Richard Smith1, Eric Brennan2 and Patricia Love1
1. University of California Cooperative Extension, Monterey County. 2. USDA-Agricultural Research Service, Salinas.
Fall-grown cover crops (planted August-September and incorporated October-November) provide a useful planting slot for a percent of vegetable crop acreage in the Salinas Valley. It is a time when some growers find an opportunity, after two crop rotations, to fit a cover crop in their operations. It has the particular advantage of allowing the grower to incorporate the cover crop and still have time to work the ground when it is still dry before the onset of winter rains.
In Ag Order 4.0 which was approved in April 2021, cover crops that meet the following criteria were granted a credit on the R side of the applied (A) minus removed (R) metric for nitrogen loading in vegetable production fields: 1) a non-legume cover crop grown for ³ 90 days during the winter fallow period (October to April); 2) accumulates more than 4,500 lbs/acre of oven-dry biomass; and 3) has a C:N ratio of ³ 20:1 at incorporation. Unfortunately, fall-grown cover crops do not meet these criteria and therefore growers cannot claim a credit when reporting nitrogen loading in their fields.
In the fall of 2021, we conducted six on-farm evaluations of fall-grown cover crops to determine their productivity, nitrogen scavenging capability and C:N ratio at incorporation. Planting dates ranged from August 25 to October 3, and the average days to incorporation was 54 (ranged from 47 to 59). Two barley varieties UC 696 and UC 937, as well as Merced rye were planted in each evaluation. The barley varieties were included because we anticipated that they would reach the heading growth stage more quickly than rye when growers typically terminate cover crops. However, in these evaluations, barley did not reach this stage any faster than Merced rye as measured by the Feekes cereal growth and development scale (Table 1). In 54 days, all cover crops produced more than 4,500 lbs oven-dry biomass and took up from 150 to 161 lbs N/A. The C:N ratios of the cover crops ranged from 13.0 to 13.4.
Fall-grown cover crops grow and mature quickly due to the longer days and warmer weather that they experience in these early planting slots. An important question is, do fall-grown cover crops help to reduce nitrogen leaching during the winter? To help answer this question, we intend to conduct mineralization studies of the cover crop residue to determine what amount of the residue remains unmineralized after twelve weeks. The nitrogen in the unmineralized portion of the cover crop residue is not immediately susceptible to nitrate leaching and could potentially be deserving of a credit. The Central Coast Regional Water Quality Control Board will update the criteria in the Ag Order each five years based on new scientific information. If there is evidence that fall-grown cover crops can help mitigate nitrate leaching, this may help to justify expanding cover cropping options for growers in the Ag Order.
- Author: Michael D Cahn
- Author: Richard Smith
The presentations from the 2022 UCCE Irrigation and Nutrient Management Meeting are now available on the UCCE Monterey Website. You can download pdf versions of the presentations from the "Irrigation and Nutrient Management Presentations" link on the website. You can also navigate to the presentations by clicking on this link. Recordings of the presentations should be available soon too. We will add the recorded presentation links to the blog and website when they become available.
- Author: Michael D Cahn
The California Chapter, American Society of Agronomy and Cooperative Extension, UC Agriculture and Natural Resources are hosting the annual Plant and Soil Conference on Tuesday, February 1 - Thursday, February 3. This will be a virtual event using zoom. The Plant and Soil Conference is a great opportunity to increase your knowledge of crop production, soil and water management, and pest management as well as receive CCA and DPR educational hours. The full agenda can be found here. Registration is currently $90, but will increase to $115 on January 25th. You can register for the conference at https://calasa.ucdavis.edu/Conference_Registration/.
