binfordw said:Neem oil is supposed to work- I just bought some to try for another option to keep them in check- today is the first day Ive used it, so will see.
It's my understanding that the neem works on the eggs and nymphs, having only a slight effect on the adults (they may or may not forget to feed due to nervous system disruption...it smothers the eggs and the nymphs forget to reproduce). That's why it's important to treat early and often (every 5 days or so if you don't get any heavy rain, every 3-ish if you get heavy rain after the last application...watering only has a moderate effect because you apply to underside of the leaves most heavily) until you see results. Apply later in the day so the oil doesn't damage the leaves in strong sunlight. Apply heavily to the underside of leaves (where they lay eggs and the nymphs hang out), and a little all over. Get plants where there's no apparent infestation, too, so they don't just move over.
ETA: neem works on whiteflies for me, too, but my plants are never in a greenhouse (start indoors then move out), so it may not work as well in a confined, climate-controlled space.
