Several broadleaf weed herbicides are available. Companies work diligently to design attractive packaging and special formulations to entice us to purchase their products. Given the right conditions and proper use, most will give acceptable results. There are just a few pitfalls to avoid.
Formulations of 2,4-D: This is the most common broadleaf weed herbicide available to homeowners. Yet, not all 2,4-D is the same. Some are amine salts and some are esters. 2,4-D ester is usually more effective on harder to control weeds but when temperatures rise (above about 80° F) they tend to volatilize and drift to non-target areas, causing collateral damage. The take home message is to use ester in cooler weather and amine when it gets hot. Under active ingredients, look for something like dimethlamine salt (amine) or 2-ethylhexyl ester of 2,4-D (ester). Esters will also typically be identified as LV4 or LV6.
What ‘Weed and Feed’ will and won’t do: This really depends on what the active ingredients are that are listed on the label. Mostly they are used for general broadleaf weed control like dandelions and clover with 2,4-D, MCPP and/or dicamba. If it is going to control annual grasses like crabgrass and cheatgrass, it needs to have something like quinclorac or pendimethalin. Undesired perennial grasses like quackgrass will not be affected.
Field bindweed and Canada thistle takes persistence to control. Both of these have aggressive root systems that are difficult to eliminate. There is no chemical available that will provide the one shot control we would like. Products containing dicamba provide some of the best results but the real key is dogged persistence and repeated yearly efforts. Over time root reserves will be depleted and acceptable control can be achieved. A new arrival on the scene is Confront herbicide that can be used on lawns and is much more effective on thistles. The active ingredients in Confront, as well as dicamba, have relatively long residual activity so pay attention to what the label says.
Know your weeds for better control: The goal of annual weeds is to produce a seed. Thus, the goal of controlling these weeds should be to prevent that seed. Regardless of the treatment method, treating early is key. This can be accomplished with pre-emergence products that prevent seed germination or simply applying a contact or systemic herbicide before viable seed is produced. If your problem weeds are perennial like common mallow, bindweed and Canada thistle, fall is the best time to provide lasting control.