99% to ToTV isolates from Italy and Poland, respectively. The information presented in this study will go a long way towards better understanding the emergence and spread of ToTV and devising sustainable management of ToTV diseases.
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Engelbrecht, Gerhard, Sarina Claassens, Charlotte M. S. Mienie und Hendrika Fourie. „South Africa: An Important Soybean Producer in Sub-Saharan Africa and the Quest for Managing Nematode Pests of the Crop“. Agriculture 10, Nr. 6 (22.06.2020): 242. http://dx.doi.org/10.3390/agriculture10060242.
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With an increase in the global population, a protein-rich crop like soybean can help manage food insecurity in sub-Saharan Africa (SSA). The expansion of soybean production in recent years lead to increased land requirements for growing the crop and the increased risk of exposing this valuable crop to various pests and diseases. Of these pests, plant-parasitic nematodes (PPN), especially Meloidogyne and Pratylenchus spp., are of great concern. The increase in the population densities of these nematodes can cause significant damage to soybean. Furthermore, the use of crop rotation and cultivars (cvs.) with genetic resistance traits might not be effective for Meloidogyne and Pratylenchus control. This review builds on a previous study and focuses on the current nematode threat facing local soybean production, while probing into possible biological control options that still need to be studied in more detail. As soybean is produced on a global scale, the information generated by local and international researchers is needed. This will address the problem of the current global food demand, which is a matter of pressing importance for developing countries, such as those in sub-Saharan Africa.
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Graziosi, Ignazio, Nami Minato, Elizabeth Alvarez, Dung Tien Ngo, Trinh Xuan Hoat, Tin Maung Aye, Juan Manuel Pardo, Prapit Wongtiem und Kris AG Wyckhuys. „Emerging pests and diseases of South-east Asian cassava: a comprehensive evaluation of geographic priorities, management options and research needs“. Pest Management Science 72, Nr. 6 (24.03.2016): 1071–89. http://dx.doi.org/10.1002/ps.4250.
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Swartz, Alison, Susan Levine, Hanna-Andrea Rother und Fritha Langerman. „Toxic layering through three disciplinary lenses: childhood poisoning and street pesticide use in Cape Town, South Africa“. Medical Humanities 44, Nr. 4 (20.10.2018): 247–52. http://dx.doi.org/10.1136/medhum-2018-011488.
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This article focuses on the devastating hidden perils of agricultural pesticides repurposed by informal sellers in urban South African townships to kill rats and other unwanted pests. Drawing on collaborative research techniques, we investigate the causal relationship between child poisoning episodes and the household use of illegal street pesticides. Such pesticides are used to safeguard homes from pests in an attempt to protect children from the harmful consequences of rodent bites and vectorborne diseases. Here, we consider the social injustice and economic inequality of episodes of child pesticide poisoning in the Western Cape from three disciplinary perspectives: public health, medical anthropology and fine art. We ultimately seek to demonstrate the complex relationship between the political economy of sanitation, waste removal and insecure housing, and the proliferation of rodents and other pests in urban townships. As a contribution to the medical humanities, the paper leans into different disciplines to highlight the toxic layering at play in a child pesticide poisoning event. The public health perspective focuses on the circulation of illegal street pesticides, the anthropologists focus on the experiences of the children and caregivers who are victims of poisoning, and the fine artist centres the rat within a broader environmental context. While non-toxic methods to eliminate rats and household pests are critical, longer term structural changes, through environmental and human rights activism, are necessary to ameliorate the suffering caused by poisoning. The medical and health humanities is well poised to highlight creative ways to draw public attention to these challenges, as well as to bridge the divide between science and the humanities through collaborative research efforts. With this paper we set the stage for discussing and balancing perspectives when addressing pest control in poor urban communities.
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Nesamari, R., T. A. Coutinho und J. Roux. „Investigations intoEncephalartosinsect pests and diseases in South Africa and identification ofPhytophthora cinnamomias a pathogen of the Modjadji cycad“. Plant Pathology 66, Nr. 4 (12.10.2016): 612–22. http://dx.doi.org/10.1111/ppa.12619.
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Gambiza. „Permaculture: Challenges and benefits in improving rural livelihoods in South Africa and Zimbabwe“. Sustainability 11, Nr. 8 (12.04.2019): 2219. http://dx.doi.org/10.3390/su11082219.
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Feeding a growing global population using conventional agricultural practices is leading toadverse environmental impacts. There is a call for alternative forms of agriculture that address social,economic, and environmental aspects of sustainability. Permaculture is a holistic design frameworkthat incorporates sustainable agricultural practices, potentially improving livelihoods. This studylooked at the challenges and benefits of permaculture in improving rural livelihoods in Zimbabweand South Africa. We used semi-structured interviews to collect data. Permaculture contributed over40% to total income for participants in both countries. However, permaculture was not the dominantsource of income and periodically straddled multiple livelihood strategies. The main benefits ofpermaculture were identified as improved human health, increased resilience to environmentalchanges, and reduction of input costs. The key challenges included high labour input, infestationof pests and diseases, and lack of knowledge on permaculture practices. Although permaculturepresents significant challenges, its integration with other forms of sustainable agricultural practicescan contribute to improved rural livelihoods.
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Kusse, Kutoya. „Major Root and Tuber Crops Production in South Omo Zone, Southern Ethiopia“. Current Agriculture Research Journal 9, Nr. 2 (31.08.2021): 74–82. http://dx.doi.org/10.12944/carj.9.2.02.
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Increasing production and productivity of agriculture in general and root and tuber crops in particular require a strong linkage between the agricultural and non-agricultural sectors. The growing in agriculture sector does not occur without non-agricultural sectors. The major root and tuber crops production and productivity in South Omo Zone, Southern Ethiopia is very low in relation to the land coverage under the crops, due to poor and under recommended rate of improved agricultural technology utilization and low skill of management and related practices by the producers. To solve these root and tuber related problems and increase the production and productivity of the crops, strong and result based farmers training centers and interlinked research extension system are important and strongly interconnected . This study was conducted in five districts of South Omo Zone namely Debub Ari from agricultural based, Malle and Bena-Tsemay from agro-pastoral, Hammer, and Dasenech from pastoral. The districts are selected purposively based on root and tuber crop production potential. The result shows that the area coverage, production and productivity of the major root and tuber crops decreases from time to time and their diseases and pests increases thoroughly. Farmers in the study area should use disease resistance varieties and the production inputs at a recommended rate and time. The major root and tuber crops that are grown in the study area are sweet potato (Ipomoea batatas), potato (Solanum tuberosum), cassava (Manihot esculenta), taro (Colocasia esculenta), and enset (Ensete ventricosum).
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Mansvelt, E. L., und E. Carstens. „Outbreak of Erwinia carotovora on Zantedischia spp. in South Africa“. Plant Disease 83, Nr. 10 (Oktober 1999): 966. http://dx.doi.org/10.1094/pdis.1999.83.10.966c.
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In South Africa, summer-flowering Arum lilies are grown for the tuber, potted plant, and cut flower markets. In 1998, an outbreak of soft rot was detected on Zantedischia oculata cv. Black Magic and Z. elliottiana plants from several nurseries. Crop losses of up to 25% were incurred. The initial symptom was wilting of leaves. When plants were lifted from the soil, soft rot of the tuber was found. Tuber rot usually developed on one side, and plants developing from affected tubers wilted and died. No discoloration of leaf or tuber tissues was found. Isolations from diseased tissues consistently yielded bacterial colonies that were translucent, white, and glistening and that had entire margins on nutrient agar. Ten representative isolates were chosen for further characterization. Erwinia carotovora subsp. carotovora strain B56 was included as a reference strain. All isolates were gram-negative rods, oxidase and arginine dihydrolase negative, catalase positive, and facultatively anaerobic. They degraded pectate and rotted potato slices but did not hydrolyze starch. All isolates fermented glucose, reduced nitrates to nitrites, and grew at a maximum temperature of 37°C. Isolates produced acids from D(+)-glucose, D(+)-cellobiose, melibiose, amygdalin, L(+)-arabinose, D-mannitol, L(+)-rhamnose, sucrose, ribose, D(-)xylose, and D(-)glucose but not from D-arabinose, D-sorbitol, or maltose. Isolates liquefied gelatin and used citrate, arbutine, esculin, salicin, and cellobiose as the sole carbon source. Pathogenicity to Zantedischia spp. was tested by injection of tubers with an inoculum suspension containing 108 CFU/ml. Control plants were inoculated with sterile distilled water. Inoculated plants were kept in a greenhouse at 24°C. Symptoms developed 2 days after inoculation with the pathogen and appeared to be identical to those observed on diseased material in nurseries. Control plants did not rot. The bacterium was readily reisolated from diseased plants, confirmed to be the inoculated pathogen, and identified as E. carotovora, based on morphological, biochemical, and physiological characteristics and pathogenicity. E. aroideae has been reported to cause soft rot of rhizomes of winter-flowering Arum lilies (Z. aethiopica) in South Africa (1). However, this is the first report of soft rot caused by E. carotovora subsp. carotovora on tubers of Z. oculata and Z. elliottiana plants in South Africa. Reference: (1) V. Wager. 1970. Flower Garden Diseases and Pests. Purnell, Cape Town, South Africa.
