COLUMBIA, Mo. – Be mellow until the forsythia turns yellow.

That’s the advice from University of Missouri Extension plant pathologist Lee Miller for applying crabgrass pre-emergent herbicides to lawns.

“The forsythia bloom has been used as a phenological indicator on when to apply pre-emergent herbicides and it’s a fairly easy and obvious sign,” he says.

Another method of timing pre-emergent herbicides to monitor soil temperature, waiting until it reaches 55 F at the 2-inch depth, Miller says. Soil temperatures recorded by a statewide weather station network, Missouri Mesonet, are available at agebb.missouri.edu/weather/stations.

Don’t succumb to the “white jug” disease in the spring by trying to spot treat a lawn with glyphosate, the active ingredient in Roundup, Miller says. Glyphosate is a nonselective herbicide, killing both the lawn and weed. This creates opportunities for any plant, especially weeds, to get into the treated area during the summer.

Remember that Missouri spring is chaotic, and most years much of the state still has a frost or two to experience before mid-April, Miller notes. You can find historical data on MU’s Missouri Frost/Freeze Probabilities Guide, ipm.missouri.edu/FrostFreezeGuide, which can be handy to guide plant management and establishment decisions.

To sum up, patience is the lawn owner’s best tool in early spring. In the meantime, Miller recommends these March lawn chores:

• Rake leaves off of lawns. Leaf coverings smother turf roots and cause bare spots in lawns. Removal helps green-up lawns and warm the soil.

• Start your mower to make sure the battery and other parts work. Sharpen blades if you did not do so after the last mow of fall.

• Check for moles. For control measures, see the MU Extension publication “Controlling Nuisance Moles” at extension.missouri.edu/g9440.

• If you absolutely need to overseed bare spots in lawns, do it now. “Be first out of the gate. April is too late,” Miller says. Seeds will survive even if snow or frost covers them, but expect a higher rate of attrition than in fall seeding and compensate with a higher seeding rate.

• If you haven’t had a soil test in the last five years, you can send samples to MU’s Soil and Plant Testing Laboratory to see what you’re dealing with. Visit extension.missouri.edu/programs/soil-and-plant-testing-laboratory for more information.