Want to kill weeds before they start? Try our Pre-emergent Weed Control lawn treatment OSU research found corn gluten meal not effective in a study as a pre-emergent herbicide in shrub beds and on lawns.
Inhibitor 18-0-6 Pre-emergent Weed Control
Weeds can distract from your lawn’s appeal and deprive grass of nutrients and water needed to thrive. That’s why Natural Alternative® offers pre-emergent weed control lawn treatment to help fight off pesky weed invaders before they become a nuisance. Natural Alternative® Inhibitor 18-0-6 Pre-emergent Weed Control fights all types of weeds and can be spread directly onto established turf to help prevent crabgrass and other annual weeds.
We’ve got you covered
Our Inhibitor can be used on a variety of grass types, including all Natural Alternative® seed selections. Inhibitor’s pre-emergent lawn treatment also includes a mix of nitrogen and potassium to help your lawn thrive while preventing weed emergence. Our Inhibitor offers control against annual grass weeds like crabgrass, goosegrass, foxtails and more. It’s time to enjoy your outdoor space without being burdened by invaders sprouting up in your lawn.
Summer Lawn Weeds
info Application Instructions arrow_drop_down_circle
When to Apply
Successful pre-emergence control of the annual grass weeds listed on this label requires proper timing of application. Apply this product 1 to 2 weeks prior to the germination of annual grass weeds. If application timing does not coincide with the normal germination period of any of the annual grass weeds listed on this label, weed control results may be erratic or poor. Weed seeds typically begin to germinate when soil temperatures reach 55 degrees Fahrenheit (3 to 5 days of 60-65 degree weather can change your soil temps). Typically applied mid-march in most areas, gauging your weather is the best practice when applying pre-emergents. Remember if you can see the weed, pre-emergent controls will not help. Apply before a light rain or lightly water the product in.
Apply 3 to 4 lbs. per 1,000 sq.ft. – If you have an issue with weeds, we recommend 4 lbs. per 1,000 sq.ft. as a treatment and 3 lbs. per 1,000 sq. ft. as a preventative.
Things to remember when controlling weeds:
- Anytime you treat for weeds it is important to make sure you overseed the lawn or the area the following season.
- Weeds love weak spots in the lawn, if you are treating weeds in an area that is already weak and your remove more weeds you are creating the perfect spot for more weeds. To keep a healthy, thick and growing lawn it takes work especially in the beginning. Control your weeds, continue to fertilizer through each season and overseed when it is best for your area for best lawn results. Once your lawn is doing better after all of your hard work, weed controls aren’t always necessary so you can focus on fertilizing at least 3 times a year (we recommend 5 application) and spot seeding in any areas that may need it after possible seasonal damage (seeding in Fall is best, spring if needed).
Don’t use Inhibitor on newly seeded lawns. You can seed the following season (Control in the spring, seed in the fall).
Weeds controlled when applied prior to weed germination:
Annual Grasses controlled: when applied prior to weed germination
- Annual Bluegrass
- Crabgrass (large, smooth)
In areas where germination of the annual weed grass species continues for an extended period of time, make a second application at the recommended rate 8 to 10 weeks after the first application on cool season turfgrass and 10 to 12 weeks after the first application on warm season turfgrass.
General Use Precautions and Restrictions:
- Do not apply this product to golf course putting greens.
- Do not apply this product through any type of irrigation system.
- Any cultural practices that disturb the soil, such as aeration or verticutting, should be done prior to application of this product.
- Do not apply to overseeded turf within 60 days after seeding or until after the second mowing.
Specific Use Restrictions:
- Do not make more than 2 applications totalling 11 pounds of this product per year on turfgrass.
- Maximum single application rate: 8 pounds per 1,000 square feet.
- Minimum Re-treatment Interval: Cool season turf – 56 to 70 days; warm season turf – 70 to 84 days.
Download our spreader settings sheet to find proper settings for your spreader.
Corn gluten meal did not prevent weeds from germinating in OSU study
CORVALLIS, Ore. – Corn gluten meal is a natural substitute for a synthetic “pre-emergence” herbicide and has been advertised as a more environmentally friendly way to control weeds.
