- Author: Cris L. Johnson
Once a tree has been infected by the psyllid that carries and transfers the huanglongbing (HLB) bacteria to the tree there has been no alternative but to quarantine the infected area and destroy the tree. To complicate the issue further, the disease can lie dormant and be difficult to detect as the infection spreads from tree to tree.
Efforts to control the psyllid through pesticides have been ineffective and while quarantines have helped raise awareness and slowed some of the spread, a viable weapon to combat this invasive pest has been unavailable until recently.
Mark Hoddle, director at the Center for Invasive Species Research at UC Riverside, has been experimenting with a tiny parasitic wasp, Tamarixia radiata, that feeds on and kills the psyllid. After a series of tightly controlled and successful tests, the wasps have been released on infected sites and have been effective in reducing the psyllid population. There is no danger to pets or humans and the release program has been approved by the Department of Agriculture.
To learn more about this effort, please see the UC Riverside Newsroom article.
- Author: Cris L. Johnson
The latest issue has recently been posted on our website and features articles on:
Cultural Practices to Reduce Pest and Disease in Avocado and Citrus. This article by UC Ventura County Cooperative Extension advisor Dr. Ben Faber provides guidelines for practices from selection to maintenance that can mitigate disease and pests in trees.
Polyphagous Shot Hole Borer in California. UC Cooperative Extension cross-county advisor Dr. Sabrina Drill discusses this pest and it's effects on Southern Californian trees.
Electronic "sniffer" for Detecting HLB. Dr. Faber also reports on a new device that can detect Huanglongbing (HBL) disease in trees. Learn more about how it works and the advantage it could provide in preventing HLB spread through early detection.
Important Information Sources Related to Fire Management and Protection. The fire season is still on us and this list of online and publshed resources provides useful information for property owners.
Bee Kill in Oregon - A reminder of pesticide use. The State of Oregon has issued a moratorium on an aphid control pesticide after its use killed a large amount of bumble bees. Read more about following the proper guidelines on pesticide use here.
- Author: Chris M. Webb
The Asian Citrus Psyllid (ACP) has recently received a lot of media coverage and for good reason. ACP carries the deadly Huanglongbing (HLB) bacteria, the most serious citrus plant disease in the world. The disease kills all varieties of citrus trees and related plants such as orange jasmine and Indian curry leaves. The psyllid, about the size of an aphid, does not always carry HLB, but once an ACP feeds on an infected plant the psyllid will carry the disease for life to each plant on which it feeds.
What is particularly troubling about this pest-disease complex is that it can take years for the infected citrus trees to die; therefore, owners of the infected trees may not be aware they have the disease. While fruit from infected trees can be bitter, misshapen, and inedible, the tree stays up and can continue to be fed upon by psyllids, causing HLB to spread further.
People and our global economy are moving this insect. ACP has spread through Asia, parts of the Middle East, South and Central America. It has been found in Mexico, Hawaii, Texas, Louisiana, Georgia, Alabama, South Carolina, Florida and arrived in southern California in 2008. None of the ACP’s found in California have tested positive for HLB. However, it is highly likely that HLB-infected plants, brought from infected areas, are already here.
What can you do? Do not bring in plant materials from areas known to be infected with ACP. If our area becomes infected, do not move any plant materials out of our area. Purchase only certified pest- and disease-free trees from a reputable nursery. Stay informed. Check your trees regularly for signs of ACP. Report suspected ACP and/or HLB to the County Agricultural Commissioner or the California Department of Food and Agriculture (CDFA).
- Author: Chris M. Webb
In 1823, Florida became the first state to plant a commercial citrus grove. The industry and its challenges spread across the southern states of Louisiana, Texas, Arizona and California. Because these areas include many international ports of entry, because of their proximity to international borders and because of their favorable climate, the risk of introduction and establishment of invasive pests and diseases is heightened. In recent years Florida has returned to its status of first in the US: unfortunately Florida has been the first to be hit by many of the potentially disastrous pests facing the citrus industry.
The Asian Citrus Psyllid (ACP), carrier of huanglongbing (HLB) (also known as citrus greening disease), was first discovered in Florida in June of 1998. (See previous blog post “An introduction to the Asian Citrus Psyllid” for details on the insect and disease.)The discovered psyllid tested negative for HLB. At that time the industry in Florida was attempting to eradicate another disease, citrus canker. Some people were unhappy with the aggressive battle against citrus canker, however, and in November 2000, an injunction on inspections and eradication was implemented in Broward County, which may be when and where the Florida HLB epidemic began.
In October 2005, HLB was known to exist in two counties. By the time it was discovered, however, the problem was well established. By August 2008, 32 counties were infected.
In late 2005 and early 2006 key citrus stakeholders formed the Citrus Health Response Program (CHRP). This organization’s focus is a holistic approach to protecting the industry: developing and implementing minimum standards for inspection, regulatory oversight, disease management, and education and training. The goals are developed by five sub-working groups:
- Nursery and Budwood Working Group
- Production Practices Working Group
- Packing Working Group
- Processing Working Group
- Harvesting Working Group
- Residential Citrus Working Group
Common themes within CHRP are:
- The need for education and training, research, and a balance of regulatory oversight with industry due diligence
- Flexibility in adjusting to new information
- Requirements that are based on sound science and the principles of plant quarantine
It is important that we in California and other citrus-producing states learn from the hard lessons Florida is experiencing. The ACP has already been found in our state. Although HLB has not yet been detected, our response must also be organized, science-based, and flexible to sustain an important California industry.
- Author: Chris M. Webb
The tiny Asian citrus psyllid (ACP) has the potential to wipe out the California citrus industry. It is a carrier of the deadly bacterial plant disease, Huanglongbing (HLB), which is also known as citrus greening disease. This disease is fatal to citrus trees.
The insect feeds on citrus leaves and stems. Unfortunately, ACP has already been found at several sites in California. It threatens not only the commercial citrus industry, but also the ability of California residents to grow citrus at their homes.
It can take years for the symptoms of HLB to appear. Inspection and elimination of ACP is our first line of defense. Signs of disease include: asymmetrical yellowing and splotching of leaves; new growth is misshapen and twisted; produces bitter, inedible, misshapen fruit.
To help stop the spread of this insect and disease: inspect trees monthly and whenever watering, spraying, pruning or tending to trees; plant only certified disease-free citrus trees from a reputable nursery; do not bring any plant material into California from other states or countries.
At the end of this post you will find a presentation from the Citrus Research Board, provides additional information and photos. Topics covered include: other plants that can be attacked by the psyllid; maps showing locations of pest and disease; ways that the pest moves around; what happens when ACP is detected; how an infestation affects commercial citrus orchards.
If you find the Asian citrus psyliid, call the CDFA hotline at 800.491.1899 right away.
To learn more about the Asian citrus psyllid and HLB disease, or to download printed materials in English, Spanish and Chinese, please visit www.californiacitrusthreat.com.