Citrus Pest Settles In
In a September 18 letter to CDFA secretary Karen Ross Tulare County’s top ag official asked the state to approve a countywide citrus psyllid quarantine, significantly expanding the current boundaries.
“We have 21,982 acres of citrus not yet under quarantine“ says Marilyn Kinoshita, Tulare County Ag Commissioner. The request ,expected to be approved, comes ”after over two and one half years of attempting to isolate trap finds into smaller quarantine areas.”
Pictured: Current ACP quarantine zones
Kinoshita says recent finds outside the current zones make it clear the dreaded pest “is not just more hitchhikers passing through” but an “endemic population” and the number of new finds makes it more difficult for her agency to coordinate both the fight against the pest and advising citrus growers and packers on protocol in handling fruit for shipment. “Growers are calling us all the time wondering if they are in or out of the zone.”
“We met with an industry group recently and nobody opposed the idea of a countywide quarantine” adds Kinoshita.
But UC citrus scientist Beth Grafton-Cardwell says smaller quarantine zones allow Kinoshita to mandate grower treatment 800 meters around a find and a large quarantine zone may not allow them to require such treatment. ”That issue is still up in the air” she suggests.
“There are pros and cons to a countywide quarantine” although she expect Secretary Ross will grant the request.
Kinoshita says she expects approval in a matter of weeks.
Grafton Cardwell says while there appears to be a” permanent population of ACP here – it is very small and growers have succeeded in knocking them down in commercial citrus groves.” But the fact there are new finds in urban areas shows there is likely a permanent population,not only in Tulare County but in Kern County, she believes.
“ACP are spreading from commercial groves to urban areas of Ventura County as well” she says.
A scientific panel said last March stated that “it is no longer feasible to eradicate ACP in Tulare County and all of Tulare County should be quarantined for ACP.”
Despite suggesting there is a permanent population of ACP here Grafton Cardwell notes that only one large discovery near Dinuba found what appears to be all life cycles, the hallmarks of a breeding population. ”Its such a tiny bug – it is hard to find.”
Asian citrus psyllid can carry the tree killing “citrus greening disease” (HLB) although it has not yet been found in the San Joaquin Valley. A find of an HLB infected tree in Hacienda Heights in Los Angeles two and one half years ago suggests to a CDFA – ACP scientific panel that the pests carrying HLB could be moving north and the disease’s symptomatic long latency period – 3 to 4 years- must be considered. Grafton Cardwell says she is surprised it has not been found yet in the Valley. She considers it just a matter of time.
HLB has already wiped out 135,000 acres in Florida where Grafton Cardwell says “100% of the orchards across the state already have HLB”. It is on the march in Texas as well.
HLB is a bacterial disease that spreads internally throughout the plant. The disease, which is transmitted from infected plants to healthy ones by the Asian citrus psyllid, causes fruit to ripen unevenly and become lopsided, visibly smaller and bitter-tasting. The bacteria do not pose a health threat to humans, livestock or pets, but the effect on the fruit crop is devastating.
Once the disease is found – the only thing farmers can do is pull the trees.
Grafton Cardwell says the most promising tool for citrus farmers will be the proving of early detection techniques to “manage the disease” that will enable farmers to determine what trees have citrus greening before they show symptoms.That includes a new HLB whiffing dog that shows promise as well as other so called “PCR detection techniques that are rapidly evolving.”
The current zone runs through all but about 13% of the commercial citrus groves in Tulare County but excludes major urban areas where plenty of citrus grows.