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Henzell, Robert P., Brian D. Cooke und Gregory J. Mutze. „The future biological control of pest populations of European rabbits, Oryctolagus cuniculus“. Wildlife Research 35, Nr. 7 (2008): 633. http://dx.doi.org/10.1071/wr06164.
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European rabbits are exotic pests in Australia, New Zealand, parts of South America and Europe, and on many islands. Their abundance, and the damage they cause, might be reduced by the release of naturally occurring or genetically modified organisms (GMOs) that act as biological control agents (BCAs). Some promising pathogens and parasites of European rabbits and other lagomorphs are discussed, with special reference to those absent from Australia as an example of the range of necessary considerations in any given case. The possibility of introducing these already-known BCAs into areas where rabbits are pests warrants further investigation. The most cost-effective method for finding potentially useful but as-yet undiscovered BCAs would be to maintain a global watch on new diseases and pathologies in domestic rabbits. The absence of wild European rabbits from climatically suitable parts of North and South America and southern Africa may indicate the presence there of useful BCAs, although other explanations for their absence are possible. Until the non-target risks of deploying disseminating GMOs to control rabbits have been satisfactorily minimised, efforts to introduce BCAs into exotic rabbit populations should focus on naturally occurring organisms. The development of safe disseminating GMOs remains an important long-term goal, with the possible use of homing endonuclease genes warranting further investigation.
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LIAO, JHIH-RONG, CHYI-CHEN HO und CHIUN-CHENG KO. „Predatory mites (Acari: Mesostigmata: Phytoseiidae) intercepted from samples imported to Taiwan, with description of a new species“. Zootaxa 4927, Nr. 3 (15.02.2021): 301–30. http://dx.doi.org/10.11646/zootaxa.4927.3.1.
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Global trade has increased the invasion risk of exotic organisms and damaged agricultural and natural ecosystems. The Bureau of Animal and Plant Health Inspection and Quarantine (BAPHIQ) handles quarantine services of animal- and plant-associated pests and diseases in Taiwan. The predatory mite family Phytoseiidae (Acari: Mesostigmata) is a well-known group due to the potential use of certain species as biocontrol agents for small phytophagous pests. Some species are available in commercial markets and frequently used in biological control in many agricultural systems, especially in greenhouse crops. However, exotic biological control agents may interfere with natural or naturalised populations of predatory mites and they may threaten indigenous populations via intraguild predation. The present study aims to provide a checklist of phytoseiid mite species found in plant quarantine from 2006–2013. Twenty-five species belonging to two subfamilies and eight genera were found in samples imported to Taiwan from twelve countries, including one new species Typhlodromus (Anthoseius) ueckermanni sp. nov. from South Africa. The checklist provides distribution, remarks, and also an identification key for all species.
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McLeod, A., und S. Coertze. „First Report of Phytophthora infestans on Petunia × hybrida in South Africa“. Plant Disease 90, Nr. 12 (Dezember 2006): 1550. http://dx.doi.org/10.1094/pd-90-1550b.
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Phytophthora infestans is known worldwide as the destructive, late blight pathogen of potatoes and tomatoes. However, erratic reports dating back to 1856 also have shown it to be pathogenic on petunia (Petunia × hybrida), although it has not been regarded as an important pathogen on this host (4). Recently, reports from North America showed that P. infestans is of commercial importance in greenhouse-grown petunias (2), and that late blight-infected petunias may serve as inoculum to tomatoes growing in the same greenhouse (1,2). In the Western Cape Province of South Africa, two petunia samples were received at the Stellenbosch University Plant Disease Clinic in 2005 that showed symptoms resembling P. infestans infections. The two samples were from nurseries where petunias were either grown under shading nets or in a greenhouse. In the greenhouse-grown petunias, the presumptive late blight infections resulted in substantial losses to the grower. Symptoms included gray, slightly sunken leaf lesions with white sporulation mainly on the adaxial side of the leaves. Leaflets of the petunias were incubated in moist chambers, and sporangia sporulating from lesions were identified morphologically as being P. infestans (3). Subsequently, one isolate was cultured onto synthetic media by carefully transferring sporangia from a lesion with the tip of a bended glass rod onto wheat medium (120 g/L of crushed wheat seeds, blended, boiled and filtered through cheesecloth, plus 15 g of sucrose and agar). The identity of the culture was further confirmed through sequence analyses of the internal transcribed spacer regions (GenBank Accession No. DQ479409). The isolated P. infestans strain (STE-U 6134) has been submitted to the Stellenbosch University culture collection. Inoculum for the pathogenicity tests was produced by first flooding 14-day-old cultures with sterile distilled water to obtain a 2 × 104/ml sporangial suspension, followed by zoospore induction at 4°C. A mixture of petunia cultivars (n = 24) were spray inoculated to runoff with the zoospore induced sporangial suspension. Control plants were sprayed with sterile distilled water. Inoculated plants were incubated at 22 to 25°C and high relative humidity (≥93%) within perspex humidity chambers (60 × 30 × 60 cm) lined with a wet sheet of chromatography paper. The experiment was repeated twice. The first late blight symptoms similar to those of the submitted samples appeared 5 to 7 days after inoculation, with some lesions containing profuse white mycelia and sporangiophores typical for P. infestans. The pathogen was reisolated from the leaf lesions, completing Koch's postulate. To our knowledge, this is the first report of P. infestans causing damage on petunias in South Africa. Future studies should be aimed at investigating whether late blight-infected petunias provide an important source of inoculum for potatoes and tomatoes, which are widely grown in the Western Cape Province of South Africa. References: (1) M. C. Becktell et al. Plant Dis. 89:1000, 2005. (2) K. L. Deahl and D. K. Farel. Plant Dis. 87:1004, 2003. (3) D. C. Erwin and O. K. Ribeiro, Phytophthora Diseases Worldwide. The American Phytopathological Society St. Paul, MN, 1996. (4) J. M. Hirst and W. C. Moore. Phytophthora infestans on petunia and datura. Page 76 in: Plant Pathology-A Record of Current Work on Plant Diseases and Pests. Vol. 6. Ministry of Agriculture, Fisheries and Food Plant Pathology Laboratory, Harpenden, England, 1957.
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KANTOR, Mihail, und Amnon LEVI. „Utilizing Genetic Resources and Precision Agriculture to Enhance Resistance to Biotic and Abiotic Stress in Watermelon“. Notulae Scientia Biologicae 10, Nr. 1 (27.03.2018): 1–7. http://dx.doi.org/10.15835/nsb10110242.
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Originally from Africa, watermelon is a staple crop in South Carolina and rich source of important phytochemicals that promote human health. As a result of many years of domestication and selection for desired fruit quality, modern watermelon cultivars are susceptible to biotic and abiotic stress. The present review discusses how genetic selection and breeding combined with geospatial technologies (precision agriculture) may help enhance watermelon varieties for resistance to biotic and abiotic stress. Gene loci identified and selected in undomesticated watermelon accessions are responsible for resistance to diseases, pests and abiotic stress. Vegetable breeding programs use traditional breeding methodologies and genomic tools to introduce gene loci conferring biotic or abiotic resistance into the genome background of elite watermelon cultivars. This continuous approach of collecting, evaluating and identifying useful genetic material is valuable for enhancing genetic diversity and tolerance and combined with precision agriculture could increase food security in the Southeast.
