Preemergence Applications Of S-metolachlor Research Articles

Investment Returns for Preemergence Herbicide Use in No-till Pumpkin

Preemergence (PRE) herbicides are an important part of the overall weed management plan in no-till (NT) pumpkin (Cucurbita pepo) production. A field evaluation was conducted in an NT production system using PRE herbicides labeled for pumpkins to determine the benefits of specific herbicide combinations and the economic returns on investment associated with their use. The PRE herbicide treatments evaluated were 1) s-metolachlor (1360 g⋅ha–1 a.i.), 2) clomazone (350 g⋅ha–1 a.i.) and ethalfluralin premix (1120 g⋅ha–1 a.i.), 3) s-metolachlor + clomazone and ethalfluralin premix, 4) s-metolachlor + halosulfuron (35 g⋅ha–1 a.i.), 5) clomazone and ethalfluralin premix + halosulfuron, and 6) none. The primary weed species present were tall waterhemp (Amaranthus tuberculatus), redroot pigweed (Amaranthus retroflexus), giant foxtail (Setaria faberi), and large crabgrass (Digitaria sanguinalis). The best weed control option for full-season broadleaf and grass weed control was s-metolachlor + clomazone and ethalfluralin. This herbicide combination also provided the greatest economic return on investment, ranging from a 20% to 40% improvement (depending on the year) compared with the next closest PRE herbicide treatment. Those with the lowest returns on investment were s-metolachlor combined with halosulfuron, and clomazone and ethalfluralin combined with halosulfuron. Besides providing the highest returns on investment, the PRE application of s-metolachlor with clomazone and ethalfluralin also produced the largest pumpkin fruit for the weed species present. Although growers often look for ways to reduce input costs in NT pumpkin production systems, the proper selection of PRE herbicides that considers the weed species present is clearly an important investment that improves pumpkin yields and revenues.

Manipulation of sunflower population density and herbicide rate for economical and sustainable weed management

Field study tested weed control efficacy, crop yield and economic return using various weed management strategies in sunflower growing with different population density. Treatments included four rates of PRE emergence application of S-metolachlor + fluchloridon and one POST emergence application of flumioxazin + quizalofop-pethyl. PRE-em application (1.4 + 2.4 and 1.2 + 2.0) provided at the higher crop densities (70 000) best weed control. However, PRE- em treatments with lower doses (0.8 + 1.6 and 1.0 + 1.8) and POST- em application did not maintain acceptable control of dominant weeds. Grain yield increased with the crop density, but did not statistically differ between applied herbicide treatments. Finally, the implication of this study demonstrated that sole application of tested herbicide treatments at higher crop sowing density (60 000 and 70 000) was found to be economically the best alternative strategy for reducing weed infestation and achieving a better yield.

Assessment of Integrated Weed Management Practices on Weed Dynamics, Yield Components and Yield of Faba bean (Vicia faba L.) in Eastern Ethiopia

The experiment was conducted to assess the integrated effects of pre-emergence herbicides and hand-weeding on weed control, yield components, yield, and their economic feasibility for cost effective weed control in faba bean. The experiment consisted of 12 treatments viz. pre-emergence s-metolachlor (1.0, 1.5 and 2.0 kg ha-1) and pendimethalin (1.0, 1.25 and 1.5 kg ha-1), each at three rates metolachlor, s-metolachlor + one-hand-weeding, pendimethalin + one-hand-weeding, two-hand-weeding, complete weed free and weedy checks arranged. The weed flora consisted of broadleaved and sedge with the relative densities of 81.02 and 18.98 % at Haramaya district, and 80.83% and 19.17%, at Gurawa district, respectively. Application of s-metolachlor and pendimethalin 1.0 kg ha-1 each supplemented with hand weeding 5 WAE significantly (p ≤0.01) affected the broadleaved weeds, sedges and weed dry weight at both sites. S-metolachlor 1.0 kg ha-1 supplemented with hand weeding 5 WAE gave the lowest total number of weeds (8.29 m-2) following the weed free check. Higher grain yield (3555.8 kg ha-1) was produced with s-metolachlor 1.0 kg ha-1 supplemented with one-hand-weeding 5 WAE following complete weed-free at Gurawa. The benefit gained from s-metolachlor and pendimethalin at 1.0 kg ha-1 each supplemented with one hand weeding 5 WAE were greater than the value recorded from the weedy check by 216% and 198 %, respectively. S-metolachlor 1.0 kg ha-1 supplemented with hand weeding 5 WAE treatment resulted in the highest grain yield and economic benefit. However, in case labour is constraint and s-metolachlor herbicide is timely available, pre emergence application of s-metolachlor at 2.0 kg ha-1 should be the alternative to preclude the yield loss and to ensure maximum benefit.

