The Influence of Shading on the Development of Podosphaera leucotricha under Field Conditions

N. MILETICH1, N. TAMAS1, P. VUKSA1, E. PFAF-DOLOVAC2 and N. DOLOVAC2
1Institute of Plant Protection, Department of Phytopathology, University of Belgrade–Faculty ofAgriculture, 11080 Belgrade, Serbia
2Institute for Plant Protection and Environment, Department of Plant Pathology, 11000 Belgrade,Serbia

Abstract

MILETICH, N., N. TAMAS, P. VUKSA, E. PFAF-DOLOVAC and N. DOLOVAC, 2012. The influence of shading on the development of Podosphaera leucotricha under field conditions. Bulg. J. Agric. Sci.,18: 178-184

The influence of shading on the incidence and development of P.leucotricha was examined at the locality of Belgrade, during 2008 and 2009. Investigation was carried out on two-year old apple nursery trees, cultivar Idared, sensitive to causal agent of apple powdery mildew. The experiment included three variants, two with different conditions of reduced light (24 h and 48 h shading, with 24 h in the natural photoperiod) and the third variant, which included the cultivation of plants in natural photoperiod, without shading. Reduced light conditions were achieved by growing the plants under wooden experimental boxes. The boxes provided minimum differences in air temperature and RH values, inside and outside them. Inoculum was provided from two trees that were close to the experimental boxes, and the infection was carried out by direct application of conidia from infected young shoots and naturally, during growing period.
Four assessments were made, three during shading period and one after removal of the experimental boxes. In both years of investigation, the highest intensity of infection was manifested in the first variant (48 h s hading, 24 h natural photoperiod), (14.0 - 100%), slightly lower in the second (24 h shading, 24 h natural photoperiod), (12.7–93.5%) and the lowest in variant of normal photoperiod, (0.1 - 16.6%). In shading variants, intensity of infection was rapidly increasing from the first to the third assessment, while in the fourth assessment, after the removal of boxes, it significantly decreased. The results of these studies indicate that light intensity significantly affects the appearance and development of P. leucotricha, and that apple powdery mildew develops intensively in the shade environmental conditions.

Key words: Podosphaera leucotricha, apple, shading, photoperiod

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