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Julia, Sibiya, Tongoona Pangirayi, Derera John, Mak Itai und a. „Smallholder farmers perceptions of maize diseases, pests, and other production constraints, their implications for maize breeding and evaluation of local maize cultivars in KwaZulu-Natal, South Africa“. African Journal of Agricultural Research 8, Nr. 17 (09.05.2013): 1790–98. http://dx.doi.org/10.5897/ajar12.1906.
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Carnegie, Angus J., und Geoff S. Pegg. „Lessons from the Incursion of Myrtle Rust in Australia“. Annual Review of Phytopathology 56, Nr. 1 (25.08.2018): 457–78. http://dx.doi.org/10.1146/annurev-phyto-080516-035256.
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Austropuccinia psidii (myrtle rust) is a globally invasive neotropical rust of the Myrtaceae that came into international prominence following extensive damage to exotic Eucalyptus plantations in Brazil in the 1970s and 1980s. In 2005, myrtle rust established in Hawaii (USA), and over the past 12 years has spread from the Americas into Asia, the Pacific, and South Africa. Myrtle rust was detected in Australia in 2010, and the response and ultimately unsuccessful eradication attempt was a lesson to those concerned about the threat of exotic pests and diseases to Australia's environment. Seven years following establishment, we are already observing the decline of many myrtaceous species and severe impacts to native plant communities. However, the recently developed Myrtle rust in Australia draft action plan identified that there is no nationally coordinated response strategy for the environmental dimensions of this threat. Recent reviews have identified a greater need for involvement from environmental agencies in biosecurity preparedness, response, and resourcing, and we believe this approach needs to extend to the management of invasive environmental pathogens once they establish.
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Yusuf, Shehu Folaranmi Gbolahan, Oluwabunmi Oluwaseun Popoola, Lindokhule Gwala und Thinandavha Nesengani. „Promoting University–Community Alliances in the Experiential Learning Activities of Agricultural Extension Postgraduate Students at the University of Fort Hare, South Africa“. Sustainability 13, Nr. 18 (18.09.2021): 10411. http://dx.doi.org/10.3390/su131810411.
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This study examines the university–community alliance with regard to experiential learning activities that may be used to enhance the competencies of agricultural extension postgraduate students (AEPS). Through research and alliance, university education provides agricultural extension students with ideal learning spaces to explore cause-related social, economic, and sustainability aspects of agriculture. The objectives of the study were for the AEPS to work on community farms for between six to eight weeks, to identify production challenges, and to attempt to solve problems using a participatory action research (PAR) approach. Students collected data daily, using parameters that included types of agro-enterprise, agricultural practices, observation and control of pests and diseases, identification, and control of weed infestation types, control of predators, and management of various security challenges. Social media were also used to share posts (pictures and videos) of the various project activities with the public for discussion and knowledge sharing. Findings show that there was an improved relationship between the students and their community collaborators. All participants mutually benefited from the programme; students gained indigenous farming knowledge from the farmers, while farmers benefited from the scientific approaches to solving common farming problems employed by the students—mostly improvised technologies with local content. Both the students and the farmers learned from the knowledge shared by various followers on Facebook, who gave suggestions to address some of the challenges posted on social media. The programme advocates the need to shift from a mostly rigid, conventional curriculum to a more dynamic, interactive one, which embraces active experimentation with theoretical knowledge. It underscores the significance of experiential learning for developing students’ technical competencies. The success of the programme could influence curriculum development and re-design to accommodate more experience-based modules.
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Hinojosa, Leonardo, Alex Leguizamo, Carlos Carpio, Diego Muñoz, Camilo Mestanza, José Ochoa, Carmen Castillo et al. „Quinoa in Ecuador: Recent Advances under Global Expansion“. Plants 10, Nr. 2 (04.02.2021): 298. http://dx.doi.org/10.3390/plants10020298.
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Quinoa is a highly diverse crop domesticated in the Andean region of South America with broad adaptation to a wide range of marginal environments. Quinoa has garnered interest worldwide due to its nutritional and health benefits. Over the last decade, quinoa production has expanded outside of the Andean region, prompting multiple studies investigating the potential for quinoa cultivation in novel environments. Currently, quinoa is grown in countries spanning five continents, including North America, Europe, Asia, Africa, and Oceania. Here, we update the advances of quinoa research in Ecuador across different topics, including (a) current quinoa production situation with a focus on breeding progress, (b) traditional seed production, and (c) the impact of the work of the nongovernment organization “European Committee for Training and Agriculture” with quinoa farmers in Chimborazo province. Additionally, we discuss genetic diversity, primary pests and diseases, actions for adapting quinoa to tropical areas, and recent innovations in quinoa processing in Ecuador. Finally, we report a case study describing a participatory breeding project between Washington State University and the Association of Andean Seed and Nutritional Food Producers Mushuk Yuyay in the province of Cañar.
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Mansour, Sameeh A. „Persistent organic pollutants (POPs) in Africa: Egyptian scenario“. Human & Experimental Toxicology 28, Nr. 9 (September 2009): 531–66. http://dx.doi.org/10.1177/0960327109347048.
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Persistent organic pollutants (POPs) are organic (carbon-based) compounds that include synthesized substances (pesticides and polychlorinated biphenyls [PCBs]) and other by-product substances generated as a result of human and natural activity (dioxins and furans). Extensive scientific studies have shown that POPs are some of the most dangerous pollutants released into the environment by humans. Great efforts have been made since the early 1960s to enhance chemical management and safety issues. Various conventions have been adopted for this purpose: the Stockholm Convention (SC) is one of the well-known meetings in this context. The SC on POPs (May 2001) focuses on reducing and eliminating releases of 12 POPs coined the ‘Dirty Dozen’ by the United Nations Environment Program (UNEP). Persistence of such chemicals in soils, air, and water, together with natural processes such as evaporation to the atmosphere and washout by rain and flood, give rise to their ubiquitous distribution in the environment and eventual penetration into food chains and bio-accumulation in humans. Public concern about contamination by POPs increased recently because several of these compounds are identified as hormone disruptors, which can alter normal function of endocrine and reproductive systems in humans and wildlife. African countries are using pesticides, such as dichlorodiphenyltrichloroethane (DDT), lindane, toxaphene, endrin, dieldrin, heptachlor, since more than 50 years for combating agricultural pests and controlling disease vectors, especially malaria. The way in which pesticides are used in Africa caused serious environmental and health problems much more than elsewhere. These problems are represented by accumulation of organochlorine pesticide (OCP) residues in different environmental samples and hosting of at least 50,000 tons of obsolete pesticides, as well as tens of thousands of tons of contaminated soil. Within the framework of the Africa Stockpiles Program (ASP), huge quantities of pesticidal POPs have been completely or partially destroyed in a number of African countries (e.g. Egypt, Namibia, Niger, Senegal, Seychelles, South Africa, Sudan, Tanzania, Uganda, Zambia). At regional level (i.e. African Countries), a strategic plan for monitoring and getting rid of POPs in the continent should be set up and implemented through coordination between all governments. Among issues of top priorities are to find alternative non-combustion technologies for disposing obsolete pesticides, and to use alternative control measures for mosquitoes’ management and other vector-borne diseases.
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Levi, Amnon, Judy Thies, Kai-shu Ling, Alvin M. Simmons, Chandrasekar Kousik und Richard Hassell. „Genetic diversity among Lagenaria siceraria accessions containing resistance to root-knot nematodes, whiteflies, ZYMV or powdery mildew“. Plant Genetic Resources 7, Nr. 03 (05.02.2009): 216–26. http://dx.doi.org/10.1017/s1479262109225354.
