Topic Tuesday: Two-Spotted Spider Mite
It finally feels like fall with cool temperatures moving into North Florida last week! Cool temperatures mean we can start planting crops that require cooler temperatures and shorter days to grow. Not many people know this, but strawberries thrive in cooler temperatures around 50°F to 80°F and less than 14 daylight hours. They need these conditions to flower and produce fruits. Due to our winter climate, Florida is one of the top growers of strawberries. Unfortunately, these ideal conditions for growing strawberries, are also suitable for several pests that can impact your strawberry crop.
What is the Two-Spotted Spider Mite?
The two-spotted spider mite goes through incomplete metamorphosis, meaning gradual changes will occur during the development from egg to adult. Adults will lay eggs attached to their silk webs and will hatch in ~3 days. The two-spotted spider mite will go through two larval stages, nymphal stage, and then adult stage. Time from egg to adult can vary depending on the temperature, but under optimal conditions, will complete in 5-20 days. Adult females will lay several hundred eggs during the life cycle, which can last 2-4 weeks.
Two-spotted spider mites can vary in color from brown to orange-red, to green, but usually they will be found green-yellow or translucent. They are oval in shape about 1/50 inch long. The spider mite body has two separate parts- gnathosoma (mouthparts) and idiosoma (abdomen, thorax, and head). Larvae will have 3 pairs of legs and the later stages will have 4 pairs of legs. Spider mites, once in a crop, can move around easily by walking from plant to plant or by using their webs and wind to travel from plant to plant.
Two-spotted spider mites have piercing-sucking mouthparts. They penetrate plant tissue to suck juices out of leaves, causing chlorosis. When scouting for spider mites in your strawberries, use a hand lens to look for spider mites on the underside of leaves, spider webs on the plant, graying/yellowing of leaves, defoliation, or necrotic spots on the leaves. Finding these may be a good indicator that there is spider mite pressure in your crop. Spider mites also cause damage to flowers, negatively affecting overall yield.
- Start with clean transplants, free of eggs or larvae
- Introduce predator mites into the field after strawberries establish
- Use insecticidal soap or oil
- Destroy or control weeds, since they can be host plants
- Clean-up field after harvest and destroy residue
Miticides can help control two-spotted spider mites since they are a common pest on strawberry. However, many miticides are not effective on eggs, so 2 or more applications are necessary at 5-day intervals in the summer or 7-day intervals in the winter. Also, spider mites develop resistance to most chemicals, so rotating modes of action is important. Check out the Vegetable Production Handbook of Florida for proper management practices. THE LABEL IS THE LAW. If you have concerns of two-spotted spider mite in your strawberry crop, feel free to call me at the UF/IFAS Suwannee County Extension Office, an Equal Opportunity Institution, for spray recommendations at 386-362-2771.