Prevalence and harmfulness of winter wheat brown leaf rust (Puccinia recondita Rob. ex desm. f. sp. tritici) in the Southern Steppe of Ukraine

Abstract

Apart from making farmers adapt agricultural technologies to new, more arid conditions in order to obtain sustainable and high yields, global climate change is also known to alter the pathogenicity of plant pathogens, the biological cycle of which is tightly associated with environmental factors. One of the most common diseases of winter wheat is brown leaf rust, caused by Puccinia recondita Rob. ex Desm. f. sp. tritici. In terms of its harmfulness and prevalence among other leaf and stem diseases, brown leaf rust is comparable to yellow and stem rust, septoria leaf blotch and other leaves blotches. Under arid conditions of the Southern Steppe of Ukraine, the disease manifests itself once every five years provided that sufficient moisture, indicated by the hydro-thermal index above 1.0, is present during the spring and summer vegetation periods. The main factor influencing the intensity of pathogen development is moisture supply from April to June (ΣTP> 50 mm). In 2019, the amount of precipitation during this period was 194 mm, which led to the disease development at the level of 18.4% with a spread of 27.2%. Productivity of winter wheat varieties such as Antonivka, Blago and Maria was reduced by 10.8-11.3%, when infected in the phase of milk grain stage (stages 73-77 on the BBCH scale), while net photosynthesis productivity decreased by 14.2-14.3%, which translates to lower average yields of 2.3-3.1 t/ha. To maximize the productive potential of varieties and effectively control the development of the causative agent of brown leaf rust in winter wheat under favourable conditions for epiphytic development, the application of systemic fungicides with long-term protective effect imparted by the chemical group of triazoles (Colossal e.c., 1.0 l/ha ) is recommended in stages 69-71 on the BBCH scale. This provides not only reliable crop protection (Eff.: 77.9-82.0%), but also yields at the level of 3.3 - 4.6 t/ha, depending on the variety under non-irrigated conditions.

The effect of diversity on disease reverses from dilution to amplification in a 22-year biodiversity × N × CO2 experiment

“…2c). This result was also consistent with the diversity-disease reversal because greater light penetration should reduce disease severity [39][40][41][42] . Soil moisture (H2B) increased with richness in 1999 (p = 0.003) and decreased with richness in 2019 (YxR: p = 0.017; Fig.…”

“…Similarly, in a grassland field experiment, plant diversity affected fungal disease severity most strongly via changes in humidity 5 . Fungal pathogens tend to grow best under warm, moist, shaded conditions [39][40][41][42] . In general, species richness could impact these habitat variables in dense communities that block light and inhibit evaporation.…”

Productivity of Winter Wheat Cultivated by Direct Seeding: Measuring the Effect of Hydrothermal Coefficient in the Arid Zone of Central Fore-Caucasus

“…While the investigations on the application of such widespread varieties as Triticum aestivum L. [69][70][71][72], Triticum aestivum Kosack [73], Triticum sphaerococcum [28], Triticum turgidum ssp. Durum [13,74], Kekeba [75], or Antonivka [76] in arid and semi-arid conditions have been rather abundant, the results on testing the performance of local winter wheat varieties in specific climate and soil conditions of Russia's South have not been presented and discussed in the international literature. Consequently, this study aims to bridge the above gaps by revealing the influence of the hydrothermal coefficient on the parameters of ecological and genetic variability of three local winter wheat varieties (Zustrich, Bagrat, Bagira) cultivated by direct seeding method in the arid zone of Central Fore-Caucasus.…”