Breaking News: Cal Poly Opens New Greenhouse and Insect Rearing Facility

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 Screenshot 2016-07-25 12.24.41.png

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 as a 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.

Mark Hoddle UC Riverside Department of Entomology
Mark Hoddle UC Riverside Department of Entomology

“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.

Nick Hill, CPDPC chair
Nick Hill, a Tulare County citrus producer and Citrus Pest & Disease Prevention Program (CPDPC) chair.

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-ACP Research Greenhouse1.5 million wasps. “It’s a very nice facility,” said Hill. “We are trying to boost the biological control program to produce four million Tamarixia a year.”

California Quarantine

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.

Asian Citrus Psyllid Cooperative Program California, Arizona, Baja California, and Sonora (USDA-APHIS)
Asian Citrus Psyllid Cooperative Program
California, Arizona, Baja California, and Sonora (USDA-APHIS). Visit our Citrus Diseases page to identify a plant infected by citrus greening, citrus canker, citrus black spot and sweet orange scab. If you detect an infected plant, report it  immediately.

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Is Pongamia the New Citrus?

Source: Sam Brasch; Modern Farmer

Citrus greening disease, also known as huanglongbing or HLB, may have Florida’s limes, grapefruit and oranges headed for near extinction.

The state’s output has dropped from about 30 million field boxes in 2000 to about 15 million boxes in 2013-14. Researchers at the USDA estimate up to 70 percent of the state’s citrus trees could now be infected.

Peter McClure, the Agriculture Research Manager at one of Florida’s largest citrus operations, thinks the state might not have to wait for aphid-like phyllis flies to touch every tree with deadly bacteria. “If we go further, we will reach the threshold where we can’t feed [citrus processing] plants and they will just go away,” he said.

Farmers who haven’t already sold their orchards to developers are looking for ways to hedge their bets. In an extensive report on the disease published last year, the Huffington Post outlined a laundry list of alternatives for Florida’s estimated 525,000 acres of citrus in 2013 — down from a peak 858,000 acres in 1996.

Citrus researcher Bill Castle has identified a few varieties of pomegranates that could succeed in Florida. Others have floated the idea of peaches, blueberries, pineapples and olives, but each alternative has its limits.

Pineapples freeze at the smallest drop in temperature below 28 degrees Fahrenheit. Little infrastructure exists for olive pressing or pomegranate juicing. And even if a small portion of Florida citrus farmers transitioned their acreage to peaches or blueberries, such massive production could drop prices to the point where farmers couldn’t recover a profit.

McClure has turned to Oakland company Terviva Inc. for what he thinks could be a better idea: pongamia pinnata, better known as pongamia.

A native of Australia and India, the pongamia tree is already no stranger to Florida. Since it was brought to the state in the 1920s, bright lavender blooms have added some color to front yards and parks on the southern, east and west coasts of the state.

The tree is so fitted for the environment that it has a habit of showing up in the vacant lots and backyards of Miami (indeed, some, including Miami-Dade country, label it an invasive species).

Terviva and Florida citrus growers don’t mind evergreen shade or the blossoms’ “pea-like fragrance,” but it is the tree’s seed pods that have their attention.

Inside each one is an oil-rich legume. Each season, an acre of mature pongamia trees can produce about 10 times as much oil as an acre of soy beans.

The liquid can then be turned into bio-fuel or higher-value products like lubricants and natural pesticides. The seed cake has also been used as an high-protein animal feed in India.

Unlike their some other alternatives, citrus farmers could use their existing field architecture for the pongamia. Farmers like McClure wouldn’t need to raze the beds that once rooted orange or grape fruit trees because pongam trees thrive in the same sandy soil.

Equipment is also within easy reach. Nut shakers can harvest the seeds each summer, peanut shellers can separate the seeds from the pods and a soybean crushers can separate the oil and the seed cake for their respective markets.

In addition, Schenk claims the trees are incredibly low-maintenance once they’ve been established.

The trees fix nitrogen, so they need little to no fertilizer and actually encourage grass growth, which could help farmers graze livestock between the orchard rows. A deep tap root makes them drought-resistance. And because the oil works as a natural pesticide, bugs and bacteria have a hard time messing with the early-summer harvest — a huge advantage when other Florida growers have come under environmental scrutiny for contaminating water runoff.

“In no field — in Hawaii, Texas or Florida — have we had to use any pesticide,” said Schenk. Terviva has its largest test grove near Port Lavaca, Texas, where it grows 160 acres of pongamia trees.

‘Basically, we are domesticating a wild tree. But there is no short cut to that other than having mother trees that have been observed, documented, measured and tested’

Even as Australia’s University of Queensland has shared Schenk’s enthusiasm for pongamia as a contributor to biofuel feed stock, some skeptics are holding out. In a 2011 news analysis from Reuters, officials from around the biofuel industry all note the tree as a promising option, but urge caution to investors until companies like Terviva can prove it on an industrial scale.

Schenk understands the challenge. His company has been scouring India and Australia for the best trees and improving the genetics at test facilities. “Basically, we are domesticating a wild tree. But there is no short cut to that other than having mother trees that have been observed, documented, measured and tested,” he said.

In the meantime, citrus growers in Florida like McClure might not have much time to wait for verified proof. They are already Terviva’s largest set of customers.

“Sure, it’s experimental now, but it has a lot of potential,” said McClure.

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