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.
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.
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
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
- Author: Cheryl Reynolds
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.
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.
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.
Stippling and eventual necrosis of damaged tissue in chiko burdock. (Photo by Don DeLano, Pomona)
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 email@example.com 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>
A homeowner in Goleta recently reported severe infestation and damage of tomatoes by the tomato bug, Cyrtopeltis modesta (Distant) in their home garden. It also appears that they have become more frequent in recent years. This article provides an overview of the pest and some management options.
Tomato bug also known as tomato suck bug belongs to the family Miridae in the order Hemiptera. Lygus bug and other plant bugs also belong to the same family. There seems to be some confusion in the description of C. modesta (Engytatus modestus) and without a good key, identification of related species such as C. tenuis, C. geniculata, and Dicyphus spp. can be complicated.
Origin and distribution: Origin of C. modesta was not clear in literature, but Carvalho and Usinger (1960) referred to it as an American species while reporting a new species of Cyrtopeltis from Hawaii. Tomato bug is reported from Europe, South America, and North America and its related species from other parts of the world.
Biology and identification:
Adults are 7-8 mm or 0.25” long. Body is slender, pale and has a green or red tinge. Pronotum (shield like plate on the thorax) is narrow. Eyes are small. Wings are membranous, pale green or translucent. Nymphs look similar to adults, but without wings or with developing wing pads. There are four to five nymphal instars. Eggs are laid inside the petiole or the terminal shoots. Nymphs and adults actively feed.
Nymphs and adults actively feed by inserting their piercing and sucking mouthparts in plant tissues and sucking the juices. Yellowish red rings develop around the stem as a result of feeding. These areas are corky and break easily leading to the dropping off of flowers or developing fruit. Tomato bugs are common in Central Valley and Southern California both in organic and conventional tomatoes. However, they are usually not a problem in large farms where pesticides are applied to manage major tomato pests. They can be a problem in home gardens and small farms where pesticide treatments are less common (Tom Turini, personal communication).
There is no information available on natural enemies, pesticide treatments, or other management options specific to tomato bugs. Pesticides that are usually effective against lygus bugs (http://www.ipm.ucdavis.edu/PMG/r783301611.html) or stink bugs (http://www.ipm.ucdavis.edu/PMG/r783300211.html) in tomatoes can be effective against tomato bugs. Based on my research on other hemipterans, botanical insecticide/insect growth regulator – azadirachtin (especially against nymphal stages) and insect pathogenic fungi – Beauveria bassiana, Metarhizium brunneum (M. anisopliae), or Isaria fumosorosea (Paecilymyces fumosoroseus) can also be effective against tomato bugs. These could be good alternatives to chemical pesticides for home gardens.
Carvalho, J.C.M. and R. L. Usinger. 1960.New Species of Cyrtopeltis from the Hawaiian Islands with a Revised Key (Hemiptera: Miridae). Proc. Hawaiian Entomol. Soc. 17: 249-254.
Goula, M. and O. Alomar. 1994. Míridos (Heteroptera Miridae) de interés en el control integrado de plagas en el tomate. Guía para su identificación. Bol. San. Veg. Plagas 20: 131-143.
Letourneau, D. K. and B. Goldstein. 2001. Pest damage and arthropod community structure in organic vs. conventional tomato production in California. J. Appl. Ecol. 38: 557-570.
Swezey, O. H. 1925. Notes and Exhibitions (Sept. 4, 1924). Proc. Haw. Ent. Soc, 6:18.
University of Arizona http://ag.arizona.edu/ceac/sites/ag.arizona.edu.ceac/files/pls217nbCH4_3.pdf.