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In recent years, there has been an increased interest in Europe and in the USA in grafting watermelon onto bottle gourd,Lagenaria siceraria(Mol.) Standl. In this study, genetic diversity and relationships were examined [using 236 sequence-related amplified polymorphism markers] among 56 United States plant introductions (PIs) ofL. sicerariaand PIs of important cucurbit crops [includingCucurbita maximaDuchesne (winter squash),Cucurbita pepoL. (squash and pumpkin),Citrullusspp. (watermelon),Cucumis meloL. (melon) andCucumis sativusL. (cucumber)]. The analysis showed thatL. sicerariais distinct and has similar genetic distances to the cucurbit species examined herein. TheL. sicerariaPIs were assembled into two major clusters. One cluster includes groups of PIs collected mostly in South Asia (India) and a few PIs collected in the Mediterranean region and in Northeast Africa. The second cluster includes groups of PIs collected mainly in Southern Africa and in North, Central and South America, and PIs collected in China, Indonesia and Cyprus. AllL. sicerariaPIs in this study were susceptible to the southern root-knot nematode (RKN) [Meloidogyne incognita(Kofoid and White) Sandground]. However, several PIs, among them a group of closely related PIs collected in Mexico and Florida, were less infected with southern RKNs. AllL. sicerariaPIs were infested with whiteflies [Bemisia tabaci(Gennadius)], while several PIs were less infested than others and need further evaluation and selection for developing breeding lines that may be less appealing to this pest. Most of the PIs that showed resistance to zucchini yellow mosaic virus and tolerance to powdery mildew were collected in India and belong to the same phylogenetic groups (PGs). Experiments withL. sicerariaPIs representing different PGs showed similar grafting compatibility with watermelon. Findings from this study should be useful for the development of superiorL. sicerariarootstock lines with enhanced resistance to diseases and insect pests of cucurbit crops.
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Saccaggi, D. L., K. Krüger und G. Pietersen. „A multiplex PCR assay for the simultaneous identification of three mealybug species (Hemiptera: Pseudococcidae)“. Bulletin of Entomological Research 98, Nr. 1 (13.12.2007): 27–33. http://dx.doi.org/10.1017/s000748530700538x.
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AbstractMolecular species identification is becoming more wide-spread in diagnostics and ecological studies, particularly with regard to insects for which morphological identification is difficult or time-consuming. In this study, we describe the development and application of a single-step multiplex PCR for the identification of three mealybug species (Hemiptera: Pseudococcidae) associated with grapevine in South Africa: Planococcus ficus (vine mealybug), Planococcus citri (citrus mealybug) and Pseudococcus longispinus (longtailed mealybug). Mealybugs are pests on many commercial crops, including grapevine, in which they transmit viral diseases. Morphological identification of mealybug species is usually time-consuming, requires a high level of taxonomic expertise and usually only adult females can be identified. The single-step multiplex PCR developed here, based on the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene, is rapid, reliable, sensitive, accurate and simple. The entire identification protocol (including DNA extraction, PCR and electrophoresis) can be completed in approximately four hours. Successful DNA extraction from laboratory and unparasitized field-collected individuals stored in absolute ethanol was 97%. Specimens from which DNA could be extracted were always correctly identified (100% accuracy). The technique developed is simple enough to be implemented in any molecular laboratory. The principles described here can be extended to any organism for which rapid, reliable identification is needed.
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Kishlyan, N. V., V. D. Bemova, T. V. Matveeva und V. A. Gavrilova. „Biological peculiarities and cultivation of groundnut (a review)“. Proceedings on applied botany, genetics and breeding 181, Nr. 1 (12.04.2020): 119–27. http://dx.doi.org/10.30901/2227-8834-2020-1-119-127.
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Peanut is one of the most important crops in the Fabaceae Lindl. (Leguminosae L.) family. South America is considered to be the homeland of peanut, but now this crop is cultivated in America, Africa, Australia, Europe and Asia. The modern phylogenetic system of the genus Arachis L. includes 79 wild species and one cultivated species of common peanut (A. hypogaea L.). Diploid species contain 2n = 20 chromosomes of the A, B or D genome, tetraploids have A and B genomes. The А and В genomes are sequenced. Special biological features of all peanut varieties are the presence of chasmogamous and cleistogamous flowers and the development of pods only underground (geocarpy). Along with high requirements for improving the quality of oil and food products, much attention is paid to their safety: resistance to aflatoxin contamination and mitigation of allergenicity. Peanut cultivars vary in plant habit, shape and color of pods and seeds. Their growing season in Africa, Latin America and Asia is from 160 to 200 days, so early-ripening forms need to be selected for the south of the Russian Federation. Breeders from the Pustovoit Institute of Oil Crops (VNIIMK) have developed peanut cultivars with a yield of 2.0–3.3 t/ha and growing season duration of 115–120 days, adaptable to the environments of Krasnodar Territory. At present, there is no large-scale peanut production in Russia, nor any breeding efforts are underway. As for the world, along with conventional breeding practices (individual selection, intra- and interspecies crosses, etc.), peanut is widely involved in genomic studies. A number of cultivars highly resistant to pests, diseases and drought have been released. Over 15,000 peanut accessions are preserved in the world’s gene banks, including 1823 accessions in the collection of the Vavilov Institute (VIR). Utilization of the worldwide genetic resources of peanut and use of modern research technologies will contribute to the revival of peanut cultivation in Russia.
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Pahlevi, Omar, und Muhamad Kusumo Atmojo. „Application of Expert System for Diagnosing Diseases Cocoa Plants Using the Forward Chaining Algorithm Method“. SinkrOn 4, Nr. 2 (09.03.2020): 10. http://dx.doi.org/10.33395/sinkron.v4i2.10481.
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Cacao plants originated from South America, then spread to North America, Africa and Asia. In Indonesia, cocoa has been known since 1560, but has become an important commodity since 1951. Cacao commodity plays an important role in the national economy and is a national mainstay commodity. This shows that cocoa is one of the results of plantation commodities that have a high economic value and play an important role as a source of foreign exchange through exports, as well as encouraging the regional economy, especially in rural areas. But behind the high value of cocoa production, there are problems faced, including the low quality of cocoa in Indonesia because cocoa plantations in Indonesia are threatened by pests and plant diseases. Lack of information that is known by the plantation and cocoa farmers about the types of diseases that attack cocoa plants, causing many cocoa plants that are not handled properly. If this is allowed to continue it will impact on the declining quality and production of cocoa plants. Current advances in information technology, especially cellular phones, can be used as a means to improve public services, one of the results of the development of cellular technology is the birth of cellular phones with the android operating system. In this research produced if the symptoms data entered could not find the type of cocoa plant disease because the input data did not match any disease data in the database, the system would display the word "Can not find the disease you are looking for because it is not related to fruit rot disease, stem cancer, vascular antraknosem, streak dieback, upas fungus and root fungus ". From the data of symptoms, diseases and relations above, the algorithm is depicted using a decision tree. Decision tree is a picture of tracking symptoms, determining the disease and concluding results in the form of a solution. In this application, using the Forward Chaining method so that tracking begins with the selection of symptoms experienced then the results of the diagnosis in the form of cocoa plant diseases.
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Moradi, Parviz, Farhad Aghajanloo, Ahmad Moosavi, Hossein Hosseini Monfared, Jafar Khalafi, Mehdi Taghiloo, Tooraj Khoshzaman, Mohammad Shojaee und Andrea Mastinu. „Anthropic Effects on the Biodiversity of the Habitats of Ferula gummosa“. Sustainability 13, Nr. 14 (14.07.2021): 7874. http://dx.doi.org/10.3390/su13147874.
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The uncontrolled exploitation of soil and plants by people has generated important ecological imbalances all over the world. This manuscript focuses its attention on the ecosystem of Ferula gummosa (FG). FG belongs to the Apiaceae family and has a vast distribution from central Asia to South Africa, as well as northwest Iran, including the Zanjan Province. This plant has diverse applications across industrial, forage and medicinal fields. To investigate the effective factors on the FG distribution, four main natural habitats were selected based on field visits and a literature review. Then, environmental factors, such as climate features, topography conditions, and soil characteristics, were collected and analysed. According to the results, the slope is mainly north-northeast with a slope of 55 to 70 degrees, and an elevation range above 2200 m is suitable for the growth of FG in the Zanjan Province. The main companion plants were Silene bupleuroides L. and Thymus kotschyanus. The results show that in the habitats where FG grew, the soil was mostly shallow, sometimes semi-deep and consisting mainly of loam, loamy sand, loamy clay and mostly clay loam with very low salinity (less than 0.7 dS/m), and was in the neutral range of soil acidity (6.9 to 7.33). Soil organic carbon was relatively high, but the amount of nutrients, such as phosphorus and potassium, was less than optimal in these soils. Next, using a Geographic Information System (GIS), maps of homogeneous areas for possible FG establishment across the province were created. In conclusion, the main factors affecting the FG distribution in the Zanjan Province were land use conversion, harvesting fodder and grazing livestock, improper exploitation of rangelands, pests and diseases of Ferula gummosa in the region. The ecological data collected on FG may be useful to understand how human action can affect the existence and extinction of many plant species.
