Impact of growing seasons and pesticides used on the occurrence and severity of the gummy stem blight in melon cultivation in Brazil

Abstract

Recent agricultural expansion into regions of the Brazilian savannah or Cerrado has improved agricultural knowledge and management practices. Under this biome’s favorable conditions, the incidence of diseases such as gummy stem blight (GSB) could be a limiting factor for some crops (i.e., Cucumis melo L.), due to high losses in productivity and fruit quality. We conducted field experiments to assess the temporal progression of the incidence and severity of GSB disease in melon plants under five pesticide treatments and three growing seasons (dry, rainy, and transition periods). Furthermore, the susceptibility of six cultivars of melon to GSB was evaluated with and without pesticide application. In the dry season, although the incidence of the disease was high and dependent on the applied pesticides, its severity was low, allowing the crop cycle to be completed and marketable fruits to be harvested. However, in the rainy and transition periods, the high incidence and severity of the disease recorded in all plants, independent of the pesticides used, resulted in a premature end to the growth of the melon crops. Moreover, the commonly cultivated cultivar (Eldorado 300) showed a higher incidence and severity of the disease than the other potential cultivars. The results suggest that melon crops should be grown exclusively under the Brazilian Cerrado conditions during the dry season, dominated by favorable climatic conditions for the melon and unfavorable conditions to the pathogen. Other cultivars need to be investigated for their suitability to this region.