Everyone is saying this is a very unusual spring. And it is! Everything is ahead of schedule, including weeds. If you are like me and don’t like these plants that are out of place that we call weeds, do things correctly and save time and money.
1. When using any kind of weed killers, the plant you want to get rid of must have maximum foliage for it to be most effective. In the lawn this means:
A. Do not apply a weed killer right after mowing. Mow, then wait a minimum of two to three days to apply the weed killer.
B. Do not water right after applying a weed killer. Wait a minimum of two days before watering.
C. Wait at least 2 days after applying a weed killer before mowing. This gives the weed a chance to grow after mowing and to have good foliage for the weed killer to work on. Wait and give the weed killer time to work before you water and wash it off or mow it off.
2. Some weed killers including Trimec, 2-4-D, Glysophate (Round-up, Kleen-up, and Hi-Yield Killzall II Weed and Grass Killer) do not work to maximum if the air temperature is below 55 to 60 degrees F. when applied and for 4 to 5 hours after applying. The product will work, but much slower if the temperature is lower.
3. There are some weed killers that will work when the temperature is 45 to 50 degrees F. and above and for 4 to 5 hours after applying. This includes Bonide “Super Brush Killer” – a weed killer that, when applied according to label directions, will not hurt bluegrass or turf type tall fescue grass.
4. If you are using a granular weed killer such as a Weed and Feed, the foliage of the weed should be growing vigorously when the granules are applied. For maximum effectiveness the granules need to stick to the weed and stay on it as long as possible. Many weeds have a slick, shiny surface which makes this difficult. One solution is to water lightly just before application so the leaf is damp. Or put on in the early morning when there has been a heavy dew so the granules will stay on the leaf. Do not water or mow for a couple days after application so the granules do not wash off or are cut off before they have done their job.
That’s why I prefer a liquid spray (with large drops so it is less likely to drift) over a granular formulation. I spot treat my weeds and have not used a hose-end sprayer for weeds for years. The hose end sprayer is hard to control and kills too many desirable plants. A whole yard spray is hard on the environment and is usually not needed if you do things correctly each year. Watch your cultural practices so the grass is not under stress, as grass under stress is more likely to get insect and fungus damage.
5. Dandelions, ground ivy (creeping charley), and winter annuals such as henbit are best destroyed in the fall. Triclopyr is the chemical of choice for henbit and ground Ivy. This can be found at most full service garden centers by itself or found in some multi-chemical formulations.
(A) Apply a fall pre-emergent herbicide between mid-August and Sept. 15, to stop or reduce seed germination of fall-germinating weeds, especially henbit. (Some locations in South Central Nebraska will probably be a week earlier than in Lincoln.)
(B) Apply a liquid herbicide sometime between Sept. 1 and Oct. 15 for weeds still growing such henbit, ground ivy (creeping charley), and dandelions. Apply a second application about 10 days to 2 weeks later, and a third application about 2 weeks later. The first application will weaken the plant; the second and third will put the final nails in the coffin. It will be cool during the second and third applications so use the appropriate herbicide and apply on a fairly warm day. The desired temperature must be at the time of application and for 4 to 5 hours thereafter for maximum effectiveness, and the wind speed below 6 miles per hour to prevent drift to desirable plants.
6. Do not worry about crabgrass in the fall as it is an annual and will die with the first hard frost.
7. Apply a pre-emergent herbicide every next spring at the proper time for crabgrass and other weeds that germinate in the spring. A second application of pre-emergent 6 weeks later (about June 30) will probably be needed for foxtail, and spurge that do not germinate tell June, and for late germinating crabgrass and other weeds. By mid-June, when these weeds germinate, most pre-emergent herbicides are worn out or so weak they are not effective. This saves spraying for the weeds after they are growing.
8. Cultural practices that help to reduce stress on your grass include mowing, watering, and application practices.
A. Mowing: Do not mow shorter than 2.5 inches year around. Never take off more that 1 /3 of the blade at one time and do not catch your clippings unless used in compost pile or as mulch.Grass clippings do not cause thatch. Thatch is caused by over watering, over fertilizing, and mowing lawn too short. Thatch is actually roots. Control thatch by core aerating at least once a year.
B. Watering: Do not water after 2 p.m. to help prevent disease problems. Water deeply by applying at least one-half inch of water then wait for lawn to use that water before watering again. Use a tuna can, a cat food can, or any straight-edged container to measure how much your sprinkler puts out. If you have an underground system, check it at least once per month for problems.
C. Application of lawn products: Read the manufacturers label before application and follow all recommendations.