i know this is an old post, but got PM on couple plants with about 6 weeks from harvest time and tried Grower ally based on reco. so far so good & took care of PM. now controlling water & humidity so it does not come back. i was a little concerned about reco above as 1 tsp does not seem like a lot, but applied according to direction on grow ally site:
DIRECTIONS FOR USE
Prior to mixing, shake the concentrate well. For outdoor application, spray plants early in the morning or evening to avoid the hottest part of the day. Avoid spraying in temperatures over 90°F. For indoor application, keep lights and fans off for 2–3 hours after spraying.
CURATIVE
Mix at 1.2% or 45 mL of concentrate per 1 gallon of water. Thoroughly spray the leaves and stems of the plant you are treating until there is runoff. Wait 4 hours, then repeat application a second time. Treat every 3-5 days as necessary. For maximum effectiveness, apply at the first sign of disease and use a sprayer that emits a fine mist for full coverage.
PREVENTATIVE
Mix at 1.2% or 45 mL of concentrate per 1 gallon of water. Thoroughly spray the leaves and stems of the plant you are treating until there is runoff. Treat every 7 days.
No limitation on the number of applications per growing cycle.
just my experience but hey, I'm a newbie