Keeping Trees Healthy After Removing IPCs

Researchers and growers have found that individual protective covers (IPCs) can keep young trees free of HLB for two or more years while providing additional benefits like improved tree growth. The IPCs work by keeping HLB-infecting Asian citrus psyllids out of the tree canopies.

But trees outgrow the covers and must eventually be removed. Researchers have found that about 60% of trees become HLB infected six months after IPC removal, and fruit quality starts declining the second year after IPC removal.

So, the question becomes: How can growers keep the trees healthy and productive after the IPCs are removed? University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researcher Fernando Alferez thinks the use of brassinosteroids (Br) after removing the covers might be the answer. His team will investigate whether combining IPCs and Br will prolong tree health and improve fruit yield and quality in newly planted trees.

Alferez made a recent presentation on IPCs during a seminar at the UF/IFAS Southwest Florida Research and Education Center, where he is an assistant professor of citrus horticulture. During the presentation, he pointed out:

• Trees are healthy and still young when the IPCs are removed.
• Research data suggests that Br treatment may still be effective in protecting the trees for more than a month after application.
• Researchers are now working to know if Br will improve fruit quality further and avoid the decline in Brix over time.

Alferez noted that Br reduces the rate of HLB infection in trees not protected by IPCs. Only 25% of non-covered trees treated with Br were HLB infected after six months, compared to 80% of untreated trees infected at that time.

While discussing IPCs, Alferez said that different citrus varieties perform differently under the covers. For instance, Sugar Belle growth is constrained by the third year under IPCs, so this variety shouldn’t be covered more than two years. Early Pride did not perform well under IPCs, he added.

Multi-county citrus Extension agent Mongi Zekri hosted the seminar, which also featured a presentation on oxytetracycline trunk injection by UF/IFAS researcher Ute Albrecht.  

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