Irrigation and Fertilization Effects on Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) Damage Levels and Pupal Weight in an Intensively-Managed Pine Plantation’,*

J. Entomol. SC!. 38(4): 621-630 (October 2003) Abstract The widespread application of intensive forest management practices throughout the southeastern U.S. has increased loblolly pine, f inus faeda L., yields and shortened conventional rotation lengths. Fluctuations in Nantucket pine tip moth, Rhyacionia frustrana (Comstock), population density and subsequent damage levels have been linked to variations in m a n a g e m e n t i n t e n s i t y . W e e x a m i n e d t h e e f f e c t s o f t w o p r a c t i c e s , i r r i g a t i o n a n d f e r t i l i z a t i o n , o n R . f r u s t r a n a d a m a g e l e v e l s a n d p u p a l w e i g h t s i n a n i n t e n s i v e l y m a n a g e d P . taeda p l a n t a t i o n i n South Carolina. Trees received intensive weed control and one of the following treatments: irrigation only, fertilization only, irrigation + fertilization, or control. Mean whole-tree tip moth damage levels ranged from <l to 48% during this study. Damage levels differed significantly among treatments in two tip moth generations in 2001, but not 2000. Pupal weight was significantly heavier in fertilization compared to the irrigation treatment in 2000, but no significant differences were observed in 2001. Tree diameter, height, and aboveground volume were s i g n i f i c a n t l y g r e a t e r i n t h e i r r i g a t i o n + f e r t i l i z a t i o n t h a n i n t h e i r r i g a t i o n t r e a t m e n t a f t e r t w o g r o w i n g seasons. Our data suggest that intensive management practices that include irrigation and fertilization do not consistently increase R. frustrana damage levels and pupal weights as is commonly believed. However, tip moth suppression efforts in areas adjacent to our study may have partially reduced the potential impacts of R. frusfrana on this experiment.