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Recent research has shown that systemic acquired resistance (SAR) sprays can protect young citrus tree flushes from Asian citrus psyllid (ACP) feeding, HLB and citrus canker. ACP is the vector that spreads HLB disease from tree to tree.
Researchers with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and Bayer Crop Science report that SAR sprays can be used to protect young flushes after oxytetracycline (OTC) efficacy starts declining and after individual protective cover (IPC) removal. The researchers are Ozgur Batuman, associate professor at the UF/IFAS Southwest Florida Research and Education Center, and Denise Manker, Jeremy Dufour, Thomas Knobloch and Stephane Brunet with Bayer Crop Science.
A summary of the researchers’ findings is as follows:
A therapeutic screening pipeline for HLB management was established, where compounds of interest were identified that include a class of synthetic SAR inducers in citrus trees. These SARs have been tested for their efficacy in preventing HLB infection of young shoots in the greenhouse and slowing HLB infection of new trees in the field.
By spraying SAR treatments on young flushes before ACP colonization to activate plant defense (priming) and prevent bacterial infection, it was observed that young flushes could be protected from reinfections of the HLB-causing bacterium due to ACP feeding. Some preliminary field experimental results were encouraging, providing a substantial delay in HLB infection (approximately three to seven months) after two to three applications.
Moreover, some SARs were also significantly effective in citrus canker control. Some of these compounds are currently being tested on newly established citrus trees across four grove sites in Florida.
The researchers propose that emerging young flushes, particularly after OTC injection or IPC removal from young trees, could be sprayed with SARs to protect them from HLB in the grove.
Source: UF/IFAS
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