Tools for managing OBLR in apples

In recent years we have been seeing more obliquebanded leafroller damage in apple orchards. Late season leafroller damage can greatly slow harvesting crews since they need to look closely at the fruit for pin point holes. Effective management of this pest is important, and fortunately we have received a lot of excellent new products for managing obliquebanded leafrollers in apples.

One of the best ways of managing OBLR populations is using aggressive thinning and pruning to improve spray coverage and decrease fruit clustering. Varieties that have clustered fruit like Cortland, short stems like Macoun and tight leaf spacing like spur Red delicious are more susceptible to OBLR infestation since they provide a protective habitat for this pest.

There is widespread resistance to organophosphates (Imidan, Guthion) and pyrethroids in OBLR populations in Ontario. Although these products may be cheaper than newer reduced risk products they are not effective in managing OBLR and as a result using them will result in increased damage at harvest and reduced yields. New products are all registered at the lowest efficacious rate, and the efficacy trials conducted with these products are done on high density plantings. So while it is tempting to think about reducing the rates (Tree row volume) or applying alternate row sprays, these products work best if applied at the label rate. Larvae must consume products for maximum control. Good coverage is essential to managing leafrollers, so ensure equipment is calibrated. Be aware that some products (Success, Delegate, Dipel, Foray and Bioprotec) require pH adjustments to optimize product efficacy. Alternate the use of different chemistries between generations. Do not apply the same product against successive generations. If you need to apply 2 sprays for a generation-use the same product.

Table 1.0 Products available for managing OBLR