- Author: Diana Cervantes
Los campos de San Bernardino y Riverside están en alerta. La mosca oriental de la fruta (OFF, por sus siglas en inglés), ha desencadenado una cuarentena que obliga a los productores a tomar medidas estrictas para proteger los cultivos cítricos. En un esfuerzo por contener esta amenaza, se están implementando programas de tratamiento supervisados y restricciones de exportación, destacando la gravedad de la situación en la región.
Nawal Sharma del Departamento de Alimentos y Agricultura de California (CDFA, por sus siglas en inglés), destaca la importancia de estas medidas en un radio de 112 millas alrededor de Redlands.
Esto significa que los productores en el área de cuarentena no pueden vender ni transferir productos fuera de su propiedad sin un acuerdo de cumplimiento. El acuerdo requiere que los productores cumplan con un programa específico de tratamientos bajo la supervisión de agentes estatales o del condado.
La cuarentena no permite la exportación internacional de cítricos frescos provenientes de esta área, a menos que los cítricos obedezcan con los requisitos de certificación de exportación existentes para los artículos reglamentados provenientes de las áreas bajo cuarentena por la presencia de OFF.
En días pasados los campos de cítricos de la Universidad de California Riverside (UCR por sus siglas en inglés), se convirtieron en el centro de un importante evento para los agricultores y profesionales de la industria, una jornada de campo dedicada exclusivamente a este sector.
Durante la reunión, expertos de UCR y de la División de Agricultura y Recursos Naturales de la Universidad de California (UC ANR, por sus siglas en inglés), dirigieron su atención hacia temas vitales que afectan a la industria, centrándose especialmente en las medidas de cuarentena relacionadas con OFF.
Entre los participantes destacó la participación de Georgios Vidalakis, especialista de UC ANR, quién habló sobre el cuidado que se debe tener con los cítricos para no transmitir enfermedades.
OFF es una plaga invasora originaria del sudeste asiático, y actualmente representa una amenaza directa para más de 230 variedades de cítricos, frutas, nueces y frutos rojos.
De acuerdo con el Departamento de Alimentos y Agricultura de California (CDFA, por sus siglas en inglés), una invasión de este tipo puede acabar con cosechas completes. En California por ejemplo en 2015 OFF ocasiono perdidas que alcanzaron los 16, 400 millones de dólares.
Cómo y cuándo llegó a los Estados Unidos
OFF se registró por primera vez en Hawái en 1946, y ahora ataca a casi todos los cultivos frutales comerciales que se cultivan allí, excepto a las piñas. La plaga se detectó por primera vez en California en 1960 y se ha reintroducido cada año desde 1966 a través del transporte de frutas y hortalizas infestadas.
Los cultivos sufren daños cuando las hembras de la mosca de la fruta depositan sus huevos dentro de la fruta. La forma más común de propagación de esta plaga es a través del transporte clandestino en frutas llevadas por viajeros desde regiones infestadas o en paquetes de productos de cosecha propia enviados desde otros países a California.
Si usted desea reportar algo sobre alguna infestación de la mosca oriental de la fruta puede comunicarse al CDFA al 1-800-491-1899 o puede visitar el sitio de internet www.cdfa.ca.gov/plant/reportapest.
- Author: Saoimanu Sope
A new avocado, one that complements the widely known ‘Hass,' will hit the world market soon. The ‘Luna UCR' variety (trademarked and patent pending) has several characteristics that should be of interest to both growers and consumers, said Mary Lu Arpaia, University of California Cooperative Extension subtropical horticulture specialist based at UC Riverside.
From the grower perspective, the tree is about half the size of the leading variety while producing approximately the same yield per tree as ‘Hass,' meaning that growers could plant more trees per acre, therefore increasing yield. It also makes harvesting easier and safer.
Another advantage is the flowering behavior of the tree. Avocado trees are categorized into either Type A or Type B flower types. It is generally accepted that you need both flower types in a planting to maximize productivity. The ‘Hass' is an “A” flower type and ‘Luna UCR' is a Type “B.”
