I have got a serious white fly infestation in my front yard container garden. I have tried insecticidal soaps to no avail and live lady bugs. My aphids are gone but the white flies seem to multiply. This is an organic garden so I do not want to use serious pesticides. Any suggestions?
Whitefly are tiny, white mothlike insects (adult stage) that fly when the plant is shaken. The winged form of whitefly can be found on the underside of leaves along with barely visible yellowish bumps which resemble scale but are the nymph (wingless) stage of the whitefly . The obvious symptoms of whitefly is the white cloud of tiny flies that emerges when the plant is distrubed as well as the sticky residue called honeydew on the leaves. Their sucking mouthparts feed on plants causing the leaves to turn yellow and die. In severe infestation, a sooty black mold may also be present from the honeydew. The general health of the plant is compromised, becomes weak, produces pale, stunted and distorted growth, which eventually leads to death.
Whitefly are difficult to control because they reproduce rapidly especially in warm weather. The average life cycle is 30-34 days. They quickly build up a resistance to pesticides making them ineffective; therefore you need to be vigilant when it comes to treatment.
Try repeated sprayings of insecticidal soap every 5-7 days for at least two weeks. Make sure you thoroughly cover the undersides of the leaves. Do not spray drought stressed plants and when temperatures are above 80F.
Hang vapona strips, yellow or blue sticky fly tape, ( a color that they are attracted to) above the plants. Traps should be facing the plants but away from direct sun. Using traps will help reduce the adult whitefly population.
A natural spray solution recommended by Rodale consists of 1 cup isopropyl alcohol mixed with 1/2 TB of insecticidal soap in 1 quart of water. Apply once a week for two weeks. Don’t use on hairy or waxy plants.
Some have tried vacuuming white flies off the leaves or spraying the plants vigorously with water to knock them off.
As a last resort use botanical poisons that are plant derived like Neem or a pyrethroid spray Pyrethrum that paralyzes whiteflies on contact. Ryania is a mild alkaline contact insecticide that will not harm beneficial insects and leaves no residue.
To use Neem oil -mix 1 ounce (2tBsp) of Neem oil and 1 1/2 tsp. of diswashing detergent to 1 gal. of water. It works on the crawler stage, smothers the eggs and regulates insect growth. Several applications every 5 days may be required. Some plants can be sensitive to Neem oil and develop phytotoxicity. Follow safety precautions and manufacturers recommendations when using any chemicals.