Epidemiological aspects of witches' broom disease of cupuassu tree in the microregion of Belem, PA, Brazil

A field experiment was set at Embrapa-Centro de Pesquisa Agropecuaria do Tr opico Umido, in Belem, PA(1 degrees 28' S; 48 degrees 27' W), from June/91 to May/94, aiming to follow vegetative brooms caused by Crinipellis pernici osa ((Stahel) Singer), produced in seven-year-old cupuassu trees (Theobroma grandiflorum (Willd. ex Spreng.) K. Schum.), from emission to basidiocarp production. Correlation coefficients between epidemiological variables (num ber of vegetative brooms, green and drying period, latent period, basidioca rp production) and climatic variables (maximum relative humidity of the air , sunshine, rainfall) were determined. The emission of vegetative brooms wa s observed mostly in July and August. Brooms remained green for 34.9 to 65. 2 days and dried after 5.8 to 10 days. After emission, vegetative brooms de layed from 79.5 to 347 days to begin basidiocarp production, which occurred mostly from May on, with the peak in June. The correlations between the cl imatic variables, maximum relative humidity of air and sunshine were signif icant only for basidiocarp production, with negative and positive effects, respectively.