How to Combat Whiteflies

This summer the farm has been littered with whiteflies: the cucumbers, sweet potatoes, squash, and butternut squash have been covered with the little pests for months. Whiteflies are harmful to plants because they remove the sap from plant leaves which can cause wilting, poor growth, and leaf discoloration; they also leave a viscous layer on the leaves. These insects are usually on the underside of leaves and will fly around when the plant is disturbed. Whitefly populations can spread rapidly in warm weather so it is important to try and catch infections early on. Here at the farm, we started treatment with insecticidal soap. We noticed that the infection would subside for a few days but then quickly revert to its original state. We used homemade insecticidal soap by mixing four teaspoons of liquid mild soap to a gallon of water; we also tried using a store bought insecticidal spray which seemed to eliminate more of the white flies for a longer amount of time. After some experimentation, we started adding neem oil to our insecticidal soap. We spray the solution once or twice a week and spray the plants down with the hose especially on the undersides of the leaves every couple of days. When we spray the solution we wash it off with hose water to reduce the possibility of leaf burn from the neem oil. This method has worked better than others we have tried; we have still not completely gotten rid of the infestation, but we are working each day to make it better for our plants. When planning our fall gardens we will also try to plant crops that are prone to whiteflies in areas away from crops that have had pre-existing whitefly issues; this will help reduce the spread of whiteflies to new crops.