Epidemic evolution of Cercosppora leaf spot (Cercospora beticola Sacc.) under Ezăreni farm conditions

Abstract

This study presents the evolution of Leaf spot caused by Cercospora beticola on sugar beet plants (Beta vulgaris L.) cultivated on Ezareni Farm conditions from U.S.A.M.V. ”Ion Ionescu de la Brad”, Iasi. Infections caused by this pathogen occurs each year with a different intensity mainly dependent on climatic conditions, at this losses are contributing: the variety cultivated, the moment of infection, harvesting age, also presence of abiotic stress factors or other diseases. The study of this pathogen was due to the fact that, the differences between cultures treated properly and those inadequately (by reducing the number of treatments, optimal timing of intervention failure, wrong application of plant protection products etc.). This differences are often 10-15% higher compared with estimated production and for untreated cultures reach values of 30-35% [Cioni, F., Maines, G., 2010]. The experience were conducted during 2009, at the experimental field from Ezăreni Farm. The biological material for study consisted in five sugar beet varieties and hybrids and the settlement of cultivar were based on block method, in three repetitions. Studied varieties showed different levels of resistance to the fungus Cercospora beticola Sacc attack. Observations and determinations consisted in a frequent register of the pathogen Cercospora beticola Sacc. on sugar beet leaves, aiming the frequency (F%), intensity (I%) and degree of attack (GA%). As criteria for assessing this pathogen attack level was used a scale with six classes of intensity attack, corresponding to intervals of intensity attack percentage (Rafaila, C., 1980).