Grower Notes and Pest News
Adult light brown apple moth (Photo by Jack Kelly Clark, UC IP)
Nursery workers are our first line of defense in detecting light brown apple moth when growing ornamental plants in commercial nurseries. A new brochure and video can help those in the field distinguish light brown apple moth from several look-alike caterpillars.
Light brown apple moth is currently under a California Department of Food and Agriculture quarantine that regulates the interstate shipment of plants to keep the moth from spreading to new areas. It has been quarantined in various counties throughout coastal California ranging from Mendocino to San Diego.
Light brown apple moth larva (Photo by Jack Kelly Clark)
Correct field identification of the light brown apple moth is the first step in containing the spread of this moth. Unfortunately several other leafroller caterpillars, including the orange tortrix, omnivorous leafroller, avocado leafroller, and apple pandemic moth, look similar to light brown apple moth caterpillars. This makes photo identification tools that can go into the field with workers, like the Field Identification Guide for Light Brown Apple Moth in California Nurseries, a useful resource for nursery workers.
The field guide was created by Steven Tjosvold, Neal Murray, University of California Cooperative Extension; Marc Epstein, Obediah Sage, California Department of Food and Agriculture; and Todd Gilligan, Colorado State University with the Statewide Integrated Pest Management Program (UC IPM).
An exotic and invasive pest from Australia, light brown apple moth has a host range of more than two thousand plants. It is a pest to a wide range of ornamental and agricultural crops, including caneberries, strawberries, citrus, stone fruit, apples, and grapes. The caterpillars eat leaves and buds, leading to weak or disfigured plants. They also can feed directly on fruit, causing the fruit to be unmarketable.
For more information on light brown apple moth and other leafrollers found in nurseries, see the UC Pest Management Guidelines for Floriculture and Nurseries.
Average annual precipitation in California is 200 million acre-feet, out of which 42% of water is used for agriculture while 11% is used in the urban areas (municipal and industrial users) and the remaining 47% by the environment (native vegetation, ground water, and oceans) (Doug Parker, personal communication). According to the National Drought Mitigation Center's Drought Monitor, 95% of California is currently in a severe to exceptional drought condition. Drought has impacted California agriculture in different ways in different regions. Depending on crop needs, geographic location, and availability of ground water, production of each crop is affected in one way or the other. Compared to the Central Valley which is affected most by the drought, agriculture on the Central Coast and Southern California is less affected according to a study conducted by the Center for Watershed Sciences at University of California Davis.
Water use in California (Source: Doug Parker, Director of California Institute for Water Resources and Water Strategic Initiative Leader)
Drought conditions in California as of October 16, 2014. Source: US Drought Monitor.
Some strawberry and vegetable growers in San Luis Obispo and Santa Barbara Counties were contacted recently to assess the current impact of drought. Their feedback helped to put together the following summary of the current status and recommendations to address drought conditions.
Strawberry growers continue to use available groundwater although with concern for future availability. Current impact of the drought on strawberries:
- Strawberries require 21-24 acre inches of water and rainfall accounts for 3-6 acre inches during normal rainfall years. Rainfall leaches salts away from the root zone while meeting irrigation needs. Compared to three years ago, it is estimated that there is up to a 10% increase in some salts, especially calcium and magnesium due to the current drought conditions. This could lead to 5-10% reduction in fruit yields, but severe salt injury could cause higher losses. Additionally, plants would be vulnerable to pests and diseases which could lead to further yield reduction.
- Strawberries are very sensitive to salinity and frequent irrigation is practiced to prevent the accumulation of salts in the root zone. Growers are aware of diminishing groundwater resources and are carefully monitoring water and salinity levels. Extra irrigation to push out salts from the root zone results in nutrient leaching.
- These practices are expected to continue as long as groundwater is available, but acreage could diminish if groundwater becomes unavailable.
Salt injury to strawberry plant (Photo by Surendra Dara)
Strategies to address drought conditions in strawberry production:
- Continue to monitor groundwater levels and provide irrigation to meet water needs as well as to leach out salts.
- Monitor health of plants and regularly scout for pests and diseases which might require more timely treatment actions than usual because plants are already under stress.
- Check nutrient levels in the soil and plant and compensate as needed if irrigation is causing nutrient loss.
- Modify leaching fractions based on salt levels and plant maturity to flush salts away from the root zone.
- Reconsider acreage planted based on groundwater availability to minimize losses.
Vegetable growers are experiencing the impact of drought conditions on their production and are currently relying on available groundwater.
- Water needs for vegetables vary from about 7 to 36 acre inches based on the crop and location. Rainfall during a normal season contributes up to 24 acre inches depending on the crop and season.
- Drought conditions resulted in increased salinity, which has caused 10-20% reduction in yields of some crops and a significant increase in pest and disease pressure. Some growers are managing without any yield losses.
- Some growers have already reduced their acreage by 10% or more while others continue to maintain the current acreage.
- Reducing or completely avoiding pre-irrigation is currently practiced by some growers to cope with water shortage. This practice has also increased salinity in the soil and increased weed populations.
- Some growers have reduced fertilizers or are choosing ones with less salt content.
- In order to monitor salinity and nutrient levels, additional expenses are incurred for water, soil, and plant analysis. Increased weed, pest, and disease problems have also increased management costs.
- Some growers are prepared to reduce acreage up to 25% if drought conditions continue.
Strategies to address drought conditions in vegetable production:
- Continue regular monitoring of groundwater levels, salinity conditions, nutrient status, and provide irrigation and fertilizers as appropriate.
- Regularly monitor for pests and diseases and make timely management decisions.
- Reduce or avoid sprinkler irrigation and use drip irrigation as much as possible.
- Continue to reduce or avoid pre-irrigation to conserve water.
