Labor Day fertilization and rust on turf

Weather this summer resulted in most lawns growing vigorously throughout the entire summer. As Labor Day weekend approaches, a fertilizer application will ensure the turf maintains density and competes with pests such as weeds and rust.

As summer quickly fades into the rearview mirror, late August or early September is a perfect time for a fertilizer application. Most lawns made it through this summer very healthy due to cool temperatures and ample precipitation. The recent stretch of high temperatures and a brief period without rain has slowed turfgrass growth in some areas.

Almost on cue, as growth slows in late summer, rust sightings become common. Rust is the disease homeowners notice when their white tennis shoes and white poodles traverse through the lawn and come back in looking less than white. There are several types of rust: stem rust, crown rust, leaf rust and stripe rust. As a general rule in almost all cases, rust is considered a cosmetic turfgrass disease that, although it may discolor the turf, will not result in turfgrass death.

Rust on turf
Rust on turf. Photo credit: Kevin Frank, MSU

If you find yourself inundated with a bad case of rust, make sure to keep up on your mowing and a fertilizer application around the Labor Day (Sept. 2) weekend should help stimulate turf growth that will help diminish the impact of the rust. Read more details on rust from Michigan State University Extension.

Mower deck
Mower deck after mowing a really rusty lawn. Photo credit: Kevin Frank, MSU

For the Labor Day fertilizer application, choose a fertilizer that has slow release nitrogen in the analysis such as sulfur-coated urea, polymer-coated urea or methylene urea. I would generally avoid applying 100 percent fast release nitrogen fertilizers such as urea at this time of year as they can force too much top-growth that results in more mowing and reduced rooting. Remember that phosphorus restrictions in Michigan limit phosphorus applications in most instances except when a soil test indicates need and also impacts the use of many natural organic fertilizers that contain phosphorus. Read more on phosphorus fertilizer restrictions in Michigan.

Fertilizing around Labor Day will result in moderate top-growth and give the turf some extra energy to develop roots and continue to compete with weeds that have been particularly troublesome this year.

Dr. Frank’s work is funded in part by MSU‘s AgBioResearch.

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