My observations of the field were that there were patches of several nearby plants with symptoms, but across the three contiguous fields, the patches were widespread. I suspected a vascular disease because of what appeared to be a progression of the disease from yellowing to necrosis to eventually plant death. I submitted samples to the plant pathology lab at UC Davis, and they diagnosed Fusarium oxysporum f. sp. ciceris, which is the Fusarium wilt pathogen for garbanzos. Fusarium wilt (also called Fusarium yellows) has the external symptoms previously described, but in addition to these symptoms, splitting the stems may reveal reddish-brown streaking in the vascular system at the center of the stem (i.e. xylem). The roots won't show discoloration with Fusarium wilt like they will with Fusarium root rot. Fusarium wilt should not be confused with yellowing caused from virus, which will exhibit discoloration in the phloem. Fusarium wilt can reduce yield by reducing seed quantity and size.
In general, cultural practices are the only ways to manage this disease. Luckily, the Fusarium wilt pathogens are crop-specific, so this pathogen will only infect garbanzos. The pathogen, however, can survive for a long time in the soil (upwards of 6 years or more) because it can survive under wide temperature and pH ranges. Therefore, crop rotation is an important management practice. Crop rotation will help to slow the proliferation of the disease, but it generally won't eliminate it. Growers should plant certified disease-free seed. They should not save seed for planting because Fusarium wilt (and Ascochyta blight) can live externally on the seed. Growers should also consider planting UC-27, which has disease resistance and is adapted to the Central Valley. Disease management may also include cleaning soil from equipment when moving from an infected field to a non-infected field. In some studies, soil solarizaton has been shown to reduce Fusarium wilt in subsequent garbanzo crops, but to my knowledge, there hasn't been any work on soil solarization in California garbanzos.
Garbanzo beans are an important crop worldwide for human and animal nutrition. In California, they are grown during the winter months, like small grains, and provide growers with another crop choice that can be winter rain-fed. Because they are a legume, they can fix atmospheric nitrogen to fulfil some of their nitrogen needs. Garbanzos also are more tolerant of soil salinity than common beans and limas. In California, we annually grow approximately 10,000 acres of garbanzos. California garbanzos are generally a high-quality product grown for the canning industry. More information on garbanzo production in California can be found in the UC production manual.
Methods: The trial is a randomized complete block design (approximately 4.5 acres) with three replicates of each treatment. The soil type across the trial is a Valdez silt loam. Baseline soil samples were collected in July 2018 following wheat harvest but prior to tillage. Soil was sampled from 0-6, 6-12, 12-24, and 24-36 inch depths. On July 30, 2018, a cowpea cover crop (Vigna unguiculata cv. ‘Red Ripper', Figure 1) was inoculated with Rhizobium and planted after a pre-irrigation. Pre-irrigation was only applied to the cover crop plots. The cover crop was drill-seeded at 7-in row spacing with a planting density of approximately 50 pounds of seed per acre. A second irrigation was applied approximately one month after planting. End-of-season soil sampling (0-6 and 6-12 inch depths) occurred on October 23, 2018, prior to cover crop termination. Soil properties of interest include bulk density, soil moisture, salinity, pH, total nitrogen (N), and total carbon (C). Soil properties were analyzed by the following methods: pH from the soil saturated paste, salinity by the saturated paste extract, and total N and C by combustion method.
Preliminary Results: Soil properties are presented for the baseline condition (Table 1) and for the end of the first cover cropping season (Table 2). Bulk density averaged 1.0 g/cm3 across sample timings, depths, and treatments. Soil moisture (% by volume) was observed to increase from the baseline condition in the cover crop (“CC”) treatment. At baseline sampling, salinity increased with depth from 0.47 to 2.44 dS/m. After one cover cropping season, salinity increased in both treatments, but increased more in the no cover crop (“No CC”) treatment, averaging 1.22 dS/m from 0 to 12 inches. Soil was acidic, which is typical for the region. The pH averaged 5.5 across sample timings, depths, and treatments, but there may be a trend for cover cropping to increase the pH. Total N and C decreased with depth at the baseline sampling. After one cover cropping season, there was little change from the baseline condition in both treatments.