Influence of Integrated Weed Management Practices on Weed Dynamics, Yield Components and Yield of Faba bean (Vicia faba L.) in Eastern Ethiopia

The experiment was conducted to assess the integrated effects of pre-emergence herbicides and hand-weeding on weed control, yield components and yield of Faba bean to assess their economic feasibility for cost effective weed control in Faba bean. The experiment consisted of 12 treatments viz. pre emergence S-metolachlor and Pendimethalin each at three rates S-metolachlor+one-hand-weeding, pendimethalin+one-hand-weeding, two-handweeding, complete weed free and weedy checks arranged in randomized complete block design with three replications. The weed flora consisted of broadleaved and sedge with the relative densities of 81.02 and 18.98% at Haramaya, and 80.83% and 19.17%, at Gurawa, respectively. Application of S-metolachlor and Pendimethalin 1.0 kg ha-1 each supplemented with hand weeding 5 WAE significantly (p ≤ 0.01) affected the broadleaved weeds, sedges and weed dry weight at both sites. S-metolachlor 1.0 kg ha-1 supplemented with hand weeding 5 WAE gave the lowest total number of weeds (8.29 m-2) following the weed free check. Higher grain yield (3555.8 kg ha-1) was produced with S-metolachlor 1.0 kg ha-1 supplemented with one-hand-weeding 5 WAE following complete weed-free at Gurawa. The benefit gained from S-metolachlor and Pendimethalin at 1.0 kg ha-1 each supplemented with one hand weeding 5 WAE were greater than the value recorded from the weedy check by 216% and 198%, respectively. S-metolachlor 1.0 kg ha-1 supplemented with hand weeding 5 WAE treatment resulted in the highest grain yield and economic benefit. However, in case labour is constraint and S-metolachlor herbicide is timely available, pre emergence application of s-metolachlor at 2.0 kg ha-1 should be the alternative to preclude the yield loss and to ensure maximum benefit.

Herbicide-based Weed Management in Miscanthus sacchariflorus

Although miscanthus is well known for its fast growth and high biomass productivity, its plant establishment and early growth are sensitive to weed interference. Thus, greenhouse and field experiments were conducted to establish an herbicide-based weed management system with pre-emergence (PRE) and post-emergence (POST) herbicides and their sequential applications. The plant establishment and early growth of miscanthus in the first 2 years of planting were significantly affected by weed interference, resulting in a greater than 90 % biomass yield loss in an untreated weedy control in which no herbicide was applied. PRE applications of S-metolachlor, alachlor, and pendimethalin were safe for M. sacchariflorus under both greenhouse and field conditions and showed good weed control under field conditions. POST applications of all of the tested auxinic herbicides, bentazon, thifensulfuron, and mesotrione were safe for M. sacchariflorus and showed good weed control. Sequential applications of PRE (S-metolachlor, pendimethalin or isoxaflutole) and POST herbicides (dicamba, bentazon, or mesotrione) showed better weed control than did their sole applications, resulting in better establishment. In particular, the sequential application of either S-metolachlor or pendimethalin followed by mesotrione showed the most effective weed control (85 % less weeds than the untreated weedy control) with good safety for M. sacchariflorus and thus provided the best early establishment and biomass yield. The mesotrione-based sequential application achieved approximately 15.4 ton ha−1, 79 % of weed-free control in the second year of establishment. Therefore, our results suggest that the sequential applications of PRE and POST herbicides are essential for the first and second year of M. sacchariflorus cultivation.

Response of dry bean to pre-plant incorporated and pre-emergence applications of S-metolachlor and fomesafen

There is limited information on the tolerance of various market classes of dry bean to the soil application of fomesafen alone or in tank mix combination with S-metolachlor. Field trials were conducted in Ontario over a two year period (2006 and 2007) to evaluate the tolerance of black, cranberry, kidney, and white (navy) bean to the pre-plant incorporated (PPI) and pre-emergence (PRE) application of S-metolachlor and fomesafen alone and in tank mix combination. Treatments included a non-treated check. All treatments were maintained weed free during the growing season. Visible injury differed among the four market classes of dry bean at 14 days after emergence. Visible injury was generally greater in the smaller seed market classes (black and white bean) compared to the larger seeded market classes (kidney and cranberry bean). Visible injury seen in some market classes of dry bean early in the season was minimal and transitory and caused no adverse effects on plant height, shoot dry weight, seed moisture content, and yield. Based on these results, S-metolachlor and fomesafen alone and in combination applied PPI or PRE at the proposed maximum use dose can be safely used for weed management in black, cranberry, kidney, and white bean production in Ontario.

