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Safer, Non-Selective Weed Control for Organic Growers and Home Consumer

Coleman, Robert
Summerdale, Inc
Start date
End date
Phase I Technical Objectives: Key, general objectives for Phase I is to demonstrate that one or more selected formulations is (are): a) as effective or more effective than commercial products, b) competitively priced with commercial products and c) effective for both grass and broadleaf species.

Specific Phase I technical objectives are important and must be met before the efficacy of these formulations as herbicides can be fully realized as new products: 1) Develop, stable herbicide formulations, as stand-alone herbicides where formulations will include natural actives, emulsifiers and adjuvants and then compare formulation efficacy with existing control methods in greenhouse and field trials and 2) Calculate cost ($)/acre for promising stand-alone formulations and determine cost and performance characteristics and advantages that would be attractive to end-users: growers (conventional and organic), home consumers and industrial/commercial buyers.

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NON-TECHNICAL SUMMARY: Use of more environmentally-friendly products by pesticide consumers would greatly reduce risk to the applicator and the surrounding environs including both the air and water supplies. As well, the development of alternative herbicides that protect food safety would agree with some of the goals for sustainable agriculture and protect quality of life. Public education on safer pesticide choices could be continued through university extensions, vendors and satisfied consumers. Safe, effective herbicides accepted by the organics industry, which is growing at 20% per year, would generate considerable attention and recognition in the U.S. and abroad. Since current herbicide choices for organic growers are quite limited, new products for improved weed control are being sought. Summerdale, Inc. has identified synergistic combinations of fatty and selected synergists, as candidate herbicides. The compounds, common to many foods, are GRAS compounds and the formulations are stable and clearly superior to Scythe, one of the few safer choices as a non-selective herbicide, primarily used for landscaping and by the home consumer. Objectives include: 1) further development of candidate herbicides containing only natural, environmentally-compatible ingredients and 2) evaluation of characteristics (cost/performance) and other advantages versus current products for weed control.

APPROACH: Objective #1: The components in natural herbicide formulations will include those compounds that are naturally-derived and have the best opportunity for USDA or OMRI approval as a method for weed control. The 3 fundamental types of ingredients will include an active ingredient (AI), emulsifier (s) and adjuvant/amendment (s) functioning as a synergist for the AI. The nature and ratio of various formulation ingredients have been carefully evaluated based on cost, safety, availability in bulk quantities, compatibility with other formulation ingredients and effect on herbicide activity against a broad spectrum of weed species. Formulations having favorable ingredient combinations will be screened to achieve: a) stable, homogeneous formulations as concentrates (over 2 months of storage), b) stable mixtures or dilutions of concentrates in water, without phase separation for up to two hours of storage and, c) excellent herbicide activity based on greenhouse and field-trial test results. Natural emulsifiers and promising adjuvants/amendments will be formulated with a specific fatty acid as the active ingredient. The most promising weed control formulations will be compared with current chemical treatment methods; such as organic approved vinegar (acetic acid), citric acid, corn gluten and soybean oil. Application rate studies will be conducted by both Michigan State University (greenhouse trials via Donald Penner, Department of Crop & Soil Science) and Summerdale, Inc. (field trials by Robert Coleman). Sufficient greenhouse facilities (over 1,000 ft2) are available to Donald Penner at Michigan State University to evaluate and compare experimental formulations to current weed control products during proposed work to meet objective #1.

Objective #2: Based on bulk costing (truck or 45,000 lbs) a cost of goods sold (COGS) of ingredients likely to be used in experimental formulations (fatty/organic acid herbicides) is about $1.15/lb. This averages the active, emulsifier and adjuvant/amendment costs, where the 3 ingredients in a natural herbicide formulation (objective #1) would fall within certain ranges; i.e., 85% active (fatty acid), 10 to 14% synergist and 1 to 5 % natural emulsifier. There may be some variation to those ratios but the ingredient percentages represent a good point at which to begin. A factor of 2.5 to 4.0 (X COGS) would be used to estimate projected grower costs ($/lb) for a new herbicide. The range of 2.5 to 4.0, based on pricing models obtained from two pesticide manufacturer/distributors, would include profit and recovery for distribution, sales, marketing and registration costs for a natural product via the US EPA bio-pesticide route.