- Author: Richard Smith, UCCE Monterey
- Author: J.P. Dundore Arias, CSU Monterey Bay
- Author: Michael Cahn, UCCE Monterey
Pythium wilt of lettuce (Pythium uncinulatum) continued to be a significant production problem in lettuce fields in 2021. The levels of infection were not as extensive or severe as in 2020, but the damage caused by this disease was nonetheless problematic and serious in many fields. Pythium wilt was more frequently observed towards the end of the production season, and the development of noticeable foliar symptoms and severity of the disease appears to increase with higher temperatures. As an example, we observed growers successfully growing spring lettuce crops on blocks that were wiped out with Pythium wilt the prior fall, likely due to the lack of conducive conditions for the disease to develop. Given the rapid rise of Pythium wilt as a serious soilborne disease of lettuce in the Salinas Valley, there is a great need to better understand its biology and epidemiology to help determine the most promising means of managing it: cultural, chemical and/or varietal. In this write up we report on studies conducted in 2021 that included 1) evaluations of applications of fungicides and biologicals, 2) evaluation of effect of irrigation management on the incidence of the disease and 3) observations of varietal tolerance. Bottom line is that fungicides and biological control of Pythium wilt was measurable but limited in our studies. In the irrigation trials, we did not see higher incidence of Pythium wilt in the plots receiving greater quantities of irrigation water. There is good varietal tolerance to Pythium wilt in some commonly used lettuce varieties and to-date, this looks to be the most promising method for effectively reducing Pythium wilt losses.
Fungicide and Biologicals Evaluations: Twelve trials were conducted to test the efficacy of fungicides and biologicals for controlling Pythium wilt of lettuce. In ten trials, materials were applied over-the-top of the lettuce and incorporated into the soil by subsequent sprinkler irrigation applied within two days of application; in two trials, Ridomil Gold was injected into the drip system during an irrigation (see Table 1 for details). Top of the label rates of the fungicides and biologicals were used for each application to increase the chances of obtaining a signal from the materials. Fungicides tested in the over-the-top trials included Ridomil Gold, Previcur, Alliette and Ranman. Biologicals tested were Minuet (Bacillus subtilis) and LifeGuard (Bacillus mycoides). Over-the-top applications we made at-planting, thinning and/or at the rosette stage, but applications at each of these timings was not always possible in each trial and Table 1 shows the application timings for specific trials.
Planting dates for the trials ranged from June 12 to August 25. Trials were evaluated at or near harvest by counting all plants in each plot and then counting plants infected with Pythium wilt to get the percent infected plants. At times plots were also infected with Sclerotinia and a vascular wilt, and plants infected with these diseases were kept separate from the Pythium wilt totals. Trials planted before late July had levels of Pythium wilt that were too low to effectively evaluate (data not shown). However, trials planted in late July or after had greater incidence of disease. A confounding factor that affected the level of infection in later trials (Nos. 8, 9 and 10) was that by chance, the trials were located in fields planted with the green leaf variety Green Teen which appears to have significant tolerance to Pythium wilt and thus, these trials had little incidence of Pythium wilt (data not shown). Trial No. 7 provided the most useful data to evaluate the efficacy of over-the-top applications. The materials were applied at all three application timings and, on three evaluation dates, there was a trend indicating a lower percent of infected plants in each fungicide and biological treatment (Table 2). Although the trend was weak, it was consistent over each evaluation date. The data indicate a measurable but limited level of efficacy from over-the-top applications of these materials. Both Ridomil injection trials (Nos. 11 & 12) had significantly fewer infected plants in the Ridomil treated plots at harvest. Both fields had high levels of infection by Pythium wilt, and the reduction in infected plants was measurable but limited.
In summary, there was a modest level of control of Pythium wilt with the applied fungicides and biologicals. Injection into the drip system appeared more effective than over-the-top applications. It appears that evaluating a more effective means of applying fungicides and biologicals may be useful to see if better control may be achievable, especially in fields with history of high incidence of the diseases and during the fall lettuce crops when warm temperatures are expected. However, the challenge remains getting the material to move throughout the volume of soil occupied by the root system. This is important because infections with Pythium wilt can start on finer lateral roots or deeper in the soil and come up the tap root. Getting effective concentrations of a fungicide or biological material to the whole root system becomes a great challenge. Similarly, determining the right time of application requires further investigation.
