NURSERY DISEASES IN THE NORTHEAST OF THAILAND Y KAWABE l, S KAMIZORE 2, and H AIHARA 2 l Kyushu Research Center, Forestry and Forest Products Research Institute, Kurokami 4-11-16, Kumamoto 860, Japan; 2Reforestation and Extension Project in the Northeast of Thailand, Mahasarakham Nursery Center, Ban Kuthong, Tambon Kuthong, Amphur Chiangyeun, Mahasarakham 44160, Thailand Background and objectives Forest in Thailand has seriously decreased within the past thirty years. The Reforestation and Extension Project in the Northeast of Thailand (REX) between Japan International Cooperation Agency and Royal Forest Department of Thailand, started to promote reforestation activities by local people in the Northeast of Thailand, through a social forestry approach at April 1992. Nursery field of REX has four large scale nurseries and these nurseries produced about one million of seedlings a year. As production of seedlings progressed, damages of diseases appeared in practices of seedling production. There are a few reports about diseases of seedling tree and nursery in Thailand[l, 2]. We tried to survey seedling diseases in REX nurseries and indicate diseases important to seedling production. Materials and methods.< /b> Seedling diseases were surveyed at four large scale nurseries on Mahasarakham, Udonthani, Yasothon and Nakhonratchasima Nursery Centers of REX, located on each prefecture in the Northeast of Thailand, at December 1996 and July to August 1997. Surveyed seedlings cultured in plastic pot were current or biennial. Results and conclusions Ninety-one species of seedlings were surveyed, and something symptom of diseases occurred on about fifty percents of them. Symptoms of diseases occurred almost on leaves and stems of seedlings. Diseases brought severe damages into the growth of seedling were as follows. Powdery mildew (pathogen Oidium sp.) occurred on Acacia mangium and A. auriculiformis. A. mangium-,/i> was more susceptiblity than A. auriculiformis. Small size seedling at a few months was very susceptible to this disease and died as the case may be. However, seedling was becoming resistant to the disease by growing and damage of seedling was reducing. Rust (Ravenelia sp., Olivea tectona and unknown) occurred on Dalbergia cochinchinensis, Tectona grandis and Afzelia xylocarpa. Black tar spot (Phyllachora sp.) occurred on D. cochinchinensis and P. macrocarpus. Brown leaf spot caused by Cercospora sp. occurred on P. macrocarpus. Brown circular leaf spot (unknown) occurred on D. cochinchinensis
  • . In these four kinds of diseases, deformation and necrosis of leaves were severer as size of seedling was smaller, and defoliation happened at the earlier stage. When D. cochinchinensis or P. macrocarpus became plural diseases, damage of seedling become more seorious. All of these diseases were discovered in all surveyed nurseries. Those species of seedlings are mainly produced as local and economical tree, or first growth tree in REX nurseries, because local people are favorite them to reforest. Although sanitation practices aiming to reducing the inoculum sources of pathogenic fungi in nursery by removing and burning infected seedlings are needed for control of diseases at first, they are not enough. Therefore we pointed out necessity of chemical uses to control those seedling diseases. References 1. Giatgong P, 1980. Host index of plant diseases in Thailand (2 ed.), Bangkok, pp.1 18 2. Tanaka K, 1992. CFRUTC Research Report 3, Research and Training in Re-afforestation Project, RFD of Thailand and JICA, Bangkok, pp.1 1-20