- Author: Sonia Rios
- Author: Niamh Quinn
- Author: Eta Takele
Wild pigs currently exist in 56 of California's 58 counties and can be found in a variety of habitats ranging from woodland, chaparral, meadow, grasslands and in agriculture cropping systems. Wild pigs are commonly found in the foothill areas, and they prefer areas of dense brush, however the drought has led them to encroach into orchards. Wild pigs can cause significant damage to farm and rangelands, natural resources, environmentally sensitive habitats, and property. Wild pig depredation on livestock and poultry can cause high economic loss (Choquenot et. al. 1996). Also, wild pigs can carry a number of diseases and parasites that can be transmitted to livestock, wildlife, and humans. In California, wild pigs can be carriers of Brucellosis, Cholera, Leptospirosis, Tuberculosis (Bovine, Avian, and Swine), Q fever, Trichinosis, Toxoplasmosis, Pseudorabies, and Plague (Barrett and Tietje 1993).
DESCRIPTION OF THE PEST
Domestic swine were imported to the United States by European settlers in the 1700s. Whereas Domestic swine foraged freely, eventually becoming semi-wild, or “feral” (CDFW 2017), California's wild pigs were descendants of the Eurasian wild boar, introduced to Monterey County, California in the 1920s. The physical characteristics of California's wild pigs vary significantly throughout the state. Some exhibit the long hair and snouts, small erect ears and angular shaped bodies of their wild boar ancestors, while others have short hair, long floppy ears, and a barrel-shaped body. Colors range from solid black to red, striped, grizzled or spotted (CDFW 2017). Domestic pigs that are unmarked and roam freely are also considered to be wild pigs.
DAMAGE IN CITRUS
Cultivation operation disruption
Evidence of wild pigs' presence is obvious even if you don't see them physically. Wild pigs use their snouts to root up the ground in search of food, including plant roots, fungus, and other items. Wild pigs are omnivorous, consuming both plant and animal matter. In general, wild pigs feed on: grasses and forbs in the spring; mast and fruits in the summer and fall; and roots, tubers and invertebrates throughout the year.
Wild pigs will feed on insects and underground vegetation. This rooting behavior can disrupt parts of the orchard floors. it could lead to the trees becoming susceptible to root rot diseases that could spread throughout the grove. They are also known to eat fruit off of the lower branch scaffolds. Pigs will contribute to erosion which can affect water quality and also create large uneven basins, or wallows in moist soil during hot weather. Both rooting and wallows can disrupt the application of irrigation water by ruing or displacing irrigation equipment and resulting pools can become breeding habitat for mosquitoes.
Food safety
Wild pigs can also create a food safety issue. Growers are now required to show a Food Safety Good Agricultural Practices for California Citrus Growers (GAPs). This practice is focused on the grower's particular role in providing safe citrus fruits for consumers. The grower should assess the impact of domestic, livestock and wild animal activity for potential pathogen contamination of the grove and fruit. The assessment should include the extent of intrusion, nearness to the grove, proximity to harvest and other relevant factors. Based on the assessment, the grower should put into place measures to exclude domestic animals and minimize the intrusion of wildlife into the grove.
- The grower should monitor the grove and adjacent land for evidence of animal activity and the potential for contamination of fruit or equipment.
- The grower should return bins to packers if there is evidence of contamination.
- When the assessment or monitoring indicates possibility of contamination with pathogens, the grower should take action as needed to minimize potential for contamination of the fruit and to prevent the harvest of any potentially contaminated fruit
Pre-Harvest
- The grower should perform a documented evaluation of the grove environment for changes that may be likely to result in contamination of the citrus fruit with pathogens. Evaluation should include inspection for:
o Evidence of animal intrusion such as downed fences, presence of live or dead animals, animal tracks or animal feces. If animal intrusion is detected, measures shall be taken to remove or prevent from harvest any potentially contaminated product.
o Presence of potentially contaminating materials (e.g. uncomposted manure, etc.) likely to pose a contamination risk to the grove to be harvested.
o Evidence that the irrigation water source and delivery system may potentially be compromised.
