Export-Friendly Alternatives for Blueberry Fruitworm Treatments
As blueberry bloom nears its end in most of North Carolina, growers are starting to consider management of petal fall pests. Chief among these are cherry and cranberry fruitworms. Both these caterpillars hatch from eggs laid on the surface of blueberry fruit and then feed inside berries. Petal fall insecticide treatments are the primary means of management for these two pests, and timing is crucial for these application because caterpillars are no longer vunerable to control once they tunnel into fruit.
Regional recommendations for fruitworm control materials are available in the Southern Region Small Fruit Consortium Blueberry IPM Guide, and North Carolina specific recommendations are available in the NC Agricultural Chemicals Manual. Two questions have recently been raised about fruitworm control materials:
First, many of the recommended materials for fruitworms are also recommended for use against spotted wing drosophila (SWD). Because SWD is a much more significant pest than fruitworms, I strongly recommend that growers reserve effective SWD materials to treat that pest and do not use them against fruitworms.
Second, residues of some of the recommended materials commonly used for fruitworms are not acceptable for export to Canada or other potential trading partners. It’s hard to say if pesticide residues will be present at harvest from materials applied right after bloom, but some growers and marketers are cautious about these materials.
Two active ingredients are not currently recommended for SWD and are acceptable for use in Canada are acetamiprid (Assail) and novaluron (Rimon). These may be reasonable choices for growers seeking fruitworm materials without concerns for Canadian export.
The USDA Foreign Agricultural Service’s MRLDatabase (maximum residue level database) is the go-to resource for determing what pesticides are acceptible at what levels for international export markets. This tool is useful for answering the question of “What insecticides are acceptable where?”
Regardless of what material is used, it is important that any pesticide (including insecticides, fungicides, or herbicides) used around this time year be applied in a way to minimize bee exposure. This includes applying materials only to plants which no longer have blooms and applying in the evening when bees have ceased foraging. In fact, all pesticide labels will soon include pollinator protection information.