Chris L. Gillard

Effect of application timing of glyphosate and saflufenacil as desiccants in dry edible bean (Phaseolus vulgaris L.)

McNaughton, K. E., Blackshaw, R. E., Waddell, K. A., Gulden, R. H., Sikkema, P. H. and Gillard, C. L. 2015. Effect of application timing of glyphosate and saflufenacil as desiccants in dry edible bean (Phaseolus vulgaris L.). Can. J. Plant Sci. 95: 369-375. Early application of desiccants in dry edible bean may cause yield reductions and unacceptable herbicide residue levels, resulting in rejection of exported shipments. The effect of application timing of two registered desiccants, glyphosate and saflufenacil, was examined in 12 field trials conducted over a 4-yr period (2009-2012) at Exeter, Ontario, Carman, Manitoba, and Lethbridge, Alberta. Desiccants were applied alone and in combination at five crop maturation stages. When glyphosate or saflufenacil alone, or in combination, was applied at 100% crop maturity, herbicide residue levels were acceptable (less than 2.0 and 0.01 ppm for glyphosate and saflufenacil, respectively) and there was no reduction in yield or hundred seed weight. Glyphosate residues remained below 2.0 ppm when the desiccant was applied alone or with saflufenacil at 75% crop maturity, but crop yield decreased by 16% compared with the untreated control when glyphosate and saflufenacil were combined. Residue levels were unacceptable when glyphosate was applied at 0, 25, and 50% maturity; generally the earlier glyphosate was applied, the greater the residue concentration in the seeds at harvest. Although no application timing resulted in saflufenacil residues above 0.01 ppm, crop yield was reduced when the desiccant was applied at 0, 25, 50, and 75% crop maturity. This information will provide dry bean processors with the necessary information to design guidelines concerning the application timing of glyphosate and saflufenacil so that bean yield and quality remain unaffected and seed residues remain below accepted levels.

Desiccation in dry edible beans with various herbicides

Soltani, N., Blackshaw, R. E., Gulden, R.H., Gillard, C. L., Shropshire, C. and Sikkema, P. H. 2013. Desiccation in dry edible beans with various herbicides. Can. J. Plant Sci. 93: 871-877. There is little information available on the effect of diquat, carfentrazone-ethyl, glufosinate ammonium, flumioxazin and saflufenacil applied alone or in tankmix combination with glyphosate as harvest aids in dry bean production under environmental conditions of the various production regions in Canada. A total of 11 field trials were conducted over a 3-yr period (2010, 2011, 2012) at Exeter, Ontario, Carman, Manitoba, and Lethbridge, Alberta, to evaluate various harvest-aid herbicides in dry bean. Comparison of leaf, pod and stem visual dry down at 4 and 8 d after desiccation application (DAA) indicated that adding a tankmix partner to glyphosate increased visual dry down of leaf, pod and stem 17, 10 and 15% at 4 DAA and 20, 17 and 14% at 8 DAA, respectively. At 8 DAA, glyphosate (450 or 900 g a.e. ha-1), diquat, glufosinate ammonium, carfentrazone-ethyl, flumioxazin and saflufenacil provided 13-58, 65-80, 64-71, 12-34, 36-52 and 41-73% dry down of the dominant weeds (AMARE, AMBEL, CHEAL and SETVI), respectively. Diquat, glufosinate ammonium, carfentrazone-ethyl, flumioxazin and saflufenacil tankmixed with glyphosate (450 or 900 g a.e. ha-1) provided 67-77, 65-71, 22-62, 45-69 and 44-74% weed dry down, respectively. Dry bean yield was not reduced with any of the desiccation treatments. Among desiccant treatments that provided consistent desiccation of dry bean and weeds, saflufenacil had the least environmental impact followed by flumioxazin, glufosinate ammonium and then diquat. Based on this study, diquat, glufosinate ammonium, flumioxazin and saflufenacil alone or in combination with glyphosate (450 or 900 g a.e. ha-1) provide consistent desiccation of weeds and dry bean.

