Weed and feed is a commercial granulated lawn care product that is designed to improve the quality of your lawn. It contains fertilizer that boosts the production of turf grass in order to choke out weeds as well as an herbicide that is targeted to kill specific weeds such as dandelions and crabgrass.
Fertilizers contain three products--nitrogen, phosphorus and potassium--which is expressed in fertilizers as N-P-K. In all fertilizers, nitrogen boosts the production of foliage and helps increase photosynthesis. Lawn fertilizers are typically nitrogen fertilizers such as a 10-5-5 fertilizer. In order to boost the production of green turf, weed and feed is naturally rich in nitrogen.
Weed and feed also contains an active ingredient to kill broadleaf weeds. These active ingredients may include triclopyr,2, 4-D, dicamba, or MCPP. Triclopyr is a systemic that is typically applied to the leaves of weeds such as creeping Charlie to kill them while leaving grass intact. 2, 4-D is the most commonly used herbicide in the world. It targets dicots (two-seed leaves) and leaves monocots (one seed leaves) behind. Dicamba is used to kill volunteer plants such as bracken or roses in grain crops. MCPP is one of the most common broadleaf herbicides used in weed and feed. It is usually used in combination with one of the other pesticides.
Pre-emergent herbicides are ingredients that are included in weed and feed for use on crabgrass or bluegrass. Typical pre-emergent herbicides include dithiopyr, prodiamine, pendimethalin and oxadiazon. Dithiopyr is sold under the brand name Demension. Prodiamine is often sold under the brand name Barricade. Pendimethalin is used to control weeds in food crops such as potatoes and rice. Oxadiazon can be used around crops such as soybeans or sugarcane.