For more information regarding Citrus GAP: http://ccqc.org/wp-content/uploads/2009/05/Final-Food-Safety-GAP-document-_Oct-26_.pdf
MANAGEMENTClassified as a game mammal in California, wild pigs provide year-round hunting opportunity and fall under the jurisdiction of the California Department of Fish and Wildlife (CDFW). A hunting license and a tag is required to hunt wild pigs. If wild pigs are causing damage to your property, pigs can be trapped or shot, but this requires a depredation permit. Contact your local CDFW representative for further details on depredation permits (https://www.wildlife.ca.gov/Conservation/Mammals/Wild-Pig/Depredation).
Monitoring and Management Strategies
Fencing
Fencing can be extremely effective but because of costs it can be extremely prohibitive. However, on smaller scales, exclusionary fencing can be an effective option. One of the most effective designs seems to be the installation of sturdy wire mesh fencing. The bottom wire should be either tightly stretched on the ground surface or buried. The addition of an electrified wire about 6 to 8 inches off the ground is also recommended. The fence should be at least 36 inches high. Electric fencing alone has also been shown to restrict the movement of wild pigs also. Poorly designed and constructed fences will significantly increase repair and maintenance time. It is important to carefully consider the costs and benefits of fencing for pig exclusion before embarking on such a venture.
Trapping
Trapping can be an effective method of removing wild pigs from your orchard. The most commonly used traps are box traps and corral traps. Corral traps are much larger than box traps and are designed to capture multiple pigs. It is important to consider that all wild animals can be unpredictable when approaching captured pigs.
In some counties, the agricultural commissioner has trappers who can assist; other counties have contracts with USDA-Wildlife Services to assist with problematic pigs.
Toxicants and Repellents
Currently there is one toxicant registered for use on wild pigs in the United States (EPA Reg. No. 72500). This product is not currently registered for use in California. This product may only be used to control wild pigs on pastures, rangeland, forests, non-crop areas, and crop lands. This bait may only be applied in hog feeders equipped with heavy lids (8 to 10 lbs. of total weight) on bait compartments so as to limit direct access to bait by nontarget animals. This product may be toxic to fish, birds and other wildlife. Dogs and other predatory and scavenging mammals and birds might be poisoned if they feed upon animals that have eaten the bait. Wild pigs must be conditioned to accept feed from the bait dispensers and to open the weighted lids to bait compartments.
Repellents are not generally considered effective against many mammalian pests and this is also true for the management of wild pigs.
Collecting information on wild pig damage
UCANR is asking California growers and landowners to help keep track of the state's wild pigs and the damage they are causing through a new Wild Pig App. The app is available for download on Apple and Android devices and will collect information on wild pig damage throughout California. Cell service at the site of pig damage is also not required to collect the information. The information collected will be used by University of California Cooperative Extension Specialists and Advisors to learn more about wild pigs in the State.
Download the app at your App Store to participate in the wild pig damage project without the app, landowners and growers can fill out a short survey at http://ucanr.edu/wildpig2016.
Additional Resources
Barrett, R. H. and G. H. Birmingham. 1994. Wild Pigs. The Handbook: Prevention and control of wildlife damage. Cooperative Extension Division, University of Nebraska-Lincoln.
California Department of Fish and Wildlife <https://www.wildlife.ca.gov/Conservation/Mammals/Wild-Pig> Accessed: 24 July 2017.
Barrett, R. H., and W. Tietje. 1993. The wild pig in California oak woodland: ecology and economics. Conference Presentation Summaries. Univ. of California, Berkeley.
Coping with Feral Hogs. Texas A&M AgriLife Extension Service.
Feral Hog Biology, Impacts, and Eradication Techniques (PDF). 2010. USDA APHIS Wildlife Services New Mexico.
Finzel, J. A. and Baldwin, R. A., (2015) Pest Notes: Wild Pigs. UC ANR Publication 74170
Hamrick, B., M. D. Smith, C. Jaworowski, B. Strickland. 2011. A Landowner's Guide for Wild Pig Management(PDF). Publication 2659.
Jay-Russell, M. T., A. Bates, L. Harden, W. G. Miller, and R. E. Mandrell. 2012. Isolation of campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California. Zoonoses and Public Health. 59:314-319.
