- Author: Brad Hanson
Several years ago, I had what seemed like a great weed research idea.
My idea addressed a serious agricultural weed problem in California, it was applicable to several cropping systems, it used an integrated approach to weed management, and it utilized a pretty novel approach (or so I thought). I proudly laid out this idea to my UC weed science colleague at a meeting, only to hear "That's great Brad but I think your predecessor tried that in the late 80's and it didn't work very well". After my damaged pride recovered a bit, I started thinking about the volume of research that we do that is not very easy to find out about after it is done.
As scientists, we often think about publications in terms of the work we publish in various peer-reviewed journals. These are very important but only encompass a portion of the written reports on our research. There's a whole other category of the "gray literature" that is not easily accessed or searched, but often makes up a substantial part of our extension programs or base knowledge. This includes research progress reports to commodity commissions and funding agencies, herbicide screening trials, the one-off side projects, that grad student research that wasn't ultimately published in a journal for one reason or another, the write-up prepared for an extension meeting, the pilot study that didn't generate sufficiently interesting results to follow up on, etc.
Some of this information can be accessed on online (if you look in the right place), but other than the person who created the report, much of this information is essentially lost once the report has been submitted or the presentation made. Worse yet, some research results simply aren't available anywhere but in the writers file cabinet or hard drive and can completely disappear with a computer replacement,office cleansing, or researcher retirement. Our colleagues, students, and successors (and even ourselves) cannot build upon research they don't know about (or don't remember doing).
So, to take a stab at this problem, several Weed Research and Information Center colleagues and I started building a UC Weed Science Report Database. We used an existing database platform in the UC ANR system but built a web interface with a simple search function for key words, authors, publication year, or several broad categories of reports. We elected to use an "all word search" rather than to manually categorize each report by weed/crop/herbicides, trade names vs chemical names, etc.
Although far from being a complete set of reports (that is probably an impossible goal), there are currently nearly 1700 reports, publications, research posters, and CWSS abstracts that have been uploaded so far. Our goal is to keep adding to these reports on a regular basis into the future. Where possible, we're also trying to include reports from the archives as we obtain and scan them.
I have to acknowledge the UC ANR programmers who helped answer dozens of my database questions and for programming the upload and search functions. Also, the California Weed Science Society provided some support for the scanning and uploading of several decades of CWSS proceedings that have been included in this project and will also be available at the CWSS website in whole volume format.
The database is available at this link or directly at this web address:
Please take a look if you have interest. As this project is still very much "in process", please share any comments or suggestions via the comments below.
Take care,
Brad
- Author: Ben Faber
Problem: There was a Valencia farmer in Ojai, farming on a rocky loam. More rocky than loam, on a 10 % slope, where he had been spraying the weeds down, the soil had gradually washed away and all he had left was scattered cobbles.
Solution: He planted a winter cover crop to protect the soil from erosion. He weed whipped it three times a year because that's all he could afford.
Result: After two years he had stopped the erosion, and there was actually a little duff layer forming in the orchard from the decomposing ground cover.
Problem: But now that wonderful cover crop and the cover it provided had attracted gophers that were chewing on the trees and because of inattention had killed a few of them. He couldn't trap fast enough.
Solution: He brought in a ‘Jack Russell' terrier that did a marvelous job at keeping the beasts down.
Problem: About the same time he noticed that he was getting gobs of snails that were getting into the trees. Even though he had lifted the skirts and painted copper on the trunks, they were still getting into the trees. He couldn't keep up with the winter weeds.
Solution: He brought in weeder geese to help with the ground cover and chickens to help with the snails and they worked.
Problem: Now the terrier is distracted by the fowl and is killing the chicks and goslings, as well as the gophers. In fact, he would prefer chasing the fowlings to going after gophers.
Solution: He tied a tether ball around the terrier's neck which slowed it down enough so that the young ones could get away.
Problem: Also with the introduction of birds, he also brought in coyotes which killed the larger birds.
Solution: He brought in a ‘Queensland Heeler' which is a bred that is noted for killing dingos in Australia. They are short-legged, barrel chested dogs that roll over on their back and pretend to be dead and when the coyote comes sniffing around, it grabs the coyote's neck and kills it.
Problem: What's next in this cause and effect chain of events?
This is a true story, but in today's world because of Food Safety and Good Agricultural Practices Certification would not happen with all these animals in the orchard, but something like it happens every time we overturn the flow of events. This is not the only scenario that is played out in agriculture. But hey, that's what a good grower is doing, managing a somewhat chaotic chain of events.
- Author: Oleg Daugovish
When Richard Smith tells you that he is impressed with efficacy of an organic herbicide you better take notice. Richard shared his results on this blog site last year and showed good weed control with 'Suppress' from Westbridge. This OMRI approved herbicide is a mix of caprylic and capric acids and is a contact material that interferes with plant cells membranes causing leakage and desiccation.
It looked like a good fit for organic plasticulture systems such as strawberry that have wet weedy furrows which are difficult to access with mechanical tools because of proximity to plastic. We placed a trial in a very weedy field that also had one of the SoCal classics–yellow nutsedge. 'Suppress' at 6 and 9% by volume was applied to well-established weeds just before strawberry planting.
The effects of application were noticeable in minutes. We learned that:
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Both 6 and 9% rates provided nearly 100% control of common lambsquarter (predominant species) and other occasional broadleaved weeds.
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About 10-15% of common purslane plants survived and yellow nutsedge seemed unaffected by application. However, biomass of both purslane and nutsedge were significantly reduced, suggesting that production of seed and tubers for the two weed species, respectively, may be delayed.
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Good coverage was important and some of the horizontally–inclined leaves of broadleaf weeds likely intercepted the herbicide deposition to vertically inclined nutsedge shoots.
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When we simulated drift by over-spraying strawberry, it responded just like any broadleaf perennial plant—the canopy wilted and dried but in 3 weeks the new leaves developed from the crown. This was also true for the neighboring bindweed that lost above ground canopy but had new growth within a month after 'Suppress' application.
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Since perennial weeds or those in soil seedbank are not controlled, repeated applications are needed with obvious caution of avoiding the spray drift to the crop.
- Author: Ben Faber
Tada
There are some new pest management guidelines out from UC ANR. This is a free publication and you access it as a web page or downloadable PDF document.
These official UC-approved guidelines for pest monitoring techniques, pesticide use, and nonpesticide alternatives for agricultural crops are essential tools for anyone making pest management decisions in the field. This 124-page guideline covers citrus fruit.
A hard copy version of these guidelines can be purchased as Publication 3441P.
The PDF version of this publication is best viewed using the free Adobe® Acrobat® Reader. You can download a free copy of the Acrobat Reader from Adobe Systems Incorporated.
Some users have experienced problems using Preview with these documents; we recommend using the Adobe® Acrobat® Reader.
- 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)