California Citrus Greening Disease Progression

California Quarantine for Asian Citrus Psyllid and HLB

California Citrus Greening Disease Progression

The Asian citrus psyllid (ACP) was first discovered in the United States, specifically Florida, in 1998. A decade later in 2008, the insect was detected for the first time in California. This insect is a carrier of the deadly huánglóngbìng (HLB), commonly known as citrus greening disease. This disease can go undetected in citrus trees for years and drastically reduce the life expectancy of trees, but before it kills the tree, it leaves it producing undesirable fruit.

California Citrus Greening Disease: First Detection

Agricultural leaders and California officials came together early on to try and prevent the devastation that had occurred in Florida, in California’s citrus industry. Once the ACP was identified in California, citrus growers began spraying various pesticides and insecticides to control the population of the insect. Concerns arose for many reasons, but the idea that the insect could develop a resistance to the chemicals, leaving growers with no methods to keep the population in check, had other methods of controlling the population spring up.

In 2011, officials released a wasp originally from Pakistan to help control the population of the Asian citrus psyllid. This wasp, Tamarixia radiata, lays its young under the young of the ACP, leaving them to essentially hollow out the nymphs of the Asian citrus psyllid. You can read more about how state officials are using these wasps to control citrus greening here.

The first California citrus greening disease case was detected in 2012 in a backyard. The state was vigilant in quarantines and trying to control populations, but eventually the disease spread to more local citrus trees. In 2017, California thought they had less than 90 cases of HLB.

California Citrus Industry Overview

For the 2017-2018 season, California was the top utilized citrus producer in the U.S., accounting for 59 percent of the market. For the same season, the number of bearing acres totaled 265,300. While California’s utilized production may have topped Florida’s, their production was actually down 7 percent from the previous season. Today, California’s citrus industry is valued around US$7 billion.

By 2019, with more advancements in testing and detection, more than 1,100 infected trees have been identified. While new cases are easier to identify, scientists are hopeful that advancements in science, detection and testing will slow the spread of the disease. So far there have not been any cases of HLB in commercial groves, and California aims to keep it that way by following Brazil and cutting down infected trees. Additionally, dogs have now been trained to sniff out the infection.

Current Treatments for HLB

  • Treat trees with antibiotics
  • Kill the Asian citrus psyllid via parasites and pesticides
  • Setup quarantines
  • Remove and destroy infected trees
  • Increase nutrition until trees (and fruit) are no longer viable

No current treatment methods are an effective way of stopping the spread of the disease and protecting other trees. While some of the methods being practiced are generally okay for the environment, others could have serious consequences and the use of antibiotics is a highly controversial method to treat HLB.

While California’s citrus trees are still widely untouched by HLB, it is important to bring a solution to market to stop further decline. Learn more about how MitoGrow is working to stop the spread of HLB by clicking here.

For further information on the topics discussed above, check out our main sources for this post:

  1. California farmers and scientists race to combat a citrus disease infecting trees
  2. The USDA APHIS on Citrus Greening
  3. USDA Citrus Fruits 2018 Summary
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