best lawn weed killer for a house on well water

Asked September 6, 2019, 1:13 PM EDT

I live in a house with a well and a three acre lawn infested with many, many weeds. I would like to get the lawn in shape, but I'm concerned about herbicides getting into the well. What lawn weed killer would you recommend? As further information, the soil is very sandy, and there are bushes and trees (oak, pine, maple, and apple) that I don't want to damage. I would prefer a solid herbicide so I can use a spreader rather than a sprayer (due to cost), and I would prefer an herbicide that kills existing weeds rather than just preventing new ones from growing. Thanks!

Washtenaw County Michigan

1 Response

Sandy soil is the concern since movement of nutrients, herbicides can move down through the soil. Depth of well is important but also herbicides should not be used near the well head.

All herbicides have on their label an Environmental Hazard Statement, which will tell if the product is likely to leach through the soil - "This chemical has properties and characteristics associated with chemicals detected in groundwater. This chemical may leach into groundwater if used in areas where soils are permeable, particularly where the water table is shallow". There is no easy answer.

First what are your weeds, dandelions, plantain, thistle, or other broadleaf weeds, or are your weeds grassy weeds like crabgrass, quackgrass or bentgrass. Weed killers that kill broadleaf weeds may be specific to them and will not kill grassy weeds. If both types of weeds are present you will need a non-selective herbicides like glyphosate that kills both by going through their leaf and stem tissue but these will also kill good grass also. You need to decide the weeds to be controlled and then to look at the product label to see if the environmental hazard says it moves through the soil. For instance a product label Triclopyr a commonly used weed control has an environmental hazard statement that says in part: "the use of this chemical in areas where soils are permeable, particularly where the water table is shallow, may result in groundwater contamination".

Many fall lawn fertilizers will have weed control (granular form) in them, such as 2,4-D , Mecoprop but what ever you buy needs to match your weeds please read the enivronmental hazard section on the label.

MSU has a site where weeds can be identified at with recommendations for types of herbicides needed to control the weeds.