Welcome to the latest issue of the Home Lawn Care Newsletter from UMN Turfgrass Science! We will provide up-to-date information to address all your lawn care tasks at the times when you need to know.
July 15, 2024: Issue 23
After a few years of managing lawns through drought, Minnesotans are starting to see the effects of a very wet early summer.
What does the above average rainfall mean for our lawns?
Extended periods of high temperatures known as heat stress are often the cause for poor summer turfgrass performance. Normally, these high temperatures are combined with drought. So far this year, above average rainfall combined with the high temperatures means turf is experiencing multiple threats.
Several years of drought left thin stands of turf and abundant dormant annual weed seeds. As a result, this spring there was less competition from turf for light, moisture and space, which encouraged weed invasions. Additionally, the window for pre-emergent application was small due to the warmer spring. The combination of high temperatures and waterlogged soil stressed many lawns, making for a tough spring for weed prevention.
Higher moisture generally means more disease pressure, as the fungal causes of these diseases prefer these conditions. The higher moisture combined with higher temperatures favors many warm season diseases like pythium, rust, dollar spot, leaf spots, and brown patch. The presence of these diseases is normally dependent on the growing conditions of the lawn and how it is managed. Excessive nitrogen from fertilizer can promote some diseases like pythium and brown patch; in these cases, consider reducing nitrogen rates in future fertilizer applications. Other diseases like rust and dollar spot prefer low nitrogen environments. Although lawns having one or some of these diseases could benefit from nitrogen, July is not the time of year to do it. Encouraging the plant to grow from supplemental fertilizer could lead to other problems like excessive growth. Reducing other stresses this summer is the best bet while the lawn grows out of damage from disease until cooler temperatures arrive in September. In most cases, summertime diseases on home lawns will not result in death of the lawn and do not require fungicide applications. If the affected areas are increasing rapidly or if the majority of the lawn is affected by the apparent disease, consider contacting a lawn care professional, or submit a question through Ask a Master Gardener.
In some instances, higher temperatures following a heavy rainfall event can cause etiolation. Etiolation refers to yellow or chlorotic turf that appears to have irregular and elongated growth and is often confused with a disease. This is caused by the turf actually growing too quickly for it to complete its normal physiological functions. It is nearly always non-threatening as the plants will either slow their growth if the high temperatures remain, or growth will resume normally if temperatures lower.
Soil moisture sensors for irrigation scheduling | UMN Extension
Nutrient Loss and Water Quality | Oklahoma State University
Does corn gluten meal reduce weeds in lawns?
Based on research that began at Iowa State University, corn gluten meal has been used for several decades as a natural fertilizer and herbicide in lawns. Corn gluten meal is a byproduct of milled corn and naturally contains 10% nitrogen and 60% protein by weight. It is available in powdered form as livestock feed or granulated forms that are labeled for lawn and garden use. The Environmental Protection Agency describes the corn gluten meal as “generally recognized as safe”, and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) identifies it as a “minimum risk pesticide”, being non-toxic to humans and bees.
Corn gluten meal is a root-inhibiting growth regulator that was shown to be 58% effective in inhibiting common lambsquarters, crabgrass, black medic, and other weeds, compared to several synthetic herbicides that show better effectiveness at around 80% control. Corn gluten meal has reduced length of activity in the soil compared to synthetic preemergent herbicides, and would need to be applied throughout the season to provide season-long preemergent weed control. Corn gluten meal will not control weeds that have already germinated.
This product also makes a great slow-release natural fertilizer with recommended application rates of 0.5-1.0 pounds of nitrogen per 1000 sq ft (the equivalent of 5-10 pounds of livestock feed product). The thicker turf this produces is also an excellent deterrent to weed germination and growth. Some granulated formulations have phosphorus added; remember that in Minnesota phosphorus is not allowed for use unless a recent soil or tissue test indicates that it’s needed.
Corn Gluten Meal Research | Iowa State University
Corn Gluten Meal Profile | Cornell University
Phosphorus Lawn Fertilizer Law | Minnesota Department of Agriculture
Research highlight
If you are reading this newsletter, you probably aren’t thinking about installing an artificial turf lawn. But are these fake lawns a good idea? What do people generally like or not like about using this type of surface? Dr. Michael Barnes, a social scientist in the turfgrass science group at the University of Minnesota has studied these questions and more. You can read more about his work at the UMN Turfgrass Science blog.
A fake grass future? Not so fast! | UMN Turfgrass Science
Events
We will be at these events to answer questions on smart irrigation and lawn care as part of our collaboration with the Metropolitan Council.
- Summer in the Sun at Woodview Park in Coon Rapids, MN on Tuesday, July 16 from 6:30 to 8:00 p.m.
- Victoria Truck Rodeo in Victoria, MN on Thursday, July 18 from 6:00 to 8:00 p.m.
- Sustainability Day in Golden Valley, MN on Sunday, July 28 from 9:00 a.m. to 1:00 p.m.
- Park Discovery Days at Vermont Park in New Brighton, MN on Monday, July 30 from 10:00 a.m. to 12:00 p.m.
- St. Francis Farmer’s Market in St. Francis, MN on Wednesday, July 31 from 3:00 to 7:00 p.m.
- Lake Elmo Night Out at Lions Park in Lake Elmo, MN on Tuesday, August 6 from 6:00 to 8:00 p.m.
- Camden Neighborhood Sunday Market at Dancing Bear Chocolate in Minneapolis, MN on Sunday, August 11 from 9:00 a.m. to 2:00 p.m.
Have a question on a topic we didn’t cover in this email?
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We provide research updates, lawn care tips, info about field days, and more at @UMNTurf.