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A New Benzothiadiazole Derivative with Systemic Acquired Resistance Activity in the Protection of Zucchini (Cucurbita pepo convar. giromontiina) against Viral and Fungal Pathogens
The ability of plant resistance inducers to provide protection against viral diseases is one of their main advantages over conventional pesticides. In the case of viral diseases that cannot be controlled directly with pesticides, insecticides are used to control the vectors of viruses. However, the effectiveness of such treatments is strictly dependent on the time of application. The plant response to the application of systemic acquired resistance (SAR) inducers, as a result of the stimulating action of these substances, does not depend on the time of application as it triggers the plantâs natural defence mechanism. The best-recognised substance showing SAR inducer activity is acibenzolar-S-methyl ester (ASM, BTH). As its activity against different plant pathogens of crops has been well documented, the current research is concentrated on the search for novel substances of the type. The tested substance, N-methoxy-N-methylbenzo(1,2,3)thiadiazole-7-carboxamide (BTHWA), is an amide derivative of benzothiadiazole, showing plant resistance-inducing activity. This article presents the activity of BTHWA that has led to increased resistance of zucchini (Cucurbita pepo convar. giromontiina) towards viral infections. In addition, since the occurrence of the fungal pathogen, powdery mildew, was also observed during the two-year field experiments, the activity of BTHWA related to the reduction of infection with this fungus was also investigated. The substance was applied in two different variants either four or eight times, over the whole vegetation season. Surprisingly, the variant of four applications performed at the beginning of the vegetation season proved more effective in protection against viruses and fungus. A possible explanation may be the occurrence of the growthâimmunity trade-off phenomenon that is known in the literature. Disturbance in plant metabolism resulting from eight applications may lead to lower yields of plants treated with SAR inducers. Perhaps such overstimulation of the plants we treated eight times may not have brought the optimum increase in plant resistance.
Soil mite communities (Acari, Mesostigmata) in pure stands on post-agricultural lands: does season matter?
AbstractPost-agricultural land differs from typical forest land in physical, chemical and biological features. In addition, the environment of this land type is determined, among other things, by the introduced tree species. These differences may be revealed by the biodiversity and abundance of the soil fauna. We analysed the abundance, species richness and diversity of different instars of mesostigmatid mites inhabiting three different habitat types on post-agricultural land (shaped by pure Pinus sylvestris L., Tilia cordata Mill. and Betula pendula Roth stands). We collected 288 soil samples from eight plots in three stands. The collection was conducted in July and October in two consecutive vegetation seasons (2021 and 2022) for Mesostigmata mites community. Soil characteristics (determination of soil group and analysis of physical and chemical properties of soil and litter) were done in July 2021. In total, 399 individuals (266 females, 50 males and 83 juveniles) were classified into 38 taxa (33 species, five genera). Most individuals belonged to the Parasitidae, Laelapidae and Veigaiidae families. The most abundant species were Hypoaspis aculeifer (Canestini) (21.6% of all recorded mites), Veigaia nemorensis (C.L.Koch) (7.8%) and Trachytes aegrota (C.L.Koch) (7.0%). Abundance, species richness and diversity were shaped by collection month and Fe content in soil. The abundance was influenced by N litter content and was significantly lower in P. sylvestris stand in July (0.57â±â0.23; meanâ±âSE) than in P. sylvestris (2.17â±â0.54) and T. cordata (2.15â±â0.48) stands in October. Moreover, abundance in P. sylvestris stand in October was higher than in B. pendula stand in July (0.78â±â0.26). Similarly, species richness was significantly lower in P. sylvestris stand in July than in P. sylvestris and T. cordata stands in October (2.17â±â0.54 and 2.15â±â0.48, respectively). Higher Shannonâs diversity of mite communities was reported in P. sylvestris stand in October (0.40â±â0.10) than in P. sylvestris and B. pendula stands in July (0.12â±â0.06 and 0.14â±â0.08, respectively). Large fluctuations of abundance, species richness and diversity of soil mite communities in P. sylvestris and B. pendula stands between collection months give the insights for creating mixed stands on post-agricultural land. It is worth noticing that the wet season creates the most favourable living environment for mesostigmatid mites in P. sylvestris litter.
Stan odnowienia naturalnego jesionu wyniosĆego (Fraxinus excelsior L.) na znieksztaĆconych siedliskach z udziaĆem sosny zwyczajnej (Pinus sylverstrius L.)
