Reaction of RD10 and Sanpatong1 Rice Varieties to the Rice Gall Midge Infestation and Their Yields

Abstract

Rice gall midge is an important insect pest of the upper north of Thailand. From the studies of reactions of two glutinous rice varieties i.e. RD10 and Sanpatong1 to gall midges in natural conditions conducted at 5 farmers fields in wet season 1999-2001 and 6 different planting dates at Phrae Rice Research Center in 2000. It was found that damaging by gall midges at all sites was more severely in RD10 than in Sanpatong1, while grain yield was higher in Sanpatong 1 regardless of levels of severity caused by gall midges. In farmers fields where rice gall midge infestation was as high as 50-70%, yields of Sanpatong 1 was 59-68 % higher than that of RD 10, and number of panicles/hill of Sanpatong 1 was clearly higher. for both varieties, yields was negatively correlated with percentage of damage caused by gall midge, In Phrae Rice Research Center, yield of rice grown at usual planting date was highest. Later planted rice delayed their flowering to face cool temperatures causing grain yields reduced by 41-67 %, while number of infected tillers per hill and percentage of damage were not much different from previous grown rice.