Weed Control in Turf
Summer is upon us and we have been experiencing a wonderful stretch of warm weather where we can be out enjoying our lawns and landscapes with friends and family. As we’ve been playing kickball with the kids we may be noticing more than normal weeds in our lawns. I thought it might be helpful to write about broad-leaf weed control in turf so we can understand more why there might be more weeds this summer.
The primary objective of every good turf weed control program is building a healthy stand of turf. The healthier and and thicker the grass, the less opportunity we have for weed germination. The weather we have been having this summer (to date) in northwestern Vermont has not been ideal for cool-season grass development. We are experiencing borderline drought conditions and have had a slightly warmer than average temperature. Cool season turf grows best up to 75 to 78 degrees Fahrenheit. When the grass is less vigorous there is opportunity for weeds that are better adapted to these climatic conditions to invade the turf.
When the turf isn’t healthy or other conditions prevail that allow for weed growth we need to enhance the turf health strategy with some help from some selective herbicides. Selective herbicides are those that can be applied to your lawn grass that will kill out the weeds while not killing the grass. Round-up is a non-selective herbicide that will kill grass. The only time Round-up should be used against turf weeds is during a completed turf renovation scenario–a blog post for another time. There are many selective herbicide blends and brands. Each blend has a series of weed targets that it will effectively control and it is important to match the correct herbicide to the correct weed pest to minimize the amount of herbicide applied. Within the blends there are options on formulation either ester based or amine based. In layman’s terms oil based vs. water based. The ester formulations (oil based) are the most effective at the lowest dosage, but cannot be used in temperatures above seventies because they will volatilize. The amine formulation (water based) can be used all summer. The bottom line for all herbicides is that the weed needs to be actively growing to take in the herbicide at any dosage. In the heat and drought many plants slow down growth and “close-up” to reduce the loss of their structural water to the atmosphere. This slow down also drastically reduces the intake of the herbicide into the weed and thus will reduce efficacy of the herbicide. So the hot dry weather has been doubly difficult for weeds in the turf. Don’t despair.
If this describes your lawn and your struggle with weeds there are options. First–hire a licensed professional. In the state of Vermont you must be licensed to commercially apply pesticides. This includes all applications including “I bought this at Home Depot.” Second, work with a local company that knows turf care and local soil conditions and doesn’t just want to sell you on a program. Third, analyze the program–does it focus on turf health? How and when to they control weeds? Is that the best weed control method for the best efficacy at the lowest input level?
We are fast approaching the best time of year to get your lawn back into shape–fall weed control, fall fertilization, full lawn renovation (seed or sod), and aeration and overseeding. All are key strategies in winning the war on weeds. We would love to talk to you about how we can make your weed control in turf more effective with less inputs.
