D3121: Effects of hail netting on a variety of apple pests in 3 Michigan orchards

Hail netting in apple orchards has been proposed as a way of reducing damage from severe storms, protect fruits from sunburn, to prevent pressure from larger insects and birds, and recently it has been suggested as a possible way to thin apples organically. Some studies have shown that hail netting is indeed an effective measure to protect apples from larger motile arthropods like Cydia Pomonella, but it also increased infestations in other species like Eriosoma Lanigerum. While others tested the effects in larger cage nets, we looked at the effects of drape-style hail netting which were zip tied around the trunks of a single row of trees. For this study we had three farm sites with two sampling locations each. We assessed traps under trees with hail netting and non-netted trees and conducted fruit dmamge assessments post-net removal. We laid out traps for Cydia Pomonella and Quadraspidiotus perniciosus, checked for fruit damage by Conotrachelus Nenuphar, conducted aerial colony assessments for Eriosoma Lanigerum, and placed out passive glue traps to look at natural enemy presence. We will be assessing the effects of nets from may until the nets were removed in fall. Similar to other studies we have found the trees with hail netting have completely excluded Cydia Pomonella, Rhagoletis pomonella and even Grapholita molesta compared to the non-netted control. The nets also reduced levels of Quadraspidiotus perniciosus, but dramatically increased levels of Eriosoma Lanigerum.