Academic literature on the topic 'Common sowthistle'

A new species of eriophyoid mite from Australia is described and illustrated. Aceria thalgi sp. n. causes severe curling and rolling of leaves of common introduced sowthistle, Sonchus oleraceus L. It also affects introduced Sonchus asper (L.) Hill and native Sonchus hydrophilus Boulos. The native species may be the original host for this mite. Aceria thalgi sp. n. is shown to be a separate species to Aceria sonchi (Nalepa), which forms distinctive leaf galls on Sonchus spp. in southern Europe. English translations of past descriptions of A. sonchi are included for comparison. Historical observations and records from New South Wales suggest that A. thalgi sp. n. has been known for at least 80 years prior to its recent rediscovery in Western Australia. This implies that the newly described species may be widespread across the continent. There is also a past record of similar damage symptoms occurring on sowthistles in New Zealand. Aceria thalgi sp. n. has the potential to be a useful biological control agent in Australia and Canada, where sowthistles are major weeds of agriculture.

We investigated potential post-emergence herbicides for managing broadleaf weeds in broccoli, Chinese cabbage, cabbage, and cauliflower, as no products are currently registered for these uses in Australia. Subsequent to spraying clopyralid, picloram, or pyridate 5�weeks after direct-sowing broccoli or Chinese cabbage, or transplanting cabbage or cauliflower seedlings, we recorded crop phytotoxicity symptoms, measured marketable crop yields, and assessed weed control achieved. Neither maximum application rates of 90 g clopyralid/ha, nor 45�g clopyralid/ha mixed with 30 g picloram/ha, adversely affected vegetable yields. Spraying 60 g/ha clopyralid controlled burr medic (Medicago polymorpha), and suppressed common sowthistle (Sonchus oleraceus). Applying 90 g clopyralid/ha, or mixing 22.5 g clopyralid/ha with 15 g picloram/ha, controlled both burr medic and common sowthistle. At the rates tested, neither clopyralid nor picloram affected deadnettle (Lamium amplexicaule). Applying 450 g pyridate/ha caused chlorotic spotting of the sprayed vegetable leaves, but did not affect marketable yields of broccoli, cabbage or cauliflower. This rate controlled deadnettle, reduced sowthistle growth by only 30–50% compared with an unweeded control, and had no impact on burr medic. Spraying 900 g pyridate/ha increased the severity and persistence of chlorotic spotting, and resulted in lower broccoli and Chinese cabbage yields than obtained in the best treatments in the respective experiments. Cabbage and cauliflower yields were unaffected by spraying 900 g pyridate/ha. This rate improved sowthistle control to a commercially acceptable level. Our studies suggest that both clopyralid and pyridate could be successfully utilised in Australian vegetable brassica production, providing issues of the residual activity of clopyralid on following crops, and optimal application rates and timing for pyridate, were resolved.

Mortality of weed seeds at temperatures of 39, 42, 46, 50, 60, and 70 C was recorded through time under controlled laboratory conditions similar to those of soil solarization for six weed species: annual sowthistle, barnyardgrass, black nightshade, common purslane, London rocket, and tumble pigweed. Time and temperature requirements for thermal death varied considerably among the species studied. Barnyardgrass, London rocket, and annual sowthistle were more susceptible to heat treatment than black nightshade, common purslane, and tumble pigweed. Temperatures of 50 C and above were lethal for seeds of all species. Common purslane seeds were unaffected at 46 C and below, tumble pigweed and barnyardgrass seeds were unaffected at 42 C and below, and black nightshade seeds were unaffected at 39 C. Nonlinear models for mortality as a function of duration of heat treatment were developed for each species at each temperature at which mortality occurred. These models provide an empirical relationship for the construction of field-applicable decision models that could predict the accumulation of time and temperature combinations for effective solarization of weed seeds.

