Beauveria bassiana for western flower thrips
Thrips take the higher label rate. UC IPM lists BotaniGard among its floriculture thrips options, at 1–2 qt or 1–2 lb per 100 gallons every 7 days if warranted, and warns not to tank-mix it with most fungicides. Thrips hide in buds and folds that sprays do not reach, so start early and pair it with predatory mites, which UC IPM rates it low-risk to. In Quebec field onions it did no better than untreated against onion thrips, so treat it as a greenhouse tool.
Before you order
Spores of an insect-killing fungus, sprayed on to the pest. They stick, germinate and grow through the insect's skin, so coverage is everything. It is slow, working over 7–10 days, and must start while numbers are low. It can also infect some beneficial insects. How it works, how to tell it has established and the supplier list are on the full Beauveria bassiana strain GHA profile.
Other controls for western flower thrips
- Amblyseius cucumerisPredatory mite · 50–100 /m² per release (Koppert); UC IPM: 10–50 mites per plant, weekly; or sachets
- Orius insidiosusPredatory bug · 1–2 /m² per release; up to 10 /m² in hot spots
- Orius laevigatusPredatory bug · 0.5–1 /m² preventive once the crop flowers; 5–10 /m² in and around hot spots
- Amblyseius swirskiiPredatory mite · 25 /m² preventive, 50 at first detection, 100–300 on hot spots (Cornell); sachets repeated after four weeks
- Stratiolaelaps scimitusPredatory mite · 100–500 /m² of compost surface per release (Koppert); once at planting (UConn) or repeated once or twice (Koppert)
- Metarhizium brunneum strain F52Microbial — insect-killing fungus · Label rate — granules 1.5–3 lb per cubic yard of potting mix; liquid drench 4–8 fl oz per 10 gal