- Author: Pamela Kan-Rice
Monitor for rodent activity and use bait stations before the growing season to prevent problems, UC ANR scientists recommend.
Roof rats are running rampant in California orchards this year, according to UC Agriculture and Natural Resources scientists.
“In pistachio and other nut orchards, roof rats are burrowing and nesting in the ground where they're chewing on irrigation lines, causing extensive damage,” said Rachael Long, UC Cooperative Extension advisor. “They are also nesting in citrus trees, feeding on the fruit and terrifying field workers when they jump out as people are picking fruit. The chewing pests are also girdling citrus limbs, causing branch dieback.”
Holes in the ground around the base of pistachio trees throughout a Yolo County orchard puzzled the grower.
“We looked for ground squirrels, but never saw any,” Long said. “We set up game cameras, but only got birds and rabbits. We put rodent bait in the holes, but the digging didn't stop.”
Long, the pest detective, cracked the case by consulting Niamh Quinn, UC Cooperative Extension human-wildlife interactions advisor based in Irvine. “She informed us that the damage we were seeing was from roof rats.”
Burrowing roof rats sounds like an oxymoron. While roof rats generally don't burrow in urban environments, their country cousins have been known to burrow.
“It's not true that they don't burrow,” Quinn said. “When I worked as staff research associate for Roger Baldwin, UC Cooperative Extension wildlife specialist, that is mostly what we studied, burrowing roof rats in orchards.”
Baldwin said, “It seems to be a good year for rats in a number of different areas and crops throughout the state. I've received more questions and comments about rats this year than perhaps the last 10 years combined. As for bait application, putting bait down burrow systems for rats doesn't usually work too well, so I'm not surprised that approach didn't work. Growers will likely have better luck with bait stations in the trees.”
Because the rats climb, Baldwin suggests attaching bait stations to tree branches.
“In addition, elevating the bait stations will eliminate access to bait for many protected mammal species, such as kangaroo rats,” Long said. “The bait diphacinone grain can be purchased from some ag commissioners' offices. This is what Roger Baldwin said they tested and it worked.”
As for the bait stations, they should be designed so that there isn't any spillage for nontarget animals to eat, Long said.
When roof rat outbreaks occur, rodenticides are often needed to prevent crop damage. However, timing is critical as diphacinone use is highly restrictive and not allowed during the growing season, which is beginning as the weather warms.
“Check the product label for application instructions,” Long reminds growers. “It's the law.”
Identifying the pest
“Roof rats can forage away from their nest, so you won't likely find signs of their activity, such as rat droppings outside their burrow, to help identify them,” Long said.
Ground squirrels are active during the day, so they are more likely to be seen, dig holes about 4 inches in diameter and forage above ground near their burrows. Vole and mouse holes are 1- to 2-inches in diameter. Roof rat holes are typically 3 to 4 inches in diameter and might have nut shells in front of them, for example pistachio or almond shells. Rabbits will feed on seedling crops, but do not dig burrows.
“Rats are sneaky and hard to spot,” Long said. “If you see damage, including digging in the soil but no wildlife, suspect rats.”
For more information on controlling roof rats, download Quinn and Baldwin's free UC ANR publication 8513, Managing Roof Rats and Deer Mice in Nut and Fruit Orchards at http://anrcatalog.ucanr.edu/Details.aspx?itemNo=8513.
- Author: Jeannette E. Warnert
Almond farmers will remember a UCCE demonstration last February when the 50,000-pound Iron Wolf rolled like a tank through an almond orchard in Chowchilla, ripping whole trees into shreds and incorporating the wood into the soil.
Researchers are now considering a less dramatic approach to removing an old orchard and incorporating the wood chips into the soil onsite. Combining a traditional horizontal chipper with a wood chip spreader modified for this purpose can be a viable alternative to the now-mostly banned burning of old orchards or transport of almond tree residue to co-generation facilities that convert biomass to energy.
“It's still cheaper for the farmer if he or she can sell the wood chips for co-generation,” said Brent Holtz, UC Cooperative Extension advisor in San Joaquin County and the research leader. “But co-generation plants are closing and our research is showing that incorporating the biomass into the soil has many benefits.”
When the wood breaks down, it returns nutrients to the soil. Organic matter increases, resulting in carbon sequestration, important for moderating the release of greenhouse gases into the atmosphere that may contribute to climate change.
The chipper and spreader combination pencils out at about $1,000 per acre, while the Iron Wolf costs about $1,500 per acre.
“The Iron Wolf turned out much more expensive and slower than we anticipated,” Holtz said. “It could only grind up and incorporate about two acres of trees per day, while the horizontal chipper can chip 15 acres per day. With the chipper and spreader combination, the chips do have to be disked in, which most growers can easily do.”
The whole orchard recycling project was funded by the Accelerated Innovation Management program of the Almond Board of California.
Whole Orchard Recycling Demonstration
11630 S. Airport Way (near Roth Road), Manteca, Calif.
Thursday, Oct. 13, 2016
Whole almond orchard recycling and the effect on second generation tree growth, organic matter and soil fertility presentation
Brent Holtz, Ph.D., UC Cooperative Extension advisor
Kuhn & Knight Wood Chip Spreading Demonstration
Randy Fondse, G & F Ag Services, Ripon, Calif.