Summary: The Delta is a unique agricultural region with unique environmental challenges. Some soils in the region are subsided due to oxidation of organic matter, and some soils suffer from salinity, having limited ability to leach salts due to low permeability soils and shallow groundwater. Cover cropping is not a typical practice in the annual crop rotations of the region, and summer cover cropping is particularly rare. After the first year of a three-year study, cover cropping had no observed effect on bulk density, Total N, and Total C. Cover cropping may have slightly raised the pH in the top 12 inches, compared to dry fallow. The cover crop treatment, having received two irrigations, had lower salinity in the upper layers of soil compared to dry fallow. We also observed that the 2018-2019 triticale crop that was planted in the field germinated roughly five days earlier in the cover crop plots compared to the fallowed plots. Thus, it appears that summer cover cropping with a legume has the potential to improve soil tilth at a time of year when the field would otherwise be fallowed and dry with no soil cover, and there could be agronomic benefits to subsequent crops. We will continue to monitor these soil properties in 2019 and 2020, and additionally, we will monitor small grain yields and greenhouse gas (CH4, N2O) emissions.
We would like to thank Dawit Zeleke and Morgan Johnson (Staten Island), Tom Johnson (Kamprath Seed), and Margaret Smither-Kopperl and Valerie Bullard (USDA-NRCS) for their cooperation on this trial. We would like to acknowledge the California Climate Investments program for funding, and our UC colleagues who are cooperating on this grant in other parts of the state (Jeff Mitchell, Will Horwath, Veronica Romero, Sarah Light, Amber Vinchesi-Vahl, and Scott Stoddard).
Survey: We would also like to alert readers of a cover cropping survey that is being conducted by the Contra Costa County Resource Conservation District. The survey is found here. The purpose of the survey is to learn more about cover cropping practices and barriers to adopting cover cropping on-farm. Even if you farm in another county, please consider filling out the survey, which should take about 10 minutes. The survey is open through the end of June. Your responses will help inform CCC RCD and UCCE programming. Thank you for your participation.
June 1 through June 9, 2019 is California Invasive Species Action Week. According to the CA Department of Fish and Wildlife (CDFW), the purpose of CA Invasive Species Action Week is to “increase public awareness of invasive species issues and promote public participation in the fight against California's invasive species and their impacts on our natural resources.” CDFW describes prevention as the most important action toward managing invasive species. Invasive species negatively impact our resources, including water and native plants and animals, but they also impact our way of life, including agriculture, recreation, our economy, and human health.
As of May 22, 2019, 510 nutria have been taken in California, most in Merced County. They have also been detected in Stanislaus, San Joaquin, Fresno, Tuolumne, and Mariposa counties. In the San Joaquin County Delta, nutria were found near the City of Lathrop in 2018; however, in May 2019, one nutria was detected at Rough and Ready Island in Stockton, indicating that they have moved north.
Unlike other rodents found in the Delta – like muskrats, otters, and beavers – nutria are not native. (Hence, I'm highlighting them during Invasive Species Action Week!) Adult body size is about 2 feet in length, tail length is about 1 foot, and weight is approximately 10-20 pounds. They have partially webbed back feet, which they use to propel themselves in water. They have white whiskers and often have orange teeth. They are primarily active at night.
CDFW is working to eradicate nutria, and you can help in their efforts. Please report sightings by calling 866-440-9530, or by emailing email@example.com. Land owners may take nutria by legal means to protect crops and property, and it is illegal to import, transport, or possess them in California. More information about reporting sightings, eradication efforts, takings, and identification (including photographs) is available from the CDFW website. It is important that we work together to prevent the expansion of this or other invasive pests in California.
