There are many pests that affect citrus trees in both the commercial groves and in the dooryards of homeowners. Two of the more serious pests are the Asian citrus psyllid and the citrus leafminer.

The Asian citrus psyllid is responsible for transmitting the disease called citrus greening from tree to tree. Use of insecticides to control the psyllid vector is a major component of greening management strategies in Florida and elsewhere. There is good evidence that reducing psyllid populations via insecticides application not only slows the rate of greening but also reduced the severity of the disease once established.

The psyllid feeds on the leaves produced in spring resulting in curling and distortion of the young leaves due to toxins present in saliva. It is easy to spot the notch where the psyllid has entered the leaf.

Broad spectrum foliar sprays targeting adults are most effective when used prior to the presence of a new flush which usually occurs in spring. A once-a-year application of a product containing imidacloprid drench is useful. Citrus growers should be aware that most insecticide recommended for psyllid control have restrictions on the pesticide label due to the impact these products may have on pollinators.

Planning ahead to control psyllids prior to the presence of the bloom will help reduce the need to apply pesticides during the bloom period and prevent bees and other pollinators from being hurt.

Leafminers are not vectors of citrus canker but set the tree up for the disease. Adults of the citrus leafminer are tiny moths that hide within the canopy during the day and emerge at night to lay eggs individually on young, expanding leaf flushes. The egg first appears as a tiny dew drop, usually alongside the midvein on the underside of an unexpanded leaf. The larva emerges directly into the leaf tissue, mining first along the midvein then back and forth at it make its way to the leaf margin where pupation occurs. The visual effect are tunnels in the middle of the leaf. The damage to the leaf allows the citrus canker to invade the leaf. Populations of leafminers build rapidly on the spring flush. The summer period of high leafminer damage coincides with the rainy season when canker spread is most likely. Spraying with copper every two weeks is the recommended treatment for leafminer problems.

There are a number of other pests that affect citrus trees. These include aphids, white flies, mites, scales, chewing insects like grasshoppers, katydid and caterpillars. Many of these come along with other problems. When treating with copper and other insecticides, these pests are usually taken care of. The most important task is to apply only enough insecticides to treat the pest but leave the good guys alone. Following the label recommendations is so important.

It is close approaching the no fertilizer ban in Lee County which starts on June 1. We have a few days left in May and if you haven’t applied a good citrus fertilizer recently do so now. Follow the recommendation on the back of the bag.

Kathy Woodlock is the Past President of the Garden Club of Cape Coral, a Master Gardener/citrus consultant and NGC Flower Show Judge.