Purdue News 
Purdue News
"The fall, up until mid-November, is the ideal time to control broadleaf weeds in turfgrass, because broadleaf weeds are most susceptible to herbicides at this time," says Zac Reicher, associate professor and turfgrass extension specialist. "This autumn, that time is extended a bit because of the unusually dry and warm weather."
Killing weeds in November offers other advantages, too, Reicher says. The turf is growing well enough that it can quickly fill in the spaces where the weeds once were, and there is reduced risk of damaging herbicide-sensitive ornamentals at this time of year
According to Reicher, broadleaf weed herbicides should be applied to the foliage of the weeds when the weeds are actively growing.
"Pick a sunny day with moderate temperatures, no wind, ample soil moisture and no rain in the 24-hour forecast. This will have the maximum effect on the weeds with the least potential of damage to lawns," he says.
A herbicide containing three chemicals -- 2,4-D; MCPP; and dicamba -- will control most broadleaf weeds with one application, Reicher says. Caution must be used when spraying the herbicide around flowers, vegetables, trees or shrubs, because these herbicides can also damage these plants, he adds.
Creeping weeds, such as wild violet or ground ivy (creeping Charlie), in the lawn are extremely difficult to control because they spread through underground stems or root stalks.
"Herbicides are very effective at controlling the foliage but usually cannot translocate to the root or stem," Reicher says. "The violets and ground ivy will often resprout after the foliage is killed."
According to Reicher, these weeds originate in shadier areas where the turf cannot be vigorous and competitive.
"The best method for homeowners is to apply a product that includes 2,4-D. This should be applied preferably in mid- to late fall for maximum control and then possibly again when it is flowering in May."
In addition to using lawn chemicals, Reicher notes that proper lawn care, such as mowing the grass at about three inches tall, fertilizing primarily in the fall to encourage turf growth, and irrigating to improve turf density during dry periods will allow homeowners to use less chemicals.
"Remember, too, that these weeds are tough to overcome and many homeowners will eventually give up this fight," Reicher says. "Many people learn to like the flowers that these weeds produce."
More lawn and turf information, including weekly updates by Purdue turf experts, can
be found on the Internet at http://www.aes.purdue.edu/agronomy/turf/turftips.htm
CONTACT: Reicher, (765) 494-9737; e-mail, zreicher@dept.agry.purdue.edu
Compiled by Chris Sigurdson, (765) 494-8415; E-mail, sig@ecn.purdue.edu
Purdue News Service: (765) 494-2096; e-mail, purduenews@purdue.edu