Kreith, M. 2007. Wild pigs in California: the issues (PDF). AIC Issues Brief No. 33. Agricultural Issues Center, University of California.
Sweitzer, R. A. and D. H. VanVuren. 2002. Rooting and foraging effects of wild pigs on tree regeneration and acorn survival in California's oak woodland ecosystems (PDF). USDA Forest Service General Technical Report PSW-GTR-184.
Waithman, J. 2001. Guide to hunting wild pigs in California. California Department of Fish and Wildlife, Wildlife Programs Branch.
West, B.C., A. L. Cooper, J. B. Armstrong. 2009. Managing wild pigs: A technical guide (PDF). Human-Wildlife Interactions Monograph 1:1.
- Author: Ben Faber
7:00 A.M. Check In and Breakfast Buffet
8:00 A.M. Welcome
8:10 A.M. Opening Keynote - Our Organic Resources
Evan Johnson, Science and Policy Advisor, CalRecycle
Biomass Sources and Concerns
8:30 A.M. The Agricultural Perspective
Moderator: Ben Faber, Ph.D., Farm Advisor,
UC Cooperative Extension-Ventura and Santa Barbara Counties
Presentation: Introduction to the Agricultural Perspective
Robert Atkins
ACP/HLB Statewide Coordinator;
California Invasive Species Advisory Committee Past Chair;
Retired San Diego County Agricultural Commissioner
Panel Discussion:
Eric Larson, Executive Director, San Diego County Farm Bureau
Duane Schnabel, Branch Chief, Pest Exclusion Branch,
California Department of Food and Agriculture
Tim Spann, Research Program Director, California Avocado Commission
Dr. Jerrold Turney, Pathologist, County of Los Angeles,
Department of the Agricultural Commissioner/Weights and Measures
9:30 A.M. The Rural and Natural Landscapes Perspective
Moderator: Sabrina Drill, Ph.D., Natural Resources Advisor,
UC Cooperative Extension - Los Angeles and Ventura Counties
Presentation: Introduction to the Rural and Natural Landscapes Perspective
Sheri Smith
Regional Entomologist, USDA Forest Service, Region 5
Panel Discussion:
Paul Noring, President, Main Street Materials, Inc.
Michael Puzzo, Environmental Scientist, California State Parks-Colorado Desert District
Kevin Turner, Invasive Pests Program Coordinator/Forester, CA Department of Forestry and Fire Protection (CAL FIRE)
10:30 A.M. Break
11:00 A.M. The Urban Landscapes Perspective
Moderator: Jennifer Pelham, Environmental Horticulture Advisor,
UC Cooperative Extension-Orange and San Diego Counties
Presentation: Introduction to the Urban Landscapes Perspective
John Kabashima
Advisor Emeritus, University of California Cooperative Extension
Panel Discussion:
Richard Demerjian, Assistant Vice Chancellor, Environmental Planning and Sustainability, University of California, Irvine
Andy Trotter, Vice President-Field Operations, West Coast Arborists, Inc.
Roc White, Manager, Viramontes Express Mobile Grinding
12:00 P.M. Lunch
Environmental and Regulatory Issues
Moderator: Kevin Turner Invasive Pests Program Coordinator/Forester,
CA Department of Forestry and Fire Protection (CAL FIRE)
1:00 P.M. Julee Malinowski-Ball, Public Policy Advocates, LLC
1:20 P.M. Woody chips as landscape mulch in fire-prone areas
Pam Padgett, Pacific Southwest Research Station, USDA Forest Service
1:40 P.M. Developing a Regional Biomass Management Strategy: Balancing Multiple Interests
Michael Wonsidler, Coordinator, Solid Waste Planning and Recycling,
County of San Diego Department of Public Works
Biomass Utilization Methods
Moderator: Tracy Ellis, Entomologist, County of San Diego,
Department of Agriculture, Weights and Measures
2:00 P.M. Wood and Biomass Utilization Overview
Larry Swan, Wood & Biomass Utilization Specialist, USDA Forest Service, Region 5
2:20 P.M. Composting
David Crohn, Extension Resource Conservation Specialist, UC Riverside
2:40 P.M. Air Burners
Michael O'Connor, Director, North America Sales Division, Air Burner, Inc.
