Thrips gather in large numbers on onion leaves, causing wrinkled or ribbony shoots. White or gray spotting, called silver top, may eventually cover the entire leaf, giving it a sickly appearance. Thrips are a primary pest of onions, reducing photosynthesis and yield by cutting open leaf cells to suck up their sap. Emptied of chlorophyll, the dead cells leave bleached silvery streaks. If the onion plant lives through an early infestation, the bulbs may be distorted and undersized. Thrips are too small to be readily seen by the naked eye, so the silver top appearance is the best indicator of an infestation.
Spray with insecticidal soap or pyrethrins from the time seedlings are set out. Thrips are also susceptible to horticultural oil, which works both by suffocating and by repelling thrips. We recommend Plant Guardian Houseplant Insecticidal Soap, Pyola Insect Spray and Oil-Away Supreme Insecticidal Spray.
Pyola® Vegetable, Fruit & Ornamental Insect Spray
Pyola® Insect Spray is easy to use, fast acting, and can be used up to and including day of harvest on most plant types. This fast and effective solution eliminates a wide range of insect pests from aphids and ants to larvae, beetles and...Read More
Oil-Away™ Insecticide is a vegetable oil made exclusively from renewable resources produced in the United States. It's an extremely low-impact form of insect control for a wide variety of plant pests on fruits, vegetables and...Read More