Improved disease management system for mango anthracnose and stem-end rot

In the Philippines, anthracnose and stem-end rot are considered the most serious and destructive diseases of mango. Anthracnose infects almost all mango parts including floral panicles, twigs, leaves, and fruits of mature and immature trees. Next to anthracnose, stem-end rot is considered a major problem limiting the storage and shelf life of mango fruits. This disease occurs only on ripe fruits where rotting usually begins at the stem end. In May 2002-May 2004, Opina (UPLB) studied on integrated disease management alternative to control anthracnose and stem-end rot of 'Carabao' mango and reduce the incidence and severity of these important diseases. Specifically, the research project aimed to identify fungicides that can provide optimum protection to mango fruits with optimized application frequency. Under moderate-high-disease pressure, application of either mancozeb or azoxystrobin at 7-, 10- and 14-day spray interval significantly provided adequate protection against fruit rot. Under low disease pressure (ECJ Farm), two sprays of mancozeb (need-based spray program) provided acceptable level of protection against fruit rot. The protectant fungicide, mancozeb, applied at least four times during the early fruit development, 35-75 days after flower induction (DAFI), provided 53 percent control of fruit rot incidence and 83 percent disease severity. One or two applications of systemic fungicide (azoxystrobin) at early fruit development (35-45 DAFI) provided adequate fruit protection. Additional application of azoxystrobin gave high level of fruit protection or complete freedom from fruit rot infection. Azoxystrobin applied three times during fruit development achieved 95-99.6 percent control of fruit rot while five sprays of mancozeb attained 50-75 percent control. While azoxystrobin was 44 percent more expensive than mancozeb using the above spray applications, the additional expense was compensated with the added control efficacy. Under low-to-moderate disease, pressure spray combination of mancozeb-azoxystrobin applied at young fruit stage (35-70 DAFI) or before bagging reduced fruit rot incidence and severity to as low as 10 percent and 1 percent, respectively. Under high-disease pressure, additional spray of protectant or systemic fungicide was required to achieve similar result. The effectiveness of the same test fungicide and their spray combinations against stem-end rot was not determined with certainty due to low incidence of the disease. Experiments to improve the fruit bagging technique failed to demonstrate the significant effect of bagging, time of fruit bagging, and bagging materials and dimension on the incidence and severity of fruit rot and stem-end rot.