The Growing Threat of Huanglongbing and How You Can Protect California Citrus

orange orchard

The Asian citrus psyllid (ACP), a vector of the bacterium that causes Huanglongbing (HLB) disease, has been identified in southern California. Vigilant pest control is necessary to protect California citrus from the devastating effects of HLB.

What’s at stake for California growers? California represents 41% of U.S. citrus production with 270,000 acres of citrus valued at $2 billion dollars. According to California Citrus Mutual, 32 infected trees have been found in Southern California.




HLB Can Be Devastating

HLB is the most devastating citrus disease worldwide and threatens all commercial citrus production. According to the USDA’s National Agricultural Statistics Service 2016 Annual Statistical Bulletin, Florida has lost 24% of its citrus production since 2010 as well as 100,000 acres of citrus trees and $334 million dollars since the rise of ACP. In the U.S., 3.8 million metric tons of citrus were lost due to ACP per the USDA Citrus: World Markets and Trade, July 2016.

Impact of ACP and HLB

How ACP Works in Citrus Plants

The psyllid damages citrus directly by feeding on new leaf growth (flush). More importantly, the psyllid is a vector of the bacterium, Candidatus Liberibacter asiaticus (CLa), that causes HLB and transmits the bacteria into the phloem when it is feeding on flush. HLB disease spreads from tree to tree when a bacteria-carrying psyllid flies to a healthy plant and transmits the bacteria as it feeds on the leaves and stems. The bacteria multiply in the tree’s phloem tissue, blocking the flow of nutrients through the plant. If not well managed, trees will eventually die within 3 to 5 years. Effective control of the Asian citrus psyllid reduces the chance that a citrus tree will become infected by the bacteria and helps ensure a healthy, productive tree.

How ACP Works in Citrus Plants

ACP and Insect Management from Bayer

Bayer has a proven portfolio of insecticides that controls other citrus pests in California and provides the foundation for season-long ACP control using multiple modes of action as well as a range of application times and methods to ensure crop quality and to help growers stay ahead of Huanglongbing.


Nymph ACP Control

In a study on mature Valencia oranges, Roy Morris of Bayer CropScience in Fort Meade, Florida, showed that Movento® helped control nymph ACP by 92%.


 Nymph ACP Control

Movento® helps control nymph ACP by 92% with superior allover plant protection above and below ground.


Adult ACP Control

A trial conducted by Dr. John Curtis of Better Crops in Fort Pierce, Florida, showed that Sivanto™ Prime helped control adult ACP by 93%.

Adult ACP Control

Sivanto™ Prime helps control adult ACP by 93% while preserving beneficials.


University of Florida trial conducted by Dr. Michael Rogers in Winter Garden, Florida, showed that Baythroid® XL helped control adult ACP by 93%.

Baythroid® XL helps control adult ACP by 93%.

Baythroid® XL helps control adult ACP by 93%.


Feeding Cessation of Adult ACP

University of Florida trial conducted by Dr. Michael Rogers showed that Admire® Pro and Sivanto™ Prime cause a feeding cessation in adult ACP that reduces and prevents, respectively, xylem and phloem feeding and HLB bacterium transmission.

Feeding Cessation of Adult ACP

Admire® Pro & Sivanto™ Prime caused immediate feeding cessation in adult ACP by 64.5% and 86.2%, respectively.

Proven Season-long Protection Application Timeline

For season-long protection, use Movento® at pre-bloom to help control ACP and red scale. At full-bloom, use Sivanto Prime to help control ACP and citricola scale and to suppress citrus thrips. Admire Pro at post-bloom helps control ACP and citricola scale. At fruit growth, Movento also helps control ACP. During harvest, Baythroid XL helps protect against not only ACP but also citrus thrips and katydids.

Proven Season-long Protection Application Timeline

Protecting the California Citrus Industry

To help prevent the spread of Huanglongbing and preserve the California citrus industry, Bayer has partnered with California Citrus Mutual (CCM) through the #CitrusMatters campaign, the Abandoned Citrus Tree (ACT) Removal Program and, most recently, a series of fall grower meetings throughout California. Monitoring residential trees is a critical line of defense since more than 60% of California homeowners have citrus trees in their yards. The ACT Removal Program allows growers to identify and request removal of abandoned trees that can pose a threat to their groves.


Make Bayer’s proven portfolio a cornerstone of your insecticide program to help ensure tree protection and productivity with season-long control of ACP, as well as other key citrus pests.

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Work Cited

1 https://www.cacitrusmutual.com/build-wall-strategies-stopping-acp-hlb/

2 United States Department of Agriculture, Florida Annual Statistical Bulletin, 2016.

3 United States Department of Agriculture, Citrus World Markets and Trade, July 2015–16.

4 University of California Integrated Pest Management Program, “How to Manage Pests: Asian Citrus Psyllid and Huanglongbing Disease.”

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