Apply Weed Control When Seeding?! Yes, You Can! For years, professionals lived by a simple rule when establishing a new lawn or overseeding: never apply weed control as it will limit the ability The OSU Weed Science Group conducts greenhouse, laboratory and small plot herbicide evaluation trials in support of the development of weed management activities in the diverse cropping systems of Western Oregon. Labeled and experimental herbicides are evaluated for crop safety and weed control efficacy in the following crops: Winter and Spring Wheat, Cool-season Grasses grown From April SportsTurf “Q&A with Pamela Sherratt: Q: We are getting ready to overseed our soccer field this spring. What weed control options are there? A: Successfully growing cool-season turf from seed in the spring can be a challenge because the weed pressure is so great, which is one if the reasons why the recommended
Apply Weed Control When Seeding?! Yes, You Can!
For years, professionals lived by a simple rule when establishing a new lawn or overseeding: never apply weed control as it will limit the ability to raise a healthy stand of turf. This meant that weeds had free reign to germinate and compete with the new turf for up to a full month. Then they would need to be controlled once the turf was established.
Now there’s a new product with pre-emergent weed control that you can apply when you seed –whether bare-ground seeding or overseeding.
Lebanon’s ProScape® Starter Fertilizer 21-22-4 with Mesotrione is ideal for use during turf establishment (bare ground seeding, sodding, sprigging or plugging), renovation or overseeding. The mesotrione ingredient is a game changer that offers pre-emergence control of 33 listed broadleaf and grassy weeds. It even controls crabgrass!
The 35% slow release nitrogen from methylene urea insures continuous feeding throughout the early stages of the plant’s life, while the Mesotrione controls weeds for up to 6 weeks. Weeds sprout white and then die quickly without harming the new grass.
This product is a game changer: Healthier new turf with fewer noxious weeds to eradicate later. Invest less effort and get instantly better results.
Get it now from your experts at Central. Contact us for more information.
Willamette Valley Field Crops
The OSU Weed Science Group conducts greenhouse, laboratory and small plot herbicide evaluation trials in support of the development of weed management activities in the diverse cropping systems of Western Oregon. Labeled and experimental herbicides are evaluated for crop safety and weed control efficacy in the following crops: Winter and Spring Wheat, Cool-season Grasses grown for seed, Native cool-season Grasses and forbs grown for seed, Canola, Meadowfoam, Camelina, Clovers and Peppermint among others.
Sharp Point Fluvelin
Weed Science Related Links:
Weed Identification Resources:
109 Crop Science Building
Oregon State University
Corvallis, OR 97331-3002
Office: (541) 737-2821
Fax: (541) 737-1589
Weed control during spring seeding
From April SportsTurf “Q&A with Pamela Sherratt:
Q: We are getting ready to overseed our soccer field this spring. What weed control options are there?
A: Successfully growing cool-season turf from seed in the spring can be a challenge because the weed pressure is so great, which is one if the reasons why the recommended time to do renovation is in the fall. In the real world however, athletic fields are in a constant state of renovation and so seeding is a season-long operation.
Weeds that emerge in spring, like crabgrass, prostrate knotweed, yellow nutsedge, goosegrass and annual bluegrass are particularly troublesome on athletic fields because they can germinate and establish quickly, even on compacted soils. Weed seed present in the soil is laying dormant just waiting for an opportunity under the right environmental and cultural conditions to invade a weakened turf with bare soil. Because weed pressure is so great in the spring and early summer months, it is important that the soil is not disturbed (avoid tilling as this will bring up weed seeds) and that the seedbed be treated with an herbicide that does not adversely affect germination of the desired grass seed.
There are several approaches to using an herbicide during the seed establishment period. Following is a summary of those options, based on years of herbicide trial work by Dr. Dave Gardner. One strategy is to seed in early spring and then after the seedling turf has established, apply an herbicide with pre and early postemergence activity, such as dithiopyr (Dimension, others*). This strategy requires very careful timing, and on most athletic surfaces, overseeding is not a once per year operation. Once the application of dithiopyr is made, as is the case with most preemergence herbicides, future overseeding operations must be delayed according to the label.
In fact, on areas that you plan on seeding or over-seeding in late spring or summer, hopefully you did not apply a preemergence herbicide. If you did, then be aware that almost all of the preemergence herbicides on the market are very effective at controlling not only weed seedlings, but also the seedlings of our desired turfgrasses. Fortunately, there are three preemergence herbicides that are labeled for use at seeding time: siduron (Tupersan), mesotrione (Tenacity), and topramazone (Pylex).
Siduron has been available for use in turf for many years. It is safe for use on seedling turf. Follow the label directions carefully. When used properly, siduron will reduce crabgrass, goosegrass, foxtail, and many summer annual broadleaf weeds by about 80%.
Mesotrione is in a unique class of chemistry and this product has a very diverse label, including pre- and postemergence control of both broadleaf weeds and annual grasses. It also controls sedges preemergence and certain perennial weedy grasses postemergence. One of its key uses is the preemergence control of annual grassy and broadleaf weeds in newly seeded turfgrass. When used as directed, mesotrione will result in nearly complete control of crabgrass, goosegrass, foxtail, and many summer annual broadleaf weeds. But, it will not affect the growth and development of the seedling turf. Most effective use of this product is to apply it to the soil surface right after the seeds have been raked in but before mulch is applied.
You can then begin to irrigate as you normally would to establish seedling turfgrass. Mesotrione is very safe to seedling turf. However, some phytotoxicity has been reported if it is applied to young turfgrass seedlings. If you are using multiple applications of mesotrione as part of a program to control stubborn weeds, such as creeping bentgrass, then you want to avoid overseeding or reseeding the area until you are making your last mesotrione application. In other words, it is better to wait and reseed with the second or third mesotrione application, then to seed when the first round of mesotrione is being applied.
Topramazone is a more recent introduction to the turfgrass market. It is similar to mesotrione in its weed control spectrum and its safety to seedling turfgrass. Make sure to follow the label recommendations carefully.
After the seed has germinated there is a period of time in which your options for weed control become limited. Most postemergence herbicides for broadleaf weed control have language on the label that states that following seeding, the turf needs to be sufficiently established so that it has been mowed three times before the product can be safely used.
All of the herbicides mentioned in this column are good products and can be quite effective. You can help to improve your chances of success by avoiding the 2-4 week period each year that is the peak of germination for the particular weed species that dominate your fields. For example, each of these products is quite effective at reducing weed establishment when seeding or over-seeding in July when weed competition begins to drop off. However, each of these products can produce less than complete weed control if used in mid to late May. This is more likely to be a problem if the May timing is in conjunction with seeding a slower to germinate species such as Kentucky bluegrass. By simply waiting a couple of weeks (or seeding a couple of weeks earlier), weed seed competition may be greatly reduced, which further increases your chances of success when seeding or overseeding.
*Mention of a specific product does not constitute an endorsement over other products that may be similar