Greensmith APN Ensures the Best of Both Worlds for Biological Control
By Mikenzi Meyers, Associate Editor
Integrated Pest and Crop Management, otherwise known as IPM, is a critical component of all forms of crop production. Perhaps one of the most important aspects of IPM is the practice of biological control, which includes the control of any pests or invasive plants by using other organisms to monitor their populations.
Lee Tecklenburg of Greensmith APN (Advanced Plant Nutrition), works with both conventional and organic operations in order to help maximize biological control.
Greensmith APN is currently working to put together and market products that work simultaneously with biocontrols on the nutrient side of things.
“We’re trying to create a situation where the plants can thrive and become more tolerant and more resistant,” Tecklenburg explained.
This includes integrating all parts of production, whether it be organic or conventional, in order to tie the entire system together.
“It’s all-encompassing. If you can register something organically today, a conventional grower can use it as well, and it’s not the reverse,” Tecklenburg added. “This approach ensures that everyone is able to benefit from the program Greensmith APN is creating.”
New Greenhouse Facility Opens to Save Citrus from Psyllids that Vector HLB
Facility to Rear Tamarixia Radiata, Natural ACP Predator
By Patrick Cavanaugh, Farm News Director
Scores of citrus industry leaders, citrus growers, scientists and CDFA officials attended the ribbon cutting event TODAY at the opening of a new greenhouse on the Cal Poly Pomona campus to rear Tamarixia radiata, a tiny parasitic wasp imported from Pakistan because it is an Asian Citrus Psyllid (ACP) nymph predator. ACP, in turn, is a serious nonnative citrus pest that can vector Huanglongbing (HLB)—a deadly citrus disease also known as Citrus Greening—that has devastated the powerhouse citrus
industry in Florida, threatens to ruin additional citrus economies, and is the biggest threat the California citrus industry has ever faced.
According to the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS), infected citrus trees “produce fruits that are green, misshapen and bitter, unsuitable for sale as fresh fruit or for juice. Most infected trees die within a few years.” ACPs have been detected in Alabama, American Samoa, Arizona, California, Florida, Georgia, Guam, Hawaii, Louisiana, Mississippi, Northern Mariana Islands, Puerto Rico, South Carolina, Texas and the U.S. Virgin Islands. Of those locations, the HLB disease has been detected in California, Florida, Georgia, Louisiana, Puerto Rico, South Carolina, Texas and the U.S. Virgin Islands.
ENTER: Tamarixia radiata
Use of the ACP predator, Tamarixia radiata asa biological control for ACP was discovered by Mark Hoddle, biological control specialist and principal investigator, UC Riverside ( UCR), Department of Entomology. The first release of Tamarixia was in December 2011 after USDA-APHIS cleared the natural enemy for release from the Quarantine Facility at UCR.
“Tamarixia can kill ACP nymphs in two different ways,” explained Nick Hill, a Tulare County citrus producer and Citrus Pest & Disease Prevention Program (CPDPC) chair. “The first is parasitism. In this instance, a female parasitoid lays an egg underneath a fourth or fifth instar—the larger and final developmental stage of the ACP nymph before becoming an adult—nymphs that are most preferred by Tamarixia for parasitism. When the egg hatches, the Tamarixia larva begins to feed on the under-surface of the ACP nymph. Eventually the larva completely excavates the body cavity of the ACP nymph and pupates inside the empty shell of its host.”
Hill explained the first releases of the tiny and harmless wasp will occur this fall in urban areas, “to help control ACP so that we do not have to do mitigations such as spraying in those areas. We hope to get to a point where we no longer need to go into people’s yards and ask if we can treat the trees.”
“The issue,” commented Valerie Melano, professor and chair, Cal Poly Pomona Plant Sciences and interim chair, Cal Poly Agribusiness & Food Industry Management/Agricultural Science, “is that we need to come up with the best possible ways to raise enough wasps for big releases to prey on ACP. We will have CDFA employees working in this green house, as well as student workers who have participated in our research program all along,” noted Melano.
Hill added, “The idea is to get enough Tamarixia out there so they start reproducing themselves and they become self sufficient. This is tough to accomplish, but researchers think if they can get big numbers of the wasp into the urban areas, they can put a big dent in lowering the populations of ACP.”
