Tomato (Potato) Psyllid

The adult psyllid is a small insect (about 1/8 inch or 3 mm) that resembles a cicada. The adults have white or yellowish markings on the thorax, clear wings, and lines on the abdomen between segments. The tiny eggs are laid on stalks, most commonly on the underside of leaves and along leaf margins, and are best seen with the use of a hand lens. Initially white, they turn a pink color a few hours after they are laid.

Nymphs hatch from eggs in 4 to 15 days and have scalelike, flattened, oval, yellowish green to orangish bodies with red eyes and three pairs of short legs. Older nymphs are greenish and fringed with hairs and have wing buds, which make them easy to distinguish from whitefly nymphs. They develop through five stages (instars) in 2 to 3 weeks before becoming winged adults. Nymphs feed most often on the underside of leaves.

Tomato psyllids have an extensive range of acceptable hosts, but solanaceous plants (tomatoes, potatoes, nightshades) are preferred.

Psyllids have the potential to rapidly build up large populations on peppers. The nymphs, and possibly the adults, inject a toxin while feeding on the foliage, which can cause transplants to die. In larger, pre-flowering plants it can cause stunting, chlorosis, and curling of the leaves. This can lead to either no fruit production or overproduction of very small, non-commercial grade fruit. Collectively, these symptoms are known as psyllid yellows.

In coastal and San Joaquin Valley growing areas they are also known to transmit Candidatus Liberibacter solanacearum, a pathogen of solanaceous crops,which amplifies psyllid feeding damage.

In addition to direct feeding damage, psyllids produce large amounts of honeydew, which often causes sooty mold to colonize. This can result in significant crop losses if the fruit becomes unmarketable. Unlike aphid honeydew, which is a liquid, psyllid honeydew is white and powdery. The powdery deposits must be removed to make the fruit marketable.

Management strategies are aimed at preventing the development of large populations in the field when fruit is present. An application of imidacloprid at planting is an important component of tomato psyllid management. Monitoring fields by inspecting plants as well as the use of sticky traps is essential to detecting a population before it can become established and will help determine the need for in-season foliar treatments.

While predators and parasites may attack psyllids, most parasites attack too late in the psyllid life cycle to stop crop loss and biological control does not appear to be a promising control strategy in the field.

Sprays of the Entrust formulation of spinosad are acceptable for use on organically certified produce.

Monitor fields to determine the need for in-season treatments. Where psyllids occur, place yellow sticky cards near the tops of plants growing at the field margins to monitor psyllid movement. Place the traps on adjustable poles so the height of the traps can be modified with plant growth. If tomato psyllids are caught in traps, examine the foliage of pepper plants located at the field margins for eggs and nymphs. If more than five psyllids per plant are found, treat. Be sure to alternate treatment materials to help prevent the development of insecticide resistance.

Consider treating with imidacloprid at planting if psyllids are present. It is very important not to use carbamates (Sevin, Lannate, Vydate) for the control of other pests as these materials actually promote the development of psyllid populations.