A survey undertaken in northern New South Wales after the 1989 wheat harvest investigated the effects of cultural practices used by dryland farmers on summer weed flora. Only 50% of fallow paddocks surveyed between December and February were weedfree, and by mid January 65% had inadequate stubble cover (<1000 kg/ha) for protection from soil erosion, mainly because of excessive tillage. By February, only 10% of paddocks were being sprayed with a herbicide to control weeds. Examination of 65 uncultivated fallow wheat stubble paddocks and 25 grain sorghum crops identified 87 and 51 different weed species, respectively. In fallow paddocks where no herbicide had been used, 69 and 61 species were found in ungrazed and grazed paddocks, respectively. Where glyphosate had been used the number of species was 37 (grazed) and 39 (ungrazed), and for glyphosate plus atrazine, 23 and 18 species. The number of weed species found in grain sorghum was 29 for cultivated without atrazine, 35 for cultivated with atrazine, and 35 for no-tillage with atrazine, The most important weeds found in fallow were liverseed grass, native millet, common sowthistle, wireweed, and barnyard grasses. Black bindweed was a problem where atrazine had not been used. Native millet was the most abundant species where atrazine had been applied. In grain sorghum the most common broadleaf weeds for cultivated paddocks with no atrazine treatment were Tribulus spp., Australian bindweed, pigweed, and Bathurst burr, while the most common grass weeds were barnyard grasses, liverseed grass, stinkgrass, and native millet. When cultivation plus atrazine was used, barnyard grasses, native millet, wild oats, and liverseed grass were the most common weeds. In minimum tillage or no-tillage paddocks treated with atrazine, native millet, Queensland blue grass, liverseed grass, common sowthistle, Australian bindweed, and windmill grass were the most common weeds.

Lack of understanding the effects of single- and multiple-weed interference on soybean yield has led to inadequate weed management in Primorsky Krai, resulting in much lower average yield than neighboring regions. A 2 yr field experiment was conducted in a soybean field located in Bogatyrka (43.82°N, 131.6°E), Primorsky Krai, Russia, in 2013 and 2014 to investigate the effects of single and multiple interference caused by naturally established weeds on soybean yield and to model these effects. Aboveground dry weight was negatively affected the most by weed interference, followed by number of pods and seeds. Soybean yield under single-weed interference was best demonstrated by a rectangular hyperbolic model, showing that common ragweed and barnyardgrass were the most competitive weed species, followed by annual sowthistle, American sloughgrass, and common lambsquarters. In the case of multiple-weed interference, soybean yield loss was accurately described by a multivariate rectangular hyperbolic model, with total density equivalent as the independent variable. Parameter estimates indicated that weed-free soybean yields were similar in 2013 and 2014, i.e., estimated as 1.72 t and 1.75 t ha−1, respectively, and competitiveness of each weed species was not significantly different between the two years. Economic thresholds for single-weed interference were 0.74, 0.66, 1.15, 1.23, and 1.45 plants m−2for common ragweed, barnyardgrass, annual sowthistle, American sloughgrass, and common lambsquarters, respectively. The economic threshold for multiple-weed interference was 0.70 density equivalent m−2. These results, including the model, thus can be applied to a decision support system for weed management in soybean cultivation under single and multiple-weed interference in Primorsky Krai and its neighboring regions of Russia.

Four experiments in northern New South Wales comparing fallow management treatments of no-tillage, cultivated with the stubble retained, and cultivated with the stubble burned, from 1981 to 1990, were sampled for weeds between wheat harvest and seeding on a number of occasions during this period. Eighty weed species were identified, 23 of which were found at all 4 sites but only 13 were recorded in the samples taken. These were dwarf amaranth, wild turnip, spear thistle, Australian bindweed, fleabane, bladder ketmia, prickly lettuce, turnip weed, variegated thistle, common sowthistle, dandelion, wild oats and native millet. The density of weeds during the fallow period decreased by 97% from 1981 to 1990 with some species eliminated, probably because of the herbicides used, particularly glyphosate and chlorsulfuron. These included Boggabri and redroot amaranth, button grass, caustic weed, dense crassula, fat hen, legumes, common peppercress, hedge mustard, London rocket, shepherd’s purse, wild mustard, sorghum-almum, paradoxa grass, wild zinnia, and wireweed. Twenty-four weed species were classified as a problem or a potential problem in the future at 1 or more sites. Seventeen weed species, including perennial grasses, often were tolerant to glyphosate at the rates used. The densities of common sowthistle and wild oat were reduced after 10 years, but still remained at all 4 sites. Plant density of species with wind-blown seeds was greater in no-tillage plots than stubble-retained or stubble-burned plots. Weeds whose seeds are dispersed by wind and weeds tolerant to glyphosate were the most troublesome. The perennial grass native millet increased at all 4 sites.

