- Author: Oleg Daugovish
Using organic herbicides in production fields and non-crop areas.
The forecasts call for rainy winter and that means a lot of weeds. During dry times perennial weeds tend to grow better than annual weeds, since perennial structures such as underground rhizomes or tubers can support them and give competitive advantage. Seed of annual weeds in dry soil may have been losing viability, senescing or eaten during this time, but many have remained dormant and look forward to the wet winter us much as the rest of us.
Controlling weeds ‘organically' is always an extra challenge whether you are in a certified field or in an area where synthetic herbicides are not desired. Hand-weeding, already expensive, is even a greater burden with limited labor availability, and frankly not much fun either. Of course sanitation and prevention, mechanical and cultural management are essential in organic systems. That requires time and commitment and can quickly become your not-so-favorite pastime.
Organic herbicides have traditionally been contact materials with no systemic activity. This means that they only affect tissue that they contact and do not translocate through the plant like most synthetic herbicides. Thus, good coverage is critical for these contact materials. Many years ago the first herbicides were sulfuric acid and diesel fuel, current organic materials are often acids or oils too, although a lot more benign.
Recent trials by the University of California weed scientists showed that several organic herbicides provided decent control of easy to control pigweed and nightshade when they were small. When weeds were 12 days old, a mixture of 45% clove and 45% cinnamon oil, 20%-acetic acid and d-limonene gave 61-89% control; however only d-limonene controlled 19-day old weeds and none was effective on one-month old ones. As weeds get bigger they also develop a protective cuticle that minimizes efficacy of these herbicides.
This year we conducted trials with a recently OMRI approved herbicide for row crops, trees and vines that is a mix of caprylic and capric acids. It disrupts cell membranes of plans and causes the contents to leak and plants to desiccate. It worked well at 6 to 9% by volume mixture with water and gave 90% control of little mallow and >95% of annual sowthistle compared to untreated checks. We have also tested it in organic strawberry furrows before planting the crop to prevent potential injury from drift. Furrow cultivation does not get close to the plastic mulch that covers the beds to prevent tears, so the weeds in that zone are good target for the herbicide. This fatty acid herbicide provided excellent control of common lambsquarter, reduced the growth of common purslane but didn't do much for yellow nutsedge - one of our notoriously difficult to control perennial weeds (Figure). The bigger weeds need higher rates (9% is the maximum labeled rate) and better coverage. When you have multiple layers of weed leaf canopy and diverse architecture some plants or their parts may be protected by others that intercept the deposition of the herbicide. When on target, this contact material acts fast – you can see results within 2-3 days, however, it does nothing to weed propagules in soil and has no residual activity against wind-dispersed weed seed that fly in after application. This means the control does not last and you will need additional applications or other control measures. Repeated application is not a problem in a non-crop area and is a great way to deplete your weed seedbank, but crop protection from drift, such as shielded sprayers, is necessary to avoid off target plant injury.
Figure. Weed control in strawberry furrows prior to planting with 9% by volume of fatty acid herbicide (top) and weeds in untreated check (bottom)
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Meet the Buyer: An L.A. Produce Market Tour for Los Angeles Growers and Food Advocates
Do you want to find new channels for selling your produce and make connections with produce buyers? Join us on a one day tour of produce distributors in the L.A. area where you will meet with senior buyers and leaders at these distribution companies committed to building their local base of suppliers:
Santa Monica Farmers' Market - our early start will allow for a special behind-the-scenes market tour to learn about the vibrant business-to-business transactions occuring there every week.
Space Exploration Technologies - meet the culinary team feeding the folks at the frontier of space exploration seasonally-inspired menus, much of it sourced from farms nearby.
Whole Food Distribution Center - talk with buyers committed to small, local and organic producers at the new state-of-the-art distribution facility and enjoy a yummy lunch.
Heath & Lejeune - learn the art of distributing orgranic produce from a seasoned buyer / seller.
These high-level buyers are positioned to appreciate your farm and products—whether organic, local, family-owned, sustainably grown, or high quality specialty crops. You'll gain an understanding of what it takes to work with them, have a chance to network with other farmers, and learn tips on how to tell a compelling story about your farm and its products that will expand your sales opportunities. This tour will be valuable for ANY farmer who wants to learn more about different distribution channels for their products, as well as for healthy food advocates and policy makers who want to have a better understanding of what small farms need to do in order to connect with willing buyers.
Space is limited; advance registration is required. Please reserve your space by December 4th, 2015. Lunch and snacks will be provided. There is no charge for this tour thanks to our generous sponsors.
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The latest cost of production study done on oranges came out recently.
It applies to the San Joaquin parts of the Valley for sure, but many of the assumptions are true for evergreen tree crops in general. The cost of weed control, or fertilizing are not going to be different. Pest and disease control are going to be very different if you are a navel orange grower in Bakersfield or a cherimoya grower in Santa Barbara. The key to these studies are the different issues/categories a grower should be addressing and the studies provide a framework for that study. Also it gives general costs for different inputs, such as urea and glyphosate to make a comparison to what you might be paying
To help Ventura County's citrus community better understand the nature of the ACP epidemic — and the bitter lessons from Florida's failure to address it proactively — Farm Bureau and the ACP-HLB Task Force will host a workshop on Dec. 2. As speakers, we've invited three experts whose presentations were among the most compelling at last February's International Research Conference on HLB in Florida:
- Mike Irey, director of research and business development for Southern Gardens Citrus (which farms nearly 15,000 acres of oranges in Florida), who will speak about conditions in his state and provide an industry perspective on what it's like to live with HLB for a decade;
- Dr. David Bartels, an entomologist at the U.S. Department of Agriculture's Mission Laboratory in Texas, who will discuss his analysis of HLB survey data and what it can tell us about possible HLB infection sites throughout Southern California;
- Dr. Neil McRoberts, an epidemiologist and associate professor of plant pathology atUC Davis, whose computer modeling and research into the economic and social factors affecting disease spread can help guide development of an HLB management strategy for California.
The workshop will be from 1 to 4 p.m. on Wednesday, Dec. 2, at the Museum of Ventura County, 100 E. Main St., Ventura. It's free, but RSVPs are required. Please contact us at email@example.com or (805) 289-0155 if you plan to attend.