- Author: Emily C. Dooley, UC Davis
Low-cost wine industry additive also improved feed efficiency and milk quality
Researchers at University of California, Davis, added fresh grape pomace left over from winemaking operations to alfalfa-based feed for dairy cows and found that methane emissions were reduced by 10% to 11%.
The preliminary findings could offer a low-cost sustainable pathway for vineyards to reduce waste while helping dairy operations maintain quality while cutting back on emissions of methane, which is a powerful greenhouse gas.
“This is the first time anybody has shown that this can work in California,” said Ermias Kebreab, an animal science professor and associate dean of global engagement at UC Davis. “You're reducing emissions, you're improving the quality and it may also reduce the cost of production.”
The pilot research project, which will be detailed in a paper later this year, also found that mixing in grape pomace improved feed efficiency and increased healthful fats, said Selina Wang, an associate professor of Cooperative Extension in small scale fruit and vegetable processing.
“We found that the feed with the additive of grape pomace changed the fatty acid composition of the milk and, in particular, increased the polyunsaturated fats, which are the main fats in grape pomace,” Wang said. “This suggests that supplementing the feed with an optimal fatty acid profile may have positive impact on the fatty acid profile of the milk and increase their health benefits.”
Symbiotic commodities?
In 2022, California was the leading dairy producer in the country, generating $10.40 billion in sales, while 90% of wine production came from the Golden State, with a market value of $5.54 billion.
Processing grapes for wine generates thousands of tons of waste in the form of grape pomace, which consists of leftover seeds, skins and stems. Dairy and livestock are responsible for more than half of the state's methane emissions, owed largely to cow burps.
They are the top two agricultural commodities in California, according to state production statistics, and reducing waste and emissions for both industries are key to the state meeting its climate goals.
Tannins for emission reductions
Wine grapes are high in fats and tannin, which is known to reduce methane emissions, so Kebreab sought to test if adding grape pomace to feed could have a positive effect while not adversely affecting production.
“It's a byproduct that's not being used much,” he said. “This is something that can be included in our efforts to try to reduce emissions.”
A mix of feed options
To do the research, scientists worked with Holstein dairy cows and gave the animals feed consisting of alfalfa, wheat, almond hulls, cottonseed and grain. After two weeks, the cows were split into three groups: A control group with no change in diet, another where the feed combination included 10% grape pomace and a third that received 15% grape pomace.
Every four weeks, the cow groups would change feed combinations.
They were fed twice daily by postdoctoral students and interns, and emissions were monitored daily. Milk production was documented in the morning and evening and milk samples were collected weekly to analyze for fat, protein, lactose and other measurements, which showed no differences between the control and other groups.
Methane and hydrogen emissions were reduced compared with the control group, suggesting that grape pomace reduced enteric emissions without affecting production.
“I think the dairy industry will be very interested in this,” Kebreab said. “Sometimes when you're using additives, they have palatability issues. With grape pomace, they absolutely love it.”
Next on the list is a trial with olive pomace and working to understand the mechanism that reduces emissions. “If we have a better understanding of the mechanisms, we can select the feed additive or a mix of feed additives to reduce dairy cattle emissions and make dairy milk healthier while making use of the agriculture byproducts,” Wang said. “There's a lot of room to grow in this space and we're excited about this work.”
The research was supported by the California Dairy Research Foundation.
This article was first published on the UC Davis news site.
/h3>/h3>/h3>/h3>
- Author: Mick Canevari
- Author: Brent A Holtz
- Posted by: Gale Perez
The 2023 post-harvest season is upon us and it's time to prep for your fall/winter weed control activities. The long-range forecast is calling for another wet winter, and November is the ideal time to plan your early winter weed control program, to check that your spray equipment is functioning properly and calibrated, and to clean your orchard floor of nuts and debris.
There are a variety of herbicides available today for our tree and vine production systems. No one herbicide will control all the weeds present, but choices exist to achieve excellent control for almost every weed combination. However, it takes patience and persistence to win the weed war. Before programs are decided, the following key questions should be discussed with your pest control adviser (PCA). Tree age, root stock, soil composition (sand, clay, gravel), irrigation design and practices, water source and quality, cultural practices used, a list of weed species present, and whether they are annual, biennial, or perennial weeds, your spray nozzle design, spray volume required, and if there are sensitive crops nearby. Discussing these questions early will provide the basis for your PCA to make the best recommendations possible while allowing your applicator to minimize the risk of crop injury or drift issues.