Cal Poly Pomona Greenhouse
The new Cal Poly 5,040-square-foot research greenhouse, built in collaboration with Citrus Research Board and constructed through a $400,000 grant from the Citrus Pest & Disease Prevention Program, will house the second Tamarixia production program in California. CDFA’s Mount Roubideaux facility in Riverside houses current production. Both facilities will support the CPDPC biological control program that oversees releases in urban areas with high ACP populations.
The new greenhouse should produce a 1-1.5 million wasps. “It’s a very nice facility,” said Hill. “We are trying to boost the biological control program to produce four millionTamarixiaa year.”
The California Department of Food and Agriculture(CDFA) operates an extensive monitoring program to track the distribution of the insect and disease in both residential areas and commercial citrus groves. Results have determined quarantine zones, guided releases of biological control agents, and prioritized areas for a residential chemical control program. Nearly all of southern California is under quarantine for ACP, due to the fact that more than 15 residential trees have been discovered to be in infected with HLB.
The ACP quarantine in California includes parts of the following counties: Fresno, Kern, Kings, Madera, Monterey, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, and Stanislaus; and the following entire counties: Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare County, and Ventura.
Two portions of San Joaquin County have been placed under Asian citrus psyllid (ACP) quarantine following detections of one ACP within the City of Manteca and one within the City of Lodi. The quarantine zone in Manteca measures 105 square miles and in Lodi it measures 95 square miles.
The quarantine prohibits the movement of citrus and curry tree nursery stock out of the quarantine area and requires that all citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area. An exception may be made for nursery stock and budwood grown in USDA-approved structures that are designed to keep ACP and other insects out. Residents with backyard citrus trees in the quarantine area are asked not to transport citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area.
The ACP, a tiny (0.125 in. length) mottled brown insect that is about the size of an aphid, is an invasive species of grave concern because it can carry the disease huanglongbing (HLB), also known as citrus greening. All citrus and closely related species such as curry trees are susceptible, and there is no cure. Once infected, a diseased tree will decline in health with yellowing shoots, asymmetrical leaf mottling and abnormally shaped bitter fruit until it dies—typically within three years. HLB was detected once in California, in 2012, on a residential property in Hacienda Heights, Los Angeles County. This plant disease does not affect human health.
Residents in the area who think they may have seen ACP or symptoms of HLB on their citrus trees are urged to call CDFA’s Pest Hotline at 1-800-491-1899. For more information on the ACP and HLB, please visit: www.cdfa.ca.gov/go/acp
ACP Effective Treatments
The University of California Agriculture and Natural Resources’ Integrated Pest Management (IPM) Program has developed treatment guidelines for citrus growers within the quarantine zones. A general principle when applying insecticides to control ACPs in commercial citrus is that no one insecticide fully controls ACP across all life stages because:
All stages are difficult to contact with insecticides; eggs and nymphs are tucked inside new foliage and adults can fly.
Some insecticides show better efficacy against one stage over another.
Because systemic neonicotinoid insecticides require root activity for uptake, they are best applied during June through September.
According to Mark Hoddle, UC Riverside (UCR) Director, Center for Invasive Species Research, “The science of biological control, the use of a pest’s natural enemies to suppress its populations to less damaging densities,”shows promise against the ACP with releases over the last three years of Tamarixia radiata–a parasitic wasp from Pakistan–in urban areas of southern California. Thus far, this natural ACP enemy helps to control ACP growth in residential areas, but is inadequate for commercial application.
Biological Control Scholarship Fund
Harry Scott Smith was the first to use the phrase “biological control” in 1919 at the meeting of Pacific Slope Branch of the American Association of Economic Entomologists at the Mission Inn in Riverside. Smith worked on the biological control of gypsy moth with USDA, then moved to the University of California Riverside where he eventually created and chaired the Department of Biological Control, which offered the only graduate degree in biological control in the world.
The Harry Scott Smith Biological Control Scholarship Fund at UCR aims to attract the brightest students to study biological control by providing assistance to its students to attend conferences to present their research or to participate in training workshops. More information on the Scholarship, past awardees, and a list of donors can be reviewed on the website.
Sources: CDFA; UC IPM; UC Riverside (UCR); UCR Center for Invasive Species Research; USDA Animal and Plant Health Inspection Service (APHIS)