This is a potential boost for growers since the current varieties that are “B” flower types ripen green and generally receive lower prices for the grower. Similar to ‘Hass,' however, the ‘Luna UCR' colors as it ripens.
“Hopefully, it will receive similar returns to the ‘Hass' once it is an established variety,” Arpaia added.
Fruit breeding is a long-term process that she has navigated by building upon the work of her predecessors. Of course, Arpaia has had strong support from colleagues as well, including Eric Focht, a UC Riverside staff researcher and co-inventor of ‘Luna UCR.'
“We had been looking at ‘Luna UCR' for some time and it was always a very good eating fruit,” Focht said. “After the 2003 release of ‘GEM' (registered and patented as ‘3-29-5', 2003) and ‘Harvest' (patented as ‘N4(-)5', 2003) varieties, ‘Luna UCR' was always the top contender for a next release due to the small, narrow growth habit, “B” flower type and the fruit quality.”
“It's a very nice-looking fruit as well and seemed to be a pretty consistent bearer from year to year.”
A glimpse at how it all started
In spring 1996, Arpaia took over the UC Avocado Breeding Program following Guy Witney who led the program from 1992 to 1995, and Bob Bergh whose initial efforts in the 1950s were foundational in the inception of ‘Luna UCR.'
Arpaia recalls the first trials in the early 2000s of ‘Luna UCR,' which were tested alongside other promising selections from the Bergh program. “There were a lot of varieties that didn't perform well, some of which had poor storage life, an important trait that we need if we are going to get the fruit to consumers across the country,” said Arpaia.
The original seed and selection were planted at the Bob Lamb Ranch in Camarillo, and originally advanced trials of the ‘Luna UCR' variety were planted in four locations: UC Lindcove Research and Extension Center in Tulare County, UC South Coast Research and Extension Center in Orange County, a privately owned farm in San Diego County and another one in Ventura County.
The RECs are among the nine hubs operated by UC Agriculture and Natural Resources to support research and educate the public on regional agricultural and natural resource challenges.
ANR Research and Extension Centers become vital
Unfortunately, the 2017 Thomas Fire burned the avocado trees in Ventura, said Arpaia. After a change in management, the trial located in San Diego County was also terminated, leaving the two trials at Lindcove and South Coast REC.
“South Coast REC has a long history of supporting research and extension activities of high value crops important to California, including avocados,” said Darren Haver, director of the South Coast REC, which was often used to show growers the new varieties that were being developed.
“Many of the REC staff have worked with the avocado-breeding program researchers for more than two decades and continue to work closely with them to ensure the success of new avocado varieties, including ‘Luna UCR',” he added.
In addition to the support provided by South Coast and Lindcove RECs, Arpaia said that UC Kearney Agricultural Research and Extension Center in Fresno County – another UC ANR facility – made it possible for her team to conduct critical postharvest and sensory research, and consumer testing of the fruit, which included up to six-week trials of fruit ratings for storage life and taste.
“UC ANR has played an important role in our ability to not only identify ‘Luna UCR', but in preparing it for the world market, too,” she said.
Preparing to share with the world
Since 2015, Focht had been collecting data for the patent application. Now that he and Arpaia have successfully patented and trademarked ‘Luna UCR,' they are preparing to expand production by engaging interested growers with the commercial partner, Green Motion who is based in Spain.
“Green Motion contracted for 1,000 trees to be generated by Brokaw Nursery and those trees are currently being distributed, with earliest field plantings likely taking place in fall,” explained Focht.
Focht also said that Mission Produce, based in Oxnard, CA has contracted to graft over a small number of “B” flower type pollinizer trees to the new ‘Luna UCR' variety, possibly making way for a small number of avocados to be available the following year.
Once planted, the avocado trees will come into “full” production in about five years.
