Evaluation of eyespot incidence and structure of Oculimacula spp. population in winter rye in Lithuania

Abstract

Eyespot of rye, caused by two fungal pathogens Oculimacula yallundae and O. acuformis, is widespread throughout many cool and wet cereal growing regions. The study was aimed to estimate eyespot incidence in winter rye crops in three agro-ecological zones of Lithuania, and to quantify eyespot disease causal agents O. yallundae and O. acuformis in the population using the real-time polymerase chain reaction (RT PCR) method. During the 2008–2012 periods, 69 winter rye fields were surveyed and eyespot-affected stems were identified in 92.7% of the crops surveyed. The incidence of eyespot in winter rye crops varied from 8.0% to 82.7% depending on the year and location. The average disease incidence in the reviewed crops was 26.0%. The highest incidence of eyespot averaging 34.0% was identified in the winter rye crops of the Middle Lowland zone. Both eyespot causal agents O. yallundae and O. acuformis were often found to co-exist on the winter rye stems. In the majority of the winter rye crops tested, O. acuformis was predominant in the Oculimacula spp. population. In most cases, O. yallundae was identified only at trace-level concentrations.