Advantages of early weed control
The advantage of implementing an early pre-emergent herbicide program, “before leaf fall occurs” is to get a jump start on winter germinating weeds at a time when they are just emerging and susceptible. Applying a pre-emergent ahead of a rain, or by activating with sprinklers, will control millions of weed seeds and provide a clean tree row for 4-6 months into spring. Applying a pre-emergent ahead of leaf drop also eliminates an additional operation of sweeping or blowing leaves after leaf drop has occurred. Weed control is enhanced and herbicide efficacy is extended when the herbicide is already in place before leaves cover the soil. A leaf barrier after an application inhibits weed germination and improves herbicide efficacy. As more orchards and vineyards turn to drip irrigation, relying on rain events to set herbicides becomes critical. A weed management program applying soil active herbicides early in the fall (November/December), and repeated in spring while rain events are still forth coming (March/May), will provide good weed control into summer. Orchards with sprinkler irrigation have more flexibility in timing their applications and selecting herbicides.
Pre-emergent herbicide use is also a recognized strategy to manage herbicide resistant weeds that have become established. We hear complaints every year that post-emergent herbicides are failing to control the same weeds they used to; and that higher application rates are needed to achieve the same level of control. Some of our more frequently used herbicides are developing weed resistance in the field: they include; glyphosate, paraquat, sethoxyodim, clethodim, rimsulfuron and other related acetolactate synthase (ALS) inhibiting herbicides.
Herbicide resistant weeds continue to spread across the state in different cropping systems, with the greatest occurrence in perennial orchards and vineyards. Problematic weeds include annual ryegrass, junglerice, goose grass, hairy fleabane, palmer's amaranth and horseweed or marestail with several other annual weeds close behind in developing resistance. There are several approaches to control these resistant weed species--but the best option by far is starting with a pre-emergent herbicide program early and attacking weed seeds at the point of germination.
New herbicides expected in 2023-2024
We are always anxious to share information from our various weed and herbicide research trials. But we never know for certain when a new herbicide will be registered for use in California. Two new herbicides are expected to be available this coming season, Florpyrauxifen-benzyl and a combination product with Indaziflam and Rimsulfuron.
Hulk (florpyrauxifen-benzyl) is a post emergent synthetic auxin mode of action HRAC (herbicide resistance action committee) group 4 herbicide from Corteva Agriscience. It is a foliar uptake and systemic herbicide that translocates through the phloem and xylem accumulating in meristematic tissue. It exhibits herbicidal symptoms of twisting and epinasty, typical of phenoxy herbicides. It targets many broadleaf weeds, typical of phenoxy herbicides, but with greater efficacy with certain weed species. Symptoms develop rapidly when plants are actively growing, but whole plant death may take several weeks to a month depending on the growth stage and environmental conditions. Currently, labeled crops include pome, stone, citrus and tree nuts. Grapes are being explored and may be added to the label in 2025. Tank mix partners are needed for emerged grasses which may include the use of glufosinate, glyphosate, clethodim and some ALS herbicides with post grass activity. Generally, one should avoid using contact herbicides that readily burn leaf tissue, like “paraquat” for example, since they may inhibit foliar absorption and systemic movement needed to control the weed. Check the label for specific recommendations.
Centrus (Indaziflam + Rimsulfuron) is a pre-emergent herbicide from Helena Agri company packaged with two active ingredients and modes of action herbicides in HRAC group 29 & 2. Centrus will provide long term pre-emergence control over a broader spectrum of weeds and grasses. It is labeled for tree fruit, nut, and vines for residual weed control targeting winter and summer annual weeds common in orchard and vineyards, including annual ryegrass, filarees, fleabane-horseweed, malva, shepherd's purse, willowweed, knotweed, and many more. In all cases it will be necessary to add a post emergent herbicide for emerged weeds. By combining two active ingredients with different mode of actions, it broadens weed control across more species while slowing herbicide resistance to either active ingredient. We need to be mindful of mixing different modes of action herbicides and not using the same herbicides repeatedly. By mixing different mode of action herbicides we strive to keep our products viable for years to come.
