Distribution of major pathogens casing root rot on winter wheat in Krasnodar, Stavropol and Rostov regions had been studied by KNIISH researchers during 2000-2005. Forty eight strains had been distinguished. Infestation of root system and coleoptile of various winter wheat varieties by Gaeumannomyces graminis var. Tritici showed that root damage varied between 63.3 and 100%, and stem base damage - between 0 and 80% depending on a variety. Infestation with Rhizoctonia spp. revealed that root system damage in this case varied between 36.3% and 100%, stem base damage - between 18.1 and 63.6%. Gaeumannomyces graminis var. Tritici reduced productive tiller number in winter wheat variety Krasnodarskaya 99 by 23.5%, plant height - by 32.3%, ear length - by 19.1%, number of spikes per ear - by 14.4% and TKW - by 45.5%. Fusarium fungi reduced the same figures by 18.5, 23.1, 42.2, 31.7 and 39.5% respectively; and Rhizoctonia - by 45.9, 15.4, 16.2, 5.6 and 19.5%.
Distribution of major pathogens casing root rot on winter wheat in Krasnodar, Stavropol and Rostov regions had been studied by KNIISH researchers during 2000-2005. Forty eight strains had been distinguished. The most pathogenic of the strains were used to evaluate winter wheat varieties´ response to these pathogens.
Infestation of root system and coleoptile of various winter wheat varieties by Gaeumannomyces graminis var. Tritici showed that root damage varied between 63.3 and 100%, and stem base damage - between 0 and 80% depending on a variety.
Maximal level of damage was observed on the variety Deya: root system - 100%, coleoptile - 80% (at G. gramynis var graminis infestation it had minimal damage: root system - 10.5%, stem base damage - 5.0%).
The lowest level of root system damage by Gaeumannomyces graminis var. Tritici was observed on a durum wheat variety Leukurum 21 - 63.6% as well as on bread wheat varieties Pamyat and Fortuna - 72.7%.
Stem base damage caused by this pathogen was not observed on varieties Batko and Moskovskaya 39.
Infestation with Rhizoctonia spp. revealed that root system damage in this case varied between 36.3% and 100%, stem base damage - between 18.1 and 63.6%.
The highest level of damage was observed on a durum wheat variety Leukurum 21: roots - 100%, stem base - 54.5%, and on bread wheat varieties Tanya (90.9 and 63.6%), Pamyat (72,7 and 63,6%), Batko (72,7 and 54,5%).
The lowest level of root damage was observed on Deya - 36.3%, and of stem base - on Moskvich, Nota, Yubilejnaya 100, Vostorg, Ermak, Krasnodarskaya 99, PalPich, Vita and Voronezhskaya 95 - 18.8%.
In 2007 root rot pathogens naturally occurred in field in the following proportion: Gaeumannomyces -74, Fusarium -14,5 и Rhizoctonia -10%. Their effect on grain yield structure is presented below.
Gaeumannomyces graminis var. Tritici reduced productive tiller number in winter wheat variety Krasnodarskaya 99 by 23.5%, plant height - by 32.3%, ear length - by 19.1%, number of spikes per ear - by 14.4% and TKW - by 45.5%. Fusarium fungi reduced the same figures by 18.5, 23.1, 42.2, 31.7 and 39.5% respectively; and Rhizoctonia - by 45.9, 15.4, 16.2, 5.6 and 19.5%.
As seeds were treated with Premis200 before sowing (0.2 l/t) the proportion of rot causing agents changed: Gaeumannomyces - 47,1%, Fusarium - 52,0%., while the reduction in yield components changed within the experimental error.
Pre-sowing treatment of the seeds with a mixture of lignogumat and Premis200 (0.2 l/t) increased root weight of winter wheat plants compared to the control variant where seeds were treated neither with disinfectants nor with bioactive substances.
As winter wheat varieties Leukurum and Moskvich were treated with Premis200 only under artificial infection conditions their root weight increase was 2-11% lower than when they were treated with both Premis200 (application rate decreased by 30%) and lignogumat. While in the varieties Vostorg and Voronezhskaya 95 application of Premis200 decreased root weight by 14-7%.
In those variants where only Premis200 was used both were observed increase in root system damage by 23.8% (variety Fortuna) and decrease by 54.6% (variety Deya). When both chemicals were used (Premis200 (application rate decreased by 30%) and lignogumat), root system damage either remained unchanged (varieties Tanya and PalPich) compared to that of the control, or decreased by 12.5% (variety Pamyat) - 60-66% (varieties Vostorg, Yubilejnaya 100, Doka).
As winter wheat varieties Tanya, Yubilejnaya 100 and Voronezhskaya 95 were treated with Premis200 only, the increase in their root weight under artificial Rhizoctonia infection lowered by 5-10%, while complex treatment of the seeds with both Premis200 (application rate decreased by 30%) and lignogumat caused increase of root weight by 1-5%.
In those variants where only Premis200 was used both were observed increase in root system damage by 55.6% (variety Deya) and decrease by 81.9% (variety Moskvich). After complex treatment of the seeds with both chemicals (Premis200 (application rate decreased by 30%) and lignogumat), root system damage either increased by 9 (variety Fortuna) - 36.4% (variety Pamyat) compared to that of the control, or decreased by 27.3% (variety Nota) - 72.8% (variety Moskvich).