DISEASES SURVEY OF EXOTIC TREE SEEDLINGS AT ANGKHANG, CHIANGMAI PROVINCE

Abstract

The study, carried out at the nursery site of the Highland Reforestation Project in Doi Angkhang Chiangmai Province, was aimd at surveying various kinds of diseases occurring on 1 - 2 year - old seedlings of 3 introduced tree species, namely Acacia confusa, Liquidambar formosana and Fraxinus griffithii. The results revealed that seedlings of all species were infected with spot and blight diseases. The level of severity was as follows: 92.1% and 90.7% of 2 – years - old Liquidambar formosana, 94.0% and 67.7% of 1 – year - old Liquidambar formosana, 95.5% and 98.8% of 1 – year - old Acacia confusa and 68.2% and 44.8% of Fraxinus griffithii were infected with spot and blight diseases, respectively. Based on this study it was found that Acacia confusa seedlings were the most susceptible species to the diseases while Fraxinus griffithii seedlings were the most resistant species. However, between 1 - 2 year - old Liquidamber formosana, it was found that 2 years old seedlings were more vulnerable to the blight disease than 1 year old seedlings due to lack of nutrition in the planting container compared with the latter.