Preemergence Herbicide Treatments Research Articles

Weed Control in Reduced Tillage Corn Production Systems1

AbstractTill‐planting and slot‐planting are two reduced tillage corn (Zea mays L.) production systems used in Nebraska and other states. Farm operators frequently encounter existing weed populations at planting time with these systems when tillage does not precede the planting operation. Our research investigated weed control in tillplanted and slot‐planted corn with preplant translocated and contact herbicides, broadcast or band applications of preemergence herbicides, and a cultivation variable. Field experiments utilized previously undisturbed ridges of old corn rows for till‐planting or slot‐planting corn. Applications of 2,4‐D[(2,4‐dichlorophenoxy)acetic acid] ester and paraquat (l,l'‐dimethy 1‐4,4'‐bipyridinium ion) were used in combination with preemergence herbicide treatments that were either row banded or broadcast. One or two cultivations were imposed on the two tillage systems. Till‐planting resulted in more soil surface tillage and less dependence on herbicides than did slot‐planting. Maximum corn yield was achieved in the till‐plant system by row banding several preemergence herbicide treatments, coupled with one cultivation. Slot‐planting resulted in less soil disturbance with the planter than did till‐planting and required more herbicide usage. With slot‐planting, a preplant application of 2,4‐D was essential to remove the predominantly broadleaf weed population and maximize corn yields. When preplant 2,4‐D was used with slot‐planting, corn yields were not significantly different between band and broadcast applications of the preemergence herbicides used. Two cultivations rather than one tended to increase yields of slot‐planted corn.

Preemergence Winter Weed Control in Dormant Bermudagrass Turf1

AbstractSpur weed (Soliva sessilis P. & K.) is becoming a severe winter weed problem in the Southeast and information is needed on herbicides that will give satisfactory control of winter weed mixtures which includes spur weed. Field experiments were conducted for 2 years on Cecil loam (Typic Hapludult) and Cecil sandy loam at Griffin, Davidson sandy clay loam (Rhodic Paleudult) at Lawrenceville and 1 year on Cecil loam at Macon, Ga., to determine the effects of preemergence herbicide treatments on control of spur weed and other winter annuals in bermudagrass [Cynodon dactylon (L.) Pers. ‘Common’] turf. Herbicides as preemergence treatments were made in the fall and weed control and turfgrass tolerance ratings were made the following spring.Napropamide [2‐(α‐naphthoxy)‐N,N‐diethylpropionamide] was the only herbicide that controlled spur weed almost completely. The control was acceptable with terbutol (2,6‐di‐tert‐butyl‐p‐tolyl methylcarbamate) at 11.2 kg/ha and profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐p‐toluidine] at 6.7 kg/ha. Combination treatments of bensulide [0,0‐diisopropyl phosphorodithioate S‐ester with N‐(2‐mercaptoethyl) benzene sulfonamide] with either benefin (N‐butyl‐N‐ethyl‐α,α,α‐trifluoro‐2,6‐dinitro‐p‐toluidine), terbutol, or pronamide [3,5‐dichloro‐(N,,1,1‐dimethyl‐2‐propynyl)benzamide) controlled more different weed species than when each was applied alone. All herbicides except oxadiazon [2‐tert‐butyl‐4‐(2,4‐dichloro‐5‐isoproxyphenyl)‐Δ2‐l,3,4‐oxadiazolin‐5‐one], butralin [4‐(l,l‐dimethylethyl)‐N‐(l‐methylpropyl)‐2,6‐ditrobenzenamine], and selected bensulide plus benefin combinations affected the green‐up of bermudagrass at one location in March and April. However, turf greenup was as good or better in all treated plots when final ratings were made in May.

Selective Use of Phenmedipham and EP-475 in Michigan for Weed Control in Sugarbeets

The preemergence herbicide treatment often used on hea vier soils in Michigan is a pyrazon plus TeA at 4.5 kg + 6.7 kg/ha (4 lb + 6 Ib/A). In a favorable environment, good control of many broadleaf and grass weeds is obtained. However, frequently an application of a postemergence herbicide such as phenmedipham is needed to con­ trol many of the escaped broadleafweeds or some grasses (1, 3, 4, 5)3 Redroot pigweed is an annual broadleaf weed that phenmediphaLl will not control. EP-475, an analog of phenmedipham, is effective on pigweed (10).

Evaluation of Herbicides for Use in Zero and Minimized Tilled Corn and Sorghum1

AbstractAdequate weed control has been one of the principal problems associated with developing minimized tillage systems. Recent herbicide releases appear promising for solving the weed control problem. We evaluated ten different preemergence herbicide treatments and one postemergence treatment for 3 years for weed control in till‐planted corn (Zea mays L.) and sorghum (Sorghum bicolor, L. Moench). All herbicide treatments were compared on plots that were either disked or nondisked to see if reduction of plant residues improved weed control. All herbicide treatments reduced weed populations and resulted in increased yields compared to the cultivated check. Plots that were disked as opposed to those nondisked were significantly lower in weed yields for 2 years, but were significantly better in crop yields only 1 year.Most of the herbicides gave excellent weed control even though residues of the previous year's crop averaged 5,218 kg/ha and covered 73% of the ground.