The response of mango stem end rot pathogens to heat

Abstract

In Australia, stem end rot of mango is caused by Dothiorella spp., Lasiodiplodia theobromae, Phomopsis mangiferae and other fungi. D. dominicana is the major cause of mango stem end rot in Queensland. Previous studies have shown that in the cultivar Kensington Pride, stem end rot is less effectively controlled by heat treatments (eg. hot water and vapour heat) than anthracnose (Colletotrichum gloeosporioides and C. acutatum). To investigate the reasons for this, the in vitro heat tolerance of selected isolates of D. dominicana, L. theobromae and Phomopsis sp. was studied. Mycelial suspensions of each isolate were immersed in hot water (at temperatures ranging from 46 – 55°C for times of up to 60 minutes), rapidly cooled and then plated onto potato dextrose agar. Isolates of D. dominicana were found to be the most heat resistant of the three species, and Phomopsis sp. the least heat resistant. In mango fruit (cv. Kensington Pride) inoculated with D. dominicana or L. theobromae however, vapour heat treatment (fruit seed surface temperature of 46.5°C for 10 min) more effectively controlled stem end rot caused by D. dominicana than that caused by L. theobromae. The significance of these findings will be discussed.