The interaction of annual weed and white mold management systems for dry bean production in Canada

Pynenburg, G. M., Sikkema, P. H., Robinson, D. E. and Gillard, C. L. 2011. The interaction of annual weed and white mold management systems for dry bean production in Canada. Can. J. Plant Sci. 91: 587-598. Annual weeds and white mold (Sclerotinia sclerotiorum) are serious pests in dry bean, and can cause substantial yield losses. The proper management of these pests is essential for profitable production. A 2-yr study conducted at three field locations in Ontario examined the effects of two pre-plant incorporated herbicide programs on weed management and three foliar fungicides on white mold development. In addition, thiamethoxam was evaluated for its ability to alleviate stress caused by annual weeds and white mold. Interactions among disease severity, weed control, agronomics and economic returns were examined. Thiamethoxam seed treatment had inconsistent benefits with respect to plant emergence and vigour, harvested weight, seed weight and economic returns. There were no benefits for the other parameters measured. The premium herbicide program (s-metolachlor plus imazethapyr) reduced weed ground cover, white mold severity and pod drop, and increased 100-seed weight, harvested weight and net economic return compared with the economic herbicide program (trifluralin). The foliar fungicides reduced white mold severity and pod drop, while increasing 100-seed weight, harvested yield and net economic return. Fluazinam resulted in the lowest white mold severity, and the highest yield and treatment return, when compared with cyprodinil/fludioxonil and boscalid in some environments. High weed pressure in the presence of white mold increased disease severity. Where treatment differences occurred, the premium herbicide program and fluazinam foliar fungicide resulted in the highest net economic return to growers.

Effect of five desiccants applied alone and in combination with glyphosate in dry edible bean (Phaseolus vulgaris L.)

McNaughton, K. E., Blackshaw, R. E., Waddell, K. A., Gulden, R. H., Sikkema, P. H. and Gillard, C. L. 2015. Effect of five desiccants applied alone and in combination with glyphosate in dry edible bean (Phaseolus vulgaris L.). Can. J. Plant Sci. 95: 1235-1242. Application of dry bean desiccants just prior to crop maturity is common practice by Canadian producers. As dry beans are grown for human consumption it is critical that producers pick desiccants that do not affect crop yield, seed quality, or result in desiccant seed residue levels above accepted levels. In this study the efficacy of glyphosate, diquat, glufosinate, carfentrazone, flumioxazin, and saflufenacil as desiccants was examined for navy, cranberry, pinto, and great northern dry bean. Seed herbicide residues were also tested for each of the dry bean classes tested. Navy, cranberry, pinto, and great northern dry bean yields were not impacted by use of the desiccants diquat, carfentrazone, flumioxazin, or saflufenacil when applied at labelled rates and application timings. Additionally, herbicide residues in seed following application remained lower than maximum residue limits (MRL) established by primary Canadian dry bean export partners. Generally, dry bean colour, irrespective of class, was not altered by desiccant use; diquat and flumioxazin caused minor increases in the degree of red and yellow seed pigmentation for cranberry bean only. Although colour differences were noted using a Chroma meter the differences were slight and would not likely be of economic importance. Application of glyphosate did not affect crop yield, and seed residue levels were below MRLs for navy, pinto, and great northern bean. However, seed glyphosate residue levels were above the MRL for cranberry bean when glyphosate was applied alone or tankmixed with carfentrazone, flumioxazin, or saflufenacil. Seed residue levels were also above listed MRLs for some export countries when glufosinate was applied to navy, cranberry, and pinto bean, although crop yield and seed quality remained unaffected. These findings suggest that growers and contractors should avoid using glufosinate as a dry bean desiccant at least for some markets and that care should be taken when selecting glyphosate as a desiccant, especially for cranberry bean. Across all market classes desiccation progress of bean leaf, stem, and pod tissue was slowest when glyphosate and carfentrazone were used.

Sulfentrazone tank mix partners for weed control in white bean (Phaseolus vulgaris L.)

