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LODI RULES for Sustainable Winegrowing: A Quality Winegrape Program

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No tillage and maintenance of a cover crop every vine row gets the most practice points because these practices promote soil health through better drainage, increased organic matter content, increased soil moisture holding capacity and better soil microbial activity (all photos courtesy Lodi Winegrowers Workbook 2nd edition 2008. Ohmart, C. P., Storm C. P. and Matthiasson, S. K. eds. 345pp.)

What are the Lodi Rules for Sustainable Winegrowing (LODI RULES), which entered its 16th year in 2021? It is a set of farming practices that result in higher quality winegrapes and wine according to grower and winemaker panelists on a recent webinar entitled ‘Boots on the Ground – A masterclass in sustainable viticulture & LODI RULES,’ a collaboration of the SommFoundation and the Lodi Winegrape Commission and hosted by Elaine Chukan Brown.
On a technical level, LODI RULES is California’s first third-party certified sustainable winegrape-growing program. It was initially developed for growers in Lodi’s Crush District #11 but made available to any California winegrape grower in 2008, expanded to Israel (Golan Heights Winery) in 2017 and Washington State winegrape growers in 2020. LODI RULES encompasses more than 120 farming practices, some of which will be discussed in this article, and is certified by Protected Harvest, a non-profit third-party certifier of sustainable farming programs.

To achieve certification, a vineyard must be farmed using practices that score 50% or more of the total possible points in each LODI RULES chapter and 70% of the points in the six chapters combined.

 

Origins of LODI RULES

From 2003 to 2004, I led the team of 22 winegrape growers, Lodi Winegrape Commission staff, crop consultants, PCAs, UC Farm Advisors, a wildlife biologist and a winemaker to create the first edition of the LODI RULES farming standards. They were based on what the team considered to be the most sustainable farming practices in the Lodi Winegrowers Workbook (Ohmart and Matthiasson 2000.) They were then submitted to Protected Harvest for scientific peer review and endorsed in 2005. The LODI RULES farming standards have been updated twice since then. The program has grown from six growers and 1200 vineyard acres in 2005 to more than 130 growers and 68,000 acres participating in 2021. In 2008, one winery started paying bonuses for LODI RULES certified grapes, and since then, many others have followed suit. One estimate has the annual bonuses exceeding $2 million.

The LODI RULES is organized into six chapters: Business Management, Human Resources Management, Ecosystem Management, Soil Management, Water Management and Pest Management. Each farming practice standard is assigned a number of points based on its assessed level of importance in sustainable winegrowing. To achieve certification, a vineyard must be farmed using practices that score 50% or more of the total possible points in each chapter and 70% of the points in the six chapters combined. The purpose of this scoring is so that a vineyard does not obtain certification while performing poorly in one chapter but very high in all the others. Furthermore, pesticides used in the vineyard are run through a pesticide risk model that calculates risk points for each application. To achieve certification, the risk points from the year’s pesticide applications cannot exceed a rigorous risk points threshold.

The LODI RULES is organized into six chapters: Business Management, Human Resources Management, Ecosystem Management, Soil Management, Water Management and Pest Management.

Independent professional auditors are contracted by Protected Harvest to audit annually the practices being used in each participating vineyard. An on-site audit is done on any vineyard new to the program and at least every three years after that. A desk audit is done each year for every vineyard not visited on-site. And finally, a grower is chosen at random each year for an audit to be done with a 48-hour notice. This ensures all growers are up to date with their records and practices. The auditors submit their reports to Protected Harvest near harvest for final certification decisions.

I will now highlight a few of the practices in each of the LODI RULES chapters. I will remind you that there are more than 120 practice standards, so I am only able to touch on a few of them. For a complete copy of the LODI RULES farming standards, go to lodigrowers.com in the grower resources section. A farming practice standard is a description of a practice that is required to be done in order to qualify for the points awarded for doing the practice. It is very specific and is described in a way that enables an auditor to clearly verify the practice is being done during the onsite audit of the vineyard being certified.

 

Business Management

The very first farming practice standard in LODI RULES is the requirement that a grower attend a LODI RULES workshop sponsored by the Lodi Winegrape Commission where they learn how to develop a sustainable management vision plan for their farm. They then need to draft the plan that contains elements that they were introduced to in the workshop.
One might ask, ‘Why is having a sustainable management vision plan for the farm so important?’ I will answer this question by quoting one of my favorite Yogi Berra statements: “If you don’t know where you are going, you may end up some place else!” Sustainable winegrowing is a long-term commitment and needs long-term goals so one has a target to aim for.

Other important practices in the chapter are developing plans for leadership succession within the farming enterprise and business risk management as well as tracking fuel and electricity use following the adage if you can’t measure it, you can’t manage it.

 

Human Resources Management

The first practice standard in the chapter is to develop a human resources management plan for the farm. Other practice standards relate to team building, employee training and development, employee performance evaluation, employee orientation, providing health care and benefits, safety training and a safety rewards program.

