DESEMPENHO AGRONÔMICO E FITOSSANITÁRIO DO MILHO EM RESPOSTA AO USO DE BIOINSUMOS

Abstract

Significant losses in corn yields have been caused by the leafhopper Dalbulus maidis and the complex of diseases it transmits. Due to the high migration power of the insects, controlling the pest is difficult. In the search for alternatives to chemical control, bio-inputs can bring positive responses in the integrated management of this pest and in the yield of the corn crop. This research evaluated the agronomic and phytosanitary performance of maize plants attacked by D. maidis and treated with bio-inputs based on microorganisms applied via seed treatment and spraying on seedlings. In the seed treatment trial, the following were tested: control (untreated seeds), Rhizophagus intraradices, Bacillus thuringiensis, Azospirillum brasilense, Trichoderma harzianum, Bacillus subtilis, Metarhizium anisopliae and fipronil + fludioxonil, arranged in randomized blocks with three replications. The same treatments were tested in the spraying trial and the bio-inputs were sprayed at 10 days after planting (DAP). The population of D. maidis was assessed at 10, 20 and 40 DAP, plants with symptoms of Maize rayado fino virus and severity at 20 and 40 DAP, plants with symptoms of canker at 80 and 100 DAP and the area under the disease progress curve. In addition, the diameter of the stalk, height and insertion of the first ear, length and diameter of the ear, weight of a thousand grains and yield were assessed. Plants treated with R. intraradices showed less progression of the symptoms transmitted by D. maidis and higher yields. Plants treated with T. harzianum showed a lower number of plants with Maize rayado fino virus in both evaluations. In the treatment sprayed with A. brasilense there was less progression of the diseases and with B. thurigiensis there was greater productivity. Higher yields occurred in the sprayed trial compared to the seed treatment due to the lower population of D. maidis. However, transmission of MRFV + mollicutes was 28% in both trials.