Abstract: Soil-applied broadleaf herbicides for weed management in dry beans (Phaseolus vulgaris L.) in Ontario are limited. Sulfentrazone is an effective broadleaf herbicide with some grass activity and is currently registered for use in soybean and some pulse crops in Canada. If registered for use in dry beans in Ontario, sulfentrazone would provide growers with another mode of action for broadleaf weed control. Five field studies were conducted over a two year period (2014–2015) to determine the tolerance of white beans to sulfentrazone applied pre-emergence (PRE) and if the spectrum of weeds controlled can be expanded by tank-mixing sulfentrazone with a soil-applied grass herbicide. Sulfentrazone (140 and 210 g ai ha-1) was mixed with pendimethalin, dimethenamid-p, s-metolachlor or pyroxasulfone. All the tankmixes evaluated provided good control of green foxtail (Setaria viridis L.), pigweeds (Amaranthus powelli L. and A. retroflexus L.), and common lambsquarters (Chenopodium album L.), but only sulfentrazone + pendimethalin had an adequate margin of crop safety. Based on this study, sulfentrazone combined with a grass herbicide provides acceptable control of some grass and broadleaf weed species; however, further research is required to determine if there is an adequate margin of crop safety for weed management in Ontario dry beans.

Fulvic and humic acid fertilizers are ineffective in dry bean

Abstract: Studies were conducted in Ontario on dry bean (Phaseolus vulgaris L.) in 2010 and 2011 using fulvic acid (LX7®, MTS Environmental Inc.) or humic acid (Plant XL®, Alpha-Agri) fertilizers. Twenty fulvic acid field trials and 15 humic acid field trials indicate that these fertilizers were ineffective, as plant vigour, height, 100-seed weight, and yield were similar to a control treatment.

Transmission of anthracnose (Colletotrichum lindemuthianum) in dry bean (Phaseolus vulgaris L.) with artificial and natural inoculum in a wet and dry canopy

LeClair, E., Conner, R., Robinson, D. and Gillard, C. L. 2015. Transmission of anthracnose (Colletotrichum lindemuthianum) in dry bean (Phaseolus vulgaris L.) with artificial and natural inoculum in a wet and dry canopy. Can. J. Plant Sci. 95: 913-921. Anthracnose [Colletotrichum lindemuthianum (Sacc. and Magn.) Lams. - Scrib.] is a serious pathogen of dry bean (Phaseolus vulgaris L.). Disease transmission on artificial materials and clothing has been observed in other crops, where equipment and workers transmit pathogens from infected to clean plants. Initial studies in 2008 and 2009 at Exeter, ON, determined that anthracnose transmission in dry bean as measured by resultant disease severity occurred with denim, leather, metal, and rubber using a 107 spores mL-1 prepared artificial spore inoculum in both wet and dry crop canopies. In 2012 and 2013 at Morden, MB, and Ridgetown, ON, the studies were expanded by adding a 105 spores mL-1 prepared artificial and a natural inoculum source. Inoculum source and canopy moisture had the greatest effect on disease severity, while no differences were observed between materials within an inoculum sources. Transmission in wet canopy conditions resulted in a higher infection rate. Canopy moisture impacted the natural inoculum the most. The 107 spores mL-1 inoculum transmitted the most disease followed by natural incidence and 105 spores mL-1 inoculum in wet conditions. In dry conditions 107 spores mL-1 inoculum transmitted the most disease followed by 105 spores mL-1 inoculum and natural incidence. Producers need to recognize that there is real risk for the anthracnose transmission by common materials in dry bean, and take appropriate precautions to prevent it.