The farming practice standards for ecosystem management focus primarily on parts of the farm that are outside the vineyard, such as riparian areas like the one seen here.

 

Ecosystem Management

The farming practice standards for ecosystem management focus primarily on parts of the farm that are outside the vineyard. They start with an environmental survey to identify and document important environmental features such as swales, riparian areas, trees, woodlands or vernal pools whose presence would impact how the farming is done in the vineyard.

This is followed by the development of an Ecosystem Management plan for the farm. Then there is a series of detailed farming practice standards for managing important ecosystem elements from cover crops in the vineyard, vegetation adjacent to the vineyard, and, if present, managing woodlands, individual trees, seasonal wetlands or riparian habitat.
There are other practice standards focused on biodiversity and providing nesting boxes for owls, birds and bats. And finally, if a grower has grazing animals on the farming, a grazing management plan needs to be developed and implemented.

 

Soil Management

The soil management chapter starts with farming practice standards for developing and implementing a nutrient management plan based on vine needs over the season, a soil conservation plan to minimize erosion due to wind and water and a soil map confirmed by soil coring or a soil pit. No tillage and maintenance of a cover crop every vine row gets the most practice points because these practices promote soil health through better drainage, increased organic matter content, increased soil moisture holding capacity and better soil microbial activity.

Soil and vine tissue sampling is required to be done to monitor the nutrient availability and status in vine tissue so as to guide nutrient additions if they are determined to be necessary. Several farming practice standards address nitrogen management due to its importance in vine performance as well as its mobility in the soil, making it prone to leaching into the ground water during winter rains.

 

Water Management

Water management is a critical element of sustainable winegrowing because it is a precious resource in California as well as the recognized fact that irrigation management is one of the most important ways to influence winegrape quality and therefore wine quality. The chapter starts with a practice standard for the development and implementation of a water management plan that states goals and strategies, followed by a focus on soil water holding capacity, water intake rate and permeability, and irrigation system design and performance measuring and monitoring.

Due to the importance of a properly performing irrigation system, several standards focus on amount of water used, maintenance, distribution uniformity and pump efficiency, with practices specific to micro, sprinkler or flood systems. There are also practice standards for irrigation scheduling based on monitoring vine water demand, level of soil moisture and avoidance of offsite movement of irrigation water.

Many wineries now require sustainability certification of their growers.

 

Pest Management

I have long felt that pest management is one of the most challenging areas of sustainable winegrowing to capture in a set of farming practice standards. That is because, ideally, pest problems in the vineyard are minimal due to the grower having implemented a whole range of preventative practices that preclude the development of pest problems. In other words, much is done to minimize the need for a pest control action. Many of these preventative practices are captured in farming practice standards in other LODI RULES chapters such as Water, Soil and Ecosystem Management.

The Pest Management chapter begins with a standard for development and implementation of an insect and mite management plan. It is followed by one for insect and mite population monitoring and data recording and another specifying economic thresholds for management actions against leafhoppers and mites.

There are several practice standards for disease management due to its importance in developing an economically acceptable yield, quality winegrapes and ensuring the maximum length of life for the vineyard. The first is the development and implementation of a Powdery Mildew management plan given the key role this disease plays in vineyard management. There are practice standards for when to initiate mildew treatments in the early stages of the growing season, the subsequent timing of treatments as the season develops as well as one for managing fungicide resistance. There are also practice standards for managing Botrytis and canker diseases.

Weed and vertebrate pest management are addressed through standards requiring the development and implementation of weed and vertebrate pest management plans followed by ones for monitoring and recording their respective populations.

When a pest problem needs an action, it is often in the form of spraying, whether it is due to an insect, mite, disease or weed. We all appreciate the importance of sprayer calibration and maintenance, but it is often challenging for many growers to do them in a timely manner. Therefore, there are practice standards that thoroughly address these two critical aspects of pest management.

Pest problems change through time and it is important that the LODI RULES keep up with them. New practice standards are periodically added when revisions to the program are made. For example, given the rapid rise in the importance of leaf roll and red blotch viruses and the vectoring of some of them by Vine Mealybug, new sustainable practice standards have been written to address this issue and will be added to the program in 2022.

Sustainable farming practices within and outside of the vineyard are assigned a set of points under the LODI RULES program.

 

Certification

I often hear growers say, ‘Of course I farm my vineyard sustainably, why do I need to be certified?’ One reason is that more and more wineries are requiring certification to obtain and maintain a winery contract. That, however, is a cost of doing business requirement, which is not something that is all that inspiring for a grower.

Two primary goals for the team that created the LODI RULES was that implementing them would result in higher-quality winegrapes and help a grower improve their farming operation. Based on the feedback from growers in the program and wineries that are paying bonuses for LODI RULES certified winegrapes, I think these goals have been met.
One can look at a grower farming according to the LODI RULES as doing something similar to what an airline pilot is required to do before flying their plane. They go through a checklist of all the different systems on the plane to ensure they are in working order. Many of the things are obvious, but there are so many that it is easy to overlook some of them in day-to-day flying. The checklist assures that does not happen. As passengers on the plane, we can appreciate the importance of going through this check list! The same can be said for sustainable viticulture.