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Li, J., V. L. Gaskins, H. J. Yan, Y. G. Luo und W. M. Jurick II. „First Report of Mucor Rot on Stored ‘Gala’ Apple Fruit Caused by Mucor piriformis in Pennsylvania“. Plant Disease 98, Nr. 8 (August 2014): 1157. http://dx.doi.org/10.1094/pdis-02-14-0149-pdn.
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Mucor piriformis E. Fischer causes Mucor rot of pome and stone fruits during storage and has been reported in Australia, Canada, Germany, Northern Ireland, South Africa, and portions of the United States (1,2). Currently, there is no fungicide in the United States labeled to control this wound pathogen on apple. Cultural practices of orchard sanitation, placing dry fruit in storage, and chlorine treatment of dump tanks and flumes are critical for decay management (3,4). Cultivars like ‘Gala’ that are prone to cracking are particularly vulnerable as the openings provide ingress for the fungus. Mucor rot was observed in February 2013 at a commercial packing facility in Pennsylvania. Decay incidence was ~15% on ‘Gala’ apples from bins removed directly from controlled atmosphere storage. Rot was evident mainly at the stem end and was light brown, watery, soft, and covered with fuzzy mycelia. Salt-and-pepper colored sporangiophores bearing terminal sporangiospores protruded through the skin. Five infected apple fruit were collected, placed in an 80-count apple box on trays, and temporarily stored at 4°C. Isolates were obtained aseptically from decayed tissue, placed on potato dextrose agar (PDA) petri plates, and incubated at 25°C with natural light. Five single sporangiospore isolates were identified as Mucor piriformis based on cultural characteristics according to Michailides and Spotts (1). The isolates produced columellate sporangia attached terminally on short and tall, branched and unbranched sporangiophores. Sporangiospores were ellipsoidal, subspherical, and smooth. Chlamydospore-like resting structures (gemmae), isogametangia, and zygospores were not evident in culture. Mycelial growth was examined on PDA, apple agar (AA), and V8 agar (V8) at 25°C with natural light. Isolates grew best on PDA at rates that ranged from 38.4 ± 5.3 to 34.5 ± 2.41 mm/day, followed by AA from 30.5 ± 1.22 to 28.5 ± 2.51 mm/day, and V8 from 29.2 ± 3.0 to 26.7 ± 2.17 mm/day. Species-level identification was conducted by isolating genomic DNA, amplifying a portion of the 28S rDNA gene, and directly sequencing the products. MegaBLAST analysis of the 2X consensus sequences revealed that all five isolates were 99% identical to M. piriformis (GenBank Accession No. JN2064761) with E values of 0.0, which confirms the morphological identification. Koch's postulates were conducted using organic ‘Gala’ apples that were surface sanitized with soap and water, then sprayed with 70% ethanol and allowed to air dry. Wounds 3 mm deep were created using the point of a finishing nail and then inoculated with 50 μl of a sporangiospore suspension (1 × 105 sporangiospores/ml) for each isolate. Ten fruit were inoculated with each isolate, and the experiment was repeated. The fruit were stored at 25°C in 80-count boxes on paper trays for 14 days. Decay observed on inoculated ‘Gala’ fruit was similar to symptoms originally observed on ‘Gala’ apples from storage and the pathogen was re-isolated from inoculated fruit. This is the first report of M. piriformis causing postharvest decay on stored apples in Pennsylvania and reinforces the need for the development of additional tools to manage this economically important pathogen. References: (1) T. J. Michailides, and R. A. Spotts. Plant Dis. 74:537, 1990. (2) P. L. Sholberg and T. J. Michailides. Plant Dis. 81:550, 1997. (3) W. L. Smith et al. Phytopathology 69:865, 1979. (4) R. A. Spotts. Compendium of Apple and Pear Diseases and Pests: Second Edition. APS Press, St. Paul, MN, 2014.
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Mogo, A., J. Fomekong Nopogwo, E. L. Ngonkeu Mangaptche, R. Ghogomu Tamouh, E. Temgoua, Fotso ., Noé Woin et al. „Field Evaluation of Some Cassava Cultivars against the African Cassava Mosaic Disease in the Humid Forests of Cameroon“. Annual Research & Review in Biology, 15.02.2019, 1–8. http://dx.doi.org/10.9734/arrb/2018/v30i330015.
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There is a considerable deficit in the annual production of cassava in Cameroon of about 31 million tons, and this has been mainly due to constraints related to pest attacks and most especially diseases like the African Cassava Mosaic Disease (ACMD). This study was therefore undertaken on three sites in the locality of Bityili (South Region of Cameroon), to determine amongst improved and local cassava cultivars those that provide resistance to the development of the ACMD. The severity and incidence of this disease was evaluated and its impact on cassava yield. In each site, cassava was grown in a randomized complete block design. The local cultivars (Ekobele and Ngon kribi) showed higher severity (76-100%) and incidence of ACMD compared to the improved cultivars (TMS 92/0326 and TMS 96/1414) of 0-25% and 0-10%, respectively. Strong inverse correlations were observed between ACMD severity and yield performance, measured in terms of number of tubers/plant and weight of fresh tubers. The improved cultivars, TMS 92/0326 and TMS 96/1414, could, therefore, be recommended for large-scale planting in a bid to promote cassava production in the South Region of Cameroon.
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Mrisho, Latifa M., Neema A. Mbilinyi, Mathias Ndalahwa, Amanda M. Ramcharan, Annalyse K. Kehs, Peter C. McCloskey, Harun Murithi, David P. Hughes und James P. Legg. „Accuracy of a Smartphone-Based Object Detection Model, PlantVillage Nuru, in Identifying the Foliar Symptoms of the Viral Diseases of Cassava–CMD and CBSD“. Frontiers in Plant Science 11 (18.12.2020). http://dx.doi.org/10.3389/fpls.2020.590889.
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Nuru is a deep learning object detection model for diagnosing plant diseases and pests developed as a public good by PlantVillage (Penn State University), FAO, IITA, CIMMYT, and others. It provides a simple, inexpensive and robust means of conducting in-field diagnosis without requiring an internet connection. Diagnostic tools that do not require the internet are critical for rural settings, especially in Africa where internet penetration is very low. An investigation was conducted in East Africa to evaluate the effectiveness of Nuru as a diagnostic tool by comparing the ability of Nuru, cassava experts (researchers trained on cassava pests and diseases), agricultural extension officers and farmers to correctly identify symptoms of cassava mosaic disease (CMD), cassava brown streak disease (CBSD) and the damage caused by cassava green mites (CGM). The diagnosis capability of Nuru and that of the assessed individuals was determined by inspecting cassava plants and by using the cassava symptom recognition assessment tool (CaSRAT) to score images of cassava leaves, based on the symptoms present. Nuru could diagnose symptoms of cassava diseases at a higher accuracy (65% in 2020) than the agricultural extension agents (40–58%) and farmers (18–31%). Nuru’s accuracy in diagnosing cassava disease and pest symptoms, in the field, was enhanced significantly by increasing the number of leaves assessed to six leaves per plant (74–88%). Two weeks of Nuru practical use provided a slight increase in the diagnostic skill of extension workers, suggesting that a longer duration of field experience with Nuru might result in significant improvements. Overall, these findings suggest that Nuru can be an effective tool for in-field diagnosis of cassava diseases and has the potential to be a quick and cost-effective means of disseminating knowledge from researchers to agricultural extension agents and farmers, particularly on the identification of disease symptoms and their management practices.
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Macfadyen, Sarina, Wee Tek Tay, Andrew D. Hulthen, Cate Paull, Andrew Kalyebi, Frances Jacomb, Hazel Parry et al. „Landscape factors and how they influence whitefly pests in cassava fields across East Africa“. Landscape Ecology, 15.10.2020. http://dx.doi.org/10.1007/s10980-020-01099-1.
