- Author: Pamela Kan-Rice
UC ANR joined the California Department of Food and Agriculture and other organizations in highlighting the benefits of soil health and biodiversity for California Healthy Soils Week 2022.
During the week of Dec. 5-9, the UC Master Gardener Program hosted two Facebook Live webinars and UC Cooperative Extension co-hosted a Sustainable Nutrient Management & Soil Health Field Day in Salinas.
For the “Healthy Soil: In Nature Sometimes Less is More” webinar, Mike Corby, UC Master Gardener volunteer in Contra Costa County, shared insights for improving soil health in the garden. A recording of the 47-minute webinar is published on YouTube at https://youtu.be/Y9M5uQtzLyk.
For “Harnessing the Magic of the Soil Food Web: Turning Dirt into Gold,” Kit Veerkamp, UC Master Gardener volunteer in El Dorado County, discussed why soil health matters and how to modify soils to improve plant health and reduce disease and pests. A recording of the 56-minute webinar is published on YouTube at https://youtu.be/Hqd-XDy81H0.
The Wine Institute, California Association of Winegrape Growers and Community Alliance with Family Farmers hosted representatives from CDFA, the California Legislature, the California Environmental Protection Agency, California Natural Resources Conservation Services, and other climate-focused agencies from around the state for a healthy soils tour of Bogle Family Vineyards in Yolo County.
At Bogle Family Vineyards, Konrad Mathesius, UCCE agronomy advisor for Sacramento, Solano and Yolo counties; and Hope Zabronsky, climate smart agriculture academic coordinator for the California Institute for Water Resources, gave presentations.
USDA Natural Resources Conservation Service hosts the Web Soil Survey, which provides soil data and information produced by the National Cooperative Soil Survey. NRCS has soil maps and data available online for more than 95% of the nation's counties. Phil Smith, California NRCS area resource soil scientist, and Tony Rolfes, California state soil scientist, presented a webinar on how to use the Web Soil Survey and other web tools for gathering soils information and maps. The Web Soil Survey webinar is posted at https://youtu.be/cuEMuxLGQO0.
- Author: Konrad Mathesius
- Editor: Brad Hanson
- Editor: Mark Lundy
Summary Note
Mechanical cultivation is a useful tool in controlling herbicide-resistant Italian ryegrass individuals in a rainfed wheat system but is only about half as effective as Axial in reducing overall pressure from Italian ryegrass (expressed as a percentage of total groundcover). Growers should consider multiple approaches (chemical and mechanical) and integrate IPM strategies to reduce the spread of resistance among Italian ryegrass individuals.
Italian ryegrass (Lolium multiflorum) has been shown to be a persistent weed for growers in rainfed winter grass systems. It is particularly problematic due to its biological requirement for cross-pollination. In outcrossing species, genes can be transferred within and among populations by pollen movement and, as a result, there are many opportunities for gene transfer and accumulation of different traits. Gene transfer can include various herbicide resistance traits and resistance that develops can spread quickly within a field or even to neighboring populations. This is one of the reasons why Italian ryegrass in the Sacramento Valley is widely resistant to glyphosate. Other evidence suggests that Italian ryegrass in certain areas of California has developed resistance to some ALS inhibitor herbicides (Osprey), ACCase inhibitors (e.g. Fusilade), and paraquat, often in addition to being resistant to glyphosate.
Because resistance genes can be passed around relatively quickly in Italian ryegrass, physical (non-chemical) control may help stem the spread of resistant individuals. Additional information on chemical management of herbicide resistance can be found here.
Recent California Research
In the 2019 season we compared the efficacy of mechanical and chemical preseason stale seedbed methods for control of Italian ryegrass in fall-planted wheat trial in Yolo County, CA. Four replicate plots of three treatments were evaluated in a randomized split-plot design. Treatments included a ‘control' (drill-seeding into the prepared seedbed), an ‘Axial' preplant burndown herbicide treatment, and a ‘mechanical cultivation' sequential preplant tillage treatment. In the preplant burndown herbicide treatment Pinoxaden (Axial), an ACCase inhibitor, was applied at the label rate (8.2 oz/ A) 7 days after ryegrass emergence. In the mechanical cultivation treatment, ryegrass was cultivated 7 days after emergence with a 7.5”-spaced, 1.5”-wide-tine field cultivator, and then cultivated a second time 4 days later to ensure complete control of emerged ryegrass. The control treatment was drill-seeded into the seedbed, ryegrass seedlings had already emerged and were roughly a ¼-inch in height. Four replicates of two varieties of wheat (Blanca Grande 515 and Westbred 9433) were planted into the three treatments immediately following the second cultivation (December 14th, 2018). In order to determine the relative effects of pre-season treatments, no in-season herbicide was applied. Percent ground cover of wheat, Italian ryegrass, and bare soil was determined using a 1ft2 quadrat on three occasions throughout the growing season.