There are so many practices involved in growing winegrapes sustainably. Many are obvious and are second nature to a grower. However, it is easy to overlook some in the day-to-day frenzy involved in farming. Certifying to the LODI RULES ensures this does not happen.

The 2021 Crop Consultant Conference: Where California’s Top Ag Insiders Meet to Move the Industry Forward

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Progressive Crop Consultant Magazine’s popular two-day Crop Consultant Conference will return this year as a live conference and trade show, featuring seminars worth 14.5 hours of CCA and 7 hours of DPR continuing education credits, a live trade show, and the presentation of Western Region CCA Association’s popular CCA of the Year Award and honorariums and scholarships. The Crop Consultant Conference will be held on Sept. 16 and 17 at the Visalia Convention Center.

The Crop Consultant Conference has become a premier event held in the San Joaquin Valley each September for Pest Control Advisors and Certified Crop Advisers. Co-hosted by JCS Marketing, the publisher of Progressive Crop Consultant Magazine, and Western Region Certified Crop Advisers Association, the event brings industry experts and suppliers, researchers and crop consultants together for two days of education, networking and entertainment.

“We are excited to be back to doing our events in person, and expect another sell-out event for crop consultants in the Western United States,” said JCS Marketing Publisher and CEO Jason Scott. “Agriculture is a relationship-driven business and there is no substitute for live events.”

Topics for the two days of seminars include: Various seminars on managing pests and diseases in high-value specialty crops, tank mix safety and regulations, fertilizer management, soil health, new technology, new varieties and rootstocks and their impact on tree nut pest management.

The conference will conclude with two one-hour panels offering hard-to-get CCA credits and moderated by Western Region CCA related to nitrogen monitoring, use, application and management as well as the various regulatory requirements around irrigated nitrogen management.

 

EXCLUSIVE FREE ACCESS TO VIRTUAL C.E. LIBRARY

Get exclusive access to an additional 11.5 DPR and 12.5 CCA hours as part of your 2021 Crop Consultant Conference Registration. These additional hours are available virtually, on-demand, and only to registered attendees. Exclusive access to these hours will only be available from October through December of 2021.

Registration fees for the two-day event are $150, or less than $15 per CE unit. Pre-registration is required and can be done at progressivecrop.com/conference.

Click Here to Register Now

Nitrogen Regulations in California and the Certified Crop Adviser’s Role

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California Certified Crop Advisers (CCAs) are an integral part of the nitrogen management compliance picture (all photos by Vicky Boyd.)

In the last 10 or more years, water quality regulations that address nitrate in groundwater have expanded dramatically. Starting in 2012, the regulatory agencies charged with protecting California’s water quality have increased their scrutiny of and demands on agriculture. So, it is essential for crop consultants to understand the regulations and how regulations affect their customers.

 

Regulatory History

The challenges associated with nitrate in groundwater and its sources have been recognized for at least a generation. In 1987, the California State Legislature directed the State Water Resources Control Board to prepare a report on nitrate contamination in drinking water. The convened expert panel reported that agriculture was likely an important contributor to nitrate in groundwater.

In 2012, however, the regulatory landscape changed dramatically. First, a major study of nitrate in California drinking water was published by UC Davis. This sprawling effort, titled Addressing Nitrate in California’s Drinking Water, focused on the Tulare Lake Basin and the Salinas Valley. The multi-volume report was produced by the UC Davis Center for Watershed Sciences. It showed that nitrate problems would likely worsen for the next several decades and that most nitrate currently in drinking water wells was applied to the surface decades earlier. An important conclusion of the report was that agricultural fertilizers and animal wastes applied to cropland are by far the largest regional sources of nitrate in groundwater. Thus, in the last decade, the State and Regional Water Boards have been more assertive in regulating agricultural contributions to groundwater nitrate.

The Central Valley Irrigated Lands Regulatory Program (ILRP) started in the first part of this century with a focus on pesticides in surface water. That focus expanded in 2012 when the ‘Waste Discharge Requirements for the Eastern San Joaquin River Watershed (ESJ) General Order’ was first adopted by the Central Valley Regional Water Quality Control Board (CVRWQCB). This order required grower reporting of nitrogen fertilizer applied to cropland and estimates of the nitrogen removed with harvested crops, so the efficiency of nitrogen fertilizer use could be calculated. Growers record this information in their Nitrogen Management Plans (NMPs) as specified by the CVRWQCB. The reporting of NMP data was carried out through the ESJ Water Quality Coalition, a grower-led intermediary that anonymized the data and provided statistical analysis on a township basis. A component of the statistical analysis is identification of outlier values (i.e., parcels where the nitrogen efficiency is low relative to others in township.) These outlier growers are then targeted for outreach and increasing reporting requirements. Growers in all regions of the Central Valley are represented by coalitions. Nitrogen reporting requirements are now in place for all Central Valley regions and crops with the exception of rice.

