The feared Asian Citrus Psyllid appears to be spreading across the citrus belt this fall with new finds this weekend( Sept 30) in Fresno County between Orosi and Orange Cove, a new find near Strathmore and a third new ACP find in a trap in southern Tulare County near Ducor. All three are not far from sites where the pest was discovered in Tulare County at multiple locations this summer but each some miles away.
According to Tulare County Agriculture Commissioner Marilyn Kinoshita the find in Fresno County is near the intersection of Hills Valley and Floral near the Fresno/Tulare County line northeast of Dinuba. Dinuba is where a significant find of all lifecycles of the pest was discovered earlier this month. But this latest find in commercial grove is miles from Dinuba and is closer to Orosi, south of Orange Cove . The Dinuba finds have been called a breeding population located in backyard citrus in that town discovered around September 10.
The newly found Strathmore discovery is near the Porterville quarantine zone set up by CDFA in late July but north of it. Likewise the new find near Ducor is south of the last find and also outside the Porterville area quarantine zone by miles.
“This shows the pest is the spreading” says Kinoshita noting that citrus expert Dr Beth Grafton Cardwell had predicted recently “we will find more ACP in the area this fall.”
The new finds are making it more likely that the quarantine zones will be expanded just in time for the new citrus season and impact Fresno County for the first time.
The zones include 90 square miles around Porterville, a new Kern County zone around Wasco – as a result of a backyard find – that is 88 miles and now a new zone being developed in northern Tulare County and southern Fresno Counties.
Citrus stock within the zones may not be moved outside the zones without a permit and commercial citrus fruit must be cleaned of all leaves and stems before it can be shipped.
As of yet the insects are not carrying the dreaded citrus greening disease or huanglongbing (HLB) disease that kills citrus trees and is spread by this insect, the Asian citrus psyllid.
Still the disease was found in one LA backyard some years ago and it is “just a matter of time” until the disease finds its way to Tulare County – the number one citrus producing county. ”We assume it is in LA and it is also moving up from Mexico.”
Backyard citrus is a major problem since homeowners don’t typically watch for the tiny insect. Some 60% of homes in the state have citrus and there are more backyard citrus trees in the state than commercial citrus trees ,says Grafton Cardwell.
Researchers are working on several fronts including developing a rapid detection test that “sniffs VOC’s” put out by a diseased tree.
Both cold weather and hot weather slow the insect down, a benefit of the California climate.
Researchers have a few tricks up their sleeve when disease does come here. One involves using the vector for another citrus disease – the mild strain of Tristeza (CTV) spread by aphids that causes little production losses compared to severe strains. Grafton Cardwell says the idea is to use the CVT virus as a carrier into the tree that would inoculate the tree from HLB. Also, modify a psyllid that can not acquire HLB and flood the area where these harmless insects disrupt the mating of HLB carrier psyllids.