Variáveis epidemiológicas e manejo alternativo na podridão negra do abacaxi

Abstract

The producion of fruit in Brazil is one of the sectors highlight of the agribusiness. The country has a wide variety of cultures due to the existence of diverse soil and climatic conditions, which provides economic results expressive. In Brazil, pineapple is one of the main cultivated fruits, and this production is mainly concentrated in the North, Northeast and Southeast regions. However, the yield of pineapple is still considered low due to its susceptibility to some diseases, causing significant losses. Among the main phytosanitary problems related this crop the black rot of pineapple fruit is the main postharvest disease. The etiological agent is Thielaviopsis ethacethica, a quiescent fungus that depreciates the commercial value of pineapple causing dark lesions in the fruit pulp. Due to the relevance of this disease to the crop and the high infection rate in the main producing regions, this study evaluated the effect of potassium phosphite (FK), calcium chloride (CaCl2) and calcium carbonate (CaCO3) in the postharvest period as an alternative to the use of the fungicide commonly used in the control of rot of the pineapple, with the aim of presenting a sustainable alternative and of prolonging the period of conservation of the fruit. The research verified the epidemiological variables that influence the development of the disease of two isolates of T. ethacethica and evaluated the effect of FK, CaCl2, CaCO3, in different concentrations (0.25, 0.5, 75 and 1%), applied in the of black rot postharvest management in pineapple fruits cv. Pérola, as well as to evaluate the effect these same treatments in vitro through mycelial growth measurement. For the epidemiological analyzes, the inoculum concentration (103, 104, 105, 106 and 107conidia.mL-1), wetness period (0, 12, 24, 36 and 48, 72 and 96 h) and temperature (15, 20, 25 and 30° C) ideal for establishment of the disease in pineapple. The results showed that FK and CaCO3 were able to control black rot in the fruits and in vitro the FK presented the best control of the pathogen, not differing significantly from the fungicide recommended for cultivation. The favorable conditions for the development of the disease were a wetness period of 24 hours and a temperature of 30° C, the different concentrations of inoculum did not differ in the re