DURIAN (Durio zibethinus) subject to various pests and diseases throughout the year. Attacked of pests and diseases on durian tree started from seedling stage to harvesting stage that cause serious damage if not properly controlled. Durian diseases divided to Seedling and root diseases,Trunk and branch diseases, Foliar diseases and Fruit diseases. This article I would like to share my knowledge about the durian diseases based on various study in Malaysia, Thailand, Indonesia and other growing durian countries. Few technical durian book from various researcher and extension bulletin are use as references in this article.
4) FRUIT DISEASES
4.1 FRUIT ROT (Type 1 - Phytium palmivora)
This disease caused by fungus Phytium palmivora and trouble a serious fruit rot of durian due to effect in the market. The symptom first appear of hydrotic patches on the surface of fruit. White cottony mycelia and sporangia forms forms n necrotic lesion under moist condition. The rot can extend to the arillate seeds. Spray directly fungicide such as captafol, acetate, maneb or mancozeb as a systemic fungicide. Make sure the spray does not leave any toxic residues on the edible fruits. Use the high power sprayer spray gun system for high located fruit at the durian tree.
4.2 FRUIT ROT (Type 2 - Sclerotium rolfsii)
This fruit rot disease are caused by a type of fungi namely Sclerotium folfsii or Corticum rolfsii. The appearance of fan-shape tufts of thick mycelial strands growing on a water soaked, brown, necrotic lesion on fruit. From my observation, it was commonly found on the fallen frruit on the ground. Internally the seeds also rot and able to discolouring the cotyledons. The agonomic practices to control is to collect all the fallen fruit and discarded daily. At the base of durian tree should kept free from any undergrowth due to creation of warm moist condition that ideal for the fungi spread.
4.3 FRUIT ROT (Post harvest)
The post harvest fruit rot occurred in different forms due to the nature of causal agent. In most cases as I surveyed, the lesions produce on the fruits consists of irregular necrotic patches of various shade of brown which darken overtime. If this accociated with Rhizopus, Mucor or Lasiondiploida, the lesions are soft when pressed and the necrosis often extend to the inner wall of the rind. Post harvest of fruit rot can be minimised by more frequent fruit picking. The ideal fruit picking about 2-3 time a day and brush all dirt (soils, leaves & others) immediately. To reduce the fruit falling impact to the ground, I normally advise the farmers to construct nylon or wire netting beneath the tree during ripening periods. The durian fruit fall to the netting reduce the damage and fruit rot problem.
(2 January 2013)