Tips for controlling whitetop in urban environment

50_whitetopBy Dan Picard, MSU Pondera County Extension Agent

Home owners in Conrad have the usual pesky weeds like dandelions, henbit and black medic, but a few of us have tougher weeds like whitetop in our lawns.

In order to get on top of weeds like whitetop, that start early in the spring, lawn owners need to have a plan and be ready to start their management programs in April and early May when the weeds are still small and easier to control.  There are options that include cultural, mechanical and chemical practices.  It will usually take a combination of management practices for the best results.

The first step is to have a healthy lawn that has adequate fertility.  A thick healthy lawn provides competition and can crowd out many of the weeds. MSU Extension recommends an application of lawn blend fertilizer in split applications around Memorial Day, Labor Day and Columbus Day.  The rate for the split application should be no more than 1 1/2 pounds of actual nitrogen per 1000 square feet each time you fertilize.

Other cultural practices include planting and maintaining competitive grasses, a good fertility program and maintaining an adequate watering program.  Watering will depend on the time of the year and texture of the soil, but can range from 1 inch per week in the spring and fall to as high as 2 ½ inches per week in the mid-summer.  Thorough, but less frequent watering promotes deeper root systems and will make your lawn more drought tolerant.  Soil sites that are hard, like boulevards or heavy thatched lawns, will greatly benefit from core aeration.  Core aerate each spring when the grasses are actively growing really opens up the soil, improves water infiltration, and root health.  Some lawn owners have had good luck over seeding those areas with grass right after plugging.  The grass seed germinates and grows quickly out of the holes as tufts of grass.  This can really help thicken up a stressed lawn area. Also, it is generally advised to not mow your lawn shorter than 1 1/2 inches.

Mechanical practices for weed management include mowing to help slow the spread and reduce the seed production of whitetop.  Mow the white top patches during the bud stage and repeat when the plants rebud.  The effectiveness of mowing can be increased by planting competitive perennial grasses. Mowing may increase the effectiveness of subsequent herbicide applications. Hoeing small spots at 3 to 4 week intervals for up to 2 years may deplete the root reserves of the whitetop.  Soil must remain moist between hoeing so that plants regrow and deplete the whitetop root reserves.

The use of herbicides in lawns is another option. For best results apply herbicides before the weed flowers.  There are a number of retail products available in town that is labeled for lawns.  Any of the products that have a combination of 2,4-D, MCPA, and dicamba will control most broadleaf weeds.  Follow all label recommendations for application, including use of a surfactant, to ensure effective weed control. Watch for drift to sensitive plants in flower beds and garden areas and trees growing in the lawn area.  Lawn owners will need to retreat the whitetop spots and are urged to follow the herbicide label guidelines on rates and the number of times each year the product can be applied. Areas in the lawn or boulevard that have sparse grass stands will always have high weed pressure.  Those sites need to have the weeds spot sprayed or managed by an extended hoeing program.  Reseed those areas with a competitive grass and water to insure good establishment. Lawn owners that do not want to apply herbicides themselves can contact a local licensed lawn professional like Golden Triangle Property Services LLC and have them provide a quote on a lawn-boulevard weed management program.  At this time they are the only city licensed business listed for this service in Conrad.  Check the City Office for a current list of licensed lawn care providers.

For more information on general lawn management contact the MSU Pondera County Extension Office at 271-4054 and request a copy of the Montana State University Extension MontGuide “Successful Lawns,” a self-learning resource that will help you better understand proper lawn management.   Also, watch for dates and times for Lawn Management and Sprayer Calibration Workshops at various business in Conrad this spring.