In 2018, the State Water Board stepped into the picture and revised the ESJ Order to include new provisions to be precedential to all regional boards. The precedents adopted include reporting of nitrogen application (A) to and removal (R) from cropland, reporting of irrigation water used, testing on-farm domestic wells for nitrate and reporting nitrate exceedances to the well users. With these new requirements, the NMPs became the Irrigation and Nitrogen Management Plans (INMPs). The regional boards were directed to use both A/R and A-R (the nitrogen efficiency ratio and the total excess nitrogen, respectively) to evaluate compliance. All regional boards are required to adopt these precedents into orders by February 2023. The CVRWQCB updated its ILRP orders in 2019.

Another major nitrate-related regulatory effort in the Central Valley is the Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS). This is a multi-stakeholder effort that seeks to manage the long-term loading of salts in the Central Valley. Of interest here is the focus on nitrate. The CVRWQCB adopted the regulations proposed by the CV-SALTS stakeholders in 2018. The goals of CV-SALTS regulations are “1) to ensure a safe drinking water supply; 2) to achieve balanced salt and nitrate loadings; and 3) to implement long-term and managed aquifer restoration programs where reasonable, feasible and practicable.”

While the CV-SALTS process affects all discharges in the Central Valley, each of the above goals represent challenges to growers in terms of costs of compliance and improving nitrogen fertilizer management. Fortunately for growers, the administration of regulatory requirements is handled by the coalitions that were established for the ILRP.

Looking again at 2012, the Central Coast Regional Water Quality Control Board (CCRWQCB) adopted its first order to require reporting of nitrogen applications. This information was reported directly to the Regional Water Board. Just this year, the CCRWQCB adopted the updated “Ag Order 4.0,” incorporating the ESJ precedents and setting long-term limits on excess nitrogen applied to crops. Farming operations must now submit information on nitrogen applied to and removed from cropland. The order includes a schedule of targets for excess nitrogen fertilizer roughly defined as A-R. After 2026, specific excess nitrogen targets are in place for all crops. Those targets rachet down from 300 lbs/ac in 2026 to just 50 lbs/ac in 2050. For reference, the CCRWQCB estimates that currently only approximately 6% of the acres of high-value crops meet the 2050 benchmark.

The situation in the Central Valley is different than in the Central Coast. The Central Valley coalitions have developed a methodology to determine what those targets should be on a township basis. The methodology, a sophisticated modelling effort for the entire Central Valley, has been approved by the CVRWQCB Executive Officer and is scheduled to produce target excess nitrogen values in 2023.

Irrigated nitrogen management is a crucial area for CCAs.

 

The Crop Adviser’s Role

California Certified Crop Advisers (CCAs) are an integral part of the nitrogen management compliance picture. The CVRWQCB determined that CCAs who received special training in nitrogen management are qualified to certify growers’ INMPs. There are now nearly 900 CCAs eligible to certify INMPs.

For several years, CCAs became eligible to certify Central Valley growers’ NMPs through training received via a day-and-a-half in-person conference given once a year and presented by UC faculty. Funded by the CDFA Fertilizer Research and Education Program (FREP), this successfully certified nearly 1,000 CCAs. On October 1, 2020, the certification program changed to a Nitrogen Management Specialty category managed by the International Certified Crop Adviser organization. All CCAs who had the nitrogen management certification were “grandfathered” into the new Nitrogen Management Specialty category. CCAs who had not yet been certified now must take the Nitrogen Specialty category exam to be qualified to sign INMPs. UC staff developed online training modules to assist CCAs in passing the specialty exam. The training is available to any CCA and provides 16 continuing education units (CEUs) for a cost of $120. More information regarding the online training and the specialty exam can be found at certifiedcropadvisor.org/ca-nsp/. CCAs who have the California Nitrogen Management Specialty (CA-NSP) category must obtain eight CEUs in nutrient management and seven CEUs in soil and water management over two years but are still only required to obtain 40 total CEUs to maintain their certification. There is an additional fee required to maintain the CA-NSP.

CCAs may find that certifying INMPs, especially the irrigation portions of the forms, moves them out of the nutrient management comfort zones. Because we all recognize the importance of irrigation management in nitrogen management, we can also realize that it’s a crucial area for CCAs to step into. Information regarding anticipated crop evapotranspiration (ETc) and irrigation water to be applied is required in the INMPs.

Instructions provided with the plans suggest that the UC or coalition may provide the information to complete the ETc question, but the data are not readily available. To resolve the conflicts involving ETc determination, a statewide project was funded to create an accepted clearinghouse of coefficient values for the major crops in California. The project is nearing completion and should go a long way to helping CCAs provide accurate answers for the ETc questions in the INMP. Alternatively, this year, a project involving the National Aeronautics and Space Administration (NASA), the Environmental Defense Fund and a host of other partners will make ETc data available through interactive maps on the web. The project is called OpenET and is set to be released by the end of the year.

