Auswahl der wissenschaftlichen Literatur zum Thema „Fungicidal and phytotoxic“

Natural products are a source for pesticide or drug discovery. In order to discover lead compounds with high fungicidal or herbicidal activity, new niacinamide derivatives derived from the natural product niacinamide, containing chiral flexible chains, were designed and synthesized. Their structures were confirmed by 1H NMR, 13C NMR and HRMS analysis. The fungicidal and herbicidal activities of these compounds were tested. The fungicidal activity results demonstrated that the compound (S)-2-(2-chloronicotinamido)propyl-2-methylbenzoate (3i) exhibited good fungicidal activity (92.3% inhibition) against the plant pathogen Botryosphaeria berengriana at 50 μg/mL and with an EC50 of 6.68 ± 0.72 μg/mL, which is the same as the positive control (fluxapyroxad). Compound 3i was not phytotoxic and could therefore be used as a fungicide on crops. Structure-activity relationships (SAR) were studied by molecular docking simulations with the succinate dehydrogenase of the fungal mitochondrial respiratory chain.

In field experiments in 1990 and 1991, 16 fungicides were evaluated for the control of anthracnose (Microdochium panattonianum) on lettuce. Prochloraz, chlorothalonil, and propiconazole were the most effective. No phytotoxic effects were observed in lettuce treated with either 0.23 g prochloraz/L or 1.15 g chlorothalonil/L, and both provided significantly better control than the recommended rates of mancozeb, propineb, and cupric hydroxide, widely used on lettuce in Australia. A mixture of prochloraz and chlorothalonil did not reduce the severity of anthracnose compared with either fungicide applied alone. Propiconazole at rates of 25 and 62.5 mg/L severely stunted plants, and this fungicide is not recommended for use on lettuce. Fungicides applied weekly were more effective than those applied on a 14-day schedule or those applied only after periods of leaf wetness. In most experiments unsprayed plants were severely diseased and weighed less than half of those treated with fungicides.

The elaboration of new fungicidal protectants is an urgent issue due to the ability of pathogens to develop resistance. This fact contributes to the constant production of new protectants, so it carries an additional environmental impact. The main problem of development of new fungicides is choice of methods for identifying of optimal combinations and concentrations of fungicides. The optimization of the composition of fungicides is aimed to reduce the amount of active substances due to the synergistic effect. The use of fungicidal preparations with a reduced amount of active substances carries a lower environmental impact and gives a greater economic effect. One of the main problems in the application of fungicides is the phytotoxicity of the fungicides in relation to the protected plants. Phytotoxicity in general is the ability of pesticides or other substances to have a depressing (toxic) effect on plants. This problem is solved through researches of the germination of seedlings during the development of protectants. Researches of the germination power of seeds of soft winter wheat and white mustard after treatment with tebuconazole, рrothioconazole, and fludioxonyl were considered in the article. The main traits of the influence of the named substances on the germination of wheat grains and white mustard seeds, and morphological features of wheat seedlings, such as the length of their roots and shoots are revealed. In accordance to the results of the research, combinations of active substances (a.s.) that provide high effectiveness against the causative agents of diseases, and also do not have a phytotoxic effect on the protected culture have been determined. The aim of the work was the identification of traits of the phytotoxic effect of tebuconazole, рrothioconazole, fludioxonyl in the combination of seed protectants which are used to protect seedlings from plant diseases. Materials and methods. An assessment of the effect of three active substances of fungicides on wheat of the Grom cultivar and white mustard was given. The analysis was carried out in two replications for 48 possible combinations of tebuconazole, рrothioconazole, and fludioxonyl as well as fot two control variants. The ratio of normal, infected, abnormal and non-germinated seeds was analyzed. Results. According to the realized studies, tebuconazole has the greatest suppressive effect on germination and growth of shoots. Prothioconazole had no effect on germination, but it had a stimulating effect on the development and growth of wheat’s roots and shoots. With the combined action of prothioconazole and fludioxonyl, the greatest decrease in germination of wheat was observed. Conclusion. The possible phytotoxic effect, which depends on the dose of the protectant, should be taken into account when choosing a protectant and developing combined products. So the results of research demonstrated that the following combinations had no phytotoxic effect on protected plants: tebuconazole with рrothioconazole 5:10 and 5:15, tebuconazole with fludioxonyl 5:10, рrothioconazole with fludioxonyl 5:10.