AbstractIn Australia, glyphosate is widely used in glyphosate-tolerant crops and fallows to control weeds such as common sowthistle (Sonchus oleraceus L.). It has been hypothesized that glyphosate at sublethal doses, as a consequence of herbicide drift, may have a stimulatory effect on S. oleraceus growth. In 2017, pot trials were conducted to evaluate the effect of low doses of glyphosate on growth and seed production of this weed at the Weed Science Screenhouse Facility at the University of Queensland, Australia. At the 4- to 5-leaf stage (3-wk-old rosette), plants were treated with low doses of glyphosate (0 [control], 5, 10, 20, 40, 80, and 800 g ae ha−1), and their responses were recorded until plant maturity. The study was repeated after completion of the first experimental run. An additional glyphosate dose (2.5 g ha−1) was added in the second run. The low doses of glyphosate (<40 g ha−1) caused a significant increase in S. oleraceus plant height and number of leaves compared with the no-glyphosate treatment. The highest stimulatory effect was observed at 5 g ha−1. At 5 g ha−1 glyphosate, S. oleraceus seed production increased by 154% and 101% in the first and second experimental runs, respectively, compared with the no-glyphosate treatment. The results of this study suggest that the sublethal doses of glyphosate produced hormetic effects on growth and seed production of S. oleraceus that changed the dynamics of weed–crop competition.

A novel actinobacterium, designated strain NEAU-QY2T, was isolated from the leaves of Sonchus oleraceus L. specimen, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic position of this strain. The organism formed single spores with rough surfaces on substrate mycelia. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-QY2T belonged to the genus Plantactinospora and formed a monophyletic clade with its closest related strains Plantactinospora endophytica YIM 68255T (99.2 % 16S rRNA gene sequence similarity), Plantactinospora veratri NEAU-FHS4T (98.8 %) and Plantactinospora mayteni YIM 61359T (98.7 %), an association that was supported by a bootstrap value of 90 % in the neighbour-joining tree and also recovered with the maximum-likelihood algorithm. However, DNA–DNA hybridization values between strain NEAU-QY2T and the three closely related strains were below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA–DNA hybridization results, strain NEAU-QY2T was distinguished from closely related strains and is classified as representing a novel species of the genus Plantactinospora, for which the name Plantactinospora sonchi sp. nov. is proposed. The type strain is NEAU-QY2T ( = CGMCC 4.7216T = JCM 30345T).

Weeds are a major impediment to crop and pasture production and profitability in Australian farming systems, and knowledge of their occurrence is vital in devising weed management solutions. This study examined the relationships between weed and crop species from observations made during surveys of randomly selected fields in grain and/or pasture production. Between 2013 and 2017, 996 fields across New South Wales (NSW) were surveyed to record the occurrence and density of weed species. Annual ryegrass (Lolium rigidum) (69% of fields), wild oats (Avena spp.) (60%), and sowthistle (Sonchus oleraceus) (34%) were the most common species identified, with a total of 65 weed species recorded to be occurring in NSW cropping fields. Densities of occurring weeds were low, at one plant per square metre or less. Multiple species of wild oats were recorded, with their occurrence varying between survey regions; for example, Avena sterilis subsp. ludoviciana was more prevalent in the north and Avena fatua in the south. Differences in weed species occurrence were noted between this survey and those previously conducted in NSW, with marked increases in annual ryegrass and sowthistle, and this is attributed to the change in crop production practices between survey periods. The study of variable distribution patterns of weed species across cropping systems allows for informed decision-making regarding weed management research and development planning.

