| This work was done to broaden the knowledge base for understanding the effects of forest management practices on the Nantucket pine tip moth, Rhyacionia frustrana (Comstock). The work also deals with management practices used to reduce the impact of this pest on forest production in the most effective, economic, and ecologically compatible manner possible through the use of properly timed applications of efficacious and ecologically safe insecticides. Chapter Two examines some of the relationships between tip moth damage levels and forest management practices used to increase tree growth in newly planted stands. Herbaceous vegetation control accounted for most of the variation in tree growth and tip moth damage levels over the two year study. Fertilization increased the number of tip moth pupae per shoot in the first year, but not in the second year. Chapters Three and Four address chemical control issues such as the most effective insecticides, spray timing values, and the insecticides least detrimental to hymenopteran parasitoids. We tested four available insecticides for use in loblolly pine plantations and found that lambda-cyhalothrin was the most effective insecticide available for use. Spinosad was found to be as effective as the industry standard permerthrin, a pyrethroid. They also had similar spray timing values. In a laboratory study, we found that spinosad was initially less toxic to hymenopteran parasitoids than permethrin and lambda-cyhalothrin, but there was no differences at 24 hr. Indoxacarb, a new type of insecticide did not appear to have a detrimental impact on the natural enemies over a 24-hr period. In conclusion, this work provides forest resource managers more information for making informed decisions on preventative and suppressive techniques to reduce the impact of the Nantucket pine tip moth on loblolly pine production and adds to the basic understanding of this insect. Chapter Five covers experiments designed to test the hypothesis that tip moth damage predisposes trees to pitch canker disease, caused by the fungus Fusarium circinatum. Although a relationship was shown between tip moth damage and the presence of the fungus, there was no evidence of pitch canker disease on the trees exposed to the fungus. |
