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.
The UC Agriculture and Natural Resources' Agricultural Issues Center has released two new studies on the estimated costs and returns of producing garbanzo beans, also known as chick peas, in the Sacramento and San Joaquin Valleys.
“Although acreage is relatively small, garbanzos are an important crop because California growers produce the large, cream-colored seed that's used for the canning industry, often used for garnishes for salads,” said Rachael Long, UC Cooperative Extension farm advisor serving Sacramento, Solano and Yolo counties.
The studies estimate the cost of producing garbanzo beans on 200 acres as part of a row crop rotation, using subsurface drip irrigation. A three-row bed tillage implement shallowly chisels, tills and reshapes the beds, avoiding disturbance of the buried drip tape left in place. Planting of seed treated for fungal and seedling diseases, Ascochyta rabiei, Rhizoctonia and Pythium, into residual soil moisture occurs in December. Seeding rates for the garbanzo beans are 85 pounds per acre.
Input and reviews were provided by UC ANR Cooperative Extension farm advisors and other agricultural associates. Assumptions used to identify current costs for the garbanzo bean 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.
“The importance of these studies right now is that they are currently being used to help secure USDA crop insurance for garbanzo production, expected in 2020,” Long said.
The new studies are titled “Sample Costs to Produce Garbanzo Beans (Chick Peas), in the Sacramento and Northern San Joaquin Valleys – 2018” and “Sample Costs to Produce Garbanzo Beans (Chick Peas), in the Southern San Joaquin Valley – 2018.”
Both studies can be downloaded from the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu. Sample cost of production studies for many other commodities are also available at the website.
For additional information or an explanation of the calculations used in the studies, contact the Agricultural Issues Center at (530) 752-4651 or the local UCCE Farm Advisors; Sarah Light, firstname.lastname@example.org, Rachael Long, email@example.com, Michelle Leinfelder-Miles, firstname.lastname@example.org, or Nicholas E. Clark, email@example.com.
Bats, those night-flying creatures of horror film fame, are beginning to migrate back to the Central Valley. It is an annual journey for most bats, flying south for the winter and returning home in the spring to their birth place to roost and give birth to their own pups during the summer.
“I'm getting a number of calls from people who see bats and are worried about them,” said Rachael Long, UC Cooperative Extension advisor for Sacramento, Solano and Yolo counties. “If people see bats on the ground or tucked into eaves, they're likely resting, not sick, from their long migration north.”
Because the insect-eating winged mammals are important allies to U.S. farmers, Long hopes people won't harm the bats while they are tired and vulnerable. Bats feed on some of the most damaging crop pests – including the moths of cutworms and armyworms – which helps to protect food crops naturally.
Farmers appreciate the pest control provided by bats and many look forward to having bats return to their farms each year, according to Long, who coauthored a study of farmer perceptions of wildlife recently published online in Conservation Letters, a journal of the Society for Conservation Biology.
“Most of the farmers surveyed reported that they like bats and the pest control and crop protection services they provide,” Long said. “Many put up bat boxes on their farms to provide a home for them.”
In their long journey north, bats need to rest along the way. Sometimes they turn up in areas where they're not wanted, such as in a corner of a porch or in an eave. The presence of bats is often revealed by their mouse-like droppings, or guano.
“In the sun, the guano sparkles, as it's made of bits of insect parts, making it a good source of nitrogen for plants,” Long said.
Bats live for about 30 years and bear only one pup a year. Males roost independently of females and their pups, so if you see a lone bat, it's likely a bachelor.
“If you find a bat, please leave it alone if it's not bothering anyone because it may be perfectly healthy, just tired,” Long said. “A farmer somewhere may be waiting for that bat to come home to help protect crops from insects.”
If you see a bat on the ground, Long suggests placing a box over it and calling a wildlife rescue organization, such as Northern California Bats in Davis. She recommends wildlife rescue because animal control officers must euthanize all bats they catch to test for rabies, which may be unnecessary unless a person or a pet had contact with the bat.
California farmers grew about 23,000 acres of baby and large limas with a value of about $30 million in 2012, according to the National Agricultural Statistics Service.
“While that's not a lot compared to some crops in our state, it's significant because California growers produce 60 to 80 percent of the world's market of dry limas,” said Rachael Long, UC Cooperative Extension advisor.
The primary export market for California baby lima beans is Japan, where they are used to make Japanese confections, such as sweet bean filling for manju.
Dry lima beans, which are canned or packaged for domestic or export markets, are grown in California. Thick green lima beans for freezing are grown on the East Coast.
Among California lima beans, there are baby limas and large limas, and bush and vine types of both. Baby limas are grown primarily in the Sacramento Valley, while the large limas are grown south of Tracy and on the Central Coast. Large limas grown on the Central Coast are mostly dry farmed and used for canning.
“Baby limas are produced in the warmer areas north and south of the Bay Delta and large limas in the south Delta area, which has a slightly longer and drier harvest season and cooler night temperatures favoring flowering and pod filling,” she said. “So there's lots of baby limas in the Knights Landing area and large limas in the Patterson area.”
Farmers like to grow lima beans because they fix nitrogen, improve soil health, use relatively few pesticides and help control weeds in field crop rotations with crops including wheat, corn, tomatoes, alfalfa and sunflowers. Because lima beans are not a widely planted crop that would attract research investment by private companies, growers depend on UC research for improved varieties.