Results
Data indicate that Italian ryegrass ground cover was similar among mechanical cultivation and Axial in January (Figure 1). In February, compared with control treatments, mechanical cultivation treatments saw ryegrass ground cover reduced by 68%, Axial reduced ryegrass ground cover by 95%. Despite the significant difference in ryegrass coverage among treatments, wheat ground cover was not significantly different among non-control treatments (20% and 22% for mechanical cultivation and Axial, respectively) (Figure 2).
However, by April, both wheat and ryegrass ground cover percentages were significantly different among all treatments. Compared to the control treatment, the mechanical cultivation treatment had 22% less ryegrass ground cover while Axial reduced ryegrass cover by 62%. Wheat ground cover in the mechanical cultivation treatment was less than half that of the Axial treatment (20% and 47% for mechanical cultivation and Axial, respectively). (Figure 3). The difference in ground cover impacted spike count and yield. Among the three treatments April foliar coverage of wheat was positively correlated with spike count at the end of the year (Figure 4).
Figure 1 Italian ryegrass and wheat ground cover percentages in January (42 days after planting). Significant differences are indicated by different letters. Uppercase letters correspond to differences in Italian ryegrass ground cover among treatments. Lowercase letters correspond to difference in wheat ground cover among treatments.
Figure 2 Italian ryegrass and wheat ground cover percentages in February (69 days after planting). Significant differences are indicated by different letters. Uppercase letters correspond to differences in Italian ryegrass ground cover among treatments. Lowercase letters correspond to difference in wheat ground cover among treatments.
Figure 3 Italian ryegrass and wheat ground cover percentages in April (108 days after planting). Significant differences are indicated by different letters. Uppercase letters correspond to differences in Italian ryegrass ground cover among treatments. Lowercase letters correspond to difference in wheat ground cover among treatments.
Figure 4 Wheat cover as an indicator of spike count. Control plots were largely devoid of any spikes due to substantial Italian ryegrass pressure. Other treatments show a link between ground cover and spike count.
As expected from the ryegrass ground cover data, and the subsequent impact on spike counts, there were significant yield differences among treatments (Figure 5).
Figure 5 Yields resulting from different preseason treatments averaged across two varieties.
Discussion and Conclusion
The difference in ground cover among these treatments is likely due to several factors. One being the fact that cultivation disturbs the soil, bringing new seed up to the surface. Combined with consistent rainfall throughout the winter, a fair amount of new seed may have had an opportunity to sprout and survive in the cultivated treatments. Whereas the herbicide treatment may have terminated individuals that sprouted with the initial rains and, without additional soil disturbance, resulted in recruitment of fewer new seedlings close to the time of wheat seeding and emergence. While later flushes of weeds occurred in the Axial treatment as well, these were either: a) resistant individuals or, b) late-emerging individuals due to differences in dormancy within the seed bank population. What this could mean is that the mechanically cultivated treatment may have had relatively more mature, established, Italian ryegrass individuals, putting the crop at a competitive disadvantage relative to the crop in the Axial treatment.
Cultivation may also have a lower efficacy rate in terminating individuals as some are likely to reestablish despite the disturbance to rootlets. Any escapes would have emerged 11 days before wheat was planted, giving surviving individual ryegrass plants a significant head start over the crop.
In the case of pre-season treatments, mechanical cultivation can provide some relief, but pinoxaden does a better job of mitigating ryegrass pressure.
This study shows that growers can consider the use of mechanical cultivation to remove potentially resistant individuals, but should still consider herbicides to be a part of their pre-season tool kit. As is often cited by IPM specialists, utilizing a wider array of tools to control weeds (both chemical and physical) will help curtail the spread of herbicide resistance and improve grower capacity to maintain economic sustainability.