FREP is holding its annual conference this year in San Luis Obispo from October 26-28. There will be sessions on OpenET, ILRP water quality coalitions and other nutrient and irrigation management topics. For more information, see cdfa.ca.gov/is/ffldrs/frep/FREPConference.html.

Mark Cady is currently supervisor of the CDFA FREP. His understanding of water quality regulation comes from four years as an environmental scientist with the CVRWQCB. FREP’s role is to fund and facilitate research and education to advance the environmentally safe and agronomically sound use and handling of fertilizing materials. Please visit cdfa.ca.gov/is/ffldrs/frep for more information.

Protect Almond Tree Roots at Planting

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Irrigation systems for new orchards should be designed to ensure a wetting pattern that promotes good root distribution.

Protecting the roots of young almond trees at planting is a vital step toward long-term tree health.

At the 2021 San Joaquin Valley Almond Day, UCCE Farm Advisors Mae Culumber and Brent Holtz outlined care for new trees during orchard establishment.

If possible, avoid planting on hot, windy days, Culumber said. The small root hairs on dormant trees can dry out quickly when exposed to air. Since roots store carbohydrates needed to support new growth, the trees should be handled and planted carefully. Roots should not be pruned prior to planting unless they are damaged. Roots can also be treated with Galltrol before planting to prevent crown gall infections.

The holes for the new trees should be wide and deep enough so roots are not cramped and can spread. The largest, strongest roots should be oriented in the direction of the prevailing wind. The highest root should be slightly higher than the soil line, but covered with soil. Soil should be tamped down around the tree to eliminate air pockets.

After the trees are in place, Culumber said 1 to 3 gallons of water should be used to soak the soil around the tree.

Irrigation systems for new orchards should be designed to ensure a wetting pattern that promotes good root distribution. In the weeks and months ahead, over-irrigation should be avoided as saturated conditions kill small roots due to poor aeration. Over-irrigation also creates conditions favorable to phytophthora.

There is potential to lose irrigation efficiency when larger soil surfaces are wetted. With soil-applied nutrients, efficiency of the delivery system is dependent on water delivery.

Culumber explained one approach is to run tubing for button emitters. Using a riser with two outlets, one button is placed a half-foot from the center of the trunk at a rate of one gallon. Two more buttons are placed two feet from the first at two gallons per hour.

For second leaf trees, two more buttons are added at 8.5 gallons per hour. At third leaf, tubing is run for micro sprinklers with a pressure compensator in between each tree with a rate of up to 18 gallons per hour.

Holtz reported in his whole orchard recycling studies that young trees experience less water stress planted where wood chips are incorporated back into the soil due to increased moisture holding ability.

In WOR plantings, Holtz said the carbon to nitrogen ratio can become unbalanced and early N applications are important.

This drawing supplied by UCCE Farm Advisor Brent Holtz illustrates the correct procedure for planting almond trees on berms.

Water Stress Contributes to Smaller Vineyard Canopy

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Small canopy while clusters are at bloom indicates stunted early canopy growth due to a dry winter. Typically, the small canopy can recover after irrigation events; however, yield will be significantly reduced due to excessive cluster shatter (photo courtesy G. Zhuang.)

Smaller-than-normal canopies in wine grape vineyards are a common sight in the San Joaquin Valley this year due to lack of irrigation water.

George Zhuang, UCCE Fresno County viticulture advisor, said the dry winter and spring contributed to stunted growth and production issues growers are seeing in this year’s wine grape crop.

“In some varieties, we are seeing shatter in clusters and yield losses,” Zhuang said.

Postharvest irrigation is important every year to relieve water stress and help the vines store carbohydrates for next year’s production. This year, it is critical. The goal of postharvest irrigation is to avoid delayed, erratic bud break and ensure canopy growth the next growing season. It will also help with production and fruit quality, Zhuang said.

This year, securing enough water for postharvest irrigation may not be possible. Zhuang said growers and vineyard managers will have to decide if they want to apply water after harvest or save it for next spring. If the Valley experiences another dry winter, the water will help next year’s growth. Stressing the vines postharvest will have a carryover effect into the next year, he said.

If irrigation water is available postharvest, the goal is to maintain a photosynthetically functional canopy, but avoid overwatering to prevent vines from pushing new growth.

At least 10% of seasonal irrigation water should be applied postharvest. For early season wine grape varieties with a longer postharvest growth period, more water may be needed if hot temperatures persist. To ensure a more even bud break and an adequate carbohydrate reserve, irrigation, if possible, should continue until leaf senescence.

Adequate soil moisture postharvest and during dry winters will also hydrate vines, prepare them from cold hardiness and help with even budbreak the following season.