To read this story in Spanish, visit: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=58991
- Author: Dong-Hwan Choe
32nd Annual UCR Urban Pest Management Conference (UCR UPMC) was held at UCR Campus (HUB Conference Rooms) on March 28, 2023. Over 120 attendees (including 114 registered conference attendees and sponsors from urban pest management industry) and several students (graduates and undergraduates) from UCR Entomology urban entomology program enjoyed this one day (8AM - 4:30PM) educational event, which was filled with many useful and interesting talks. Dr. Vernard Lewis from UC Berkeley (emeritus) has provided our annual Ebeling Memorial Lecture, going over the rich and diverse tradition of urban entomology work in the western US, including California, and University of California system.
Here are some photos from the event.
- Author: Jules Bernstein, UC Riverside
Disappearing native is like an environmental Swiss Army knife
Though it is disappearing, California's official state grass has the ability to live for 100 years or more. New research demonstrates that sheep and cattle can help it achieve that longevity.
Purple needlegrass once dominated the state's grasslands, serving as food for Native Americans and for more than 330 terrestrial creatures. Today, California has lost most of its grasslands, and the needlegrass occupies only one tenth of what remains.
It is drought resistant, promotes the health of native wildflowers by attracting beneficial root fungi, burns more slowly than non-native grasses and speeds the postfire recovery of burned lands. For these and other reasons, many who work toward habitat restoration hope to preserve the needlegrass.
“Where it grows, these tall, slender bunches become focal points, beautiful as well as environmentally beneficial,” said Loralee Larios, a UC Riverside plant ecologist affiliated with UC Agriculture and Natural Resources. “However, identifying successful management strategies for a species that can live for a couple hundred years is challenging.”
To meet that challenge, Larios teamed up with University of Oregon plant ecologist Lauren Hallett and Northern California's East Bay Regional Park District. They tracked the health of nearly 5,000 individual needlegrass clumps over six years, including an El Niño rain year as well as historic drought.
The researchers took measurements of plant health including growth and seed production. They placed small bags over many of the grass clumps to capture the seeds and quantify the number of seeds they produced.
Their findings, now published in the Journal of Applied Ecology, were that purple needlegrass did better in places where sheep were allowed to graze. The positive effects of the grazing were amplified in times of wetter weather.
Previously, the park district spent a decade trying to assess the success of its grassland maintenance techniques. However, the district's method of applying a strategy like grazing, and then measuring the percentage of needlegrass clumps in a given area resulted in data that didn't follow a discernable pattern from year to year.
“By tracking each plant over time, rather than scanning broadly across an area, we gained much more clarity about how the grass responds to the grazing,” Larios explained. “Perhaps counterintuitively, we saw that the needlegrass generally died back when sheep weren't allowed to graze on it.”
When sheep were removed from the study sites, the needlegrass in all but two of the sites became less healthy. The researchers would like to learn whether the two sites that remained healthy have needlegrasses that are genetically distinct.
Grazing is a controversial strategy for grassland restoration. Some conservationists believe sheep eating the target grass, particularly during already stressful drought years, does not enhance their survival. As far back as the 1800s, some researchers hypothesized that the combination of grazing and drought resulted in the loss of perennial grasses.
Though drought was not beneficial for any of the plants in this study, the researchers believe grazing helped needlegrass survive in at least two ways. One, by trampling on leaf litter and other organic debris, sheep created space for new needlegrass to grow.
“Sometimes you get litter that's as deep as a pencil — so much dead, non-native grass piles up. It's hard for a little seed to get enough light through all of that,” Larios said.
Secondly, sheep eat non-native grasses that generate growth-suppressing debris and compete with purple needlegrass for resources.
When the Spanish colonized California, they brought forage grasses like wild oats that they thought would benefit cattle. Those introduced grasses spread, and now dominate the state's grasslands.
“Our grasslands are known as one of the world's biggest biological invasions,” Larios said.