PROGRESS: 2007/06 TO 2008/05
OUTPUTS: Formulation chemistry: During Phase I, numerous combinations of caprylic acid or C-8 (active ingredient) and natural lecithin emulsifiers were formulated with potential organic acid synergists such as glycolic, propionic and L-lactic acid. Selection of certain acids or adjuvants was based on their potential as or known to be effective synergists for C-8 or C-9 in other types of formulations. Greenhouse trials at Michigan State University (MSU): The more promising formulations from stability trials were evaluated by MSU as candidate herbicides. Caprylic acid formulations, containing L-lactic or propionic +/- an ester of salicylate, were emulsified with one of several different lecithin products. Formulations emulsified with lecithin were compared with existing organic herbicides such as plant oil products, Matran EC and BurnOut II. Evaluation of the pre-emergent, corn gluten product was also done. Field testing of herbicides on mixed weed species by Summerdale, Inc.: The final number of replicated, field trials completed for Phase I far exceeded those planned for Phase I. This was done to more fully understand herbicide performance for numerous experimental formulations compared to commercial products, especially to establish Phase II work. That is, to evaluate possible treatment differences for a) predominant broadleaf populations versus predominantly grasses, b) stage of growth/weed heights and c) at a preliminary level, climate variation. Twenty-eight (28) independent field trials were done, beginning early May through late September, 2007. All 28 trials were repeated and results, including treatment differences and statistical analysis (ANOVA, P at 0.05), reflect data from combined, replicated trials. Weed species most commonly tested by Summerdale, Inc. were wild carrot, common dandelion, white and red clover, buckhorn plantain, birdsfoot trefoil, yellow hawkweed, brome grass and crabgrass at a height range of 3 to 20 inches. A single application of treatments ranged from 14 to 100 gpa (40 - 60 psi), where lower amounts (14 - 40 gpa) represented herbicide spray volumes/acre typically used by growers, whereas higher application volumes such as 60 - 100 gpa or approaching "spray to drip", simulated amounts likely to be applied by home consumers and by commercial and industrial users. The disparity between commercial products and C-8 formulations was more profound in the field over what was observed in greenhouse trials; i.e., C-8 formulations were far superior. Intellectual property: Summerdale, Inc. has protected significant inventions and will continue to do so. Four U.S. patents (Patent #6,218,336, #6,509,297, #6,812,190, #6,969,696 and a Chinese patent, Application No.00817831.3 (PCT/US00/28405) have been issued to Summerdale, Inc. Two applications are pending: 1) Fungicide Compositions, R. Coleman. Pub. No. US2004/0266852 A1, Dec 30, 2004, filed on July 9, 2004 and 2) Pesticide Compositions and Methods For Their Use, R. Coleman. Pub. No. US 2007/0249699 A1, Oct 25, 2007, filed June 25, 2007, a continuation-in-part of Fungicide Compositions.
PARTICIPANTS: Nothing significant to report during this reporting period.
TARGET AUDIENCES: Nothing significant to report during this reporting period.
PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

IMPACT: 2007/06 TO 2008/05
Only a limited number of chemical control products are organically acceptable and these include contact herbicide materials such as acetic acid (in vinegar), citric acid, soap, non-synthetic plant extracts and preparations and solutions of sodium nitrate, as well as a pre-emergent material, corn gluten. Herbicides can be used for selective weed control by manipulating the timing of application or placement of material or by exploiting differences in the chemical tolerances of the crop and the target weed. Weeds that emerge before the crop can be killed or suppressed with contact herbicides (i.e., acetic acid). The efficacy of these organic-accepted herbicides is marginal at best. Currently, weed control for the organic grower can be costly, labor intensive, inefficient and has become a major issue affecting a grower's ability to be competitive especially for fruit and vegetable markets. Hence, a novel, approved method, highly effective as a non-selective herbicide treatment, will gain significant attention from organic growers, most notably if the method is shown to be consistently effective and is reasonably priced. Since caprylic acid (C-8 fatty acid) is found in mammalian systems and present in many vegetable and animal fats (i.e., an abundant fatty acid in coconut oil and at 1-4% in milk fat), C-8 appears to be a good candidate for USDA (NOP)/OMRI approval. Short chain fatty acids, such as caprylic acid, are known to be rapidly digested and absorbed in the intestinal tract. There are no chemical syntheses or modifications of C-8, nor are there chemical catalysts or any other chemicals used during any stage of caprylic acid preparation (water hydrolysis, distillation or fractional distillation) from coconut oil (Cognis, Inc.). There is a good likelihood that a herbicide formulation containing caprylic and lactic acids would have USDA (NOP)/OMRI-approval since the formulation ingredients: a) are indigenous to many foods (i.e., milk, vegetable fats) and C-8, as an even-numbered fatty acid is ubiquitous in nature (versus pelargonic or C-9), b) are FDA GRAS compounds and relatively non-toxic, c) can be directly extracted/separated from food substances such as coconut oil (C-8), d) there is no need for chemical hydrolysis or any modification processes to produce or manufacture the compounds, e) are commonly used as acidulants and flavor enhancers in the food industry and f) are used as medicinal agents for gastric ailments and indigestion (caprylic acid) while lactic and glycolic acids are found in skin creams.

Funding Source
Nat'l. Inst. of Food and Agriculture
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Chemical Contaminants