Immunity to HLB?

Mar 26, 2020

By Ben Faber

Citrus greening, also called Huanglongbing (HLB), is devastating the citrus industry. Florida alone has experienced a 50 to 75 percent reduction in citrus production. There are no resistant varieties of citrus available and limited disease control measures.

Some scientists think it is possible that orange juice could one day become as expensive and rare as caviar. In an effort to prevent this, three plant pathologists at the University of California-Berkeley and United States Department of Agriculture conducted research into ways to boost citrus immunity and protect the valuable fruit against citrus greening.

Because the bacteria that causes citrus greening cannot be grown in a lab, scientists have to find novel ways to conduct experiments. The University of California-Berkeley/USDA team looked at many different strains of the bacteria that cause citrus greening to see if they could identify peptides (a compound of two or more amino acids) that would trigger immune responses.

"This was a long list, so we narrowed it down by selecting small peptides that were a bit different in their peptide sequence, which might imply that the bacterium had made those sequence changes so that they wouldn't be recognized by the plant immune system," explained Jennifer D. Lewis, group leader of the research team. "Then we further narrowed that list to peptides from strains that caused disease in citrus."

Through this research, they showed that two peptides could trigger immune responses in multiple plant species, including citrus. These peptides may play a role in preventing or reducing yield loss from citrus greening.

According to Lewis, "We thought it was particularly interesting that some of the peptides predicted to elicit a response, could actually trigger immune responses in multiple plant species. This suggests that the immune response to these peptides is conserved across species."

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Source : ucanr.edu

Video: Sclerotinia and Lygus in Seed Canola: Field Update with George Lubberts, CCA | Enchant, Alberta

Join Certified Crop Advisor George Lubberts for this Prairie Certified Crop Advisor (Prairie CCA) field update from Enchant, Alberta. In this 12th video of the series, George takes us into a seed canola field where the male rows have been removed and the female plants are filling pods. This video was taken in the third week of August 2025.

George discusses the early signs of sclerotinia stem rot, explaining how infection begins in the stem, impacts pod development, and leads to premature ripening. He also shares insights on lygus bug management, including timing of spray applications to minimize feeding damage and maintain seed size and quality.

With cool, damp summer conditions, George notes that while disease pressure is present, overall field health remains good. The crop is just beginning to show early seed colour change, signaling progress toward maturity.

Topics Covered:

•Sclerotinia stem rot identification and impact

•Managing lygus bugs in seed canola

•Crop stage and seed colour change observations

•Timing insecticide sprays for optimal protection

•Insights from a CCA field perspective in southern Alberta