I have a tall, potted ficus tree that has been infested with whitefly for, at least 3 years. I tried the oil/dishsoap/water (palmolive or dawn or murphys) concoction which did very little. I also tried worm castings, which were useless. Did not want to use neem because of the mess, cost and marginal success. I had decided to throw out the tree, but in a last minute ditch effort (in a fit of aggravation), I grabbed my 16 oz spray bottle, added a little water, then poured in a huge amount (did not measure) of Seventh Generation lavender flower and mint scent dish soap, then filled up the rest with water (no oil). After shaking the mixture, I tipped the pot over so the tree was lying flat on the terrace, then spayed all over taking care not to get it in the soil. I rolled the pot over to spray on all sides thoroughly. After using up most of the soapy mixture, I let it sit for a while. I then put an attachment on my garden hose and power sprayed the soap off. I left a little of the soap residue on the leaves from the puddle of suds. To be safe, I repeated this once more a week or two later and, now, surprisingly (!), new leaves are popping out everywhere and no whitefly. If your plant is in the ground, I would suggest purchasing some cheap box store plastic painter cloths and cover the ground around the tree/schrubs and scrunch up newspaper around the base/trunk since there will be a lot of suds (newspaper can also sop up the suds puddle). As a bonus, it also got rid of the mealy and sooty mildew. I have no idea what role the dish soap scent played. So far so good.
I have a tall, potted ficus tree that has been infested with whitefly for, at least 3 years. I tried the oil/dishsoap/water (palmolive or dawn or murphys) concoction which did very little. I also tried worm castings, which were useless. Did not want to use neem because of the mess, cost and marginal success. I had decided to throw out the tree, but in a last minute ditch effort (in a fit of aggravation), I grabbed my 16 oz spray bottle, added a little water, then poured in a huge amount (did not measure) of Seventh Generation lavender flower and mint scent dish soap, then filled up the rest with water (no oil). After shaking the mixture, I tipped the pot over so the tree was lying flat on the terrace, then spayed all over taking care not to get it in the soil. I rolled the pot over to spray on all sides thoroughly. After using up most of the soapy mixture, I let it sit for a while. I then put an attachment on my garden hose and power sprayed the soap off. I left a little of the soap residue on the leaves from the puddle of suds. To be safe, I repeated this once more a week or two later and, now, surprisingly (!), new leaves are popping out everywhere and no whitefly. If your plant is in the ground, I would suggest purchasing some cheap box store plastic painter cloths and cover the ground around the tree/schrubs and scrunch up newspaper around the base/trunk since there will be a lot of suds (newspaper can also sop up the suds puddle). As a bonus, it also got rid of the mealy and sooty mildew. I have no idea what role the dish soap scent played. So far so good.