White Bean Sensitivity to Preemergence Herbicides

White bean producers have a limited number of herbicide options available for annual grass and broadleaf weed control. Tolerance of two white bean cultivars to preemergence (PRE) applications ofS-metolachlor,S-metolachlor + imazethapyr, flumetsulam +S-metolachlor, cloransulam-methyl, clomazone, clomazone + imazethapyr, and clomazone +S-metolachlor at the maximum labeled rate in soybean (1×) and twice the labeled rate (2×) were studied at two Ontario locations (Exeter and Ridgetown) in 2001 and 2002.S-Metolachlor, clomazone, and clomazone +S-metolachlor generally had no negative effect on plant height, dry weight, maturity, and yield.S-Metolachlor + imazethapyr and clomazone + imazethapyr reduced plant height, dry weight, and yield as much as 21, 42, and 24%, respectively. Flumesulam +S-metolachlor and cloransulam-methyl reduced plant height, dry weight, and yield as much as 39, 58, and 43%, respectively. White beans are tolerant to PRE applications ofS-metolachlor, clomazone, and clomazone +S-metolachlor. White beans are sensitive to PRE applications ofS-metolachlor + imazethapyr, flumetsulam +S-metolachlor, clomazone + imazethapyr, and cloransulam-methyl.

Sensitivity of kidney beans (Phaseolus vulgaris) to soil applications of S-metolachlor and imazethapyr

Tolerance of Montcalm and Redhawk kidney beans to preplant incorporated (PPI) and preemergence (PRE) applications of S-metolachlor, imazethapyr and their tank mix at the maximum label rate in soybeans (1×) and twice that rate (2×) was studied at two Ontario locations (Exeter and Ridgetown) in 2001 and 2002. There were no differences between the two cultivars in their responses to the herbicide treatments. Visual evaluations of crop injury never exceeded 2% for any herbicide treatment. With the exception of a 7% height reduction after the PPI application of imazethapyr plus S-metholachlor at the 2× rate, none of the other treatments reduced plant height, dry weight, seed moisture content or seed yield. At sites where there was a significant difference, the PRE application caused more crop injury than the PPI application. These results indicate that there is an acceptable margin of crop safety for PPI and PRE applications of S-metolachlor and imazethapyr alone and in tank mix combination in kidney beans in Ontario. Key words: Crop injury; crop tolerance; imazethapyr; S-metolachlor; yield.

Tolerance of cranberry beans (Phaseolus vulgaris) to soil applications of s-metolachlor and imazethapyr

There is little information on the tolerance of cranberry beans to preplant incorporated (PPI) and preemergence (PRE) applications of s-metolachlor and imazethapyr, eithe r alone or in tank mix combination, for selective weed control in cranberry beans in Ontario. Tolerance of two cranberry bean cultivars, Hooter and SVM Taylor, to PPI and PRE applications of s-metolachlor, imazethapyr and their tank mix combination at the label rate (1×) and twice the label rate (2× ) were studied at two Ontario locations (Exeter and Ridgetown) in 2001 and 2002. There were no differences between the two cultivars in their responses to the herbicide treatments. PPI and PRE applications of s-metolachlor alone at the 1× and 2× rate had no effect on visual crop injury and no negative effect on plant height, dry weight and yield compared to the control. The PPI and PRE applications of imazethapyr at the 1× rate did not result in significant visual crop injury, and had no negative effect on bean height and dry weight, but at the 2× rate there was significant visual crop injury, a decrease in height with the PPI application and decreased dry weight with PPI and PRE applications. No negative effect o n cranberry bean yield was observed with the application of imazethapyr at either the 1× or 2× rates. The PPI and PRE applications of the tank mix of s-metolachlor plus imazethapyr at the 1× rate did not result in significant visual crop injury or decreases in bean plant height or dry weight. At the 2× rate, there was significant visual crop injury, a decrease in bean plant height with PPI and PRE applications and decreased dry weight with the PPI application. The tank mix of s-metolachlor plus imazethapyr at the 1× rate had no effect on yield, but the PPI application at the 2× rate caused a decrease in yield at 1 of the 4 site-years. Key words: