Spring (April to mid-June) and Fall (Mid-September thru October) provide the best opportunities for lawn herbicide applications – you will get the best weed kill and the least damage to your lawn. Repeated applications, as allowed by manufacturer’s directions, can provide the best kill. Never treat turf weeds in the summer, if possible, as high temperatures combined with herbicide applications can result in turf damage. Always start with the lowest possible rate. If you are new to the product, testing a small, out of sight area is a safe approach.
General weed treatment guidelines: Treat healthy weeds, irrigation before herbicide applications but NOT after, don’t mow before treatment, maintain a healthy stand of turf via a proper irrigation and fertilization program, repeat treatments as necessary according to manufacturer’s directions.
Apply pre-emergents in the spring before germination occurs. This is especially important for pests such as Spotted Spurge, a summer annual, it dies off in cold weather, after setting seed). If Spotted Spurge is not controlled in early spring, apply a post emergent early in the season to prevent seed set.
To control perennial weed grasses, spot spray in the spring when flowering begins and repeat every 6-8 weeks thereafter, as new growth appears, until the fall. To minimize disturbing the soil, slit seed areas where soil is visible.
Common turf weeds include False Dandelion, Common Dandelion, White Clover, Black Medic, Oxalis, English Daisy, Mousear Chickweed and Lawn Violet.
False Dandelion, Woodsorrel, English Daisy, Lawn Violets and Clovers are all difficult to control. Fall treatments tend to be most effective as long as repeated treatments are applied. Spring treated plants often recover.
Lawn Violets are most common in shady or weak lawns. Though difficult to control, fall herbicide applications are most effective. Keeping your turf healthy through regular fertilization and irrigation, along with overseeding as needed in shady areas, is your best bet.
Black Medic is very responsive to spring treatments – apply before or during flowering.
Ground Ivy – treat in the fall, between the first of October and the first of November.
Mousear Chickweed is very responsive to herbicides; treatments can be applied any time of year.
Annual Bluegrass – Apply a pre-emergent in spring. Apply post-emergents in the fall.
Nutsedge – new growth appears in late spring. Treat in late spring or early summer. Grow from tiny tubers, which may live only one year or may persist as long as three years. Prevent Nutsedge by maintaining a healthy turf. Hand- dig any visible Nutsedge to remove entire plant before it has a chance to reproduce. If you have an established stand of Nutsedge, plan on applying multiple herbicide treatments over several years. Fall treatments are typically unsuccessful. Watering before treatments may increase success. Be sure to forgo any mowing at least 5 days before treatment to ensure complete coverage of entire plant – thorough coverage is essential.