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Abstract Context African production landscapes are diverse, with multiple cassava cultivars grown in small patches amongst a diversity of other crops. Studies on how diverse smallholder landscapes impact herbivore pest outbreak risk have not been carried out in sub-Saharan Africa. Objectives Bemisia tabaci is a cryptic pest species complex that cause damage to cassava through feeding and vectoring plant-virus diseases and are known to reach very high densities in certain contexts. However, the factors driving this phenomenon are unclear. Methods Bemisia density data in cassava across a large number of sites representing a geographic gradient across Uganda, Tanzania and Malawi were collected. We tested whether in-field or landscape factors associated with land-use patterns underpinned Bemisia density variability and parasitism. Results We found the B. tabaci SSA1 species dominated our study sites, although other species were also common in some cassava fields. Factors associated with the surrounding landscape were unimportant for explaining variability in adult density, but the in-field variables of cassava age and cultivar were very important. The density of nymphs and the parasitism of nymphs was heavily influenced by a diversity of landscape factors surrounding the field, including the size of focal cassava field, and area of cassava in the landscape. However, unlike the trend from many other studies on drivers of natural enemy populations, this pattern was not solely related to the amount of non-crop vegetation, or the diversity of crops grown in the landscape. Conclusions Our findings provide management options to reduce whitefly abundance, including describing the characteristics of landscapes with high parasitism. The choice of cassava cultivar by the farmer is critical to reduce whitefly outbreak risk at the landscape-scale.
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Osorio, J. Alexander, Casparus J. Crous, Michael J. Wingfield, Z. Wilhelm de Beer und Jolanda Roux. „An assessment of mangrove diseases and pests in South Africa“. Forestry, 18.01.2017. http://dx.doi.org/10.1093/forestry/cpw063.
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Uke, Ayaka, Hiroki Tokunaga, Yoshinori Utsumi, Nguyen Anh Vu, Pham Thi Nhan, Pao Srean, Nguyen Huu Hy et al. „Cassava mosaic disease and its management in Southeast Asia“. Plant Molecular Biology, 09.07.2021. http://dx.doi.org/10.1007/s11103-021-01168-2.
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Abstract Key message Status of the current outbreak of cassava mosaic disease (CMD) in Southeast Asia was reviewed. Healthy cassava seed production and dissemination systems have been established in Vietnam and Cambodia, along with integrated disease and pest management systems, to combat the outbreak. Abstract Cassava (Manihot esculenta Crantz) is one of the most important edible crops in tropical and subtropical regions. Recently, invasive insect pests and diseases have resulted in serious losses to cassava in Southeast Asia. In this review we discuss the current outbreak of cassava mosaic disease (CMD) caused by the Sri Lankan cassava mosaic virus (SLCMV) in Southeast Asia, and summarize similarities between SLCMV and other cassava mosaic begomoviruses. A SATREPS (Science and Technology Research Partnership for Sustainable Development) project “Development and dissemination of sustainable production systems based on invasive pest management of cassava in Vietnam, Cambodia and Thailand”, was launched in 2016, which has been funded by The Japan International Cooperation Agency (JICA) and The Japan Science and Technology Agency (JST), Japan. The objectives of SATREPS were to establish healthy seed production and dissemination systems for cassava in south Vietnam and Cambodia, and to develop management systems for plant diseases and insect pests of cassava. To achieve these goals, model systems of healthy seed production in Vietnam and Cambodia have been developed incorporating CMD-resistant planting materials through international networks with The International Center for Tropical Agriculture (CIAT) and The International Institute of Tropical Agriculture (IITA).
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Tize, Isaac, Apollin Kuate Fotso, Elias Nchiwan Nukenine, Cargele Masso, Francis Ajebesone Ngome, Christopher Suh, Venasius Wirnkar Lendzemo et al. „New cassava germplasm for food and nutritional security in Central Africa“. Scientific Reports 11, Nr. 1 (01.04.2021). http://dx.doi.org/10.1038/s41598-021-86958-w.
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AbstractCassava is a key food security crop in Central Africa, but its production depends largely on the use of local farmers’ varieties characterized by inherently low yield which is compounded by generally high susceptibility to various growth and yield-limiting pests and diseases. Improved cassava genotypes have demonstrated the potential to substantially improve cassava’s contribution to food security and the development of the cassava industry and the improvement of nutrition status elsewhere in Western Africa. Eleven improved cassava genotypes were compared with a local landrace (LMR) used as a check under field conditions over two years in eight locations, grouped in four agro-ecologies in Cameroon. Pest and disease abundance/incidence and damage severity were evaluated. At harvest, root yield and carotenoid content were measured. Best linear unbiased predictors showed the lowest breeding value for LMR with the cassava mosaic virus disease (+ 66.40 ± 2.42) compared with 1.00 ± 0.02% for the most susceptible improved genotype. Two genotypes (I010040-27 and I011797) stood out for having higher predicted fresh root yield means which were at least 16 times greater compared with LMR. Predicted total carotenoid content was the highest (+ 5.04 ± 0.17) for improved genotype I070593 compared with LMR which showed the lowest (− 3.90 ± 0.06%) and could contribute to the alleviation of vitamin A deficiency from cassava-based food systems. Diffusion of high-yielding and nutritious genotypes could alleviate food and nutritional security in Central Africa.
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Narmilan, A., und S. Puvanitha. „The Effect of Different Planting Methods on Growth and Yield of Selected of Cassava (Manihot esculenta) Cultivars“. Agricultural Science Digest - A Research Journal, OF (27.08.2020). http://dx.doi.org/10.18805/ag.d-272.
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Background: Cassava (Manihot esculenta Crantz) is a source of carbohydrate among the population after maize and rice and highly contributes to food security and livelihood to majority of small scale farmers in Sri Lanka as well as in African continent. The production of these starchy plants is declining due to the problem of low yield, high labor cost, pest and diseases damage and shortage of land. However among the yield limiting factors of cassava, the planting method of stem cuttings which depend on plant cultivar and environmental conditions. Therefore, the present study was carried out to reveal information on the effect of planting methods on the growth and yield attributes of cassava. Methods: The field experiment was conducted at the Farmer’s field in the Batticaloa and laboratory experiment was led in South Eastern University of Sri Lanka which is located in Sri Lanka. The field trail was carried out over a period of four months during from May to September in 2018. The treatments used were three planting positions (Angled, vertical and horizontal) and two cultivars (“cv. Local” and “cv Kirikawadi”) were combined in factorial arrangement and laid out in randomized complete block design with three replications. Result: The result revealed that root yield was significantly (P d” 0.05) affected by the interaction effects of the planting position and varieties. Significant differences were observed among planting methods in all tested variables. Based on the study, storage roots yield of cassava could be enhanced by planting method of angled position.
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Makhado, Rudzani A., und Amani T. Saidi. „Disaster risk assessment at Roburnia Plantation, Mpumalanga, South Africa“. Jàmbá: Journal of Disaster Risk Studies 5, Nr. 1 (12.03.2013). http://dx.doi.org/10.4102/jamba.v5i1.64.
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This study reports about disaster risk assessment undertaken at Roburnia Plantation, Mpumalanga Province, South Africa. Both quantitative and qualitative approaches were followed to collect data. A total of eight experienced foresters and fire fighters were purposively sampled for interview at Roburnia Plantation. A questionnaire survey was also used to collect the data. Risk levels were quantified using the risks equations of Wisner et al. (2004) and the United Nations International Strategy for Disaster Reduction (UNISDR 2002). Data were analysed using descriptive and inferential statistics. Analysis of variance (ANOVA, single factor) was also applied. This study found that Roburnia Plantation is highly exposed to fire risks. The mean (± s.d.) output from the Wisner risk equation shows that fire is the highest risk at 7.7 ± 0.3, followed by harsh weather conditions at 5.6 ± 0.4 and least by tree diseases, pests and pathogens at 2.3 ± 0.2. Similarly, the mean (± s.d.) output from the UNISDR risk equation also shows that fire is the highest risk at 2.9 ± 0.2, followed by harsh weather conditions at 2.2 ± 0.3 and least by tree diseases, pests and pathogens at 1.3 ± 0.2. There was no significant deference in the risk analysis outputs (p = 0.13). This study also found that the number of fire incidents were low during summer, but increased during winter and spring. This variation is mainly due to a converse relationship with rainfall, because the availability of rain moistens the area as well as the fuel. When the area and fuel is moist, fire incidents are reduced, but they increase with a decrease in fuel moisture.