A pre-emergent herbicide is one that kills seedlings as they germinate. Pre-emergent herbicides generally have to be applied and watered in before weed seeds germinate. Other herbicides, such as glyphosate (e.g. Round Up) kill plants after they have emerged.
A by-product of commercial corn milling, corn gluten meal contains protein from the corn. It poses no health risk to people or animals when used as an herbicide. With 60 percent protein it is used as feed for livestock, fish and dogs. It contains 10 percent nitrogen, by weight, so it acts as a fertilizer as well.
The use of corn gluten meal as an herbicide was discovered by accident during turfgrass disease research at Iowa State University. Researchers noticed that it prevented grass seeds from sprouting. Further research at Iowa State showed that it also effectively prevents other seeds from sprouting, including seeds from many weeds such as crabgrass, chickweed, and even dandelions. Components in corn gluten meal called dipeptides are apparently responsible for herbicidal activity.
Researchers at Oregon State University were not able to duplicate research results reported by Iowa State researchers, said OSU turf grass specialist Tom Cook. A former graduate student, Chris Hilgert completed his masters thesis by investigating corn gluten meal use as a pre-emergent herbicide in shrub beds and on lawns.
In their trials with corn gluten meal, Hilgert and Cook found the following:
Corn gluten meal did not control any weeds in any trials under any circumstances over a two-year period. They found no evidence of pre- or post-emergence weed control in any of their trials. Because it contains 10 percent nitrogen, corn gluten meal proved to be a very effective fertilizer, causing lush, dense growth of turfgrass and of weeds in shrub beds.
James Altland, nursery crops specialist at OSU’s North Willamette Research and Extension Center in Aurora, spoke to his observations when corn gluten was used in plant nurseries as a pre-emergent herbicide.
“I’ve seen nursery situations where the applied product caused a bad odor, as do some herbicides, and attracted rodents,” said Altland. “In nursery situations where the goal is complete weed suppression, my overall impression is that it doesn’t work that well.”
“My overall impression has been that in turfgrass it provides a lot of nitrogen,” added Altland. “Thicker, denser turf from high nitrogen rates will reduce weed numbers alone, without the help of herbicides.
“Applying 20 pounds per 1,000 square feet of corn gluten meal would be equivalent to two pounds of nitrogen per 1,000 square feet. That’s a lot of nitrogen! Applying that much nitrogen is not good for the environment. It doesn’t matter if it’s a ‘natural’ fertilizer or not. That nitrogen will ultimately be converted to nitrates, which potentially could leach into groundwater.”
It is not clear why the commercial version of corn gluten meal used in OSU trials was not effective, said Cook. One possibility is that the product as formulated for sale has a short shelf life and loses potency during manufacture, shipping and storage. Further research needs to be done to test this hypothesis, he said.
If you want to discourage weeds from germinating and growing in your garden beds over the winter, try adding mulch to soil surfaces. Use a minimum of three to six inches of composted material. Tuck mulch up to the shoulders of your perennials, but don’t cover the growing crown until freezing cold weather sets in. If you cover plant crowns too soon, they may begin to grow under the mulch and could be killed when temperatures dip.
Shredded bark, leaves, mint hay, wood chips, or yard waste all offer benefits. Large chunky material such as fresh clean wood chips and bark nuggets work best for weed control, as they are low in available nutrients so won’t fertilize germinating weeds.
Avoid mulching with hay or with ryegrass straw. Their seeds will sprout to create an unnecessary headache for you in the spring. And don’t use grass clippings from a lawn treated with a weed-and-feed preparation. The herbicide in the clippings can damage your shrubs.
A low-nutrient mulch such as well-rotted sawdust will benefit shrubs such as roses, azaleas, rhododendrons and hydrangeas. Lilies, dahlias and spring bulbs will do better with this type of mulching also. But be aware that composted sawdust or other fine organic material may contribute to weed growth.
Caneberries benefit from higher-nutrient mulches such as composted manure. Dormant vegetable beds can use a six-inch blanket of manure and leaves. Rhubarb and asparagus beds do best covered with a mix of well-composted straw and manure.
Over the winter, the composted material will mix with the soil, so a second application of mulch in March or April will keep your garden soil in better condition.