The Deadly Threat To Citrus

Photo Credit: H.D. Catling, Bugwood.org

Few insect pests pose a more serious threat to citrus than the tiny Asian Citrus Psyllid (ACP), a potential carrier of a disease that could ravage the citrus industry and wipe out trees in home gardens. Because it can spread the bacterial disease called Citrus Greening Disease, also known as Huanglongbing (HLB) in the West, this insect has sparked intensive quarantine and eradication efforts just about anywhere citrus can be grown outdoors.

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What Is Asian Citrus Psyllid?

ACP is a small insect with needle-like mouthparts used to pierce plants parts and suck out the juices. The tiny adults look like aphids or leafhoppers, measuring about 1/8 inch and characteristically feeding with their rear end raised at a distinct 45 degree angle from the leaf. Their bodies are grayish tan with darker brown markings and mottled brown wings. The even smaller nymphs are bright orange-yellow and exude a distinctive trail of white, waxy material.

Asian_Citrus_Psyllid_Adult

ACP prefers to feed and reproduce on the new leaf growth of citrus and closely-related species, such as:

  • Orange Jessamine (Murraya paniculata)
  • Sweet Orange
  •  Mandarin Orange and Tangerine
  • Lemon
  • Lime
  • Tangerine
  • Grapefruit
  • Kumquat 

ACP adults and nymphs damage new growth as they inject toxins into the citrus leaves while they feed. This results in curling, distortion and blackening of young leaves. Insect populations increase during periods of active plant growth, which is usually in spring and fall. ACP can carry and transmit a disease called Citrus Greening Disease, or Huanglongbing (HLB). As they feed and inject toxins that distort plant leaves, ACP can infect the citrus host with the disease simultaneously.

Citrus Greening

World-wide, Citrus Greening Disease, or HLB, is the most devastating citrus disease, and there is no known cure. ACPs don’t always carry the deadly bacteria, but the disease can only be spread by the insect or through infected propagating material. Symptoms of the disease include yellowing foliage and unevenly ripening, lopsided fruit with a bitter taste. It can take up to three years for Citrus Greening Disease symptoms to show up in a citrus tree. Once infected, trees produce inedible fruits and eventually die. Citrus trees infected Citrus Greening Disease must be destroyed.

Citrus Greening Disease has devastated commercial citrus industries around the world, causing billions of dollars in losses. In Florida alone, tens of thousands of acres of citrus trees have been destroyed. In orchards or backyards, Citrus Greening Disease threatens the very survival of citrus in the United States and around the world.

Where Is ACP?

Wherever citrus can be grown outdoors in the U.S., states have established quarantines for ACP and/or Citrus Greening Disease. This includes Alabama, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, Texas and South Carolina. Go to saveourcitrus.org for more information and a map of quarantine areas.

Help Stop The Spread Of ACP

There is only one way to prevent the spread of Citrus Greening Disease and that is to control ACP. Since citrus is such a popular and widely-planted garden tree, homeowners are on the front lines of this critical battle. Here’s how to help:

Understand and follow quarantine rules in your state, especially when it comes to purchasing and moving citrus trees (including citrus relatives), fruit and plant parts.

  • Purchase plants only from reputable nurseries and garden centers.
  • Do NOT transport plants, fruit or plant parts out of your area, especially across state or international borders.
  • Eat fruit you grow on your property.
  • Dry or double bag citrus clippings or prunings prior to disposal.
  • When propagating citrus trees, only use registered budwood that comes with source documentation.
  • Cooperate with state and federal officials who need to inspect or treat citrus trees in your yard or neighborhood.
  • In quarantined areas, protect your citrus trees against ACP with properly labeled insecticides (see below for more information) or contact your local cooperative extension service (link).

What To Do If You Think You Have ACP Or Citrus Greening

Know the symptoms of ACP and Citrus Greening Disease. Inspect your citrus trees often, at least monthly. If you see signs of ACP activity or any symptoms of Citrus Greening Disease:

  • Go to SaveOurCitrus click the “Report It” button and follow the instructions.
  • Collect samples, seal them in a plastic bag, and report it to your county agricultural commissioner immediately.
  • In California, contact the California Department of Food and Agriculture Pest Hotline at (800) 491-1899. For more information, visit Californiacitrusthreat.org 
  • In Florida, contact the Division of Plant Industry at (800) 282-5153.
  • In other areas, contact your local Cooperative Extension System office or your local agricultural commissioner.

Other Resources

SaveOurCitrus can provide a wealth of helpful information on ACP, Citrus Greening Disease and other insects and diseases that threaten citrus. It will direct you to local information on quarantines and provide necessary contacts. Californiacitrusthreat.org is also a valuable resource on all things ACP and Citrus Greening Disease.

Photo Credit:         H.D. Catling, Bugwood.org

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