Aspectos epidemiológicos da queima das folhas da cenoura (daucus ca:rota l.) causada por aternaria dauci (Kühn) Graves & Skolko - parte II - efeito da concentração de inóculo e determinação do período de geração de alternaria dauci (Kühn) Graves & Skolko

Abstract

The effect of the concentration of conidial inoculwn of Alternaria dauci (Kuhn) Graves & Skolko in rela tion to the degree of severity of occurrence of leaf blight on carrot (Daucus carota L.) cultivar Nantes Half Long at 67 - 70 days of age, was studied, The plants were cultivated under green-house conditions innoculated by atomizing with spore suspension, a􀅊d after,,:ards,maintened for 72 hours in an incubation cha􀀠 ber with temperature controlled at 18 - 24QC and relative humidity of 100% (foggy}. The spore concentrations testes were O, 10 , 10 , 5 x 10 and 2 x 10 spores/rnl. There were significant differences in the treatments at the 5% level in relation to severity of the leaf blight, the total wei ght of the plants, and the weight of the roots. The generation period of the fungus was 6-7, 5, 6 and 6 days, respectively, at 16, 20, 249C and roam tem perature. Detached leaflets were innoculated individually, by using a small brush to spread the spores. After innocul,!! tion, the leaflets were maintained in a moisture chamber. The vitality of the inoculum, seems to be a highly impo􀁊 tant factor in the deterrnination of the geieration time of the fungus.