Shortly before HLB was discovered in Florida in 2005, many trees on sour orange rootstock were lost to citrus tristeza virus (CTV), which is transmitted by the brown citrus aphid. Sour orange rootstock was extremely susceptible to CTV, so many growers stopped using the rootstock.
“Switching to non-sour orange rootstock eliminated the danger from CTV decline,” University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant pathologist Amit Levy stated in a recent presentation. “But now, with HLB, growers are switching back.” They are returning to sour orange because trees on that rootstock appear to be less affected by HLB than trees on many other rootstocks. Also, Levy noted, “it is sometimes assumed that the brown citrus aphid was eradicated by the psyllid spray programs, but this is not correct.”
In his presentation at the UF/IFAS Citrus Research and Education Center in Lake Alfred, Levy reported that in a recent survey, citrus tristeza virus was found in each psyllid sample collected from 20 Florida counties. “CTV was found on sour orange rootstocks in both Polk and Indian River counties,” he said. “Results demonstrate CTV is still present in Florida.”
Levy’s presentation concluded with the following statement: “In switching to sour orange rootstock, there is always a risk of citrus tristeza decline infection and tree loss!”
In an interview following his talk, Levy said that “CTV is here, and the aphids are also; they are not gone … From the perspective of plant pathology … I would recommend avoiding sour orange rootstock as much as possible.” He added that the risk of citrus tristeza virus may outweigh the benefits of using sour orange rootstock.
Levy made his presentation at a grower meeting, called an OJ break, hosted by multi-county citrus Extension agent Chris Oswalt.
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