Mass occurrence of sunflower head rot (Sclerotinia sclerotiorum) and its effect on yield in 2005

Abstract

In 2005, sunflower crops were attacked by the causal agent of Sclerotinia head rot (Sclerotinia sclerotiorum). The year 2005 was the year with the highest severity of this disease since the beginning of sunflower growing in the region. The number of diseased plants ranged from 2-3% to over 60% depending on the area and plot. Plots with a much larger percentage of diseased plants were reported as well, but they were very rare. By monitoring diseased plants of over 50 hybrids grown in 21 locations, we determined that the severity of Sclerotinia head rot varied between 27 and 36%, meaning there were more than 30% of diseased plants on average looking at the entire sunflower-growing area of the country. Because of this, the average sunflower yield was reduced by one third relative to estimates made before the disease broke out. The severity of the disease was the greatest in the following locations: Sombor, Aleksa Šantić, Bačka Palanka, Novi Sad and Bački Petrovac. The lowest incidence of the disease was reported in the Požarevac area and further to the south of the rivers Sava and Danube. All foreign and domestic sunflower cultivars tested in the country showed varying degrees of susceptability to sunflower head rot. None of the cultivars exhibited complete resistance to the disease.

Tokom 2005. godine usev suncokreta je bio napadnut od prouzrokovača bele truleži glavice (Sclerotinia sclerotiorum). Ovo je bila godina sa najvećim intenzitetom pojave ove bolesti od kada se suncokret gaji na našim prostorima. Broj obolelih biljaka od bele truleži glavice je varirao od 2 do 3% pa do preko 60 % u zavisnosti od regiona i od parcele. Bilo je i parcela sa mnogo više obolelih biljaka ali su one ipak bile veoma retke. Na osnovu praćenja obolelih biljaka u 21 lokalitetu sa preko 50 hibrida utvrđeno je da se bela trulež glavice javila u obimu od 27 do 36 %. To znači da je bilo u proseku preko 30 % obolelih biljaka gledajući celo proizvodno područje suncokreta. Samim tim, prosečan prinos suncokreta bio je smanjen za 1/3 u odnosu na ono kako je suncokret obećavao pre pojave ove bolesti. Najviše je oboleo suncokret u lokalitetu Sombora, Alekse Šantića, Bačke Palanke, Novog Sada i Bačkog Petrovca. Nasuprot ovome najmanji broj obolelih biljaka utvrđen je u regionu Požarevca i južnije idući od Save i Dunava. Sav svetski sortiment koji je testiran kod nas pokazuje veću ili manju osetljivost na belu trulež glavice a potpune otpornosti nema.