Overview of pre-emergent (before weed germination) herbicides currently registered
Craze (orthosulfamuron) HRAC Group 2 is a new 2022 broad-spectrum soil residual herbicide from Nichino America. The active ingredient in CRAZE is orthosulfamuron. This herbicide, an acetolactate synthase (ALS) inhibitor, works by inhibiting the enzyme responsible for the production of amino acids (valine, leucine, and isoleucine) essential for plant growth. CRAZE has demonstrated broad spectrum residual control of many broadleaf and grassy weeds including horseweed and fleabane and suppression of yellow nutsedge if applied in a timely pre-emergent manner. Several years of testing has demonstrated that it will fit into our Tree and Vine weed control program with flexibility and safety. In our testing, it included tank mix combinations with Alion, Chateau and Prowl which extended long-term control.
Prowl H2O and Surflan (pendimethalin & Oryzalin) are HRAC group 3 herbicides that have excellent annual grass control along with many broadleaves, especially those that germinate in the spring and summer. Surflan and Prowl are of the same mode of action and are similar in their weed spectrum and residual properties. Prowl H2O and Surflan remain stable on the soil without moisture no more than 21 days. Prowl is in the DNA family which controls weed seeds once the germination begins by inhibiting meristematic growth and plant cell division or mitosis, inhibiting seedling development. A common weed control strategy in the fall is to use a mode of action herbicide such as Chateau, Matrix, Alion, Pindar GT, Craze, and then switch to the DNA chemistry of Prowl/Surflan in the late winter or spring timing (February to May) to control summer annual broadleaf weeds and grasses. Prowl is an herbicide used for newly planted orchards because of its strong affinity of soil binding properties and safety to young trees. Prowl may be used before or after transplanting nonbearing nut and fruit crops and roots are covered with at least 2 inches of soil. Always follow the label instructions.
Chateau EZ (flumioxazin) is now in a new liquid formulation. Fortunately, the use rates and product rates for the new formulation remain the same, so the conversion from granular to liquid also remain the same. It is HRAC group 14, a long-lasting pre-emergent herbicide used for tree, nut, and vine crops. Applied between 8 -12 ounces per treated acre, Chateau enhances burndown of small broadleaf weeds and provides long residual control of difficult to control weeds such as fleabane and horseweed (marestail), malva, willow weed, filaree and a host of other winter weeds. Its broad-spectrum control of winter annuals makes it an excellent herbicide for use in the fall and early winter timing during the dormant period. Chateau at lower rates (6-8 ounces) has become a popular tank mix with other pre-emergent herbicides to extend control of more grass species and slow herbicide resistant issues. New Plantings: Chateau EZ provides early protection of new plantings from weeds. It can be applied immediately after planting according to label guidelines. Trunk protectors are required.
Matrix (rimsulfuron) HRAC group 2 is an ALS inhibitor pre-emergent herbicide active on many winter and summer weeds including fleabane, willow weed, and marestail, barnyard grass, jungle rice, crabgrass. Its broad-spectrum activity on grasses and broadleaf weeds, make it a good fit for an early fall application timing in November or December. It has become a popular herbicide to manage glyphosate resistant ryegrass pre-emergent and is effective post emergent on small emerged ryegrass. We have observed nice broad spectrum weed control when other pre-emergent herbicides are combined with Matrix. A post emergent herbicide should be added when weeds are emerged. Matrix is safe on young trees and a popular tank mix with Prowl or Trellis.
Mission (Flazasulfuron) is a HRAC group 2, an ALS inhibitor in the same family as rimsulfuron, orthosulfamuron (Matrix, Craze) with a similar weed spectrum. Our research has shown that Mission increased post emergent activity on certain weeds at a rate of 2.14 ounces per acre. Research from other Farm Advisors suggests improved yellow nutsedge activity when applied ahead of emergence with adequate water for soil incorporation. Use a post herbicide as a tank mix partner when weeds are up.