3:00 P.M. Break
3:20 P.M. Panel: Potential Solutions and Associated Economics
Moderator - Stephen Kaffka, Extension Agronomist, UC Davis; Director, California Biomass Collaborative
4:20 P.M. Closing Keynote
Thom Porter, Chief, Southern California Region, CA Department of Forestry and Fire Protection (CAL FIRE)
4:40 P.M. Closing Comments and Evaluation
5:00 P.M. Adjourn
Presentation and Panel Speakers
Evan Johnson, Science and Policy Advisor, CalRecycle
Thom Porter, Chief, Southern California Region, CAL FIRE
Robert Atkins, California Invasive Species Advisory Committee Past Chair, Retired San Diego Agricultural Commissioner
Sheri Smith, Regional Entomologist, Region 5, USDA Forest Service
John Kabashima, Environmental Horticulture Advisor, Emeritus,
UC Cooperative Extension
Julee Malinowski-Ball, Public Policy Advocates, LLC
Pam Padgett, Pacific Southwest Research Station, USDA Forest Service
Michael Wonsidler, Coordinator, Solid Waste Planning and Recycling,
County of San Diego Department of Public Works
Larry Swan, Wood & Biomass Utilization Specialist, USDA Forest Service, Region 5
David Crohn, Extension Resource Conservation Specialist, UC Riverside
Michael O'Connor, Director, North American Sales Division, Air Burners, Inc.
Stephen Kaffka, Extension Agronomist, UC Davis and
Director, California Biomass Collaborative
Tim Spann, Research Program Director, California Avocado Commission
Eric Larson, Executive Director, San Diego County Farm Bureau
Michael Puzzo, Environmental Scientist, CA State Parks-Colorado Desert District
Kevin Turner, Invasive Pests Program Coordinator/Forester,
CA Department of Forestry and Fire Protection (CAL FIRE)
Richard Demerjian, Assistant Vice Chancellor,
Environmental Planning and Sustainability, University of California, Irvine
Andy Trotter, Vice President-Field Operations, West Coast Arborists, Inc.
Roc White, Manager, Viramontes Express Mobile Grinding
Duane Schnabel, Branch Chief, Pest Exclusion Branch,
California Department of Food and Agriculture
Dr. Jerrold Turney, Pathologist, County of Los Angeles,
Department of the Agricultural Commissioner/Weights and Measures
Paul Noring, President, Main Street Materials, Inc.
- Author: Brad Hanson
Brad is a Weed Specialist at UC Davis
As most orchardists and pest control advisors are well aware, glyphosate-resistant weeds have been one of the biggest weed management challenges in California orchard crops for several years.
Depending on where you are located in the Central Valley, your biggest challenges in the glyphosate-resistant weed department are probably one or more of the following winter annual weeds. In the San Joaquin Valley, hairy fleabane and horseweed (also known as mare's tail), dominate. In the Sacramento Valley and in some North coast areas, annual or Italian ryegrass is more common. For an extra challenge, many growers have a mix of several of these, in addition to their other common orchard weed spectrums.
In developing management strategies for these winter annual weeds, we've typically focused our herbicide-based programs on timely applications of preemergence herbicides. Because preemergence herbicides generally work on germinating weed seed or very small seedlings, “timely” applications for these winter annual species usually means getting the herbicide treatments out in late fall or early winter. In normal rainfall seasons, this timing ensures water-incorporation of the herbicide at about the same time as the seeds germinate and, hopefully, good control. Mission accomplished, right?
Recently, we've been seeing new glyphosate-resistant weed challenges that require a different management approach. The species I mentioned a moment ago are all winter annuals, which means they typically germinate and emerge during our cool season and reach a reproductive stage by spring or early summer. However, several recently confirmed (or suspected) glyphosate-resistant species are summer annual grasses. Summer annual weeds typically germinate and emerge as our season warms up in the late spring and early summer and they grow well into the summer before reaching maturity. A few examples include junglerice, threespike goosegrass, and several other glyphosate-questionable species such as feather fingergrass, sprangletop, and witchgrass. So, how do these grasses present such a different challenge?
