3.7.39
FRUIT ROTS OF MANGOSTEEN AND THEIR CONTROL

S SANGCHOTE and R PONGPISUTTA

Department of Plant Pathology, Kasetsart University Bangkok-10900, Thailand

Background
Mangosteens (Garcinia mangostana) are a tropical fruit with high commercial appeal but poor keeping quality. Physiological disorders and disease both contribute to postharvest losses. However, increasing export market demand has led to the need to develop recommendations for controlling both postharvest diseases and disorders. To provide a basis for developing recommendations the cause of postharvest disease losses have been examined and some control measures have been assessed.

Materials and methods
Mature healthy mangosteen fruit were collected from orchards in Eastern and Southern Thailand. Prior to storage, isolations were made from various parts of half of the sound fruit. Subsequently, isolations were made from lesions that developed on the remaining fruit during storage. The effect of a postharvest dip in thiophanate-methyl on postharvest disease control was also assessed.

Results and conclusions
A high level of Pestalotiopsis sp. was recorded in assays of different parts of sound mangosteen, including the stem-end (pedicel), bracts, and stylar end, but it was a minor pathogen causing fruit rot. L. theobromae and Phomopsis sp. were also found on these parts of the fruit. L. theobromae was recovered more frequently from isolations from the stylar end. The array of fungi detected was similar for samples from both regions.

Several pathogens were recovered from disease lesions that developed on fruit during storage including: Lasiodiplodia theobromae, Colletotrichum gloeosporioides, Phomopsis sp., Gliocephalotrichum bulbilium, and Pestalotiopsis sp. L. theobromae was the main organism isolated most frequently from fruit from both areas. Dipping the fruits in thiophanate-methyl at concentration of 1000 ppm for 3 min reduced disease incidence by 20% compared with untreated fruits.

Further studies on the etiology of infection are required to develop improved control measures.