Fertilizer applications can be made in the fall to replace annual loss from harvest. It is important that the canopy is active to assimilate nitrogen applications. Early season varieties will have a longer period where this is possible.

Postharvest is a good time to apply soil amendments, including sulfur and gypsum, to adjust soil pH and improve infiltration.

If there is a positive to this year’s drought conditions, it is the lower pest and disease pressure in vineyards. This year, Zhuang said, there has been less fungal disease due to the smaller canopies. Vine mealybug has also declined in water stressed vineyards due to less vigor in the grapevines.

Keeping Pathogens Out of Produce Fields

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Vegetative barriers are narrow and parallel strips of stiff, dense vegetation planted on or close to the contour of slopes or across concentrated flow areas. These barriers can slow runoff water and have a filtering effect (photo by Ayanna Glaize, North Carolina State University.)

One of the pathways for foodborne bacterial pathogens such as E. coli, salmonella and campylobacter to contaminate fresh produce is proximity to livestock operations. Research has shown that vegetative barriers between livestock and produce fields could reduce foodborne pathogen transmission.

Most foodborne disease outbreaks can be traced back to contaminated fruits and vegetables, especially leafy greens. A research study conducted by North Carolina State University showed there was significant transmission from animal operations to fresh produce on farms where both livestock and crop systems were integrated.

Multiple pathways allow for transmission of foodborne pathogens. They include environmental sources, such as contaminated surface runoff water, insect and air transmission due to proximity of animals to fresh produce, manure contamination of irrigation systems and improper food handling.

Vegetative barriers have been proposed as a possible solution to transmission of foodborne pathogens.

Vegetative barriers are narrow and parallel strips of stiff, dense vegetation planted on or close to the contour of slopes or across concentrated flow areas. These barriers can slow runoff water and can have a filtering effect. They also loosen the soil, allowing for water penetration. The foodborne pathogens E. coli and salmonella can contaminate fresh produce through wind transmission and through surface runoff water, the study reported. Planting vegetation barriers can effectively reduce flow of runoff water and act as a wind barrier that traps spray droplets from animal operations, intercepting them and preventing them from reaching fields were produce is grown.

The study showed evidence of decreased rates of contamination of fresh produce by E. coli and salmonella from animal production when vegetative barriers were used. The study involved a five-layer vegetative barrier constructed between a dairy, a poultry operation and a produce farm. Fresh produce, manure and environment samples were collected over 15 months and tested for the level of E. coli and salmonella.

The results showed that only 18% of the total E. coli and salmonella samples isolated were present in the fresh produce after installation of vegetative barriers.

The study also noted that while the barriers are effective, other pathways, including manure applications on fields and improper food handling, can still lead to contamination.

Correctly Identify Mites in Strawberries

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Lewis mites on a strawberry leaf. Lewis mites have smaller spots that run along each side of their bodies. Identification of mite species is important for effective control (photos by Surendra Dara, UCCE.)

With mites in strawberries, it is important to correctly identify the species to achieve effective control.

At the 12th-annual Santa Maria Strawberry Field Day webinar, UCCE Santa Cruz Farm Advisor Mark Bolda reported on two strawberry pests, two-spotted mite and Lewis mite, and how to distinguish the two. This is important, Bolda said, because Lewis mite is not apparently responsive to the same materials and predators as two-spotted mite.

While the two-spotted mite generally has two larger dark spots on its back, Lewis mite has smaller dark spots that run along each side of the body. Lewis mite eggs are smaller than two-spotted mite eggs.

Lewis mite was found in Ventura-area strawberry production about ten years ago and it first appeared in the Salinas-Watsonville area in the last three years.

Feeding by Lewis mite kills leaves on strawberry plants and reduces yields. Both two-spotted mites and Lewis mites gather at the underside edge of leaves. Bolda said Lewis mite damage causes the leaves to have a purple tinge, and the damage tends to spread more slowly across a field. It is common to see both species on the same leaf at the same time.

Lewis mite has one larval and two nymphal stages prior to the adult stage. Eggs are laid on the leaf edges and larvae emerge after three days. Colonies are often found at leaf edges or veins.

A full life cycle of Lewis mite is about 14 days at 77 degrees F, according to UC IPM guidelines. The cycle can take fewer days at warmer temperatures. Two-spotted mites’ full lifecycle takes about five days at 75 degrees F.

Bolda noted that in mid-winter coastal strawberry growing areas, it is unusual for a large percentage of mites to become dormant. Instead, they continue to grow and lay eggs, although at a slower pace during the winter months.

In an efficacy study, Bolda said the most promising materials were tested first in a lab setting to get an idea of their control level.

The list included Oberon at 16 fl. oz. per acre; Vestis, a surfactant, at 13 fl. oz. per acre; Aza-Direct at 32 fl. oz. per acre; Agrimek at 16 fl. oz. per acre; and Nealta at 13.5 fl. oz. per acre. Ten leaves per treatment replicate were evaluated under a microscope. Adults and eggs were counted. Treatments were made January through mid-April. Numbers of Lewis mite were low until the end of March. Materials with the most efficacy were Vestis, Aza-Direct and Agrimek.