Morbark Horizontal Chipper Demonstration
Randy Fondse, G & F Ag Services, Ripon, Calif.
- Author: Pamela Kan-Rice
The integrated orchard management program, sponsored by UC Agriculture and Natural Resources and UC Davis, will provide participants with the practical, field-level information they need to successfully farm almonds. UC Davis faculty and UC Cooperative Extension specialists and farm advisors from throughout California will present their latest research.
Three full days of instruction include more than 35 presentations on orchard planning, evaluation and management of soil, tree training, irrigation, economics of almond farming, pest management and other topics.
New and experienced growers as well as other industry members interested in commercial almond production are welcome to attend. There will be opportunities to network with other participants and presenters, along with a chance to have questions answered by professionals in the industry.
The almond short course will be held at the Modesto Centre Plaza at 1000 L Street in Modesto. Registration for the program is $950 until Oct. 24 and includes full course participation, course materials, three lunches and two receptions, and continuing education credits.
For more information and to register, visit http://ucanr.edu/sites/almondshortcourse.
If you have questions about the almond short course, please contact Lauren McNees at (530) 750-1257 or firstname.lastname@example.org.
UC Agriculture and Natural Resources researchers and educators draw on local expertise to conduct agricultural, environmental, economic, youth development and nutrition research that helps California thrive. Learn more at ucanr.edu.
The cost analyses are based on hypothetical farm operations of well-managed orchards, using practices common to each region. Growers, UC ANR Cooperative Extension farm advisors and other agricultural associates provided input and reviewed the methods and findings of the studies. Two studies estimate the costs for establishing and producing almonds grown in the northern San Joaquin Valley and Sacramento Valley using micro-sprinkler irrigation. These are multi-year studies, estimating costs from previous crop (orchard removal) through orchard establishment and the production years.
The study for organic almonds takes into consideration growing conditions in the northern San Joaquin Valley and complying with the National Organic Program. This study is based on an orchard that began the transition period and certification as organic after the second year of establishment. The trees in this study are in production and at full bearing. This organic almond orchard uses a solid-set sprinkler system.
The economic life of the orchards used in this cost analysis is 25 years. The authors describe the assumptions used to identify current costs for the almond crop, material inputs, cash and non-cash overhead. A ranging analysis table shows profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.
- Sample Costs to Establish an Orchard and Produce Almonds in the San Joaquin Valley – North- 2016
- Sample Costs to Establish an Orchard and Produce Almonds in the Sacramento Valley – 2016
- Sample Costs to Produce Organic Almonds in the San Joaquin Valley - North - 2016
Free copies of these studies and other sample cost of production studies for many commodities are available. To download the cost studies, visit the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu.
The cost and returns program is funded by the UC Agricultural Issues Center, which is part of UC Division of Agriculture and Natural Resources, and the UC Davis Department of Agricultural and Resource Economics.
For additional information or an explanation of the calculations used in the studies, contact Don Stewart at the Agricultural Issues Center at (530) 752-4651 or email@example.com, or Christine Gutierrez at (530) 752-1520 or firstname.lastname@example.org.
When an orchard is removed for replanting, the trees are usually uprooted, chipped and hauled to a biomass plant. However, burning the wood in a cogeneration plant removes carbon from the orchard and biomass plants are becoming fewer and farther from farms.
One alternative is grinding up the trees and incorporating the wood into the soil in the orchard. UC Agriculture and Natural Resources (UC ANR) scientists have been studying the effects of incorporating the wood chips into the soil since 2008.
“A lot of growers feared if we added that much carbon to the soil, the microbes breaking down the organic matter would tie up nitrogen and the trees would be stunted,” said Brent Holtz, UC ANR Cooperative Extension advisor. “But the research results suggest that the trees will do just as well or better in the presence of the additional organic matter.”
For the 2008 study, an IronWolf machine was used to grind up whole stone fruit trees and bury the organic matter in the soil in some plots. For comparison, the researchers burned trees and spread the ashes in the soil of other plots. Holtz compared the nutrient availability in the soil and health of trees planted in the research plots.
In a new study, Holtz hopes to compare the effects of using the IronWolf to recycle an almond orchard to using a large tub grinder, which leaves much finer particles of wood.
Holtz invites growers and other interested people to watch the IronWolf 700B, a newer version of the machine used in 2008, grind up almond trees in Chowchilla on Feb. 16 at 10 a.m.
“There has been increased interest in the project because of the closure of many of the biomass plants statewide. They used to take the debris of removed orchards,” said Holtz. “The purpose of this demonstration is to see if this method of orchard removal will be competitive with the tub grinding process, and become an economically viable alternative that improves soil organic matter and fertility.”
WHO: UC ANR Cooperative Extension advisors, growers, IronWolf equipment representatives.
WHAT: Watch a 100,000-pound machine push, grind and incorporate whole almond trees into the soil.
WHEN: 10 a.m., Tuesday, Feb. 16, 2016
WHERE: AgriLand Farming, 20875 Avenue24, Chowchilla, CA 93610