It is early May. Most strawberry beds have the mulch taken off of the plants, and new leaves are starting to grow. Now is a good time of year to scout for pests and diseases in strawberry fields.

Two spotted spider mites (Teytanychus urticae) are pests of strawberries, raspberries, blackberries, and many other crops, including vegetables. Two spotted spider mites overwinter as eggs. At this time of year, some mites are beginning to emerge from the eggs. Especially if you have had issues with mites in the past, now is a good time to grab a magnifying lens and scout for mites and eggs.

Mites and eggs can be found on leaf undersides. Use a 10X – 15X magnifying lens to look for them; look for greenish-yellow, tick-like nymphs, and spherical white eggs. The scouting threshold for applying a miticide is 5 eggs and adults per strawberry leaflet. Predatory mites such as Phytoseiulus persimilis, Neoseiulus californicus, are a biological alternative to miticides.

The wet weather last summer has increased the risk of fungal diseases. Fungal crown rots such as Phytophthora, or red stele, and Verticillium wilt, can cause leaf dieback and eventual death of the planting. To identify crown diseases, uproot a strawberry plant from the ground and slice the crown in half with a sharp knife. Scrape the skin away from the roots. Healthy crowns and roots will be a uniform creamy beige color, with a pale white band of vascular tissue.

Winter injured crowns will have ombre brown discoloration within, but the band of white vascular tissue will remain intact. Fungal diseases will cause discolorations inside of the crown and vascular tissue: verticillium wilt has a blue-green tint, phytophthora will cause a dull reddish brown, and anthracnose crown rot will cause a bright red-brown marbling. Many crown rots will spread through water movement in the soil; pulling out diseased plants and letting them rot far away from the field can help stop the spread.

Once a disease has been identified, for more information on treatment options, consult an extension specialist or the Cornell Pest Management Guidelines for treatment recommendations.

Spider mites: Description, Damage and Management | UC ANR

Cornell Pest Management Guidelines 2022 | Cornell University

Survey of Strawberry Root Problems in New York State | New York Fruit Quarterly.