There are several insect and insect-related early-season pests of strawberry that need to be monitored and, at times, controlled to prevent losses. This includes spider mites, tarnished plant bug, spittlebug, spotted wing drosophila (SWD), sap beetles, and slugs. While SWD has not been a problem to-date in June-bearing strawberries, this insect has been detected earlier each year, so that it should be monitored in commercial strawberry plantings. Of these pests, the most damaging are those that attack the berry, including sap beetles, plant bugs, and slugs.
Cultural controls are the bedrock of Integrated Pest Management (IPM). They are used preventively, before a pest might become a problem.
Key cultural controls for strawberry pests include:
- Regular and effective weed control around strawberry plantings. This helps to reduce harborages and breeding sites for plant bugs, spittlebugs, slugs, and spider mites. Similarly, reduce other places and clutter where pests might hide during the day. This would include piles of plastic, boards, old tires.
- Clean picking and good sanitation is another critically important tool. When picking berries, it is important to not only harvest the ripe berries, but also remove the unmarketable damaged and diseased berries. Leaving damaged and diseased berries in the planting attracts sap beetles and any spotted wing drosophila that might be active in the area and serves as breeding sites where they can increase their numbers.
- Weekly scouting is also necessary to catch pest problems in the initial stages before they cause serious damage. The IPM Scouting Guide for Common Problems of Strawberry in Kentucky (ID-238) will help identify pests of strawberry when scouting. Spray options for all of these pests in commercial plantings are listed in Midwest Fruit Pest Management Guide 2021-2022 (ID-232).
- Plant bugs: An average of 0.5 nymphs per fruit truss would be the threshold to spray to avoid catfacing of fruit by plant bugs. Tapping fruit trusses over a white dish is used to detect and evaluate plant bug levels.
- Spider mites: The threshold for treatment is 25% of the leaflets infested.
- Spittlebug: It is good to keep levels below 1 per square foot in U-pick fields as they will discourage pickers with their spittle.
- Sap beetles & slugs: While we don’t have thresholds for sap beetles and slugs, scouting will be able to detect their early activity.
By Ric Bessin, Entomology Extension Specialist