Additional Data: Variety Effect and the Impact of In-Season Herbicides
An additional factor evaluated in this study was the potential of varieties with shorter and longer ‘days until harvest' ratings to establish a canopy and compete with weeds (referred to here as “early” and “late” varieties). Of the two varieties used in this study (Westbred 9433 and Blanca Grande 515), neither performed significantly better in establishing an early-season canopy relative to Italian ryegrass (Figure 6). As other studies have suggested, differences in wheat variety capability to compete with weeds may be rooted in factors other than the number of days until emergence and other key growth stages, and are instead correlated to other variety traits (plant height, leaf physiology, tillering capacity, etc. Lemerle et al. 1996).
Figure 6 Italian ryegrass ground cover percentage among an early and late variety of wheat and different preseason weed management practices. Letters indicate significant difference between variety x treatment combinations. There was no significant difference between early and late varieties when averaged across treatments.
In-season herbicide treatments play a critical role in reducing weed pressure. In the broader field where this study was conducted, the grower used an in-season mixture of: 7oz Simplicity /A, ¾ pt MCPA / A, 1.5 pt Brox 2E / A. In April, the grower field had 2% ryegrass cover and 98% wheat cover, a substantially more favorable outcome than those seen in the preseason treatments. Therefore, although this study did not directly look at the relative effect of in-season herbicides on Italian ryegrass control, the importance of in-season sprays can be inferred from the condition of the grower field in the surrounding area (and by the notably low yields from the data from this study). Future studies will attempt to clarify the combined effects of in-season herbicides, pre-plant herbicides, and various cultivation techniques to control Italian ryegrass.
This article was originally posted in the Sacramento Valley Field Crops blog.
- Author: Pamela Kan-Rice
Different varieties of hops can be used to create an array of flavors and styles of beer. Does the variety of barley used in beer-making affect the flavor of the brew?
This is a question UC Cooperative Extension advisor Konrad Mathesius hopes beer drinkers will answer on Friday, July 12, at YOLO Brewing Company in West Sacramento.
To find out if barley makes a difference, the public is invited to taste a flight of five beers – four beers made from the specially grown barley varieties and YOLO Brewing's own Chinook SMASH DIPA – then fill out a short survey about what they taste.
Several varieties of malting barley were grown by a Woodland farmer in the same field, under the same conditions, then brewed with the same recipe by YOLO brewing company.
The taste test is part of the UC Agriculture and Natural Resources Malt Project evaluating malting barley's potential as new crop in California. Mathesius is also studying whether barley can be grown well in California and which varieties perform best for growers, maltsters and brewers.
“We'll conduct a consumer preference survey to answer the questions: Can the average consumer pick up on differences that come about solely from the barley variety used in the brew recipe? Are there any particular favorites that stand out?” Mathesius said.
If there is a clear favorite among the specialty barley beers, Mathesius will compare it with notes from Sierra Nevada's tasting panel to identify the flavor characteristics people tend to favor.
The beer tasting will be Friday, July 12, from 3 p.m. to 9 p.m. at YOLO Brewing Company, 1520 Terminal St, West Sacramento, California 95691.
A pre-selected flight of the four specialty beers plus YOLO Brewing's Chinook SMASH DIPA costs $10.
Sacramento calls itself the Farm-to-Fork Capital. Could it also be the Farm-to-Pint Capital?
- Author: Jessica Chiartas
Not more than three months on the job and Konrad Mathesius is hard at work bringing farmers together to discuss the unique challenges that Sacramento Valley farmers face. As the new UCCE agronomy advisor for Sacramento, Solano and Yolo counties, his role is designed specifically to help growers with their crop issues – pests, disease and fertility – but with a strong background in soil science, Mathesius hopes to shed light on the diversity of soils in the region and the unique management considerations that each necessitates.
In hopes of highlighting this diversity of soils and encouraging growers to dig a little deeper to better inform their management practices, Konrad enlisted the help of UCCE soil resource specialist Toby O'Geen to lead a field tour of three major soils in the southern Sacramento Valley. The event included three pit stops on two Yolo County farms and brought out a diversity of participants from USDA Natural Resources Conservation Service agents, to resource conservationists, to farmers and crop advisors.
Kicking things off at Rominger Brother's Ranch -- a diversified family farm in Winters that grows everything from wine grapes to processing tomatoes to rice, wheat, corn, onions, alfalfa and hay -- O'Geen took the audience on a journey back in time, describing the rich natural history of the former floodplain that has given rise to the rich, productive soils that support California agriculture today. After introducing himself as a pedologist, or a scientist who studies the nature and properties of soil, he went on to introduce the five soil forming factors and their role in molding initial (1) parent material (i.e. rocks), under the influence of (2) climate, (3) topography and (4) organisms and over a given period of (5) time into soils.