“Dr. Paul Gepts, along with Rachael Long and other researchers, plant extensive bean variety trials to select favorable genetics such as high yield, insect resistance and drought tolerance,” said lima grower Stephen Perez, who farms in Stanislaus County. “Their work is incredibly valuable to the California bean industry as well as to other bean growers around the world.”
“For years, we've been working on developing varieties of lima beans that are resistant to lygus bugs as well as nematodes, two significant pests of beans and limas in particular,” said Long. “These studies are mostly conducted by UC Davis professor Paul Gepts, UC Riverside professor Phil Roberts and UC Cooperative Extension farm advisors, continuing the research by now-retired UC Cooperative Extension specialist Steve Temple.”
Lygus bugs, which feed on buds and flowers, are very destructive to lima fields.
“With these new varieties, the use of pesticides has been decreased, saving growers unnecessary expenses and, just as important, reducing the use of these pesticides,” said Sano. “By using these lygus-resistant baby lima lines, Paul Gepts is now working on breeding that resistance into large lima varieties. This would provide those growers the same advantage.”
“We hope to identify the genetics of partial resistance, then we can select for resistance in crosses,” explained Gepts, professor in the Department of Plant Sciences at UC Davis. “We use a mix of basic and applied research in breeding, with a focus on developing new varieties.”
The UC scientists are also trying to breed lima bean plants that use less water. “We are trying to find how much we can reduce water and still get sufficient yields,” said Gepts. “Eventually we hope to test to identify markers for drought tolerance to lower the number of irrigations.”
Long and her colleagues recently published a lima bean production manual, which includes a list of large and baby lima varieties available in California and their pest-resistance levels. To help protect groundwater quality as required under new farm plans, the manual also features a table of nitrogen rates for lima production based on nitrogen levels in the soil and water. “Lima Bean Production in California” can be downloaded for free at http://anrcatalog.ucdavis.edu.
UC also has published cost of production studies for dry beans, including baby vine and bush types: "Sample Costs to Produce Beans-Common Dry Varieties-Double Cropped in the Sacramento Valley" and "Sample Costs to Produce Beans-Common Dry Varieties-Single Cropped in the Sacramento Valley." The production cost studies can be downloaded for free at http://coststudies.ucdavis.edu.
- Author: Jeannette E. Warnert
Written by Rachael Long, UC Cooperative Extension advisor in Yolo County, the story chronicles the adventures of 9-year-old Jack, who is exploring Nevada’s Black Rock Range when he falls into a cave. Jack befriends a bat named Pinta and a coyote pup named Sonny, who are determined to help him find his way home.
The story of Jack was first told to Long’s now 16-year-old son. When he was young, Long would make up stories to tell him during their long daily commute from their home on a farm outside of town.
“Each day, the stories got more and more elaborate,” Long said, “and I incorporated my long-time interest in bats.”
Long’s father, a UC Berkeley biology professor, introduced her to the world of bats. She was an early member of Bat Conservation International and she took a field class through the organization in 1992.
“The more I learned about bats, the more interesting I found them,” Long said.
As a field crops and pest management expert for UCCE, Long has worked to boost Californians’ appreciation for bats’ importance in pest control. The state is home to 25 species of bats, seven of which are commonly found in the Central Valley. Bats can consume their body weight or more in insects each night, with a colony of 500 bats eating a grocery bag full of insects from nightfall to dawn. The loss of bats in North America could lead to agricultural losses of more than $3.7 billion per year, according to an analysis published in the journal Science in April 2011. Long has researched bats’ role in reducing Sacramento Valley crop pests.
“We know that bats in the Sacramento Valley feed on insects such as moths, beetles and plant bugs that are often agricultural pests,” wrote Long when the results of her study were published in the January-February 1998 issue of California Agriculture journal. “Potentially, they may help reduce insect infestations in crops by feeding on these pests.”
Long also published a study of bats’ use of constructed bat boxes in the April-June 2006 California Agriculture journal. By evaluating the 186 bat houses in rural areas of California's Central Valley, Long learned that the flying mammals prefer houses mounted on structures such as buildings, those that are shaded or exposed only to morning sun, and within one-quarter mile of water.
Long is an author of the UC publication Songbird, Bat and Owl Boxes, which outlines methods for integrating nest boxes with farm management, provides details on construction and maintenance of nesting boxes, and information on other sources of reliable bat information. The publication includes plans for building a wildlife nesting house.
Naturally, Long sought to share what she knows about bat’s role in the environment with young readers in her fictional but scientifically sound children’s stories.
At the beginning of the book, when Jack falls into the cave, Pinta, the bat, is alarmed. “But as she flew around the cave, her keen ability to echolocate to find her way in the dark, gave her a different picture than she expected. Oh no, a boy, not a monster!” At first, Jack lies on the cave floor knocked out by his injuries. Long writes, “(Pinta) hovered above him, wings stretched more than a foot, beating rapidly but barely making a sound.”
Such tidbits about bats are sprinkled throughout the story. Young readers will be so absorbed in Jack’s journey home, the fate of an escaped jailbird and the search for gold, they won’t realize they are learning about natural science.
Tate Publishing quotes New York Times science journalist Jim Robbins as saying in a review of Gold Fever, “Bats play a little known, but vital role in the world. This book introduces young readers to their world in an engaging and entertaining way.”
Gold Fever is the first in the three-book "Black Rock Desert Adventure Series." Proceeds from the trilogy will go to fund bat conservation programs.