Complete information on this trial can be found on Bolda’s blog.

The Crop Consultant Conference Returns as In-Person Event Over Two Days

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Progressive Crop Consultant Magazine’s popular two-day Crop Consultant Conference will return this year as a live conference and trade show, featuring seminars worth 10 hours of CCA and 8 hours of DPR continuing education credits, a live trade show, and the presentation of Western Region CCA Association’s popular CCA of the Year Award and honorariums and scholarships. The Crop Consultant Conference will be held on Sept. 16 and 17 at the Visalia Convention Center.

The Crop Consultant Conference has become a premier event held in the San Joaquin Valley each September for Pest Control Advisors and Certified Crop Advisers. Co-hosted by JCS Marketing, the publisher of Progressive Crop Consultant Magazine, and Western Region Certified Crop Advisers Association, the event brings industry experts and suppliers, researchers and crop consultants together for two days of education, networking and entertainment.

“We are excited to be back to doing our events in person, and expect another sell-out event for crop consultants in the Western United States,” said JCS Marketing Publisher and CEO Jason Scott. “Agriculture is a relationship-driven business and there is no substitute for live events.”

Topics for the two days of seminars include: Various seminars on managing pests and diseases in high-value specialty crops, tank mix safety and regulations, fertilizer management, soil health, new technology, new varieties and rootstocks and their impact on tree nut pest management.

The conference will conclude with two one-hour panels offering hard-to-get CCA credits and moderated by Western Region CCA related to nitrogen monitoring, use, application and management as well as the various regulatory requirements around irrigated nitrogen management.

Registration fees for the two-day event are $150, or less than $15 per CE unit. Pre-registration is required and can be done at progressivecrop.com/conference.

Click Here to Register Now

Minimizing Drift from Orchard Spray Application by Spray Backstop System

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Cotton ribbon stretched around two rows of trees for continuous loop sampling.

The use of pesticides can be very effective in protecting trees from pests and diseases. However, many times this is also accompanied by negative impacts on humans and the environment. Off-target movement of chemical spray has always been a challenge for growers because it can contaminate the environment, reduce spray efficacy and impose liabilities.

California has stringent pesticide laws and regulations and orchard spray application is considered a high-risk operation. California law establishes a buffer between schools and any pesticide spraying location. Growers are required to notify the public when they spray pesticides. This includes schools, daycare facilities, and county agricultural commissions.

A prototype of the spray backstop system developed at the Digital Agriculture Lab at UC Davis.

Spray drift can be reduced by choosing the right type of nozzle, adjusting and calibrating sprayer settings, defining shelter zones and specifically modified practices in the downwind rows. Reducing the movement of spray droplets to sensitive areas might be accomplished by these methods, but they are in clear contrast with strategies that lead to a uniform on-target deposition. For instance, spraying with larger droplets can reduce the amount of drift, but it also decreases the effectiveness of the spray at higher parts of a tree. Likewise, reducing airflow results in reduced drift; however, it also diminishes the spray efficacy in zones farther from the sprayer, for example, on treetops. Drift can also be reduced when we use slower ground speed and higher liquid flow rate, but the impact is not significant.

Thermal view of spray cloud escaping the canopy from the top.

Spray Backstop

At the Digital Agriculture Lab at UC Davis, a sprayer attachment system called Spray Backstop was developed to minimize drift potential and possibly improve spray coverage on the treetops. The backstop system is a screen structure that can be raised above the trees using a foldable mast.

A test was conducted in a mature almond orchard to determine how much drifting could be reduced with the backstop system. A cotton ribbon loop was stretched around the trees to quantify the droplets scaping the tree canopy. The ribbon could capture all spray droplets that did not deposit on-target and were not blocked by the backstop system.

The orchard was sprayed with a mix of water and fluorescent dye. The ribbon was cut into sub-samples and analyzed with the fluorometry method. Comparing the ribbon samples from the test with and without the backstop showed that the Spray Backstop system could effectively block the spray droplets escaping the canopy from treetops or sides and reduce drift potential by 78%. Leaf samples were also collected from trees in both spray application conditions and analyzed by the fluorometry technique. Unlike the conventional drift control methods, using the spray backstop system does not change overall canopy deposition and could also help improve deposition on treetops.

A sprayer working in a young almond orchard in Northern California (all photos courtesy Digital Agriculture Lab.)

Adopting the spray backstop system into the orchard spray application practice will reduce the environmental degradation while protecting residential areas and schools from exposure to chemicals. On the other side, growers can adjust their sprayer for more air and finer droplets (that will improve spray coverage and efficacy in the upper canopy area) without being concerned about drifting because the backstop system can stop spray droplet movement above the trees. A uniformly applied treatment will significantly reduce the risk of crop failure due to pests and diseases.