Copper (Cu)-based fungicidal sprays are widely used on many crops although Cu sprays can be phytotoxic under some conditions. The mechanism of phytotoxicity is poorly understood but must involve toxic levels of Cu penetrating plant tissues. We studied the effect of different adjuvants on the deposition pattern of droplets and penetration of Cu (in Kocide fungicide) through isolated cuticles of ‘Marsh’ grapefruit leaves and ‘Valencia’ orange fruit. The addition of the silicone-based L-77 surfactant to the Kocide suspension markedly increased the spread of the droplets on cuticles and increased the penetration of Cu through fruit and abaxial leaf cuticles, both with stomatal pores, but not through astomatous adaxial leaf cuticles, which had much lower permeability. Urea and petroleum spray oil adjuvants had no effect on surface area of droplets or the penetration of Cu through leaf and fruit cuticles. Spray tank mixes of Cu fungicides with organosilicone surfactants should be avoided because these surfactants can enhance the penetration of Cu into citrus leaves and fruit thereby leading to phytotoxicity.

This study aims to highlight the antifungal, antimicotoxigenic potential and phytotoxic effect of three essential oils (EOs) of Origanum vulgare (OEO), Thymus vulgaris (TEO), and Coriandrum sativum (CEO) on wheat storage, but also the impact of EOs treatment on the sensory properties of bakery products obtained from the wheat seeds. The chemical composition of EOs was determined using GC-MS analysis; the fungal load was evaluated using the direct plating technique, while mycotoxin analyses were conducted using enzyme-linked immunosorbent assay (ELISA). A selective antifungal effect has been highlighted in terms of the action of EOs vapours. OEO and TEO are inhibited Alternaria, Fusarium and Drechslera, while Saccharomyces and Cladosporium have proven to be the most tolerant fungi. Drechslera is the most sensitive, the effect of all EOs being a fungicidal one. However, the fungicidal effect proved present in all EOs applied as vapours with values ranging between 0.2–0.4%. Regarding the phytotoxic effect of EOs vapours on the germination of the seeds, TEO and OEO had an inhibitory effect, especially at 0.4%. The effect is cumulative over time. The EOs inhibited deoxynivalenol (DON) occurrence; the maximum percentage of inhibition was obtained after 21 days of vapours exposure, being more effective in the case of 0.2%. EOs vapours treatment does not affect the quality of bread obtained from treated wheat seeds from a sensory point of view.

The pesticide formulation prepared as "ready to be used plant protection product" on the basis of tobacco oil was created and tested in two years field trials against powdery mildew of wheat (Blumeria graminis f. sp. tritici). The results showed strong fungicidal effect without any phytotoxic activities (chemotherapeutic coefficient = 10) onto treated plants. This indicates the future development of this pesticide formulation as effective, natural friendly and cheap product for plant protection, which can be used both in commercial and organic agriculture.

Ten-membered lactones (nonenolides) demonstrate phytotoxic, antimicrobial, and fungicidal activity promising for the development of natural product-derived pesticides. The fungus Stagonospora cirsii is able to produce phytotoxic stagonolides A (1), J (2), K (3) and herbarumin I (4) with high yield. The aim of this study was to create a set of structurally related nonenolides and to reveal the structural features that affect their biological activity. Stagonolide A (1) and C-7 oxidized stagonolide K (11) showed the highest phytotoxicity in leaf puncture assay and agar seedlings assay. The oxidation of C-7 hydroxyl group (as in 1, acetylstagonolide A (10) and (11) led to the manifestation of toxicity to microalgae, Bacillus subtilis and Sf9 cells regardless of the configuration of C-9 propyl chains (R in 1 and 10, S in 11). C-7 non-oxidized nonenolides displayed none or little non-target activity. Notably, 7S compounds were more phytotoxic than their 7R analogues. Due to the high inhibitory activity against seedling growth and the lack of side toxicity, mono- and bis(acetyl)- derivatives of herbarumin I were shown to be potent for the development of pre-emergent herbicides. The identified structural features can be used for the rational design of new herbicides.

Abstract The effect of the insecticides Lorsban 4 E, Guthion 35 W, and Lorsban 50 W was evaluated on the fruit on mature apple trees. Materials at rates and times noted in the table were applied to run off with a Bean hydraulic sprayer operating at 400 psi. There were 4 single tree replicates of each treatment. All treatments and the control received 7 fungicidal sprays of Rubigan 6 oz/A + Benlate 6 oz/A. Twenty fruit per replicate were examined on the trees and evaluated for side and stem end russet. These apples were placed into grade categories according to U.S. Grade standards. No phytotoxic symptoms were observed at the time of the field examination 27 Jul.