Alion (indaziflam) is a broad spectrum pre-emergent soil active herbicide registered in tree nuts and vines. It is a long-lasting soil residual herbicide exceptional in controlling many grasses and broadleaf weeds. It is effective on both winter and summer annual weeds, including fleabane, marestail, sowthistle, and willow weed, shepherd's purse, chickweed, and most grasses. At least 1/4 inch of water is needed to set and activate Alion as a soil residual. Since it is strictly a pre-emergent herbicide, it requires a tank mix with a post herbicide for emerged weeds, typically Rely, Matrix, Shark, Goal, Roundup, Venue, Treevix and Gramoxone are all compatible. Alion has shown to be an excellent tank mix partner with other pre-emergent herbicides to increase its weed spectrum, especially for malva and knotweed. Since it does not control weeds already germinated or just under the soil surface (called white phase) it should be tank mixed with herbicides that will control weeds just prior to emerging (Matrix, Mission, Pindar Gt or Goal are some popular choices).
Pindar GT (oxyfluorfen and penoxsulam) HRAC group 14 & 2 is a premix with two active ingredient herbicides. It combines both a pre- and post-emergence punch for many broadleaf weeds used in tree nuts and fruits but not registered in vineyards. An excellent herbicide for winter applications beginning in November to January, that can provide residual control lasting into spring and early summer. It is especially effective on fillaree, malva, henbit, willow weed, sowthistle, fleabane and marestail among others. If weeds have emerged, it is still recommended to combine it with a post emergent herbicide such as Roundup, Rely, or Gramoxone. If heavy grass pressure is anticipated in the orchard, an addition of Prowl, Matrix or Alion will extend long term grass control into spring. Within 14 days of application, a half-inch of water is needed to set and activate the herbicide.
Trellis (isoxaben) HRAC group 21 is registered for use in tree nut and fruit crops and for non- bearing newly planted orchards (check label for specific timing). It is a pre-emergent herbicide controlling only broadleaf weeds, therefore consider using another herbicide for grass control. Applied in the fall and winter timeframe, Trellis will provide 4-5 months of broadleaf control. It has no post-emergent activity; therefore, it must be tank mixed with the commonly used post emergent herbicides Trellis' mode of action is unique; it inhibits cellulose development making it a good rotational herbicide to manage weed resistance. If grass weeds are an issue, the addition of herbicides with grass control activity such as Prowl, Matrix, Alion, or Surflan are needed.
Broadworks (mesotrione) HRAC group 27 is registered in almond, walnut, pistachio and certain fruit crops. It is primarily a pre-emergent herbicide to control only broadleaf weeds hence the name Broadworks. We have observed some post activity on small broadleaf weeds (fleabane marsetail) when actively growing but to be safe will still require a post emergent herbicide partner for complete burn down control. Broadworks controls some of the more difficult broadleaf weeds in orchards but will need a pre-emergent tank mix partner that controls germinating grasses. We have observed a general reduction in bindweed populations when spring applications of Broadworks are used ahead of emergence.
Goal (oxyfluorfen)HRAC group 14 is a PPO (Protoporphyrinogen oxidase) post-emergent broadleaf herbicide with a soil residual of 1-3 months depending on the rate. Goal has been a mainstay in broadleaf weed control for decades and is especially useful in our fall orchard and vineyard programs as a burn down of broadleaves. It is regulated for application use due to its co-distillation (lift off in warm temperatures) issues subject to drift. Goal Tender is a different formulation of oxyfluorfen which reduces volatility issues associated with the 2XL formulation. Under our fall/winter conditions and weed species Goal is very good on malva, burning nettle, henbit, sowthistle, prickly lettuce and many more broadleaf annuals. It is weak on grass species and does miss some broadleafs as well. We encourage tank mixes with other pre-emergent herbicides of different HRAC groups for extending soil residual control.
Post-emergent herbicides (when weeds are up)
Embed Extra (2,4-D) HRAC group 4 post-emergent herbicide is registered on almonds, pistachios, walnuts, pecans and certain tree fruit. It controls a long list of broadleaf weeds, both winter and summer annuals, and broadleaf biennials and perennials including marestail, bindweed, fleabane and malva. Embed Extra is a new post-emergent phenoxy herbicide, containing choline formulation of the active ingredient 2,4-D which reduces the risk of volatility (soil lift off) while minimizing drift. The systemic action of Embed Extra provides a more thorough kill down to the roots of larger broadleaf weeds, that many contact herbicides struggle with. Embed Extra translocates at a slower pace in weeds than contact herbicides. A grower won't see immediate visible burn, since its mode of action is systemic, mimicking the action of the plant growth hormone affecting cell division and slowly twisting until dead. Embed Extra can be tank mixed with other post-emergent herbicides, such as glyphosate and glufosinate. It can also be tank mixed with many “residual”-type herbicides.” Our trials on spring treated larger plants of fleabane, marestail and willow weed showed excellent results.
