Abstract
ABSTRACT Field experiments were conducted during spring 2014 and fall and spring 2015 to determine the effect of fresh mulch on the development of Phytophthora infestans epidemics, in Lapa Municipality, Parana State, southern Brazil. The used cultivars were ‘Agata’, susceptible, and ‘BRS Ana’, moderately susceptible. The main treatment consisted in manually applying a 10cm-thick layer of fresh mulch when potato sprouts were emerging. Fresh mulch was prepared with plants available at that time of the year. For the spring experiments, fresh mulch was a mixture of oats, rye grass and wild radish (60 t/ha) and for the fall experiment, semi-ripe elephant grass (90 t/ha). Plots consisted of six 10m-long rows, spaced at 0.8m, containing 28 plants per row. Experimental design was in completely randomized blocks with four replicates. Natural inoculum was adopted. Percentage of leaf area was weekly estimated until the end of the plant cycle and the area under the disease progress curve (AUDPC) was calculated. Application of fresh mulch significantly reduced AUDPC by 32.1%, 12.4% and 23.1%, compared to control in all seasons, for ‘BRS Ana’ and by 26.1%, 2.8% and 12.0% for ‘Agata’. Application of fresh mulch showed to be a promising practice for the integrated management of late blight and for the protection of yields, especially in periods more favorable to the development of the disease. More detailed studies should be conducted on the plant type and amount of fresh mulch to be used, as well as on the possibility of reducing concentrations or increasing intervals between fungicide sprays.
Highlights
Experimentos de campo foram executados durante a primavera de 2014 e outono e primavera de 2015 para determinar o efeito de cobertura verde no desenvolvimento da epidemia de Phytophthora infestans, no município da Lapa, Estado do Paraná, região Sul do Brasil
Even though a large number of chemical, physical and biological variables and their interactions are involved when the soil is covered with plant material, the objective of this study was solely to determine the effects of fresh mulch on PLB epidemic in potatoes under subtropical southern Brazilian conditions
Under southern Brazilian conditions, the fall season is more prone to PLB development, since air temperature decreases and relative humidity increases during the growing period
Summary
Experimentos de campo foram executados durante a primavera de 2014 e outono e primavera de 2015 para determinar o efeito de cobertura verde no desenvolvimento da epidemia de Phytophthora infestans, no município da Lapa, Estado do Paraná, região Sul do Brasil. Dvorák et al (4) studied the influence of straw mulch, black textile mulch, in comparison to conventional potato cultivation, on canopy microclimate variation, PLB intensity and yield during two growing seasons in Czech Republic. They concluded that straw mulch significantly reduced the favorable weather conduciveness of PLB and haulm infection, and increased the yield in comparison with conventional cultivation. Dalla Pria et al (2) compared black polyethylene cover prior to transplanting pak choi and white polyethylene cover suspended over pak choi plants after transplanting They observed that there was a significant reduction in Alternaria sp. They observed that there was a significant reduction in Alternaria sp. when white polyethylene cover was used
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