The annual UC Davis Small Grains and Alfalfa Field Day will take place on Wednesday, May 15, 2019 at the Agronomy Field Headquarters (2400 Hutchison Drive, Davis, CA 95616). Registration opens at 7:30am, and lunch is provided between the small grains morning program and alfalfa afternoon program. The event is free and open to the public, and continuing education credits will be available. Directions are as follows:
The field day is located on Hutchison Drive, just west of Davis. Take the Hwy. 113 exit north from I-80, or Hwy. 113 south from Woodland. Exit west on Hutchison Drive. Take a right at the first roundabout, a left at the second roundabout, and the Agronomy Headquarters is about ¼ mile down in a clump of trees and buildings on the left.
The agenda is as follows:
8:00am – Noon: Small Grains Program
8:00 Welcome and Opening Remarks
8:20 Depart for field (travel to breeding trials)
8:35 Malting Barley & Oat Breeding: Alicia del Blanco, UC Davis
8:45 Barley Breeding for Food, Feed and Forage: Allison Krill-Brown, UC Davis
9:00 New Wheat Varieties: Oswaldo Chicaiza, UC Davis
9:15 Breeding Triticales for Bread and Forage: Josh Hegarty, UC Davis
9:25 Increasing Grain Size and Number: Alejandra Alvarez, UC Davis
9:35 A New Gene Controlling Number of Grains Per Spike: Saarah Kuzay, UC Davis
9:40 Balancing Source and Sink to Increase Yield: Jorge Dubcovsky, UC Davis
10:00 Herbicide Programs for Barley and Wheat: small grain herbicides and maximizing efficacy for control: Lynn Sosnoski, UC Cooperative Extension
10:20 Italian Ryegrass: Updates on Cultivation vs Herbicide Trials: resistance and methods for control: Konrad Mathesius, UC Cooperative Extension
10:30 Warm-season legume cover crop between winter small grains: Michelle Leinfelder-Miles, UC Cooperative Extension (This project was supported by the California Climate Investments program.)
10:45 Using Nitrogen Rich Reference Zones to Guide Wheat Topdress Decisions in the Sacramento Valley: Sarah Light, UC Cooperative Extension
10:55 Yield and Protein Stability for Wheat and Triticale Varieties Grown under N and Terminal Drought Stress: Mark Lundy, UC Cooperative Extension
11:05 Updates on UC Statewide Small Grain Trials: Seasonal conditions, pests and diseases, nitrogen management, and extension efforts: Mark Lundy, UC Cooperative Extension
11:15 Comments from breeders with entries in UC Statewide Small Grain Trials
11:30 UC Statewide Small Grain Trial Observations
11:50 Return for lunch
12:00 BBQ Lunch: Many thanks to the California Crop Improvement Association for the complimentary lunch!
12:30 - 4:00: Alfalfa/Forages Program
12:40 Welcome and Introductions: Dan Putnam, UC Cooperative Extension/UC Davis
12:45 Depart for field tour
12:55 Managing Alfalfa in a Wet Year- What are the Diseases? How to Keep your Fields Healthy: Rachael Long, UC Cooperative Extension
1:10 IPM and Managing for Weevil Resistance in Alfalfa: Ian Grettenberger, UC Davis
1:25 Evaluation of N Stabilizers in Corn: Michelle Leinfelder-Miles, UC Cooperative Extension
1:40 Forage Sorghum as a Summer Option: Controlling Sugarcane Aphid in Sorghum/Sudangrass: Nick Clark, UC Cooperative Extension
1:55 Innovations in Overhead Irrigation – How that might improve Water Use Efficiency: Isaya Kisekka, UC Davis
2:10 Fun with Drones –Detecting Pest and Diagnosing Problems with Aerial Photography: Umair Gull, UC Davis
2:25 Controlling Difficult Weeds in Alfalfa: Lynn Sosnoskie, UC Cooperative Extension
2:50 Alternative Crops Research: Kura Clover, Switchgrass, Hemp: Dan Putnam, UC Davis
3:05 Reduced Lignin Alfalfa Varieties and Interactions with Harvest Scheduling: Brenda Perez, UC Davis
3:20 Analyzing Alfalfa Varieties for Pest Resistance (Nematodes, Insects, Diseases) and other characteristics: Dan Putnam, UC Davis
3:35 Alfalfa and Tall Fescue Breeding Programs at UC Davis: Charlie Brummer, UC Davis
3:50 Test your Weed ID IQ: Weed Identification: Brad Hanson, UC Davis
4:15 Return to Headquarters
- Author: Michelle Leinfelder-Miles
- Author: Dan Putnam
- Author: Rachael Long
A question came to me from a crop consultant. His alfalfa grower asked him how he could increase crude protein (CP) in his alfalfa. The buyer of the alfalfa, for the most part, is happy with the hay. For example, the buyer is happy with the total digestible nutrients (TDN), but he would like to see a little higher CP. The consultant said that the grower is generally on a 28-day cutting cycle and is generally cutting the hay pre-bloom. He wondered if nitrogen (N) fertilizer would help to improve CP.