O tratamento de sementes tem como objetivo tradicional erradicar ou reduzir os fungos associados às sementes, além de protegê-las de patógenos presentes no solo. Algumas doenças que ocorrem na parte área das plantas podem ser manejadas através do tratamento das sementes com produtos sistêmicos. Essa forma de controle tem sido utilizada há muitos anos, visando o controle de fungos biotróficos em arroz e trigo. A ferrugem asiática da soja é a principal doença que ataca a cultura, a qual necessita de ferramentas eficientes para seu manejo. O objetivo desta dissertação foi verificar a contribuição do tratamento de sementes de soja com produtos fitossanitários no manejo da ferrugem asiática. Desta forma, produtos fitossanitários foram aplicados às sementes de soja em diferentes doses, a fim de se verificar os efeitos fitotóxicos sobre sementes e plântulas que eventualmente fossem causados pelos mesmos. As maiores doses não fitotóxicas de cada tratamento foram selecionadas, novamente aplicadas às sementes e distribuídas em campo experimental, onde se verificou o efeito do tratamento das sementes isoladamente ou com a aplicação foliar de fungicidas foliares, no manejo da ferrugem asiática da soja. Ciproconazol + azoxistrobina (10,0 + 25,0g i.a./100kg de sementes), difenoconazol (50,0), epoxiconazol (2,5), fluquinconazol (50,0), flutriafol (10,0), flutriafol TS (5,0), flutriafol + tiofanato metílico (10,0 + 50,0), tebuconazol (10,0), tebuconazol + trifloxistrobina (10,0 + 5,0), tetraconazol (10,0), triticonazol (25,0), acibenzolar-S-methyl (50,0) e pó de rocha (2,0) não apresentaram fitotoxicidade e foram comparados em campo. Ciproconazol + azoxistrobina (25,0 + 10,0g i.a./100kg de sementes) e epoxiconazol (2,5) diminuíram a emergência das plântulas de soja em campo. No ensaio somente com tratamento de sementes, sem aplicação de fungicida foliar, tebuconazol e tebuconazol + trifloxistrobina diminuíram a ferrugem asiática em plantas de soja. Quando se integrou a pulverização foliar de fungicidas, fluquinconazol, tebuconazol e tebuconazol + trifloxistrobina, diminuíram a severidade da ferrugem asiática da soja. Apesar de não aumentar o rendimento da cultura, o tratamento de sementes pode contribuir no manejo da ferrugem asiática da soja, mantendo a segurança e o rendimento do produtor.
Seed treatment has as traditional objective to eradicate or to reduce fungi associated with seeds and to protect them from soilborne pathogens. Some diseases that occur in the aerial part of plants may be managed through seed treatment with systemic products. This kind of control has been used for many years, aiming the control of biotrophic fungi in rice and wheat. Soybean\'s asian rust is the main disease that attacks the culture, which needs efficient tools for its management. The objective of this study was to verify the contribution of soybean seed treatment with phytosanitary products in the management of asian rust. In this case, phytosanitary products were applied to soybean seeds in different doses, aiming to verify the phytotoxicity effects onto seeds and seedlings that eventually would be caused by these products. The highest non phytotoxic doses of each treatment were selected, applied again to seeds and these were distributed on experimental field, where it was verified the effect of each seed treatment with and without foliar application of fungicides, in the management of soybean\'s asian rust. Ciproconazol + azoxystrobin (10,0 + 25,0g a.i./100kg of seeds), difenoconazol (50,0), epoxiconazol (2,5), fluquinconazole (50,0), flutriafol (10,0), flutriafol TS (5,0), flutriafol + thiophanate-methyl (10,0 + 50,0), tebuconazole (10,0), tebuconazole + trifloxystrobin (10,0 + 5,0), tetraconazole (10,0), triticonazole (25,0), acibenzolar-S-methyl (50,0) and rock powder (2,0) did not present phytotoxicity and were compared in field. Ciproconazol + azoxystrobin (25,0 + 10,0g a.i./100kg of seeds) and epoxiconazol (2,5) decreased the seedling\'s emergency in field. In the experiment with only seed treatment, with no foliar fungicide application, tebuconazole and tebuconazole + trifloxystrobin decreased asian rust in soybean plants. When the application of foliar fungicide was integrated, fluquinconazole, tebuconazole and tebuconazole + trifloxystrobin the asian rust severity decreased. Despite there was no increase in the culture yield, seed treatment can contribute in asian rust´s management, increasing the safety an the revenue of the producer.