Rely (glufosinate ammonium) a HRAC group 10 herbicide has become a mainstay for growers needing a broad spectrum burn down herbicide to control tough broadleaf weeds and grasses; willowweed, barnyardgrass, junglerice, crabgrass and glyphosate resistant fleabane and marestail. In recent years, the development and spread of glyphosate resistant weeds has shifted our growers to use more glufosinate herbicide in combination with other post emergent herbicides. Rely does not translocate totally like glyphosate, so the key to success is good coverage and smaller weed size. It is a popular tank mix with any of the pre-emergent herbicides. We have found that glufosinate plus other foliar herbicide combination to be very effective across most emerged weeds.
Treevix (saflufenacil) HRAC group 14 is a PPO (Protoporphyrinogen oxidase) post-emergent broadleaf herbicide with a short soil residual of approximately 30 days. It is registered in tree nut and fruit crops. It is recognized as an excellent post emergent herbicide for some of our toughest emerged broadleaf weeds. However, it is mostly effective on broadleaf weeds, and should be mixed with another herbicide to control emerged grasses. Like all post contact herbicides, treating small weeds, 1-6 inches tall and using a 20-40 gallon per acre (GPA) rate and thorough spray coverage is important. Treevix is excellent in controlling young fleabane, marestail, malva, willowweed, sowthistle, nettle, henbit, prickly lettuce, especially in cool conditions from fall through spring. It is not considered a long soil residual herbicide, so it should be mixed with a pre-emergent herbicide for soil residual control.
Shark, Venue (carfenthrazone, pyraflufen ethyl)are group 14 PPO herbicides. They are all post emergent herbicides especially effective on broadleaf weeds having little soil residual. Theyprovide a tank mix addition to pre-emergent herbicides to control emerged broadleaf weeds. They also work well with other post herbicides glyphosate and glufosinate (Roundup and Rely). A rule for these and all post-emergent herbicides, "Spray when weeds are small for better coverage and control!"
Roundup, Rely, Gramoxone, 2,4-D & PPO (group 14 herbicides) are registered for multiple use in nut and fruit orchards year around. Growers having certain weed species may need multiple post-emergent treatments for specific weed issues or escapes. Glyphosate is moderately effective on purple nutsedge with repeated applications prior to the six-leaf growth stage. Yellow nutsedge can be controlled by using 3-4 quarts per acre of glyphosate at two sequential application timings. Sandia has shown very good results to control emerged nutsedge but is not registered on almond. Sandia is registered for use in pistachio and walnut orchards. The key to nutsedge and other perennial weeds is persistence with repeated applications as it emerges and before it can regenerate new underground nutlets or rhizomes. Problem broadleaves such as fleabane, horseweed, malva, knotweed that germinate most of the year, should be targeted early at a small growth stage and controlled before seed heads develop. Vigilance and persistence are necessary until orchards mature and reach a full canopy of shade to slow perennials and other weeds from continuous germination.
NOTE: Before using any herbicide, always check the label for any use restrictions applicable to your area, crop, or soil type. Our comments and suggestions are from years of testing herbicides in our research plots and field trials. We appreciate our grower cooperators, who let us have access to their orchards. Again, always review and follow label instructions.
Originial source: November 2023 Field Notes newsletter
- Author: Mike Hsu
Light irrigation before flooding stimulates microbes to remove nitrates from soil
With California enduring record-breaking rain and snow and Gov. Gavin Newsom recently easing restrictions on groundwater recharge, interest in “managed aquifer recharge” has never been higher. This process – by which floodwater is routed to sites such as farm fields so that it percolates into the aquifer – holds great promise as a tool to replenish depleted groundwater stores across the state.
