Herbicides for Soil

Weeds, generally defined as plants that you simply do not care to encourage in your yard, are often described by scientists as plants that display an extraordinary tenacity for survival. Discouraging these dastardly creatures from your yard may prove frustrating. Herbicides, or chemical treatments that are used to control weeds, are often necessary for full weed control. Soil herbicides are dug into the soil before weeds occur or before planting. Non-soil herbicides are sprayed directly onto weed foliage.

Fall Bed Application

Fall bed application of herbicides is performed before weeds emerge. Napropomide controls most annual grasses. It should be dug into soil 1 to 2 inches to prevent volatization, or conversion from solid or liquid into gas. Metribuzin is another fall herbicide. Used for broadleaf control, planting should not be done for four months after application to prevent injury to crops. Oxyfluorfen is another herbicide indicated in control of broadleaf.

Pre-plant Application

Effective against nightshade and many other weeds, metam sodium must be applied when soil is loose and free of clods. Soil must be moist upon application. Metam sodium is in the fumigant category. Fumigant herbicides, because of their effect on crops and the surrounding environment, should be considered only as a last resort. Metolachlor is ineffective against emerged weeds. If not applied during the fall beds, napropamide can be used for broadleaf and annual grass control. Trifluralin can be applied only when transplants are used. It controls annual grasses and broadleaf as well as hinders the activity of seedling field bindweed. Also useful only with transplants, pendimethalin requires irrigation upon application. It controls annual grasses and broadleaf and partially controls dodder.

Post-plant Application

Rimsulfuron and Metolachlor are applied after planting. Rimsulfuron controls many weeds including most nightshade species, pigweeds, lambsquarters and others. Metolachlor controls yellow nutsedge.

Layby Application

Layby application addresses the time after planting but before weeds emerge. Many herbicides can be utilized with great effectiveness at this time. Trifluralin can be used at this point to control annual grasses, broadleaf and seedling field bindweed. Eptc is helpful in control of a wide variety of weeds including hairy nightshade, johnsongrass seedlings, yellow nutsedge and many annuals. DCPA can be used after weeds have emerged. It gives partial control of dodder if applied before dodder emerges. Metolachlor can be used now to control yellow nutsedge. Pendimethalin can be used with direct-seeded plants and transplants. Some form of irrigation is required after application to move the herbicide into the upper soil layers where weeds germinate. Pendimethalin controls many annual grasses and broadleaves and partially controls dodder. With most of these herbicides, be wary of contact with established plants. Follow all herbicide instructions. Be aware that various plants may not work well with a particular herbicide.

Keywords: herbicides, preplant application herbicides, postplant applicationherbicides, layby application herbicides, fall-bed application herbicides

About this Author

Andrea Peck has been writing since 2006. Her work has appeared in "The Rogue Voice," "Information Press" and "The Tribune." Her writing focuses on topics about gardening and the environment. Peck holds a Bachelor of Arts in mathematics and a minor in biology from San Diego State University.