Ação de microrganismos no controle da pinta preta (Asperisporium caricae) in vitro

Abstract

Papaya production holds significant economic importance in global fruit farming, with the state of Espírito Santo being the leading producer in the national context, followed by Bahia, Ceará, and Rio Grande do Norte. The cultivation of papaya (Carica papaya L.) is widely spread across the country. However, the tropical climate favors the spread of fungal diseases, such as papaya black spot. Due to the losses associated with this disease, control measures that reduce the damage are necessary. Consequently, chemical control is the most commonly used method; however, due to its indiscriminate use, it can lead to the selection of resistant populations and have adverse effects on the environment and human health. In this regard, the objective of this study was to evaluate the action of different microorganisms in controlling the fungus Asperisporium caricae, the causative agent of papaya black spot. The research was conducted in the Phytopathology laboratory of Embrapa Cassava and Fruit, using a strain of Trichoderma asperellum and five bacteria from its collection, namely BAC1, BR12157, BR12137, BR12158, and BSF66, employing the direct confrontation method on Petri dishes to select antagonists of A. caricae. Five assessments were conducted over a thirty-day period. For the A. caricae sporulation test, the BDA culture medium and nutrient agar were used. It was observed that the bacteria BR12137, BR12158, and BSF66 did not exhibit antagonism against the phytopathogen. On the other hand, BAC1 and BR12157 showed inhibitory action, and T. asperellum grew across the entire plate, completely suppressing A. caricae. Furthermore, it was observed that the phytopathogen did not readily sporulate in artificial media, taking a month to start sporulating in nutrient agar, but it did not sporulate in BDA medium. Therefore, the microorganisms that inhibited A. caricae on Petri dishes were BAC1, BR12157, and T. asperellum, with the latter performing better. Bacteria BAC1 and BR12157, as well asT. asperellum, are potential agents for the control of papaya black spot.