The challenge with glyphosate-resistant summer grasses is that even though we have a number of good preemergence herbicides that can work very well on grasses, these species emerge long after our typical orchard preemergence herbicide programs are applied. Thus, herbicide programs that are applied during mid-November to mid-February targeting winter annual weeds sometimes fail to control summer annual weeds that emerge in May-July. If spring applications of foliar materials like glyphosate fail because of resistance, problems can quickly become apparent. How can we use our existing preemergence herbicide tools to help address this problem?
To answer that question, it's useful to think about what happens to a preemergence herbicide when you apply it to the soil. Herbicides “dissipate” in soil, a term that encompasses a suite of processes by which the herbicide is either broken down or made unavailable. Chemists use terms like “half-life” to describe differences in dissipation rates but this doesn't exactly get at our interest in weed control performance. From a performance standpoint, it's more useful to think of a herbicide concentration threshold. When the amount of herbicide in the soil solution is above the threshold for a certain weed, it remains effective on that weed. However, dissipation processes will eventually reduce the herbicide concentration below the threshold and the herbicide begins to “break”. The threshold may occur at different levels for different weed species and dissipation rates may vary in different areas of the fields (wet vs dry areas, for example).
So, how do we typically account for dissipation of preemergence herbicides in orchard crops? I tend to think of three general strategies:
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Use mixtures of more than one preemergence herbicide
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Apply a higher (labeled!) rate of a preemergence herbicide
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Use a sequential approach to preemergence programs in orchards.
Mixtures: Using herbicide mixtures, particularly products with different modes of action, is a great strategy for managing and delaying herbicide resistance but doesn't really help in this situation. Because herbicide dissipation rates are affected primarily by the chemistry of the individual herbicide and the environmental conditions, a tankmix will not exactly help extend the residual control beyond what we'd expect from the longest-lasting material. Or, to say it another way: if you mix a short residual herbicide with a long residual herbicide, one will last a short time and the other a long time but the mix will not last longer.
Higher rates: Many, but not all, preemergence herbicide labels have a range rates registered in a crop to account for differences in soils, required level of control, weed spectrums, etc. Within the labeled rate, it stands to reason that given similar dissipation processes, a higher rate will result in the soil concentrations of the herbicide remaining above the efficacy threshold for a longer time than a lower rate. This is generally true and is a common approach when we only have one opportunity to make a preemergence herbicide application. However, I think this is an indirect way to approach the problem of summer grasses in orchard crops.
Sequential approach: In the orchard cropping system, some growers may want to consider using a sequential approach to available preemergence herbicides to tackle problems with glyphosate-resistant summer annual grass weeds. Conceptually, this approach simply moves a portion of the winter preemergence herbicide program to a bit later in the year to late winter or early spring. A preemergence herbicide with activity on summer grasses would be applied along with the grower's spring burndown herbicide program and, thus, would be present in the soil solution much closer to the timeframe when summer grasses begin to germinate and emerge. Importantly, I think this could be achieved in many situations with no significant changes in cost, number of field operations, or negative environmental impacts.
Illustration: An almond grower who typically uses an effective preemergence program (pick your favorite program) applied around the first of December followed by a March “cleanup” treatment with glyphosate may still have difficulty managing glyphosate-resistant grasses. The grower knows that herbicides like oryzalin or pendimethalin (eg. Surflan or Prowl H2O) could help with grasses. Using the higher rate approach, the grower could use a high label rate one of these materials in December with the idea that it will persist long enough to control summer grasses emerging six months later. Using the sequential approach, the grower could move all or part of the oryzalin or pendimethalin component of the program to the March timing to more directly target those summer germinating grasses, possibly at a the same or even lower total application rate.
Who might want to consider a sequential approach? This approach requires a bit of close management attention. First, because incorporation of preemergence herbicides is key to their performance, moving some of this product to late spring will require either timely rain or overhead irrigation capabilities. Growers with solid-set or micro sprinkler systems should have little problem with this, but single- or double-line drip irrigated orchards will need to get a rain and should not delay too late in the spring.
Second, moving all or part of the preemergence grass herbicide to late in the year requires that growers know their weed spectrum. If you know or suspect glyphosate-resistant summer weeds, this may be an approach to consider. You should also have an idea of what weeds you are managing during the winter season too and make sure that your winter program still addresses that part of the weed spectrum.