Proving that soil scientists take the term “pit stop” literally, Mathesius shifted the conversation to a 1.5-meter deep hole in the ground, dug out the day before with a back hoe. Step by step, he walked participants through the process of analyzing a soil pit – cleaning the face, identifying horizons or individual layers and using the senses to assess soil properties and determine function. As he struck the face of the pit with a rock hammer, an audible difference was detected between the surface layers and the subsurface.
Working backwards from the sound, he explained that the subsurface was significantly harder, which he attributed to a finer texture and ultimately identified as a clay pan, a restrictive layer that prevents roots from penetrating deeply and has the capacity to waterlog soils, due to poor drainage. O'Geen offered some tangible advice as to how to manage these soils, quipping that a deep rip would be no better than cutting butter with a knife (eventually it all just settles back into place) while likening a slip plow to a giant shank that just inverts the soil, mixing things to about a depth of 6 feet and permanently eliminating the problem.
From there, Mathesius segued into a hands-on exercise to determine the soil texture, or percent distribution of various size particles, allowing participants to work on their pottery skills making balls and ribbons with the clay-rich soils. Discussing the many functions that soil texture controls, led the conversation down a rabbit-hole around water holding capacity and how to calculate the range of plant available water for your soil.
With the demos out of the way, they voyaged to the next pre-dug pit, bringing participants face to face with the harsh reality of soil heterogeneity. Just 300 feet away and it was as if we had ventured into another environment altogether, yet these soils formed in the same place, under the same climate and similar vegetation, but in a completely different time with slightly different starting material.
By changing just a couple of the ingredients in the special sauce of soil formation the results are completely different featuring a clay dominant surface soil and entirely different water management challenges. And these aren't just any clays, but a special class that swell and shrink as they wet and dry, oftentimes shearing roots under the pressure and creating a hospitable environment for disease to thrive. O'Geen suggested trying to keep them in the sweet spot where they are consistently moist, but not wet, and never allowed to dry out. Unfortunately, there is no precise measurement to that formula, “you just have to be almost like an artist. It's a lot of feel to it and the numbers sometimes just don't work out. It just comes with years of experience. Its one of those native intelligence things that you just have to feel your way through,” he noted.
Caravanning 20 miles back towards Davis, the tour arrived at the third and final pit, located at Triad Farms, a tomato operation in Dixon. Well-drained, young and fertile, Yolo loam soils are the poster children of agriculture, owing in large part to regular deposits of silts from past flood events. With not many management challenges to speak of, conversation immediately shifted towards an undocumented challenge that farmers on the eastern side of the Sacramento Valley are all too familiar with – the unavailability of potassium, even under intensive fertilization regimes. While the jury is still out on the cause and while it contradicts what soil scientists expect to find in those regions, possible explanations were tossed around and O'Geen used the opportunity to stress the importance of speaking up about things growers or advisors see going on in their area. Turns out the USDA-NRCS is working on updating its inventory of soil surveys, documenting soils across the nation and is currently seeking input on what's working for growers and where things are differing on the ground.
Ultimately, in closing, Mathesius called for more engagement between the university, extension and growers. O'Geen reminded everyone that “You can really learn a lot by digging a hole, looking at stuff, and developing theories. Sometimes you're wrong, but they're kind of fun to talk about."
- Author: Jeannette E. Warnert
Mathesius, hired three months ago to serve Yolo, Sacramento and Solano counties, explained the role of UC Cooperative Extension and how it relates to the state's land grant universities.
Richter summed up Mathesius' role in three sentences:
- You're the answer man.
- You do real world research.
- You are translating research done at UC and making it public.
Mathesius works with growers who produce corn, wheat, small grains and sunflowers. Among the issues the growers are facing are drought mitigation, groundwater protection and variety selection.
"Water affects everybody," he said. "Farmers don't want to waste water. They want to use what's available and optimize it. "
Mathesius said his goal is to look at agricultural sustainability.
"I don't mean organic. I do think that sustainability is about sustaining farming economically and environmentally," he said. "Moving forward, UC Cooperative Extension is in a great position to do this."
UCCE advisors, he said, can be the voice of science in debates that can become polarized, such as the potential impacts of using genetically modified organisms in agricultural production.
"We will have a position based on scientific reasoning," he said.