Irrigation Evaluations: Pythium wilt is a water mold that can produce mobile spores. Excess water in the soil is thought to favor the development and spread of this organism. The goal of these trials was to evaluate if the volume of applied water might affect the incidence of Pythium wilt on lettuce. Four trials were conducted evaluating the impact of the amount of irrigation water applied during the crop cycle on the incidence of Pythium wilt. Trials were conducted in cooperating growers' fields. Irrigation regimes were established that compared 100% of crop ET (as calculated by CropManage) with 150 and 200% of crop ET. All trials were drip irrigated and the higher amounts of irrigation were applied in trials 1, 2 and 4 by using with separate manifolds equipped with a flow meter to measure the quantity of water applied. Trial 3 simply had two drip lines installed in the 200% ET treatment. At harvest, the plots were evaluated for the percent wilted plants (no. wilted plants/no. total plants). A sample of 10 plants from each plot was further evaluated to confirm if the cause of foliar wilting was Pythium wilt, Sclerotinia or a vascular wilt.
There were low levels of wilted plants in the first two trials (Table 3). In the later trials (3 & 4) there was significant wilting in the plots. However, there was no significant difference in the level of lettuce plants infected with Pythium wilt among the irrigation treatments in these trials.
Observations on Varietal Tolerance to Pythium Wilt:Formal variety trials were not conducted in 2021, but as opportunities to observe the response of varieties to Pythium wilt presented themselves, we made note of the level of infection in the varieties. One particularly dramatic example is shown in Table 4. At this site, there were two planting in which full beds (1 – 9 beds) of various varieties were planted in a field significantly infected with Pythium wilt. The percent of wilted plants in the different varieties, which ranged from 1.5 to 47.6% of total plants. The varieties Momentus and Copious had the lowest number of wilting plants and the lowest percent of Pythium infected plants, indicating good tolerance to this disease. In these two plantings, there were also plants infected with Sclerotinia and a vascular wilt resembling Fusarium wilt, though pathogen identity was not confirmed beyond visual observations. In some cases, it appeared that plants had both vascular wilt and Pythium wilt. These results indicate the co-occurrence of Pythium wilt and other soilborne diseases and raises the question whether they may interact while infecting a susceptible host. Clearly, more research is needed to better understand varietal tolerance of Pythium wilt and other associated soilborne diseases. In the end, varietal tolerance showed the greatest reduction in damage caused by Pythium wilt. The good news is that this tolerance is present in currently used breeding lines and hopefully can be quickly incorporated into other commonly used lettuce types.
Acknowledgements: We are grateful to the many cooperating growers and PCA's that helped us with these trials. We thank the California Leafy Greens Research Board for funding and thank the following research assistants for their help on these evaluations: Noemi Larios, Tom Lockhart, Tricia Love, Carlos Rodriguez Lopez and Yulissa Soto.
CDFA's Healthy Soils Program (HSP) and the State Water Efficiency and Enhancement Program (SWEEP) are currently accepting applications! If you are an agricultural operation looking to save water and/or improve your soils then these programs might be for you. Below is a list of things to consider for the grants.
CDFA's State Water Efficiency and Enhancement Program (SWEEP): Apply for up to $200,000 for irrigation management practices that reduce water and greenhouse gas emissions (by conserving energy).
What is CDFA's SWEEP grant? CDFA's SWEEP provides grant funding to California agricultural operations to incentivize activities that reduce on-farm water use and reduce greenhouse gas (GHG) emissions from irrigation systems.
How is SWEEP funded? SWEEP is funded from the Budget Act of 2021 which allocated $50 million this round.
Who can apply? The irrigation project must be located on a California agricultural operation and cannot build upon previously funded SWEEP projects directly affecting the same Assessor's Parcel Numbers (APNs).
What are the exclusions from applying to SWEEP?
- You cannot apply to expand existing agricultural operations.
