Ocorrência da mancha cinzenta - cercospora zeae-maydis do milho -zea mays L. na província de Niassa

Abstract

The present work was carried out in Niassa province, in the fields of Estação Agrária de Lichinga (EAL) and in the districts of Sanga, Muembe (locality of Muangata and Naikwanha) and Lichinga (localities of Lumbi and Mussa), in the period from 11th of February December 2002 to May 29, 2003. This study aimed to evaluate the occurrence of gray gait (Cercospora zeae-maydis) in maize (Zea mays L.). in order to achieve the objectives of the work, the essays were divided into three groups: "Mothers", "Babies" and "Peasants" (which in turn were divided into two sub-groups, namely Peasants from group A- constituted by three varieties and Peasants of group B - consisting of four varieties). The 'Mothers' bioassay was carried out in a randomized complete block design, split-plot arrangement, with the experimental plot consisting of fertilization (two treatments-fertilization and non-fertilization) and the subplot by corn varieties (twenty-two varieties), with three replications. The "Babies" was carried out in a randomized complete block design, with two replications and twelve varieties. The "Camponeses" trial was also carried out in a randomized complete block design, arranged in factorial experiments (3x3, with two replicates-para. farmers in group A and 3x4, with three replications - for farmers in group B) with varieties and locations (Naikwanha, Muangata and Sanga) for both groups.The studied biological characteristics were: disease incidence, disease severity and yield a correlation was made between the three characteristics. The results were submitted to analysis of variance in the statistical package SISVAR-S Statistical and Genetic Analysis Systems of the Federal University of Lavras) and the means to those submitted to the Scott and Knott test (P<0.05). The correlations were made in the SAEG program - Statistical and Genetic Analysis Systems at the University of Viçosa. The results obtained showed that the district of Sanga had a higher incidence of the disease compared to Muembe (Naikwanha and Muangata). It was also observed that the Matequenha variety is the one with the greatest severity of the disease, in the farmers' trials, which suggests that local varieties are not always the ones that react best to the disease. It was also found that the varieties Zm 621 Fc3, Sussuma, Syn Qc4, Syn2 Qc4, Zm521 Af &Zm Bf, Comp 01 Malawi -#, 00 Sadvi F3, Matuba and Manica Sr, present greater disease severity in the "Mothers" tests. The maximum severity was reached by the variety Weevil A/B C (44.5%) in the "Babies" trials. there was a strong correlation between the incidence and severity of the disease.