Weed management in orchard crops is complex and getting further complicated by new glyphosate-resistant weeds. Because of our relatively mild climate and seasonally variable temperature and moisture conditions, we encounter weed germination and emergence in every season. Strategies to manage one fraction of the weeds present in a given orchard may not work equally well for other species. Handling shifting weed problems may require different approaches in order to make the most effective use of existing weed management tools.
- Author: Oleg Daugovish
Using organic herbicides in production fields and non-crop areas.
The forecasts call for rainy winter and that means a lot of weeds. During dry times perennial weeds tend to grow better than annual weeds, since perennial structures such as underground rhizomes or tubers can support them and give competitive advantage. Seed of annual weeds in dry soil may have been losing viability, senescing or eaten during this time, but many have remained dormant and look forward to the wet winter us much as the rest of us.
Controlling weeds ‘organically' is always an extra challenge whether you are in a certified field or in an area where synthetic herbicides are not desired. Hand-weeding, already expensive, is even a greater burden with limited labor availability, and frankly not much fun either. Of course sanitation and prevention, mechanical and cultural management are essential in organic systems. That requires time and commitment and can quickly become your not-so-favorite pastime.
Organic herbicides have traditionally been contact materials with no systemic activity. This means that they only affect tissue that they contact and do not translocate through the plant like most synthetic herbicides. Thus, good coverage is critical for these contact materials. Many years ago the first herbicides were sulfuric acid and diesel fuel, current organic materials are often acids or oils too, although a lot more benign.
Recent trials by the University of California weed scientists showed that several organic herbicides provided decent control of easy to control pigweed and nightshade when they were small. When weeds were 12 days old, a mixture of 45% clove and 45% cinnamon oil, 20%-acetic acid and d-limonene gave 61-89% control; however only d-limonene controlled 19-day old weeds and none was effective on one-month old ones. As weeds get bigger they also develop a protective cuticle that minimizes efficacy of these herbicides.
This year we conducted trials with a recently OMRI approved herbicide for row crops, trees and vines that is a mix of caprylic and capric acids. It disrupts cell membranes of plans and causes the contents to leak and plants to desiccate. It worked well at 6 to 9% by volume mixture with water and gave 90% control of little mallow and >95% of annual sowthistle compared to untreated checks. We have also tested it in organic strawberry furrows before planting the crop to prevent potential injury from drift. Furrow cultivation does not get close to the plastic mulch that covers the beds to prevent tears, so the weeds in that zone are good target for the herbicide. This fatty acid herbicide provided excellent control of common lambsquarter, reduced the growth of common purslane but didn't do much for yellow nutsedge - one of our notoriously difficult to control perennial weeds (Figure). The bigger weeds need higher rates (9% is the maximum labeled rate) and better coverage. When you have multiple layers of weed leaf canopy and diverse architecture some plants or their parts may be protected by others that intercept the deposition of the herbicide. When on target, this contact material acts fast – you can see results within 2-3 days, however, it does nothing to weed propagules in soil and has no residual activity against wind-dispersed weed seed that fly in after application. This means the control does not last and you will need additional applications or other control measures. Repeated application is not a problem in a non-crop area and is a great way to deplete your weed seedbank, but crop protection from drift, such as shielded sprayers, is necessary to avoid off target plant injury.
Figure. Weed control in strawberry furrows prior to planting with 9% by volume of fatty acid herbicide (top) and weeds in untreated check (bottom)
- Author: Ben Faber
A new publication, "How to Attract and Maintain Pollinators in Your Garden," (Publication 8498) has been added UC Agriculture and Natural Resources (ANR) catalog. The document is a collaboration of UC experts which includes an entomologist, laboratory assistants, landscape designer, photographer, and pomology expert.
Pollination is crucial to the survival of much of our ecosystems and maintaining viable environments for them to thrive provides not only benefits to personal outdoor space, but adds to the well being of the community at large.
This publication focuses on ways to make your garden and outdoor environment, including avocado orchards more attractive to pollinators by identifying pollinators and the plants and landscaping practices that appeal to them.
ANR Publication 8498 is free of charge and available as a downloadable PDF.
You can download this publication here.