Resistance Inducers for the Protection of Pedunculate Oak (Quercus robur L.) Seedlings against Powdery Mildew Erysiphe alphitoides
Oak powdery mildew caused by Erysiphe alphitoides (Griffon and Maubl.; U. Braun & S. Takam.) is a common disease in European forests. One of the most susceptible species is the pedunculate oak (Quercus robur L.). Presently, a few methods are available to control powdery mildew, e.g., the use of fungicides (e.g., based on citric acid), antagonistic fungi or bacteria, chemical treatments (e.g., sulphur, potassium bicarbonate) or genetic resistance. In our study, we aimed to check the effects of using chitosan derivatives and novel active substances inducing the plantsâ natural resistance: benzodiathiadiazole (both in neutral and salt form). 84 pedunculate oak seedlings were subjected to the experiment in three treatment variants (plus positive and negative controls). The plants were treated with active substances and inoculated with E. alphitoides. Although the powdery mildew symptoms appeared in all variants, they were manifested mainly by the mycelium in the form of small spots. The experiment indicated that the highest limitation of powdery mildew mycelium was achieved by applying N-methyl-N-methoxyamide-7-carboxybenzo(1,2,3)thiadiazole (BTHWA). The application of BTHWA reduced disease development by 88.9% when compared to the effects of the other variants.
Which soil properties affect soil mite (Acari, Mesostigmata) communities in stands with various shares of European ash (Fraxinus excelsior L.)?
ZmiennoĆÄ warunkĂłw glebowych siedlisk z udziaĆem jesionu wyniosĆego (Fraxinus excelsior L.) na przykĆadzie lasu wilgotnego. Stadium przypadku
Environmental role of differentâaged pine and oak stands growing on postâagricultural and forest lands in forming the Mesostigmata mites communities
AbstractReclamation of agricultural soil and forest succession after afforestation proceeds slowly and at many levels. Therefore, the history of land use is recorded in the soil's physical, chemical and ecological parameters for many decades. This process depends on time and the form of afforestation, which primarily includes tree species. In our study, we analyzed differences in the physical and chemical characteristics of pine and oak stands on forest and postâagricultural land at 22, 42 and 62 y/o. Our study revealed that 14 of 24 examined parameters (litter pH, soil pH, litter thickness, soil organic matter, Corg, bulk density, C/N ratio, soil moisture, soil K, Mg and Mn content, N and Ca litter content, Mg litter content) differed significantly among examined habitats (land use, stand age and tree species). We calculated the abundance, species richness and diversity of the mite communities (Acari, Mesostigmata) for each habitat type. In total, 6730 mites were classified into 72 taxa (60 species, 11 genera and one taxon as family). The highest abundance was recorded in 42 y/o. oak stands on postâagricultural land, while the lowest is in 22 y/o. pine and oak stands on postâagricultural land. The highest species richness and diversity were recorded in the oldest oak stand on postâagricultural land. In contrast, the lowest diversity was recorded in the youngest oak and pine stands on postâagricultural land. Our results demonstrate that the negative impact of the agricultural history of land use weakens over time and provides a better understanding of land use history on the relations between the soil environment and soil fauna, including mesostigmatid mite assemblages.
Recommendations for soil sample preparation, pretreatment, and data conversion for texture classification in laser diffraction particle size analysis
Impact of land use history and soil properties on soil mite communities (Acari, Mesostigmata) inhabiting stands growing on postâagricultural land
AbstractDecades of agriculture in a formerâtype of ecosystem, for example, deciduous forestsâresult in severe habitat degradation. The planted tree species encounter harsh conditions due to physically and chemically transformed soil environments. In addition, afforestation itself significantly modifies the upper soil horizons. It may impact the soil fauna communities, including mites from the Mesostigmata order (Mesostigmataâ=âGamasida). Due to their sensitivity, mesostigmatid mites are good bioindicators of changes in the soil. A decrease in the density, species richness, and diversity of mites indicates disturbances in the soil environment and may confirm the impact of agricultural practice on the soil environment. Our research aim was to examine the impact of soil properties and land use history on the mesostigmatid mite communities in stands growing on forest and postâagricultural lands. These sites were afforested with different tree species (Betula pendula Roth., Fagus sylvatica L., Pinus sylvestris L., and Quercus robur L.). Thus, 21 research plots were established on forest and postâagricultural land, each on rusty soils considered to be one of the most common in Central European forests. We collected a total of 567 soil samples during three sampling sessions in spring and autumn for soil Mesostigmata investigation. We also described the soil profile on each plot and collected soil and litter samples to measure pH, litter thickness, soil organic matter, bulk density, soil moisture, soil organic carbon, and elements content. Our study revealed that 16 out of 30 environmental parameters differed between habitat types. A total of 1355 mites were classified into 58 taxa (50 species and 8 genera). The most numerous species were Veigaia nemorensis (165 ind.; 12.2% of all mesostigmatid mites), Zercon peltatus (156; 11.5%), and Paragamasus conus (141; 10.4%). The highest abundance was recorded in birch stands on forest land, whereas the lowest abundance for oak stands growing on postâagricultural land. Interestingly, in oak stands we recorded both the highest diversity of mite communities (forest land) and the lowest on postâagricultural land. Furthermore, our study showed that postâagricultural land and Na content in forest litter affected the abundance, species richness, and diversity of mesostigmatid mite communities. Species richness was additionally affected by tree species, that is, pine and oak. Our research indicated that longâterm agricultural practice negatively affected the density, species richness, and diversity of Mesostigmata communities 20âyears after afforestation.