A second tree infected with “citrus greening disease” was identified and will be removed from an east Riverside property, not far from where another diseased tree was located last month, it was announced Wednesday.
According to Riverside County Agricultural Commissioner Ruben Arroyo, lab tests confirmed the presence of huanglongbing — better known as citrus greening disease — in a tree located in the area of Chicago and Marlborough avenues.
The infected tree was within feet of where a grapefruit tree was uprooted and destroyed in late July after agricultural experts found it eaten up with Asian citrus psyllids, which cause greening disease.
The Board of Supervisors on Tuesday declared a local emergency at Arroyo’s request. According to the board resolution, “the potential exists for the spread of huanglongbing throughout Riverside County” and all resources will be marshaled to stop it. Staff from the UC Riverside Center for Invasive Species Research are taking the lead in that effort.
On Monday, the California Department of Food & Agriculture expanded a quarantine over the area where greening disease is active.
Under the state order, only citrus products that have been “commercially cleaned and packed” can be shipped out of the quarantine zone, which is now 94 square miles, encompassing parts of Riverside and San Bernardino counties. The original quarantine boundaries were limited to a seven- square-mile area centered in east Riverside.
The eastern boundary of the zone is Box Springs Mountain Reserve; the south boundary is East Alessandro Boulevard; the north boundary is Interstate 10; and the western boundary is Riverside Municipal Airport.
A map depicting the quarantine area, the center of which is the 60/91/215 interchange, is available here: https://www.cdfa.ca.gov/plant/pe/InteriorExclusion/hlb_quarantine.html .
Similar quarantines are in effect in Los Angeles and Orange counties.
State officials said no citrus nursery stock can be moved outside of the area under quarantine, and no residentially grown citrus fruit can be moved. However, growers may continue to consume and share with people within the quarantined locations.
The CDFA said a treatment program has been implemented that seeks to eliminate Asian citrus psyllid infestations within 800 meters of where the disease took root.
Psyllids are finger-tip size, moth-like insects that made their U.S. debut in Florida nearly 20 years ago.
The county’s roughly 20,000 acres of commercial citrus crops — oranges, lemons, grapefruit and tangerines — yield about $187 million a year, and citrus greening disease poses a direct threat, according to agricultural officials.
Psyllids originate in tropical and subtropical regions. They first appeared in California in 2008 and have been trapped in citrus-growing areas throughout the Inland Empire.
Psyllids host a virulent bacteria that can devastate plants’ vascular systems. The greening disease rampaged throughout Florida in 2005 and has inflicted an estimated $3 billion damage to crops in the Sunshine State, according to a study published by the University of Florida.
The U.S. Department of Agricultural said that Florida’s citrus crops are likely to produce 70 percent less this year compared to 20 years ago as a direct result of greening disease.
The first signs of citrus greening disease are yellowing leaves on trees and fruit that remains green because it never ripens, according to Arroyo.
Different methods are used to combat psyllids. In 2011, UCR scientists began releasing Tamarixia radiata — tiny stinger-less wasps — in the campus’s botanical gardens to keep psyllids out. The wasps lay eggs in psyllid nymphs, on which the wasp larvae feed, killing them.
A university has researcher has received grant funds totaling $4 million to enhance methods of defeating the psyllids, according to Arroyo.
Anyone with questions or concerns about huanglongbing and the threat posed by psyllids was encouraged to contact either the agricultural commissioner’s office at (951) 955-3045, or the state’s pest hotline, (800) 491- 1899.
–City News Service