Impacts of Insect Defoliation in Cottonwood Plantations in MississippiThis article is part of a larger document. View the larger document here.
In spring 2001, a notodontid moth, Gluphisia septentrionis Wlkr., defoliated about 2,000 acres of 9- and 10- year-old eastern cottonwood (Populus deltoides Bartr.) trees in west central Mississippi. The farm manager had never seen cottonwood defoliated by that species of moth, because it was not considered a pest in Mississippi. When the trees leafed out again, cottonwood leaf beetles (Chrysomela scripta F.) attacked them. In order to avoid two defoliations by mid-season, the manager applied an insecticide. Cottonwood leaf beetles commonly attack young Populus but seldom require treatment in trees > 2 years old. However, this defoliation by the Gluphisia moth caused a flush of leaves in mid-season when cottonwood leaf beetle populations were high. Cottonwood growth is indeterminate, so the timing of insect defoliations can have a variety of effects on growth and energy storage. In spring 2002, G. septentrionis larvae were present in the same stands and again caused defoliation. This paper considers tree mortality and growth after 2 years of defoliation, as well as some associated economic effects.