Effects of fertilizer and herbicide application on Nantucket pine tip mothinfestation (Lep., Tortricidae)

A study of fertilizer and herbicide effects on Nantucket pine tip moth (NPT M), Rhyacionia frustrana (Com stock) infestations was conducted in loblolly pine (Pinus taeda L.) plantations in Nacogdoches Co., Texas, from 1988 to 1989. Both fertilizer and herbicide applications had effects on NPTM infest ation level, pupal weight and host tree oleoresin production. Nitrogen fert ilization increased infestation levels; whereas, phosphorus applications te nds to decrease infestation rate. Herbicide treatment had a negative effect on NPTM infestations possibly because of decreased moisture stress and inc reased tree vigour. This is in contrast to general observations of increase d NPTM infestations associated with reducing competing vegetation. Fertiliz er application alone did not significantly improve pine growth due to compe ting vegetation. A combination of fertilizer and herbicide achieved the bes t growth.