Management of Asian Citrus Psyllid Key to Slowing Spread of Citrus Greening

Indianapolis, IN - May 02, 2006

Florida's citrus groves are under attack from an unseen assailant - a disease that slowly distorts and discolors the leaves, renders the fruit useless and ultimately kills the tree. And, it could be much more difficult to manage than canker.

"Citrus greening is a serious disease that is systemic in a plant and can go undetected for some period of time," explains Michael Rogers, assistant professor of entomology at the University of Florida Citrus Research and Education Center. "We don't know exactly how long it takes for a plant that's infected to begin showing symptoms.

"Right now, the disease is present throughout the southern part of the state," he continues. "We don't know exactly how far it's spread. The fact that we can't efficiently diagnose or detect greening-positive trees in the grove is a real problem for us." 

Greening is spread by an insect - the Asian citrus psyllid. The pest has been present in Florida since 1998 and has become well established throughout the state's citrus growing areas. Consequently, managing the spread of greening depends on controlling psyllid populations.

"We can't eradicate the psyllid, because it's too well established in the state," points out Rogers. "But, managing infestations will be important to slow down the spread of greening. We'll probably see several additional insecticide applications each year for psyllid management, especially on young trees."

Young citrus trees continually put out new leaves, or flush, and are the most attractive targets for psylla, which need new flush to feed and reproduce. In spring and early summer, when temperatures hold steady in the 70 to mid-80 degree range, a single female psyllid can lay as many as 700 to 800 eggs. That creates the potential for psyllid populations to grow very quickly.

"Psyllid populations are starting to build up right now," warns Rogers. "We had a cold snap several weeks ago, and psyllid populations dropped off a bit. Now we're starting to see those populations rebound and build up on the flushes that are present."

According to Rogers, an integrated pest management program, including both biological and chemical controls to keep all nursery and young trees psyllid-free, is the most effective means for controlling the pest and limiting the devastation from greening. Groves should be scouted regularly, and those where psylla are present should be treated prior to each flush.

"The most important thing when psyllid is found in your grove is to manage them and slow down the spread of the disease in that grove in order to maintain citrus production in an economically-feasible manner," Rogers suggests.

The University of Florida recommends several insecticide products for rotational use in psyllid control, including Admire, Provado, Temik, and Lorsban^® -4E insecticide.

"The goal for insecticide use is to reduce the psyllid population," reminds Rogers. "It's kind of a numbers game. We need to lower the psyllid population to help slow down the spread of the disease."

Many growers have found that the cost effective control of Lorsban helps keep psyllid populations in check, plus provides broad spectrum protection against other pests found in groves, including Citrus rust mite, scale, mealybugs, aphids, whiteflies and fire ants. The product's quick knockdown action also allows for faster recolonization of beneficial insect populations, which are also important to psyllid management.

"In countries that have been dealing with citrus greening for a number of years, growers have been able to keep the incidence of the disease fairly low," says Rogers. "And part of that program has been using insecticides to manage psyllid populations and timing those insecticides properly when populations are beginning to build up."

Lorsban-4E insecticide is a federally Restricted Use Pesticide.
Always read and follow label directions.