RICE RATOONING - IRRI books - International Rice Research Institute

200 RICE RATOONING1. Stem borer occurrence on main rice crop, ratoon crop, and seeded second crop (P=0.05). IRRI, Aug 1982-Jan 1983 (top) and Aug 1983-Feb 1984 (bottom).GLH numbers peaked during the late vegetative stage of the main crops butdeclined at the reproductive stage (Fig. 2, 3). Numbers on both ratoon and seededsecond crops were so low that generation peaks could not be discerned, butsignificantly fewer occurred on the ratoon than on the seeded second crop.Significantly more GLH were found in the wet-seeded than in the transplantedplots, indicating that closer plant spacing encouraged multiplication of this insect(Table 1). Perhaps fewer GLH parasitized in the wet-seeded plots because the plantshad more tillers and a dense canopy, which could have affected the host-searchingcapacity of the parasites. For example, fewer SB egg masses are found in wet-seededthan in transplanted rice (13).