Several times a year, researchers from Belize, Mexico and the U.S. meet to discuss research and management progress on huanglongbing (HLB) disease of citrus and its vector Asian citrus psyllid (ACP).
This week they met in Visalia. I came away from the meeting with several observations.
When HLB appears in a new region it spreads very fast when vectored by psyllids (a few years to move across Mexico to some of their major producing areas). Research in Florida continues to demonstrate that infected-tree removal and psyllid suppression with insecticides slows the spread and severity of the disease.
When HLB appears and growers hesitate to act quickly and aggressively spread continues rapidly. This is because HLB can be spread by psyllids for 6 months before it is detected in citrus trees by PCR and even longer before symptoms appear in trees.
Therefore, negative PCR results do not mean the disease is not there.
The take-home message for Californians is to test trees at frequent intervals in areas where HLB has been found and do everything possible to eradicate the disease as quickly as possible.