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| Publication Type:
| Report |
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| Author(s): | Shrefler, J. W. |
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| Author Affiliation: | Texas Agricultural Experiment Station, Overton, TX 75684; K.L. Smith, Sandoz Agro, Inc., Overton, TX 75684. |
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| Title: | Relative activity of chloroacetamide herbicides on large crabgrass Digitaria Sanguinalis |
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| Meeting Info.: | 48th Annual Meeting, Memphis, TN, January 16-18, 1995 |
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| Source: | Southern Weed Science Society Proceedings. Vol. 48, January 1995, p. 51-52. |
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| Publishing Information: | Champaign, IL: Southern Weed Science Society. |
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| # of Pages: | 2 |
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| Keywords: | TIC Keywords: Herbicides; Irrigation; Digitaria sanguinalis
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| Abstract/Contents: | "Chloroacetamide herbicides are used for PRE and PPI weed control in various crops. Labeling of these herbicides typically indicates that rainfall, irrigation or shallow incorporation may be needed to obtain optimal efficacy with PRE applications. Field observations suggest that herbicide performance may be greatly affected when these conditions are not provided. Studies were initiated to assess the importance of soil moisture factors on the performance of these herbicides. In order to do this, bioassay systems in which appropriate moisture regimes could be established were needed. These systems were designed so that moisture effects could be assessed at sub-lethal herbicide doses. Two systems were developed: an Incorporation System, which can be used to study the effect of specific soil moisture levels, and a Preemergence System, which can be used to study the effect of simulated rainfall. Using each system, titrations were conducted with dimethenamid and metolachlor to determine herbicide doses giving 50% growth reductions of large crabgrass, a species susceptible to these herbicides. Plants were grown under fluorescent plant lights. The incorporation system was designed so that large crabgrass would emerge through a ca. 1cm layer of soil that is uniformly treated with herbicide. Shoot height and fresh weight measurements were made 2 weeks after crabgrass was planted and shoot height of 8 cm was achieved in an untreated check. Using this system, shoot height and weight reductions of 50% were achieved with 0.4 and 0.5 ppm (dry soil basis) of dimethenamid, respectively, and 1.1 and 1.5 ppm, respectively, of metolachlor. The preemergence system was developed to permit large crabgrass to emerge through soil which had received a surface treatment of herbicide via an aqueous spray at 280 L/ha. Using this system, shoot height and weight reductions of 50% were received from 0.1 and 0.14 kg/ha of dimethenamid, respectively, and 0.11 and 0.17 kg/ha, respectively, of metolachlor. The results suggest that the activities of these herbicides are differentially affected by the two bioassay systems. With the incorporation system, 3x more metolachlor than dimethenamid was needed to give 50% growth reductions of large crabgrass. With the preemergence system, comparable herbicide doses gave 50% growth reductions." |
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| Language: | English |
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| References: | 0 |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Shrefler, J. W. 1995. Relative activity of chloroacetamide herbicides on large crabgrass Digitaria Sanguinalis. South. Weed Sci. Soc. Proc. 48:p. 51-52. |
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MSU catalog number: SB 611 .S6 v.48 |
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