Incidence of Phytophthora Fruit Rot on Four Durian Cultivars in Davao City, Philippines

Abstract

A two-year study was conducted in a farm in Davao City, Philippines, to investigate the incidence of Phytophthora fruit rot on four commercial durian (Durio zibethinus Murr.) cultivars previously laboratory-tested for their reaction to the disease using isolates of the pathogen, Phytophthora palmivora Butler. In year 1, disease incidence was highest on cultivars Alcon Fancy and Arancillo at 10.7% and 9.9%, respectively. Lesser infection was observed on cultivar Puyat (0.5%) and no infection was recorded for cultivar Seri Kembangan. The same trend was obtained in year 2, further confirming previous laboratory infection test results. Incidence on Alcon Fancy was 47.3%, followed by Arancillo (25.92%), Puyat (12.6%), and Seri Kembangan (2.1%). In monetary terms, the year 1 total of 545 infected fruits is equivalent to a potential income loss of PhP27,250.00, with PhP2900.00, PhP2697.00 and PhP204.38, respectively, coming from the three cultivars. In year 2, the total of 1233 total infected fruits translates to a potential income loss of PhP49,320.00. To this figure, Alcon Fancy cultivar with the highest infection (47.3%) contributed PhP21,873.34, followed by Arancillo (25.9%) with PhP15,967.35. Puyat at 12.9% infection shared about PhP11,925.00 and Seri Kembangan at 2.1% added an equivalent of PhP1294.65. Result of the study indicate that more disease management interventions will have to be exerted for the more susceptible but more commercially preferred cultivars. Several fruit nursery operators in Davao City expressed that propagating Alcon Fancy and Arancillo seedlings is no longer profitable since knowlegeable farmers do not patronize them anymore, citing high susceptibility to Phytophthora diseases as the primary reason.