But one concern, in the agricultural context, is how recharge might push nitrates from fertilizer into the groundwater supply. Consumption of well water contaminated with nitrates has been linked to increased risk of cancers, birth defects and other health impacts.
“Many growers want to provide farmland to help recharge groundwater, but they don't want to contribute to nitrate contamination of the groundwater, and they need to know how on-farm recharge practices might affect their crops,” said Matthew Fidelibus, a University of California Cooperative Extension specialist in the UC Davis Department of Viticulture and Enology.
A recently published study by UC scientists sheds new light on how nitrates move through an agricultural recharge site and how growers might reduce potential leaching. Researchers analyzed data from two grapevine vineyards at Kearney Agricultural Research and Extension Center in Fresno County – one flooded for two weeks, and other for four.
Understanding initial nitrate levels crucial
A key factor in mitigating contamination is understanding how much nitrate is in the soil at the outset, said study author Helen Dahlke, a UC Davis hydrologist and leader of UC Agriculture and Natural Resources' strategic initiative on water. In areas with little precipitation and cropping systems that require greater amounts of synthetic fertilizer, the accumulation of residual nitrate – resulting from nitrogen in the fertilizer not taken up by the plants – can be quite high.
“The percentage of nitrates in some soils can really increase over the years, particularly if you have many dry years in a row where you don't have access to irrigation water or natural precipitation flushing some of those nitrates out of the soil,” Dahlke said.
While intense rains in recent weeks have helped dilute nitrate concentrations naturally, farmers looking to participate in recharge during the dry years ahead should consider flooding their fields with greater volumes of water.
“If you're doing this for the first time – on-farm recharge in the winter – check your residual soil nitrate levels because if they're very high, you should apply a lot of water in order to make sure that the residual nitrate is diluted down,” said Dahlke, who also added that growers should check their soil properties for suitability of recharge projects.
She recommended using, as a “good first approximation,” the online Soil Agricultural Groundwater Banking Index map, a project led by Toby O'Geen, a UC Cooperative Extension soil resource specialist.
Researchers looking at other ways to reduce nitrates
Even before flooding the fields for recharge, there are several practices that can lower initial nitrate levels and risk of leaching. Cover crops such as alfalfa and triticale, for example, can help take up residual nitrates that accumulate from fertilizing a main crop over time.
Dahlke and Fidelibus – a co-author of the San Joaquin Valley vineyard study – both pointed to pre-flooding irrigation that encourages denitrification, a process in which soil microbes transform nitrates into gaseous forms of nitrogen.
“Those denitrifying microbes need to be stimulated to do the work,” said Dahlke. “What we have found is that if you do a little bit of irrigation before you start the flooding, increasing the soil moisture can get those microbes started and they can take out more nitrate from the soil.”
The timing and quantity of fertilizer applications are also major factors in reducing leaching. Although more growers are following high-frequency, low-concentration practices to maximize uptake by crops, Dahlke said there needs to be more emphasis on incorporating nitrogen transformation processes – such as denitrification – in the nutrient management guidelines that farmers follow.
“Implementing thoughtful nutrient management plans will play a particularly important role in participating farms,” Fidelibus added.
A more holistic view of groundwater recharge
In short, choices made during the growing season can affect those in the winter recharge season – and vice versa. For example, applying compost or other organic amendments to soil can give microbes the “fuel” they need for sustained denitrification.
“What we have found is that our denitrifying bacteria often run out of steam because they don't have enough carbon to do the work,” Dahlke said. “Like us, microbes need energy to do the work, and for microbes this energy comes from soil carbon.”
Then, adding moisture via recharge to that field with high organic content can stimulate mineralization and nitrification, processes in which microbes transform the organic nitrogen into ammonium – and subsequently nitrates – that the plants can then take up. Those naturally occurring nitrates would thus reduce the need for the grower to apply synthetic fertilizer.
“The winter on-farm recharge experiments have shown that altering the moisture regime in the winter has consequences for the nitrogen budget in the summer growing season,” Dahlke explained. “Theoretically, what we need to be doing is better integrating both seasons by keeping an eye on the soil-nitrogen balance across the whole year so that we can ensure, at the end of the growing season, the residual nitrate in the soil is minimized.”