California has as many as 25 million acres of grasslands, equivalent to the combined areas of Massachusetts, Connecticut, and Rhode Island. Though Larios does not believe it is possible to rid the state of all non-native grasses, she said it is possible to maintain or even increase the amount of purple needlegrass.
“It's great for carbon storage, which mitigates climate change, it doesn't serve as wildfire fuel, and cultivates a space for wildflowers that pollinators are then able to use,” Larios said. “We want to keep all those benefits.”
/h3>- Author: Jules Bernstein, UC Riverside
Scientists search for pheromone to disrupt insect mating
UC Riverside scientists are on the hunt for a chemical that disrupts “evil” weevils' mating and could prevent them from destroying California's supply of avocados.
Avocado weevils, small beetles with long snouts, drill through fruit to lay eggs. The weevil grubs or larvae bore into avocado seeds to feed, rendering everyone's favorite toast topping inedible.
“They're extremely hard to control because they spend most of their time deep inside the fruit, where they're very well protected from insecticides and natural enemies,” said UCR researcher Mark Hoddle, a UC Cooperative Extension entomology specialist.
Not only are the insects reclusive, they are also understudied, making information about them hard to come by. “All books on avocado pest management will tell you these weevils are bad. They're well recognized, serious pests of avocados, but we know practically nothing about them,” Hoddle said.
One strategy for controlling pests is to introduce other insects that feed on them. However, that is unlikely to work in this case. “Natural enemies of these weevils seem to be extremely rare in areas where this pest is native,” Hoddle said.
To combat avocado weevils in Mexico, an area where they are native, and to prevent them from being accidentally introduced into California, Hoddle is working with Jocelyn Millar, a UCR insect pheromone expert. They are leading an effort to find the weevil's pheromone, with the goal of using it to monitor these pests and prevent them from mating in avocado orchards.
Pheromones are chemicals produced and released into the environment by an insect that can be “smelled” by others of its species, and affect their behavior.
“We could flood avocado orchards with so much pheromone that males and females can't find each other, and therefore can't reproduce,” Hoddle said. “This would reduce damage to fruit and enable growers to use less insecticides.”
Alternative control strategies could include mass trapping, using the pheromone as a lure, or an “attract-and-kill” approach, where the pheromone attracts the weevils to small sources of insecticide.
The work to identify, synthesize and test this pheromone in the field is supported by grants from the California Department of Food and Agriculture, as well as the California Avocado Commission.
An initial phase of the project sent Hoddle to a base of operations three hours south of Mexico City, an area with large weevil populations. Using a special permit issued by the USDA, Hoddle brought weevils back to UCR's Insectary and Quarantine facility.
Hoddle and Sean Halloran, a UCR entomology researcher, captured the chemicals that avocado weevils release into the air. Possible pheromone compound formulas were identified from these crude extracts and are now being synthesized in Millar's laboratory.
“Weevil pheromones have complicated structures. When they're made in a lab, they can have left- or right-handed forms,” said Hoddle. Initially, Millar's group made a mixture of both forms to see if the blend would work as an attractant, as it is far cheaper to make the blend than the individual left- or right-handed forms.
Field work in Mexico with the pheromone cocktail by Hoddle, his wife Christina Hoddle, an associate specialist in entomology, and Mexican collaborators did not get a big response from the weevils, suggesting that one of the forms in the blend could be antagonizing the response to the other.
As the next step, the researchers plan to synthesize the individual forms of the chemicals and test the insects' response to each in Mexican avocado orchards.
Because the levels of avocado imports from Mexico are increasing, the risk of an accidental weevil invasion is rising as well. Hoddle is hopeful that the pheromone will be successfully identified and used to lower the risk this pest presents to California's avocado growers.
“We've been fortunate enough to be awarded these grants, so our work can be implemented in Mexico and benefit California at the same time,” Hoddle said. “The tools we develop now can be used to make sure crops from any exporting country are much safer to import into California.”
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