In a 110-acre silage block outside Woodland, pheromone traps spiked to 42/night and I’m at about 9% whorl injury five days after a spinosad pass… Before I pivot to a Group 28 rotation, is anyone else seeing a phenology shift on their degree-day models or getting better suppression with flowering strips and Trichogramma releases right now?
Seeing the same — when traps hit ‘40+/night’ I start the FAW DD clock 3–4 days early and only go Group 28 once most are ≤2nd instar, running 15–20 GPA with 0.125% MSO for canopy punch‑through. Flower strips + weekly Trichogramma cut egg hits about 30% on borders here, but late‑whorl suppression lagged, so I wouldn’t skip the diamide — stopping them early is like keeping a kid out of the cookie jar. Did you try edge‑focused releases and a 48–72 hr check after the spinosad pass?
At 42/night, I set biofix at the first 20+/night run; your “five days after a spinosad pass” reads like you sprayed the lull between waves. Before jumping to Group 28, drop water‑sensitive paper in whorls at 4–6 pm and, if it’s not blue, bump volume and slow the pass at dusk. Flower strips only move the needle for me when they’re tucked inside about 60 ft of the block.
On our Woodland acres, I start the FAW DD clock two days early whenever nighttime lows stay above 70°F for three straight nights, and I swap to twin‑fan 110° nozzles around 50 psi to push coverage into tight whorls — both bumped control for us. > strips only move the needle for me when they’re tucked inside about 60 ft of the block. Same here — edge‑only plantings didn’t change egg loads much; are your nights that warm this week?
, 42/night is when mine blow up too. Building on @simon92, what moved the needle for me was front‑loading Trichogramma pretiosum at about 150k/acre in two drops 3–4 days apart once traps hold 20+/night, plus keeping 30–40 ft buckwheat strips blooming. With 9% whorl injury five days after a spinosad pass, if you’re already seeing a lot of 3rd instars I’d slip in an SfMNPV dusk pass before your next rotation; if not, shift the next release a couple days earlier — are those strips still throwing nectar in this heat?
Quick check: if your carrier was alkaline, spinosyns fade fast — buffer water to “pH 6–7” and spray at dusk; that tweak plus 15–20 GPA pulled mine down in about 72 hours without jumping straight to a 28. If you do rotate, a quick SfMNPV edge sweep has cleaned up late hatch for me; @chlrami, is that still holding when overnights stick >70°F?
I’m seeing hatch 36–48 hours ahead of the base‑50 model when nights stay warm and we’re a bit water‑stressed — FAW didn’t get the memo. If you pivot, key the diamide on “fresh window‑paning + 2nd instar,” and run chlorantraniliprole at 20–25 GPA with 0.5–1% MSO and drops into the whorl, watching the silage PHI. If you keep the strips, time Trichogramma to “first egg mass,” not the spray — have you checked egg cards to confirm you’re hitting that window?
Seeing the same outside Dixon — my base‑50 was lagging, so I switched to base‑52 with a ‘min>68°F’ night filter and it’s lining hatch about a day earlier. If you pivot, a 60–80 ft downwind edge band with the diamide plus drops angled into whorls cleaned up late feeders for me; small caveat is mind the PHI on silage. @simon92, curious if you’ve tried a tweak like that, and UC IPM’s FAW page tracks pretty well with what I’m seeing: UC Statewide IPM Program (UC IPM).
I’ve had better luck keying sprays off ‘black‑head’ egg masses and then running a Group 28 within 24 hours with twin‑fans angled ±30° at 22–25 GPA to punch the whorl; if you’re testing strips, perimeter Trichogramma cards (50–75k/acre) where traps spike have trimmed my follow‑ups. @william_t89’s warm‑night tweak matches here; is your injury edge‑loaded or even across the block?