The study, published in the journal Science of The Total Environment, was part of the post-doctoral work of former UC Davis researcher Elad Levintal. In addition to Fidelibus and Dahlke, other authors are Laibin Huang, Cristina Prieto García, Adolfo Coyotl, William Horwath and Jorge Rodrigues, all in the Department of Land, Air and Water Resources at UC Davis.
/h3>/h3>/h3>/h3>- Author: Lynn Wunderlich
Why all of this vole damage now? Voles love tall grass, which protects them from their natural raptor predators. Our heavy rainfall in 2016-2017 and in the current season produced a large amount of grassy groundcover. If this tall grass is not controlled in the tree or vine row, it provides the perfect environment for voles-who make very shallow "runs"-to nibble on tree and vine trunks. This nibbling can be just below the soil-trunk line, and isn't always obvious. On a farm call to visit a mature olive orchard, the canopy was so
But truly, vole damage is no laughing matter. Especially for young orchards and vineyards, where voles can kill the trees and vines. Young vines with severe vole damage can turn red-sometimes being confused with virus
So, what can growers do to manage voles? #1: keep the vegetation down near the trunks of vines and trees. Cover crops should be mowed and vegetation kept down in between the rows and on the borders. Beware of adjacent open spaces, meadows, or other lands where voles may be entering. Look for vole damage and monitor regularly-look for burrow holes and runs. Vole populations can reach a high peak and then crash, or they can continue to grow and cause problems. Activity can be noted by the freshness of the runs, bare ground, pellets, and fur. Exclusion using a tree guard barrier or along the fence line is difficult. Since voles burrow just below ground, the barrier needs to be buried at least 6 inches to be effective. Traps can be used effectively in the vole runs, since voles don't deviate much from their habit trails. Rodenticides in baits (anti-coagulants that require multiple feedings or zinc phosphide) are restricted use-check with your agricultural commissioner before applying. You will need a permit or a licensed applicator to use them. UCCE Vertebrate Specialist Roger Baldwin (whose cool website you should really check out), is interested in getting an anti-feedant registered for use against vole damage in CA. This could be a very helpful tool, and I encourage you to fill out Roger's very brief survey here if you have voles and want a new tool to fight them.
You can find more information on voles by reading Roger's Chapter here.
Until next time...
- Author: Laura J. Van der Staay
Malcolm Media is providing three Ag expos this month: A tree and vine expo in Turlock was presented today; a grape expo will be in Sonoma on November 10, 2017, and a grape, nut and tree fruit expo will be at the Fresno fairgrounds on November 14, 2017. To pre-register, please use the above link.
This blog article is on the November 14th expo in Fresno. The Grape, Nut & Tree Fruit Expo is provided every year at the BIG Fresno Fair grounds. Held in the heart of grape, nut and tree fruit growing areas, the expo is sponsored by the Central Valley wine, table, and raisin grape, tree fruit and nut industries. UC ANR scientists involved with applied research and extension for these cropping systems will provide presentations to the attendees.
The expo is free, and has free seminars that provide continuing education units approved by CDPR for CE/CCA licenses (1 hour of laws and regulations, and 4 hours of other), a free breakfast, a free lunch, and industry exhibits. It starts at 7:00 am and finishes at 2:00 pm. UC ANR speakers include:
- George Zhuang, Fresno County UCCE farm advisor in viticulture will present “Cropload Management on Young Pinot Grigio Vines”
- Kent Daane, UCCE specialist at Kearney Ag Research & Extension Center (KARE), specializing in entomology, will present “Update on Black Widow Control in Table Grapes”
- Kurt Hembree, Fresno County UCCE farm advisor in weed management will present “Herbicide use for Vineyard Weed Control” and “What's New in Tree & Vine Weed Management”
- Ashraf El-Kereamy, Kern County UCCE farm advisor in viticulture will present “Improving Productivity & Quality of Grapes”
- Kris Tollerup, Cooperative extension advisor at KARE, specializing in IPM, will present “Effective Ant Management to Minimize Damage at Harvest”
- Themis Michailides, Plant Pathologist at KARE, will present “Band Canker of Almond Becoming a Threat to New Plantings”
- Kevin Day, Tulare County UCCE Director and farm advisor in pomology, will present “Lowering Labor Costs with Pedestrian Orchards”