RELAÇÃO ENTRE A OCORRÊNCIA DOCOMPLEXO DE ENFEZAMENTOS EM HÍBRIDOS DE MILHO DOCE E A INFESTAÇÃO POR Dalbulus maidis (HEMIPTERA: CICADELLIDAE)

Abstract

Many studies have been conducted to identify the best strategies for controlling the corn leafhopper, including the use of chemical and biological insecticides, as well as efforts to optimize plant nutrition. However, another management practice that should be considered is the selection of hybrids that are more resistant to the pest and the associated diseases. Thus, the objective of this study was to evaluate the response of sweet corn hybrids to the stunt disease complex and to correlate disease severity with the population density of Dalbulus maidis. The study was conducted at the Sobradinho Farm of IFTM Campus Uberlândia, using a randomized block design with six treatments (hybrids THUNDER, SVSN9298, GSS227, GSS2577, GSS3188, and GSS2576) and four replications. The experimental plots consisted of four rows spaced 0.5 m apart, with each row measuring 5 m in length. A planting density of 60,000 plants per hectare was used. At 19 days after sowing (DAS), at the V5 phenological stage, the first evaluation of the number of leafhoppers was carried out by directly counting the insects present on the sweet corn plants, with further evaluations at 26, 33, 40, and 47 DAS. The resistance level of the corn hybrids to the stunt disease complex was assessed using a rating scale from 1 to 9, with a score of 1 assigned to resistant genotypes and 9 to susceptible hybrids. The sweet corn hybrids SVSN9298, GSS2577, GSS3188, and GSS2576 exhibited lower densities of D. maidis per plant, while the Thunder hybrid hosted a higher number of leafhoppers, indicating the pest’s preference for this hybrid. The highest infestation levels were observed at 33 and 40 DAS, with values of 4.37 and 4.46 individuals per plant, corresponding to an increase of 110% and 114%, respectively, compared to the first evaluation.