Materials & Methods
The study was conducted at rubber plantations comprising rubber trees of the H. brasiliensis RRIM 600 variety in Nakhon Si Thammarat and Songkhla Provinces, both in southern Thailand. Rainfall varies greatly throughout the year due to the influence of monsoon winds. Nakhon Si Thammarat Province is located in the central southern area with a latitude of approximately 8o47'-9o00' N and longitude range of 99o97'-100o04' E. The province has two seasons: the dry season (many Thais call it “summer” because the weather is hot and dry) and the rainy season. The dry season is in February - April and the rainy season runs from May to January.