Efeito da época de inoculação do vírus do mosaico das nervuras por Aphis gossypii Glover (Hemiptera: Aphididae) no desenvolvimento e na produção do algodoeiro

Abstract

Aphis gossypii Glover is the vector of the Cotton Vein Mosaic Virus (CVMV), which causes serious damages to cotton. This work was carried out in a greenhouse at UNESP - Universidade Estadual Paulista, in Jaboticabal, São Paulo State, Brazil, to evaluate the effect of inoculation date of the CVMV on growth and yield of cotton plants. Cotton plants of cultivar CNPA ITA 90 at 20, 27, 34, 41, 48 and 55 days after the emergency (DAE) received one wingless viruliferous adult of A. gossypii, which remained confined in the plants for 48h. The percentage of plants with the symptoms of the disease and its influence in the phenological aspects of cotton plant were evaluated. The age of the plants did not influence the transmission efficiency of CVMV by A. gossypii. Percentages of plants showing disease symptoms varied from 40% to 65% when inoculated at 20 and 48 DAE, respectively. Plant height was reduced in 54.5% when they were infected 20 DAE and 1.3% when infection occurred at 55 DAE, as compared to the control. The number and diameter of the bolls were also influenced by the age the plants were infected. Plants inoculated 20 DAE did not produce cotton. Plants inoculated 55 DAE produced 20.7 g of cotton/plant, significantly less than control plants (35.9 g/plant). The severity of the symptoms was directly associated to the age the plants were infected with CVMV.