Caracterização patogênica e fisiológica de Pestalotiopsis mangiferae ocorrente em mangueira cv. ‘amrapali’

Abstract

Brazil is one of the largest producer and exporter of mango, having an important role in generating income. The market demands a high level of product quality, which intensifies the phytosanitary control and post-harvest treatment of the fruits. The fungus Pestalotiopsis mangiferae causes a disease popularly known as gray leaf spot and stem rot in post-harvest fruits, capable of reducing fruit productivity and shelf life. This work aimed to carry out the pathogenic and physiological characterization of P. mangiferae. Six isolates were obtained from leaf lesions of mango cultivar 'Amrapali'. For the physiological evaluation, P. mangiferae isolates were streaked on the Petri dishes containing BDA medium and subjected to incubation in a BOD chamber at 25°C under three light regimes (0 hours, 12 hours and 24 hours) for 6 days. The evaluations were carried out daily on Petri dishes, with the help of a digital caliper to obtain growth measures. After 6 days of inoculation (DAI) at 25ºC, a total of 10 mL of sterilized distilled water was added to each Petri dish, followed by the release of the spores with a Drigalsky loop. For the pathogenic characterization, the isolates were inoculated in leaves and submitted to controlled conditions of humid chamber in transparent acrylic boxes (gerbox) with constant humidity maintenance. The design was completely randomized, with six leaves of Mangifeare indica per isolate of P. mangiferae and one leaf per gerbox. The evaluations were performed by measuring the lesions on the leaf abaxial surface at 2, 4, 6, 8 and 10 DAI, with the help of a digital caliper, obtaining the size of the lesions in mm2 . The N-01-15 isolate was statistically superior to the other isolates in terms of the spotted leaf area (SLA) and the area under the progress disease curve (AUPDC), all isolates were able to cause injuries to the mango leaves. Regarding physiological evaluation, the daily light hours regime directly influences mycelial growth and spore production of P. mangiferae.