The spray backstop system is simple and could be easily implemented without significant modifications to the grower’s spray rigs. This system can help growers to be compliant with pesticide regulations and maintain good environmental stewardship. You can find more information about the spray backstop project at the digital Agriculture lab website: digitalaglab.ucdavis.edu.

Spray backstop blocking the spray cloud from moving upwards.

Identifying the Potential and Impacts of On-Farm Groundwater Recharge

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On-farm recharge has the potential to clean up groundwater that has been contaminated with nitrogen and/or pesticides (photo by H. Dahlke.)

Aquifers have become depleted from decades of overuse. Drilling deeper is an option for farmers, but prohibitively expensive for low-income residents in disadvantaged communities in the San Joaquin Valley.

A UC scientist believes managed aquifer recharge on agricultural lands close to populations with parched wells is a hopeful solution.

Helen Dahlke, professor in integrated hydrologic sciences at UC Davis, has been evaluating scenarios for flooding agricultural land when excess water is available during the winter in order to recharge groundwater. If relatively clean mountain runoff is used, the water filtering down to the aquifer will address another major groundwater concern: nitrogen and pesticide contamination.

“The recharge has the potential to clean up groundwater,” she said.

Five years ago, UCCE Specialist Toby O’Geen developed an interactive map (casoilresource.lawr.ucdavis.edu/sagbi/) that identifies 3.6 million acres of California farmland with the best potential for replenishing the aquifer based on soil type, land use, topography and other factors. Dahlke and her colleagues analyzed the map and identified nearly 3,000 locations where flooding suitable ag land will recharge water for 288 rural communities, half of which rely mainly on groundwater for drinking water. The research was published by Advancing Earth and Space Science in February 2021.

“If we have the choice to pick a location where recharge could happen, choose those upstream from these communities,” Dahlke said. “Recharge will create a groundwater mound which is like a bubble of water floating in the subsurface. It takes time to reach the groundwater table. That bubble floating higher above the groundwater table might just be enough to provide for a community’s water needs.”

 

Filling Reservoirs Under the Ground

Many climate models for California suggest long-term precipitation amounts will not change; however, the winter rainy season will be shorter and more intense.

“That puts us in a difficult spot,” Dahlke said. “Our reservoirs are built to buffer some rain storms, but are mainly built to store the slowly melting snowpack in the spring. In the coming years, all the water will come down earlier, snowmelt likely in March and April and more water in winter from rainfall events.”

She is working with water districts and farmers to consider a change in managing water in reservoirs.

“We want to think about drawing reservoirs empty and putting the water underground during the fall and early winter. Then you have a lot of room to handle the enormous amounts of runoff we expect when we have a warm atmospheric river rain event on snow in the spring,” she said. “However, farmers are hesitant. They like to see water behind the dams.”

Interest in groundwater banking has been lifted with the implementation of the 2014 Sustainable Groundwater Management Act (SGMA). The law requires governments and water agencies to stop overdraft and bring groundwater basins into balanced levels of pumping and recharge by 2040. Before SGMA, there were no statewide laws governing groundwater pumping, and groundwater was used widely to irrigate farms when surface supplies were cut due to drought.

“For some of the drought years, overdraft was estimated to be as high as nine million acre-feet a year,” Dahlke said.

Dahlke believes wintertime flooding for groundwater recharge can help water districts meet SGMA rules. “We have to do anything we can to store any surplus water that becomes available to save it for drier times, and our aquifers provide a huge storage for that,” she said.

Helen Dahlke, professor in integrated hydrologic sciences at UC Davis, has been evaluating scenarios for flooding agricultural land when excess water is available during the winter in order to recharge groundwater (photo by Joe Proudman, UC Davis.)

 

Farming Impacts

The Dahlke Lab is collaborating with UC ANR farm advisors and specialists as well as scientists at other UC campuses to learn about agronomic impacts of flooding a variety of agricultural crops, including almonds, alfalfa and grapes.

In the San Joaquin Valley, UCCE Irrigation Specialist Khaled Bali led an intermittent groundwater recharge trial on alfalfa. The researchers applied up to 16 inches per week with no significant impact on alfalfa yield.

“You could do groundwater recharge in winter and then turn the water off completely and still get a cutting or two of alfalfa before summer,” he said.

This past winter, Dahlke was prepared to flood 1,000 acres of land with water from the Consumnes River. Even though winter 2020-21 was another drought year, the research will go on. Her team was able to flood a 400-acre vineyard and, in collaboration with scientists from UC Santa Cruz, deploy sensors in the field to measure infiltration rates to better understand whether sediment in the flood water could clog pores in the soil. Her team also collaborates with Ate Visser of Lawrence Livermore National Laboratory in using isotope and noble gas data to determine the groundwater age and flow.

The Dahlke Lab’s groundwater banking project has planned more studies in groundwater basins across the state to close knowledge gaps on suitable locations, technical implementation and long-term operation. They also plan to address operational, economic and legal feasibility of groundwater banking on agricultural land.

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