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Rey, Chrissie. „The hunt for plant viruses in South Africa: The early days“. South African Journal of Science 116, Nr. 11/12 (26.11.2020). http://dx.doi.org/10.17159/sajs.2020/7916.
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Plant viruses cause widespread disease in agriculturally important crops, resulting in a reduction in both quality and quantity of produce. The introduction of intensive crop monoculture has resulted in an exponential increase in viral diseases which can cross over from wild indigenous plants. Viral pathogens also can occur in mixed infections, and rapid, sensitive and reliable diagnostic methods are required to identify and characterise the viruses responsible for the field diseases. In comparison to bacterial and fungal diseases, viral diseases are more difficult to diagnose. This review covers a period (1985–2011) in the history of virus discovery in South Africa during which several plant viruses from commercial and smallscale farms were identified and characterised. Interestingly, novel viruses were discovered in three crops, namely guar and cassava grown by small-scale farmers in Mpumalanga, and in commercial tobacco. The implication of these plant diseases is potential yield loss to farmers which can affect their livelihoods, and result in severe economic loss for the food and agriculture industries. Accurate identification of the causal viral agents of these viral diseases is a prerequisite for development of effective management strategies.
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Healey, Adam L., Mervyn Shepherd, Graham J. King, Jakob B. Butler, Jules S. Freeman, David J. Lee, Brad M. Potts et al. „Pests, diseases, and aridity have shaped the genome of Corymbia citriodora“. Communications Biology 4, Nr. 1 (10.05.2021). http://dx.doi.org/10.1038/s42003-021-02009-0.
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AbstractCorymbia citriodora is a member of the predominantly Southern Hemisphere Myrtaceae family, which includes the eucalypts (Eucalyptus, Corymbia and Angophora; ~800 species). Corymbia is grown for timber, pulp and paper, and essential oils in Australia, South Africa, Asia, and Brazil, maintaining a high-growth rate under marginal conditions due to drought, poor-quality soil, and biotic stresses. To dissect the genetic basis of these desirable traits, we sequenced and assembled the 408 Mb genome of Corymbia citriodora, anchored into eleven chromosomes. Comparative analysis with Eucalyptus grandis reveals high synteny, although the two diverged approximately 60 million years ago and have different genome sizes (408 vs 641 Mb), with few large intra-chromosomal rearrangements. C. citriodora shares an ancient whole-genome duplication event with E. grandis but has undergone tandem gene family expansions related to terpene biosynthesis, innate pathogen resistance, and leaf wax formation, enabling their successful adaptation to biotic/abiotic stresses and arid conditions of the Australian continent.
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Beukes, Ilze, Lindy J. Rose, Gordon S. Shephard, C. Flett Flett und Altus Viljoen. „Mycotoxigenic Fusarium species associated with grain crops in South Africa – A review“. South African Journal of Science Volume 113, Number 3/4 (29.03.2017). http://dx.doi.org/10.17159/sajs.2017/20160121.
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Abstract Cereal grains include some of the most important crops grown in South Africa and play a major role in the local economy. Maize, wheat and sorghum are extensively consumed by humans and farm animals, and are also utilised in industrial processes. Grain crops that are grown commercially contribute up to 33% of the country’s total gross agricultural production, whereas subsistence farmers grow grains mainly to sustain their families. In rural communities an average intake of maize grain of more than 300 g dry weight per person per day is not uncommon. The production of grains is often constrained by pests and diseases that may reduce their yields and quality. In South Africa, 33 mycotoxin-producing Fusarium species have been associated with grain crops. Mycotoxins, such as fumonisins and deoxynivalenol, have been found in levels exceeding the maximum levels imposed by the US Food and Drug Administration and the European Union and therefore pose a serious public health concern. We provide an extensive overview of mycotoxigenic Fusarium species associated with grain crops in South Africa, with particular reference to maize, wheat and sorghum.
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Nhemachena, Charity R., und Johann Kirsten. „A historical assessment of sources and uses of wheat varietal innovations in South Africa“. South African Journal of Science Volume 113, Number 3/4 (29.03.2017). http://dx.doi.org/10.17159/sajs.2017/20160008.
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Abstract We undertook a historical review of wheat varietal improvements in South Africa from 1891 to 2013, thus extending the period of previous analyses. We identified popular wheat varieties, particularly those that form the basis for varietal improvements, and attempted to understand how policy changes in the wheat sector have affected wheat varietal improvements in the country over time. The empirical analysis is based on the critical review of information from policies, the varieties bred and their breeders, the years in which those varieties were bred, and pedigree information gathered from the journal Farming in South Africa, sourced mainly from the National Library of South Africa and the International Maize and Wheat Improvement Center (CIMMYT) database. A database of the sources and uses of wheat varietal innovations in South Africa was developed using information from the above sources. The data, analysed using trend and graphical analysis, indicate that, from the 1800s, wheat varietal improvements in the country focused on adaptability to the production area, yield potential and stability and agronomic characteristics (e.g. tolerance to diseases, pests and aluminium toxicity). An analysis of the sources of wheat varietal improvements during the different periods indicates that wheat breeding was driven initially by individual breeders and agricultural colleges. The current main sources of wheat varietal improvements in South Africa are Sensako, the Agricultural Research Council’s Small Grain Institute (ARC–SGI) and Pannar. The structural changes in the agricultural sector, particularly the establishment of the ARC–SGI and the deregulation of the wheat sector, have helped to harness the previously fragmented efforts in terms of wheat breeding. The most popular varieties identified for further analysis of cost attribution and the benefits of wheat varietal improvements were Gariep, Elands and Duzi.
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Chimonyo, V. G. P., C. S. Mutengwa, C. Chiduza und L. N. Tandzi. „Characteristics of maize growing farmers, varietal use and constraints to increase productivity in selected villages in the Eastern Cape province of South Africa“. South African Journal of Agricultural Extension (SAJAE) 48, Nr. 2 (2020). http://dx.doi.org/10.17159/2413-3221/2020/v48n2a538.
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ABSTRACT The need to increase self-sufficiency of rural agricultural systems has been a centre of focus for many extension programs aimed at rural development and improved livelihoods. Numerous biotic, abiotic and socio-economic factors affect maize production for resource poor farmers in the Eastern Cape (EC), which is one of the poorest Provinces in South Africa. Focus group discussions and semi-structured questionnaires were used to identify farmer characteristics, and specific production constraints influencing maize productivity in Jixini and Mkhwezo villages, of O. R. Tambo District in the EC Province. Elderly farmers who are above 56 years dominated the studied farming communities. The predominant varieties used were local landraces (53%) followed by hybrids (31%) and improved open pollinated varieties (OPVs) (11%). Farmers preferred local landraces as they were considered more palatable. Unmarried farmers were the least productive farmer group due to shortages of labour, use of landrace varieties and inadequate fertilizer. The main production constraints faced by farmers, were too much rain, pests and diseases infestation, drought stress due to climate change, and lack of fencing of the out-fields. Increasing the involvement of youths in agricultural activities could improve maize productivity. Maize breeding programs should solicit information on farmer-preferred traits and incorporate them into the improved varieties to enhance their desirability and adoption. Targeting of varieties should be guided by the most common constraints affecting maize productivity in a specific location rather than issuing blanket recommendations. Additionally, agricultural extension programs could improve their service delivery by having good knowledge of target-farmer traits, their farming practices and prevailing constraints. Information in this manuscript can go a long way in improving extension service delivery in the EC Province of the country. Keywords: Maize; Focus Group Discussions; Socio-Economic; Rural Livelihood, Agricultural extension
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Sibomana, Milindi S., und Carel N. Bezuidenhout. „Statistical evaluations of sugarcane quality, deterioration and the impacts of weekend logistics in a commercial sugarcane supply chain“. Sugar Industry, 2013, 30–35. http://dx.doi.org/10.36961/si13789.
