Effects of clone, silvicultural, and miticide treatments on cottonwood leafcurl mite (Acari: Eriophyidae) damage in plantation Populus

Abstract

Aculops lobuliferus (Keifer) is a little known pest of plantation Populus spp., which is capable of causing substantial damage. This is the first documented occurrence of A. lobuliferus in South Carolina. Previous anecdotal data indicated clonal variation in Populus susceptibility to A. lobuliferus damage. A damage rating scale was created to monitor mite damage in 2000-2001 in a short-rotation woody crop plantation; damage descriptions and seasonal phenology also were recorded. Foliar damage and terminal mortality were monitored on two Populus deltoides Bartr. clones, ST66 and S7C15, receiving one of three silvicultural treatments (irrigated [I], fertilized [F], or I+F) or no treatment (control). In 2001, early season foliar damage ratings were significantly higher on clone S7C15; however, damage on clone ST66 was greater after miticide treatments later in the year. Terminal mortality did not differ between clones. Silvicultural treatment significantly affected foliar damage levels in both clones. Trees receiving I+F and F treatments had higher damage ratings than did trees receiving irrigation alone or the control at times. Clone S7C15 trees receiving fertilizer had significantly less terminal mortality than their nonfertilized counterparts. Application of a commercially available miticide significantly reduced A. lobuliferus damage levels. This study demonstrates that A. lobuliferus damage levels can be influenced by Populus clone and silvicultural treatment. Foliar and terminal damage levels observed in this study indicate the potential for substantial economic impact of A. lobuliferus on plantation Populus. Although an effective control method may be to select and plant resistant Populus clones, chemical control remains a viable option.