The best way to improve CP is to: 1) cut early, 2) choose a more dormant variety (but give up yield), and 3) manage the harvest to retain the leaf fraction. Since this grower is already cutting pre-bloom, and since the grower is not yet replanting, that would leave option 3. Retaining the leaf fraction is important because the protein content of the leaves is higher than that in the stems. Trying not to rake the hay when it is especially dry might help to retain the leaves.
Let's now focus on the consultant's question of whether N fertilizer could help to improve CP. The UC Irrigated Alfalfa Management production manual states that N fertilizer has resulted in higher CP in some instances but that an equal or higher number of trials showed no improvement to CP with N fertilizer. Dan Putnam, Rollie Meyer, Vern Marble, and other forage researchers have, for a long time, recommended against fertilizing alfalfa with N. This is based upon field data, economics, and logic!
1. Forage Quality. While N fertilizers can (in some cases) increase the apparent CP of the forage by a point or two, this "protein" is not actually well utilized by ruminants. N fertilizer usually results in a higher non-protein nitrogen content (NPN) which is NOT protein, but free N in various forms (e.g. nitrate or free amino acids), which is immediately released into the rumen upon ingestion and forms ammonia. The ammonia must be excreted by the animal at a metabolic cost (ATP), so it is actually costing feed energy. It also results in excess urea in the manure. So, even though it looks like the protein is a little higher, it isn't actually. Remember, CP is measured N content (not just protein) multiplied by 6.25.
2. Economics. Small differences in yield are sometimes (not always) observed with applied N; however, those are rarely economically advantageous. Remember that the uptake levels of alfalfa are very high. A 10-ton Central Valley alfalfa crop will remove about 700 lbs of N, which with losses, one would need to apply close to 1,000 lbs N/year to meet the N needs of the crop. One could never cost-effectively fertilize to satisfy this need.
3. Losing your free N. N applications or high soil N have the tendency of suppressing N2 fixation by making the Rhizobium lazy. Fertilizers would mostly just replace fixed N. Atmospheric N contributions to alfalfa growth are a major environmental benefit, and it's a shame not to take advantage of it.
4. Weeds. N applications encourage weeds, especially grasses. This negatively impacts quality.
5. Trade-off with Energy. Keep in mind that some alfalfa hay crops that have low N and low CP also have high TDN (energy values) such as the well-managed Intermountain spring cut hays grown under cool temperatures. This is due to dilution - if carbohydrates accumulate in the leaves, (e.g. 5-8 percentage points higher), then CP (and NDF/ADF) will be lower. When something goes up, something else goes down. Since energy tends to be more valuable in the marketplace, however, this is a good thing!
Having said all of this, there are some rare situations where N fertilization may be helpful to get the crop going after the roots have been compromised, but even these are unusual. Rachael Long detailed this in the blog When is N fertilization to alfalfa beneficial? Almost Never!
Dan Putnam does have a lingering question about applying N fertilizer in alfalfa and that is whether very small amounts (e.g. via drip irrigation) might be effective at hastening regrowth after each cutting. Growers using drip have done this, and Dan thinks it could work with overhead sprinklers or with buried drip lines where the N can be 'spoon fed' and carefully managed. We need data, however, to prove whether or not this would be effective. Dan suspects the differences would be minor.