Early detection of root diseases is a great problem in perennial crops, especially in rubber tree. Planters are continually confronted with the balance of efficiency/cost of the detection. Therefore, a trial was set up to compare three sampling densities and four exposure techniques for detection of white root rot in rubber plantings. A complete census of all trees is the only efficient method of detection in a control program. When reducing the sampling density, a lot of infected trees are not detected and they remain an inoculum source for the spread of the disease. Mulching for one month followed by root exposure is the best technique to reveal the presence of the fungus. The sampling density is of greater significance than the infection exposure method.