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Crop quality can be used for monitoring the supply chain in agro-industries, although, sugarcane quality also varies naturally and is affected by climate, nutrition, pests and diseases, cane variety and water availability. Harvest-to-crush logistics affect sugarcane quality and present a significant impact on milling efficiency. This research studied commercial sugarcane quality parameters over six years at a large commercial sugar mill in South Africa. f (sucrose content expressed as a percentage of fiber content) was derived as a new parameter that consistently flagged poor quality deliveries during the early part of the week. This is a strong indicator of increased cane deterioration over weekends as a result of logistics inefficiencies. Shewhart quality control charts (X– charts) and a non-parametric statistic confirmed significantly inferior cane qualities after weekends. Statistical techniques were also able, with 95% significance, to identify growers with systemic deterioration of delivered cane. A large number of growers who were exposed to weekend logistics problems were also experiencing significant systemic deterioration problems. These results may enable the generation of a grower performance index that will allow stakeholders to improve operations. The study shows that, although notorious for its variability, commercial cane quality data can be used to drive efficiency improvements in the supply chain, if used appropriately.
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Ali, Shawkat, Pervaiz Abbasi, Sajid Rehman und Walid Ellouze. „First Report of Moldy Core of Sweet Tango Apples from New Zealand Caused by Alternaria arborescens“. Plant Disease, 24.03.2021. http://dx.doi.org/10.1094/pdis-01-21-0025-pdn.
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Moldy core is a fungal disease of apple fruits that is characterized by mycelial growth in the seed locules and is sometimes accompanied by penetration of the immediate surrounding flesh. The disease can go undetected until the fruit is cut open, as no external symptoms appear on the fruit. Alternaria, Aspergillus, Cladosporium, Coniothyrium, Epicoccum, Phoma and Stemphylium are some of the common pathogens associated with moldy core (Serdani et al. 2002; Gao et al. 2013; McLeod 2014). The disease is more common in apple cultivars with an open calyx, where spores may initiate infections during the growing season or at the post-harvest storage stage (Spotts et al. 1988). In 2018, a shipment of ‘Sweet Tango’ apples from New Zealand to Scotian Gold Co-operative Ltd., Nova Scotia, Canada, was found to be affected by moldy core. Moderate to severe moldy core symptoms were observed when 10 apples were cut open (Figure S1). In comparison, ‘Sweet Tango’ apples grown in Nova Scotia showed no moldy core symptoms when 10 random fruits were cut open. Small pieces of the diseased fruit tissue from the core region were surface-disinfected for 1 min in 1% NaOCl, rinsed three times with sterilized water and placed onto potato dextrose agar (PDA) dishes. The PDA dishes were incubated in dark at 22 oC and single spore isolation was carried out to fresh PDA dishes. These isolate produced colonies of regular shape, tan black with prominent white gray margin and gray colour conidia (Figure S2 AB). The colonies turn dark black after 3 weeks of growth on PDA. Mycelia were septate and conidia were oval or obclavate or club-shaped with a tapering end with 4-6 longitudinal and transverse septa (Figure S2 C-D). The size of conidia ranges from 12.5-20 x 8.7-12.5 µM on 20 days old PDA dishes. Based on the size and shape of conidia and other morphological characteristics the isolated fungi were identical to Alternaria spp. (Simmons 2007). To assess the identity of the isolated pathogen species by multi-locus sequence analysis, genomic DNA was extracted from the pure cultures of two isolates (5.8 and 8) using the E.Z.N.A. SP Fungal DNA Kit (Omega Bio-Tek). The glyceraldehyde-3-phosphate dehydrogenase (GAPDH), major allergen (Alt a 1), OPA10-2, the internal transcribed spacer (ITS) region of ribosomal DNA and the translation elongation factor 1-α (TEF1-α) region from two Alternaria spp. isolates (5.8 and 8) were amplified and sequenced using primers gpd1/2 (Berbee et al. 1999), A21F/A21R (Gabriel 2015), OPA10-2/ OPA10-2L (Andrew et al. 2009), ITS1/ITS4 (White et al. 1990) and EF1-up /EF1-low (O’Donnell et al. 1998) respectively. The resulting sequences of both isolates were deposited in the NCBI GenBank (GAPDH; MW411052, MW411053, Alt a 1; MW411050, MW411051, OPA10-2; MW415762, MW415763, ITS; MK140445, MT225559, TEF1-α; MT305773 and MT305774 ). Sequences of GAPDH, Alt a 1, OPA-10-2, ITS and TEF1-α genes of both isolates were identical to each other and showed 100 %, 100 %, 99.21 %, 100% and 100% identity to A. arborescens S. (AY278810.1, AY563303.1, KP124712.1, KY965831.1, KY965831.1) respectively. Identity with reference strain CBS 102605 confirms that both of the isolated strains 5.8 and 8 are A. arborescens. The pathogenicity of the two A. arborescens isolates were confirmed by artificially inoculating healthy ‘Sweet Tango’ fruit by dispensing the conidial suspension directly on the seed locule. Briefly, surface-disinfected fruits were air-dried for 5 min and then peeled using a sterilized knife and cut transversally. Each half of the fruit was inoculated with 100 µl of conidial suspensions (∼1 × 104 conidia/ml) in potato dextrose broth (PDB) and incubated at 22 °C in a humid chamber for 7–10 days, or until symptoms with visible mycelial growth were observed. The control fruits were treated with 100 µl of sterilized PDB. Both A. arborescens isolates produced visible moldy core symptoms on the inoculated ‘Sweet Tango’ fruits, whereas no symptoms were observed on the control fruits (Figure S1). The experiment was repeated three times with at least three replicates with similar results. A. arborescens was successfully re-isolated from the artificially-inoculated fruits to complete Koch’s postulates. To our knowledge, this is the first report of Alternaria arborescens causing moldy core disease in ‘Sweet Tango’ apples from New Zealand. Acknowledgments We thank Eric Bevis for his help in sample preparation for DNA sequencing, Willy Renderos for pathogenicity assay. We also thank Joan Hebb (Scotian Gold Cooperative Ltd.,) for providing the apple sample for this study. This research was made possible through financial support from Agriculture and Agri-Food Canada. The authors(s) declare no conflict of interest. Literature Cited Andrew M., Peever T.L., Pryor B.M. An expanded multilocus phylogeny does not resolve species among the small-spored Alternaria species complex. 2009. Mycologia. 101:95–109. Berbee, M. L. et al. 1999. Cochliobolus phylogenetics and the origin of known, highly virulent pathogens, inferred from ITS and glyceraldehyde-3-phosphate dehydrogenase gene sequences Mycologia. 91:964. Gabriel, M.F. I. Postigo, A. Gutiérrez-Rodríguez, E. Suñén, C.T. Tomaz, J. Martínez 2015. Development of a PCR-based tool for detecting immunologically relevant Alt a 1 and Alt a 1 homologue coding sequences. Medical Mycology. 53 (6):636–642. Gao, L. L., Zhang, Q., Sun, X. Y., Jiang, L., Zhang, R., Sun, G. Y., Zha, Y. L., and Biggs, A. R. 2013. Etiology of moldy core, core browning, and core rot of Fuji apple in China. Plant Dis. 97:510–516. Kerry, O’Donnell, H.C. Kistler, E. Cigelnik, R.C. Ploetz. 1998. Multiple evolutionary origins of the fungus causing Panama disease of banana: concordant evidence from nuclear and mitochondrial gene genealogies. PNAS. 95: 2044-2049. McLeod, A. 2014. Moldy core and core rots. Pages 40–41 in: Compendium of Apple and Pear Diseases and Pests, 2nd ed. T. B. Sutton, H. S. Aldwinckle, A. M. Agnello, and J. F. Walgenbach, eds. American Phytopathological Society, St Paul, MN. Serdani, M., Kang, J. C., Peever, T. L., Andersen, B., and Crous, P. W. 2002. Characterization of Alternaria species groups associated with core rot of apples in South Africa. Mycol. Res. 106:561–569. Simmons, E. G. 2007. Alternaria: an identification manual. CBS Biodiversity Series. 6:780 pp. Spotts, R. A., Holmes, R. J., and Washington, W. S. 1988. Factors affecting wet core rot of apples. Australas. Plant Pathol. 17:53–57. White, T. J., Bruns, T., Lee, S., and Taylor, J. 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. Pages 315–322 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis, D. H. Gelfand, J. J. Sninsky, and T. J. White, eds. San Diego, CA: Academic Press. Woudenberg, J. H. C., et al. 2015. Alternaria section Alternaria: Species, formae speciales or pathotypes. Stud. Mycol. 82:1-21.