The following information provides examples of organic pest management (IPM) tactics for squash vine borer (Melitta curcurbitae) using the “Four T” method.
- Squash vine borer adults are the (1st) stage to emerge from their overwinter places.
- The second (2nd) target will be the eggs laid by the female adult squash vine borer moths.
- The third (3rd) target will be the young larvae that emerge from the eggs that are most vulnerable to treatments.
General calendar time: Adults emerge late June-early July
Biofix: Jan. 1
Degree days: Squash vine borer adults emerge between 900-1200 degree days in Minnesota
Tool #1: Monitor for squash bug adults and their egg masses (Type: Monitoring/Trapping)
Squash vine borers fly into garden areas to mate and lay tiny brown eggs.
Tool #2: Plant a crop that is resistant to squash vine borer (Type: Cultural)
Plant a known resistant varieties such as Butternut, Royal Acorn, Sweet Cheese. Ask your vendor about varieties that are known to be resistant to squash vine borer damage. Part of resistance is how the vines grow along the ground…the more that vines run along the ground, the less stem area is accessible to adult moths.
Tool #3a: Apply biorational “kaolin clay” (Type: Mechanical)
Kaolin clay can provide a fine layer of mineral dust that can help prevent squash vine borer from laying eggs on stems.
- Apply treatments when adults are seen.
- Spray near crown of plants and along vines.
- Always avoid spraying on or near flowers to prevent contact with bees.
Tool #3b: Apply insecticidal soaps, horticultural oil, and/or neem oil to discourage burrowing (Type: Chemical)
Thwart young larvae who may be emerging from eggs by spraying insecticidal soap near the base of plants and along vines.
- Treat plants as soon as possible after eggs are observed.
- Treat plants during periods when rain is not forecasted.
- When using a biopesticide like B. bassiana, ensure that you apply your product at the crown or interior portions of the plant.
Tool #3c: Scout for brown frass (signs of squash vine borer burrowing)
If you see brown frass, you can slice open vines with a razor blade and remove larvae from the vine. Some growers then bury the vine so that it can regenerate.
Tool #4: Use row cover material to protect crops
Row covers provide protection from insects and additional protection from sun/wind exposure, heavy rains, and other weather related damage.
- Setup row covers before adults are observed. Continue to observe plants to ensure that adults squash vine borer moths have not found access to plants under cover.
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