Microwave radiation effect with and without chemical seed treatments on halo blight infected seed, seed germination, plant vigour, and yield of dry beans

Abstract: Halo blight, caused by Pseudomonas syringae pv. phaseolicola, is a seed-borne disease of dry bean (Phaseolus vulgaris L.) that lowers seed quality and yield. Over 2 yr, laboratory and field studies were conducted to evaluate the effect of microwave radiation on two market classes: navy (‘Envoy’) and white kidney (‘GTS 402’) bean. In the laboratory, seed germination and vigour decreased up to 15% after 40 s of microwave exposure, where <7% decrease was observed during 0–30 s. Disease plating showed no correlation between pathogen colonization of the seed and microwave radiation, as incidence of pathogen colonization was low across all exposure times. In field trials in Morden and Winkler, MB, microwave radiation was tested alone and in combination with copper hydroxide 53.8% and pyraclostrobin + fluxapyroxad + metalaxyl. Seed treatment with copper hydroxide slightly decreased the incidence of halo blight but had little impact on seed pick, hundred-seed weight, yield, or return on investment. Pyraclostrobin + fluxapyroxad + metalaxyl seed treatment had no effect on any of these parameters. Microwave radiation lowered seed emergence by up to 9% but did not reduce disease incidence and severity or increase yield or return of investment when applied alone or in combination with a chemical treatment.

Tolerance of Glyphosate-Resistant Maize to Glyphosate Plus MCPA Amine Is Influenced by Dose and Timing

There is little information on tolerance of glyphosate-resistant maize to glyphosate plus MCPA amine as influenced by dose and timing under Ontario environmental conditions. A total of seven field trials were conducted at various locations in Ontario, Canada, in 2011–2013 to evaluate tolerance of field maize to tank mixes of glyphosate (900 g a.e./ha) plus MCPA amine (79, 158, 315, 630, 1260, 2520, or 5040 g a.e./ha) at either the 4- or 8-leaf stage. The predicted dose of MCPA amine that caused 5, 10, and 20% injury was 339, 751, and 1914 g a.e./ha when applied to 4-leaf maize but only 64, 140, and 344 g a.e./ha when applied to 8-leaf maize, respectively. The predicted dose of MCPA amine that caused 5, 10, and 20% reduction in shoot dry weight of maize was 488, 844, and 1971 g a.e./ha when applied to 4-leaf maize and only 14, 136, and 616 g a.e./ha when applied to 8-leaf maize, respectively. The predicted dose of MCPA amine that caused 5, 10, and 20% yield reduction was 2557, 4247, and >5040 g a.e./ha when applied to 4-leaf maize and 184, 441, and 1245 g a.e./ha when applied to 8-leaf maize, respectively. Based on these results, glyphosate plus MCPA amine applied at the manufacturer’s recommended dose of 630 g a.e./ha applied to 4-leaf maize has potential to cause injury but the injury is transient with no significant reduction in yield. However, when glyphosate plus MCPA amine is applied to 8-leaf maize it has the potential to cause significant injury and yield loss in maize.

Weed Control, Environmental Impact and Profitability of Two-Pass Weed Management Strategies in Glyphosate-Resistant Corn

Twelve field trials were conducted over a three-year period (2010, 2011, 2012) at different locations in south- western Ontario, Canada to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury, weed control, environmental impact, corn yield and profit margin. No visible injury resulted from the herbicide treatments evaluated. One early postemergence (EPOST) application of glyphosate provided good full season control of pigweed species and ladys thumb and fair control of velvetleaf, common ragweed, lambs-quarters, barnyard grass and green foxtail. One late postemergence (LPOST) application of glyphosate provided excellent control of all weed species evaluated but corn yield was reduced due to early weed interference. The sequential application of glyphosate (EPOST fb LPOST) provided excellent control of all weed species evaluated with no adverse effect on corn yield. The sequential ap- plication of a preemergence residual herbicide followed by an application of glyphosate LPOST provided excellent full season control of all weed species evaluated and corn yield was equal to the weed free control. Among the sequential her- bicide programs the lowest environmental impact was glyphosate EPOST fb LPOST and saflufenacil/dimethenamid-p, isoxaflutole + atrazine or rimsulfuron + s-metolachlor + dicamba applied PRE fb glyphosate LPOST. Based on this study, the most efficacious and profitable weed management programs in glyphosate-resistant corn are a sequential application of glyphosate or a two-pass program of a preemergence residual herbicide followed by glyphosate LPOST. The two-pass programs have glyphosate stewardship benefits.