Studies were conducted on three field trials of wheat cv. Kopara to investigate the lack of compensation by later determined components of yield because of early disease constraints. The investigation was based on the hypothesis that early disease reduces root development and thus causes the plants to be water constrained at later growth stages when soil water deficits usually occur. The reduced root development and soil water deficits may reduce the ability of the plant to compensate for reductions in early determined components. The hypothesis was tested by the application of irrigation to alleviate water stress. In a disease free crop, the possible phytotonic effects of the fungicides benomyl and triadimefon on wheat were investigated. These fungicides had no phytotonic effects on shoot, root growth, or yield under the prevailing conditions. The effect of disease on root development was analysed by root length measurements. Disease present in the crop at any stage of growth affected root development. Root development in the upper zones of the soil profile was reduced more by disease compared to those zones below 35 cm. A full disease epidemic reduced root development more than an early or late disease epidemic. The early and late disease epidemics had similar effects on root length. Alleviation of early disease constraints enabled greater development of roots to offset any earlier reductions. Soil water deficits increased root development in the lower zones of the nil disease plants. The presence of adequate soil water from irrigation reduced the requirement for further root growth in all treatments. In the 1981-1982 field trial a full disease epidemic reduced yield by 14% whereas an early disease epidemic reduced yield by 7%. The reduction in yield was attributed to a lower grain number. With irrigation the yield reduction in the full disease plants was 12% whereas in the early disease plants the reduction was only 2.4%. This indicated that plants affected by the early disease epidemic were water constrained. In this study, the results suggested that, for conditions prevailing in Canterbury, the supply of water at later growth stages increased grain weight in plants which were subject to early disease epidemics. This suggests that reduced root development caused by early disease and soil water deficits may prevent compensation by grain weight. Water use was similar in all disease treatments. After irrigation the irrigated plants of all treatments used more water. Disease affected water use in relation to yield production however, and was better expressed by water use efficiency. Water use efficiency was reduced in the full disease plants. A stepwise regression analysis suggested that water use efficiency was affected directly by disease at later growth stages, and indirectly via an effect on total green leaf area at early growth stages. This study partially proves the hypothesis that reductions in root development caused by an early disease epidemic may constrain the plants at later growth stages when water deficits usually occur. It was shown that the reduction in root development caused by disease could be counteracted by irrigation. In this respect, water served as a tool to study the effect of disease constraints on the yield of wheat. A knowledge of cereal crop physiology, root growth and function is used to explain and discuss the observations made in this research programme. The results are discussed in relation to the way in which disease affects yield through its effect on root development. The possible reasons for the continued effects of disease even after the control of disease at later growth stages are discussed. The economic use of fungicides and water in diseased crops are also outlined. Suggestions for future studies on disease-yield loss relationships are provided. The repetition of these experiments in different sites and climatic regions could provide information which may be incorporated in disease-yield loss simulation models. This could then be used to predict root development and water requirements of diseased plants, and provide a basis for economic use of fungicides and water, and for better disease management programmes.

Application of nitrogen fertilizers did not significantly affect the number of micromycetes. The restructuring of the species structure of the mycobiome did not exceed the adaptive zone of “stress” – a change in the frequency of occurrence of typical species. Typical types of leached chernozem micromycetes include deuteromycetes of the genera Aspergillus, Penicillium, Trichoderma, Gliocladium, Humicola, Fusarium, zygomycetes (genus Rhizopus), ascomycetes (genera Thalaromyces, Chaetomium). On average, the density of dominant species of micromycetes increased by 20 %, which indicates the development of the “dominance concentration” of typical species and a decrease in the share of rare and random species of fungi in the mycocomplex. In the experiment variants, the density of Penicillium daleae, P. funiculosum, Fusarium solani, and Aspergillus ustus species increased compared to control. These types of micromycetes are toxigenic and synthesize broad-spectrum mycotoxins (fungicidal, antibiotic, and phytotoxic). As a result, the phytotoxic activity of the soil increased to 7 and 20 % (native soil) and to 19-34 % (initiated microbial community). More pronounced changes were observed in the variant with ammonium sulfate. Thus, nitrogen fertilizers at a dose of N90 cause a “stress” reaction of the mycobiome, an increase in the share of toxigenic species and phytotoxic activity of leached chernozem. With long-term systematic use of nitrogen fertilizers, even in medium doses, it is possible to reduce the potential fertility of chernozems.