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Risk of damage to winter wheat by Pseudocercosporella herpotrichoides [Fron] Deighton, the causal agent of eyespot. II. Results of plot experiments

100%

Jaczewska-Kalicka A.

Journal of Plant Protection Research

1998

tom 38

nr 2

In 1987-1990 plot experiments with winter wheat were performed to investigate grain yield losses caused by Pseudocercosporella herpotrichoides. Each year wheat was sown after a cereal forecrop to increase the disease risk. Eyespot developed under natural infection conditions. In 1988 an additional experiment was established on plots artificially inoculated with P. herpotrichoides to increase infection pressure. Experimental variants included plots protected with 5 benzimidazole fungicides to control the pathogen, and chemically unprotected plots. As the effectiveness of fungicides was satisfactory, the differences in grain yield from protected and unprotected plots were regarded as grain yield loss in conditions of lack of appropriate chemical control of the disease. Average grain yield losses for the years 1987-1990 amounted to 4.21 dt/ha (10.36%). The highest losses of 8.43 dt/ha (30.28%) occurred in 1990, when weather conditions were the most fovourable to the development of eyespot, and on artificially inoculated with P. herpotrichoides plots in 1988 (5.56 dt/ha, 12.75 %). The paper also presents detailed data on the occurrence and severity of eyespot at GS 75-85 as related to grain yield losses, and data on the influence of the disease on some yield components, with a special reference to 1000 grain weight. Correlation coefficients between the most important factors related to the disease incidence revealed that grain yield and 1000 grain weight were most strongly correlated with infection index at GS 75-85. A significant correlation between the disease occurrence at GS 31-32 and the above characteristics occurred only when more than 10% plants showed infection symptoms in the spring. Severe infection occurred only in 1990, when weather conditions were conductive to the development of the disease. The results presented are also discussed in relation to parallel field observations on 356 commercial fields located in all the regions of winter wheat cultivation in Poland, published elsewhere. lt has been concluded that chemical control of eyespot on the experimental plots could have been justified only in 1990 conductive to the disease development. Economical feasibility of using fungicides at GS 31-32 could be most likely to obtain with broad spectrum fungicides, effective against eyespot and other diseases occurring at early growth stages of winter wheat. This publication as well as the previous one published under the same title as Part I, are the first reports on grain yield losses caused in Poland by P. herpotrichoides.

Progi szkodliwosci ulatwia decyzje

51%

Janczak C., Pawlak A.

Agrochemia

1996

nr 05

3-5

Ograniczanie wyników

1 Agrochemia

1 Journal of Plant Protection Research

1 Jaczewska-Kalicka A.

1 Janczak C.

1 Pawlak A.

1 1998

1 1996

Wyniki wyszukiwania

Risk of damage to winter wheat by Pseudocercosporella herpotrichoides [Fron] Deighton, the causal agent of eyespot. II. Results of plot experiments

Progi szkodliwosci ulatwia decyzje