- You cannot apply to install new groundwater wells or increase well depth.
- You cannot test new technology or perform research.
Which practices are eligible for funding? Some of the practices that are eligible for funding are replacing pumps,v variable frequency drives, using soil moisture or plant sensors, converting to a more efficient irrigation method, or adding equipment for irrigating more efficiently such as pipes, flowmeters, and pressure regulators. CDFA is open to a variety of practice, including solar conversions, as long as the overall project will save water and reduce greenhouse gas emissions. The Request for Grant Applications has a sample list of practices on page i-iii (https://www.cdfa.ca.gov/oefi/sweep/docs/2021_SWEEP_RGA_-_October_19_Release.pdf).
How long is the project duration? The project duration is 24 months.
What information or documents do I need to apply?
- Pump efficiency test for all pumps that will be included in the project. The information you will need on the pump test is overall pumping efficiency percentage, horsepower, discharge pressure and pumping depth.
- 12 consecutive months of utility bills, actual fuel receipts and/or field operational logs.
- If applying for a solar project, you are required to get a quote from the solar company. All other projects are not required to have quotes, but it is highly recommended.
For more information please go to: https://www.cdfa.ca.gov/oefi/sweep/
Also Attend the CDFA hosted online workshop on Monday 11/15/2021 from 1-3pm.
Sign up for upcoming workshop here: https://us06web.zoom.us/webinar/register/WN_vIYKUkfOQbeUSsJ3ycVxpw
CDFA's Healthy Soils Program (HSP): https://www.cdfa.ca.gov/oefi/healthysoils/
Apply for up to $100,000 for soil practices that improve soil health and sequesters carbon.
What is CDFA's Healthy Soils Program? CDFA's Healthy Soils Incentives Program provides financial incentives to California growers and ranchers to implement agricultural management practices that sequester carbon, reduce atmospheric greenhouse gas emissions and improve soil health.
How is the Healthy Soils Program funded? The Healthy Soils Program is funded from the State's cap and trade also known as the California Climate Investments and the California Drought, Water, Parks, Climate, Coastal Protection and Outdoor Access for all Act of 2018. This round the Healthy Soils Program was appropriated $50.5 million.
Who can apply? California agricultural operations who will have control of the land during the duration of the grant can apply.
What are the exclusions from applying to the Healthy Soils Program?
- You cannot apply for practices other than those that are listed on the Request for Grant Application (https://www.cdfa.ca.gov/oefi/healthysoils/docs/2021_HSP_Incentives_RGA.pdf).
- You cannot apply for practices that you have implemented in the previous year.
- You cannot apply if the practices will be implemented in potted plants or other plant growth media.
Which practices are eligible for funding? Some of the practices that are eligible for funding are cover cropping, reduced-till, compost application and conservation plantings. The complete list of practice can be found on the Request for Grant Applications on pages 30-50 (https://www.cdfa.ca.gov/oefi/healthysoils/docs/2021_HSP_Incentives_RGA.pdf).
How long is the project duration? The project duration is three years long starting in 2022 and ending in 2025. Depending on the practice chosen, you will likely implement the practice once a year for three years.
What information or documents do I need to apply?
- A list of practices you wish to apply for, examples include cover crop, compost, hedgerow planting and mulch application.
- Information regarding the last three years of crop history and management practices. No documentation is required just a written statement.
- If you lease land, a statement signed from your landowner stating that you will have control over the land for the duration of the grant.
Attend the CDFA hosted online workshop for the healthy soils program on Thursday 11/18/2021 from 9-11am. The workshop agenda can be viewed here:
Sign up for upcoming workshop here: https://us06web.zoom.us/webinar/register/WN_p6Kxg55GTbSdXU5ddpsNGw
For FREE technical assistance in filling out the application please contact Valerie Perez, firstname.lastname@example.org or (831) 595-8545
For FREE technical assistance with equipment and irrigation system design ideas, please contact Michael Cahn, email@example.com or 831-214-3690/span>