Tag Archives: epidemiology

137-140 I. Brazauskiene and E. Petraitiene
Epidemiological studies into Phoma lingam (teleomorph Leptosphaeria maculans) infections in winter and spring oilseed rape
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Epidemiological studies into Phoma lingam (teleomorph Leptosphaeria maculans) infections in winter and spring oilseed rape

I. Brazauskiene and E. Petraitiene

Lithuanian Institute of Agriculture, Department of Plant Pathology and Protection,Instituto alėja 1, Akademija, Kėdainiai distr. LT 58344, Lithuania;e-mail: brazausk@lzi.lt; egle@lzi.lt

Abstract:

Studies of the concentration of ascospores of Leptosphaeria maculans (anamorph Phoma lingam) in the air, appearance and variation of visual symptoms of phoma stem canker during the growing season of oilseed rape in relation to the main meteorological indicators were carried out. Spore samples, collected over 200 days in 2004 and 2005 using a Burkard spore trap, were analyzed using the method of microscopy. The first ascospores of Leptosphaeria maculans were found in the samples from 1 May 2004 and 9 April 2005. The abundance of ascospores in the air depended on the weather factors, especially the amount and frequency of precipitation. The first symptoms of phoma on the leaves of winter oilseed rape in 2004 were recorded at the end of October, and in 2005, in the spring crop on 3 May, i.e. three weeks later, after the first ascospores had been identified in the air. On 7 June 7 2005 the first symptoms of phoma stem canker were identified on stems of winter oilseed rape. Spring oilseed rape was more tolerant of phoma stem canker, compared with winter oilseed rape. At the end of maturity stage (BBCH 85), 83.2–81.0% of winter oilseed rape and 35.2–28.6% of spring oilseed rape stems with phoma stem canker symptoms were found in 2004 and 2005, respectively. Diseased stems of winter oilseed rape exhibited mostly double phoma symptoms – on the crown and on the stem 5 cm above the crown (78.4% in 2004 and up to 65% of diseased stems in 2005). Diseased stems of spring oilseed rape mainly displayed phoma symptoms 5cm above the crown (69.2–98.7%).

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