Spring barley is an important high-value crop globally.However, it is highly susceptible to soil-borne diseases in Kazakhstan and the world. Bipolaris sorokiniana (Sacc.) Shoemaker is the most important soil-borne pathogen that causes root rot and spot blotch diseases in cereal crops. This study aimed to evaluate the ability of B. sorokiniana isolated from spring barley leaves to survive in plant residuals of different crops. The fungus was isolated from spring barley leaves from the Zholbarys agro farm of Kerbylak district of Almaty, southeastern Kazakhstan, in 2021. Laboratory experiments were conducted at Kazakh National Agrarian Research University. The study was conducted on 10 th days of seedlings of cereal, legume, and oilseed crops. The obtained results showed that seedlings of spring barley, spring wheat, and oats retained the B. sorokiniana infection. Interestingly, the infection of B. sorokiniana isolated from leaves of spring barley statistically significantly increased symptoms of spot blotch on spring wheat and spring barley seedlings, while symptoms decreased on oats (P-value <0.01). The introduction of rapeseed, chickpeas, peas, and oats into the crop rotation system in southeastern Kazakhstan could limit the volume of the B. sorokiniana infection in spring wheat and spring barley. On rapeseed, peas, and chickpeas seedlings no symptoms of spot blotch were observed (P-value <0.01).

One of the main drawbacks of winter wheat varieties cultivated in Kazakhstan is their lack of resistance to common root rot. In 2020-2022, samples affected by root rot were taken in the earing phase in stationary experiments of the department of field crops and plant protection of the Kazakh research institute of agriculture and plant growing in the Almaty region. The research aimed to study the harmfulness of common root rot in commercial varieties of winter wheat. The weather did not significantly affect the harmfulness of common root rot. The harmfulness of the disease depended on the variety and degree of disease infestation. These indicators correlated with indicators of plant height, spike length, number of spikelets, and number and weight of grains (p<0.05). All varieties were affected by the disease to a low and moderate degree. In the varieties Almaly and Steklovidnaya 24, yield losses from the disease were 6.4-6.8%; in Farabi, Azharly, and Zhetysu 8.8-9.4%; and in Naz 13.0%. A total of 32-41% of plants were affected by the disease to a low degree and 10-21% to moderate and severe degrees. With a low degree of infestation, yield decreased by 2.4-7.1%, and with moderate and severe degrees by 4.5-12.1%. Factors of the degree of plant infestation and variety correlated (p<0.05) with dependent variables of productive business, stem length, spike length, number of spikelets, and weight of 1,000 grains. Using the method of linear regression, the authors concluded that the winter wheat spikelet number variable was significantly influenced by the variables of stem number (medium correlation) and spikelet length (strong correlation).

Cereals in the southeastern part of Kazakhstan can be affected by the crown and common root rot and spot blotches mostly caused by Bipolaris sorokiniana and Fusarium spp. Triticale is a man-made crop obtained from the crossing of wheat (Triticum sp.) × rye (Secale cereale L.) and it is mainly cultivated as a feed grain for livestock in Kazakhstan. Mycotoxins are secondary metabolites of fungi secreted by the toxigenic species Alternaria, Aspergillus, Fusarium, and Penicillium. The study aimed to determine the effect of the varietal factor and the type of mycotoxin on their content in 15-day triticale seedlings. The spread and development indices of root rot were calculated and the Liquid Chromatography coupled with tandem Mass Spectrometry (LC-MS/MS) was performed to determine the concentration of mycotoxins. The content of micro-toxins depended both on their type and the triticale variety (P-value <0.001). The maximum content of mycotoxins Ochratoxin A and Deoxynivalenol in some seedlings reached 100-120 mcg/mL, on average 12.4 and 15.1 mcg/mL, respectively. In Rondo, Fidelio 5, and Valentin varieties, the mycotoxin content was 11.2; 16.9, and 8.6 mcg/mL, with a spread of 79.0-93.0%, the development of common root rot reached 30.5-34.2%, while in Idea, TI 17, Nevo and Dokuckaevsky 9, the average mycotoxin content was lower, within 1.4-3.9 mcg/mL, with a spread of 50.0-65.0% and the development of common root rot reaching 20.5-25.0%. In the triticale Alnaiskii 5 variety, these indices equaled 0.7 mcg/mL; 55.0 and 19.2%, respectively. A high positive correlation (0.8) was found between the content of mycotoxins and the infestation of triticale seedlings with root rot.