Les invasions biologiques sont un des facteurs majeurs de perte de la biodiversité. Face à cette menace, plusieurs approches sont utilisées pour contrôler l’expansion des populations d’espèces invasives. La lutte biologique par introduction s’appuie sur la sélection et l’introduction des ennemis naturels spécialistes de l’espèce invasive, appelés agents de lutte biologique, depuis l’aire d’origine vers l’aire d’invasion pour limiter les populations invasives sous un seuil de nuisibilité écologiquement et économiquement acceptable. Ces travaux de thèse se place dans un contexte de lutte biologique par introduction contre le laiteron maraîcher, Sonchus oleraceus (Asteraceae) en Australie. Dans une visée appliquée de gestion de S. oleraceus, nous avons alors adopté une démarche multidisciplinaire pour adresser plusieurs étapes critiques inhérentes au programme de lutte biologique, concernant 1) l’identification de la cible, 2) la compréhension du processus d’invasion et 3) l’anticipation des risques associés aux lâchers des agents via l’étude des réseaux écologiques. L’identification correcte de la cible étant un prérequis pour la recherche des agents de lutte, nous avons défini un caractère diagnostic fiable et pratique à utiliser lors des prospections, à savoir l’ornementation des akènes. Ensuite, nous avons évalué si l’évolution rapide des traits chez S. oleraceus était un mécanisme qui pouvait avoir contribué au succès d’invasion. Nous avons montré que les populations invasives étaient plus performantes que les natives, et que le compromis qui existe entre l’allocation des ressources à la croissance et la reproduction avait évolué, conduisant les populations invasives à investir davantage dans les fonctions de croissance pour un investissement équivalent aux populations natives dans les fonctions de reproduction. Ces résultats ouvrent la voie à d’autres études utiles pour déterminer les conséquences de ces changements pour les futures populations d’agents de lutte. De plus, nous avons abordé de façon préliminaire le rôle du relâchement de la pression d’herbivorie dans le succès d’invasion. Par des inventaires réalisés en Europe et en Australie, nous avons mis en avant un déficit d’ennemis naturels spécialistes dans l’aire d’introduction. Les introductions délibérées d’agents de lutte ne sont cependant pas anodines et un des challenges en lutte biologique réside dans la capacité à anticiper les risques pour la communauté indigène de l’aire d’introduction. Dans le dernier axe de cette thèse, nous avons exploré l’intérêt de l’analyse des réseaux d’interactions écologiques pour aider à la sélection d’agents de lutte. Pour cela une approche solide et transposable combinant technologies moléculaires et données d’observations a été développée pour reconstruire avec fiabilité et une résolution élevée les interactions trophiques entre plantes, herbivores et ennemis naturels. L’analyse de réseau, nous a permis d’identifier 37 espèces utilisant S. oleraceus en aire native et d’apporter des précisions sur la gamme d’hôte écologique de ces herbivores conduisant à 1) cibler ou exclure certains agents de lutte candidats et 2) questionner l’existence de complexes d’espèces lié à la plante hôte, nécessitant confirmation. Par ailleurs, nous avons révélé l’utilisation de ces herbivores par une large gamme d’ennemis naturels, ce qui présente des implications pour l’évaluation des risques indirects. En somme, cette thèse a participé à renforcer les connaissances quant aux processus d’invasion impliqués dans la colonisation du laiteron maraîcher en Australie, justifiant en partie la stratégie de lutte adoptée, et a montré le potentiel de l’analyse des réseaux écologiques pour complémenter les démarches classiques de sélection d’agents présentant un minium de risque
Biological invasions are one of the main driver of biodiversity loss. Several strategies are employed to tackle the expansion of invasive species populations. Among them, introduction biological control is based on selection and release of specialist natural enemies, called biological control agents, from native range to introduced range to decrease the invasive population densities below an ecological and economical acceptable threshold. This PhD thesis is part of a biological control program targeting the common sow thistle, Sonchus oleraceus (Asteracae), an invasive species in Australia. We employed a multidisciplinary approach to address several critical steps of the program, directed towards applied management perspectives, regarding 1) the identification of the target plant, 2) the understanding of the invasion process, and 3) the prediction of risks associated to biocontrol agents release through ecological networks analysis. The accurate identification of the target plant is a prerequisite for the survey of biocontrol agent candidates. As a first step, we thus defined a reliable and convenient diagnostic character to be used in the field, which is the achene ornamentation. Then, we assessed whether rapid evolution could be one of the process that could have contributed to S. oleraceus invasion success. We showed that introduced plants outperformed native ones, and detected a significant shift in the relationship (trade-off) between growth and reproduction, introduced populations tended to invest more in growth that native ones for an equivalent investment into reproductive functions. More investigations would be necessary to determine whether those changes would affect future biocontrol agents. Post-introduction evolution seemed however moderated, and preliminary results obtained through filed surveys realised in Europe and Australia tended to indicate that enemy release had also probably benefited S. oleraceus in Australia. However, the deliberated introduction of biocontrol agents poses risks to the recipient community, and their anticipation is an ongoing challenge in introduction biological control. In the last part of this thesis, we explore the interest of ecological network analysis in supporting biological control selection. Therefore, a powerful and transferable approach based on the combination of molecular tools and observational data have been developed to reconstruct with high levels of taxonomic resolution and interaction recovering, trophic links between plants, herbivores and natural enemies. Network analyses, allowed to determine 37 species using S. oleraceus as food plant in the native range. We were able to detail their field host range, 1) leading to the selection and exclusion of candidate biocontrol agents, and 2) raising the question of potential cryptic host races, that needs to be confirmed. We revealed a wide range of natural enemy species using S. oleraceus herbivores, which is of particular interest for indirect risk assessment. Ecological analysis proved to be complementary to classical specificity tests and has a great potential to support biocontrol agent selection. In conclusion, this PhD thesis strengthened our knowledge on invasion processes involved in the colonisation of the common sow thistle in Australia, partly justifying the control strategy used, and demonstrated the potential offered by ecological network analysis in supporting the selection of minimal-risk agents

Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in southern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Chiricahua National Monument (NM), Coronado National Memorial (NMem), and Fort Bowie National Historic Site (NHS) during water year (WY) 2019 (October 2018–September 2019). Overall annual precipitation at Chiricahua NM and Coronado NMem in WY2019 was approximately the same as the normals for 1981–2010. (The weather station at Fort Bowie NHS had missing values on 275 days, so data were not presented for that park.) Fall and winter rains were greater than normal. The monsoon season was generally weaker than normal, but storm events related to Hurricane Lorena led to increased late-season rain in September. Mean monthly maximum temperatures were generally cooler than normal at Chiricahua, whereas mean monthly minimum temperatures were warmer than normal. Temperatures at Coronado were more variable relative to normal. The reconnaissance drought index (RDI) indicated that Chiricahua NM was slightly wetter than normal. (The WY2019 RDI could not be calculated for Coronado NMem due to missing data.) The five-year moving mean of annual precipitation showed both park units were experiencing a minor multi-year precipitation deficit relative to the 39-year average. Mean groundwater levels in WY2019 increased at Fort Bowie NHS, and at two of three wells monitored at Chiricahua NM, compared to WY2018. Levels in the third well at Chiricahua slightly decreased. By contrast, water levels declined in five of six wells at Coronado NMem over the same period, with the sixth well showing a slight increase over WY2018. Over the monitoring record (2007–present), groundwater levels at Chiricahua have been fairly stable, with seasonal variability likely caused by transpiration losses and recharge from runoff events in Bonita Creek. At Fort Bowie’s WSW-2, mean groundwater level was also relatively stable from 2004 to 2019, excluding temporary drops due to routine pumping. At Coronado, four of the six wells demonstrated increases (+0.30 to 11.65 ft) in water level compared to the earliest available measurements. Only WSW-2 and Baumkirchner #3 have shown net declines (-17.31 and -3.80 feet, respectively) at that park. Springs were monitored at nine sites in WY2019 (four sites at Chiricahua NM; three at Coronado NMem, and two at Fort Bowie NHS). Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included modifications to flow, such as dams, berms, or spring boxes. Examples of natural disturbance included game trails, scat, or evidence of flooding. Crews observed 0–6 facultative/obligate wetland plant taxa and 0–3 invasive non-native species at each spring. Across the springs, crews observed six non-native plant species: common mullein (Verbascum thapsus), spiny sowthistle (Sonchus asper), common sowthistle (Sonchus oleraceus), Lehmann lovegrass (Eragrostis lehmanniana), rabbitsfoot grass (Polypogon monspeliensis), and red brome (Bromus rubens). Baseline data on water quality and water chemistry were collected at all nine sites. It is likely that that all nine springs had surface water for at least some part of WY2019, though temperature sensors failed at two sites. The seven sites with continuous sensor data had water present for most of the year. Discharge was measured at eight sites and ranged from < 1 L/minute to 16.5 L/minute.