- Modify leaching fractions based on the current salt and crop conditions and administer irrigation as needed.
- Modify acreage to suit future water availability.
My current research is evaluating the potential of entomopathogenic fungi in improving water and nutrient absorption by plants, which could play a role in conserving water resources.
Acknowledgements: Thanks to the strawberry and vegetable growers in San Luis Obispo and Santa Barbara Counties who responded to the survey on drought impact and provided their valuable feedback.
UC and other resources:
California agriculture faces greatest water loss ever – College of Agricultural and Environmental Science, UC Davis
Center for Watershed Sciences - UC Davis
Water use in California – Public Policy Institute of California
California harvest much smaller than normal across crops – The Sacramento Bee
In virtual mega-drought, California avoids defeat – Los Angeles Times
Female (top), male and female in compulation (middle) and a mature nymph (bottom) of Bagrada bug on a dime. (Photo by Surendra Dara)
Bagrada bug (Bagrada hilaris) is an invasive pest that was first reported in California in 2008 in Los Angeles County. It is currently reported from the following counties in California on various host plants.
Biology, damage, and management of Bagrada bug
Voraz plaga ataca huertos y jardines
UC IPM Kiosk displaying information in Spanish. Photo by Karey Windbiel-Rojas.
National Hispanic Heritage Month (September 15 – October 15) celebrates the contributions, culture, and history of Hispanic and Latino Americans originating from Spain, Mexico, Puerto Rico, Central America, and South America. These Americans make up the largest minority group in the United States and represent a very important part of the UC Statewide IPM Program's audience.
In recognition of National Hispanic Heritage Month, we'd like to highlight several important resources available from UC IPM to help Spanish-speaking audiences manage pests and apply pesticides safely.
For our Spanish-speaking urban audiences, several short videos on common pests such as ants, spiders, snails, bed bugs, and mosquitoes are available as well as Quick Tips (Notas Breves) offering advice on many pest problems and information on using pesticides safely. There are also 16 touch-screen computer kiosks located in various locations around the state where users can find pest and pesticide information in English or Spanish.
For maintenance gardeners preparing to take the California Department of Pesticide Regulation's Pesticide Applicators exam in the category Q, UC IPM offers a study guide and free online training course in Spanish.
National Hispanic Heritage Month actually originated in 1968 as “Hispanic Heritage Week.” In 1988, it was expanded to an entire month-long event in order to include many important historical events such as the anniversary of independence of Mexico, Chile, and several Central American countries (Belize, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua). It ends after Columbus Day.
For more on other pest management and pesticide safety information available, please see the UC IPM Web site.
Current status of the invasive Bagrada bug in California: geographic distribution and affected host plants
Bagrada bug [Bagrada hilaris (Burmeister)] is an invasive hemipteran insect (Family: Pentatomidae) that was first reported in Los Angeles County, California in 2008. It has now spread to several counties in California and is moving northwards.
Distribution: Citizen scientists have been instrumental in reporting the occurrence of Bagrada in various counties and are helping map its current distribution. As of September 2014, Bagrada bug is known to be present in Imperial, San Diego, Orange, Riverside, Los Angeles, San Bernardino, Kern, Kings, Inyso, Fresno, Merced, Ventura, Santa Barbara, Monterey, San Benito, Santa Cruz, San Mateo, Santa Clara,Alameda and Yolo Counties and is likely to be present in some other.
Distribution of Bagrada bug in various California counties as of September, 2014.
Bagrada bug is also spreading eastwards from California and is currently reported in Nevada, Arizona, Utah, New Mexico, and Texas.
Host plants affected: While Bagrada bugs are known to feed on a variety of host plants in addition to their preferred cruciferous hosts, serious damage to barley, carrot, corn, pepper, potato, tomato, and sunflower was recently reported by growers or gardeners. In a previous study where multiple food sources were offered, Bagrada bugs did not feed on tomatoes. They were also found on strawberries and reported to be present on other hosts, but damage has not been confirmed. Bagrada bugs might have been present on these plants as they move around in search of suitable food sources.
Damage to carrots from Bagrada bug feeding. (Photo by Rick Machado, Menifee)
Stippling and eventual necrosis of damaged tissue in chiko burdock. (Photo by Don DeLano, Pomona)
Backyard corn damaged by Bagrada bugs. (Photo by Larry Adcock, Arroyo Grande)
Adult Bagrada bugs on damaged pepper leaves. (Photo by Rick Machado, Menifee)
Seriously damaged seed potato plants (above) and tubers (below). (Photo by Rick Machado, Menifee)
Bagrada bug damage to sepals on sunflower. (Photo by Larry Adcock, Arroyo Grande)
Bagrada bug feeding damage to tomatoes. (Photos by Rick Machado, Menifee, above and Jennifer Evangelista, San Luis Obispo, below)
Bagrada bugs on strawberry foliage. Not seen to cause any feeding damage. (Photo by Jennifer Evangelista, San Luis Obispo)
Management: Regular monitoring, mechanical exclusion or removal, destruction of weed hosts, and chemical, botanical, and microbial pesticides continue to be available management options. There have been several queries in the past two months from home owners, community garden operators, and organic growers about serious Bagrada bug infestations. Avoiding cruciferous and other hosts at risk should be a serious consideration for community and home gardens where using some of the currently available management options is difficult.
What to do: If you see Bagrada bug in an area or on a host that is not previously reported, please contact Surendra Dara at firstname.lastname@example.org or 805-781-5940. This information will be useful to track the distribution of this pest.
Biology, damage, and control video: www.youtube.com/watch?v=gSj3AZoJIRM
Biology, damage, and control: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=4047
Potential organic solutions: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=11031
Host preference: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=9611
General information: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=8438/span>