Jun 18, 2026
Three-cornered alfalfa hopper (TCAH) is the only confirmed insect vector of grapevine red blotch virus in Vitis vinifera, yet many growers first realize they have the pest only after spotting petiole girdling in the vineyard. Cindy Kron, North Coast IPM Advisor at UC ANR, shares findings from two years of weekly sweep-net monitoring at Oakville Research Station that revealed TCAH adults are present well before bud break, suggesting grapevines are not their preferred host.
She explains the insect’s life stages, why legumes serve as key feeding and reproductive hosts, and why detecting early instars remains a major challenge for vineyard IPM. Cindy also discusses how degree-day models may help growers better time tillage to reduce TCAH populations and limit grapevine red blotch risk.
Resources:
- 71: New Techniques to Detect Grapevine Leafroll Disease
- 131: Virus Detection in Grapevines
- Can a pesky treehopper be foiled because its growth is regulated by temperature?
- Cindy Kron
- How to use a model for reduction of three-cornered alfalfa hopper in vineyards
- Identification of Nonhost Cover Crops of the Three-Cornered Alfalfa Hopper (Spissistilus festinus)
- Use of Ground Covers to Control Three-Cornered Alfalfa Hopper, Spissistilus festinus (Hemiptera: Membracidae), and Other Suspected Vectors of Grapevine Red Blotch Virus
- Weather Models and Degree Days
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