Sorry for missing last week, personal issues interferred.
Crabgrass Control and prevention
The second most problematic weed behind dandelions in lawns is crabgrass. As with most problems, prevention is better than curing. If your lawn is mostly free of crabgrass, never, never let crabgrass go to seed. Weed seeds can last for many years in the soil. Problems in lawns but not ornamental beds, or ornamental beds but not lawns will be a problem in both if either is left uncontrolled.
Preventing crabgrass is as simple as buying and correctly applying crabgrass preventers to your lawn and ornamental beds. Some of the many products that may be used are (listed in order of choice by the The Garden Doc):
(I apologize to companies whose products are not listed, I intentional did not list many store brands)
Products with Dimension (dithiopyr) Can be used in lawns and ornamental beds.
- Crabgrass Preventer with Dimension is a great product from Green Light.
- Vigoro Weed Stop Crabgrass & Weed Preventer (Dimension)
- Ace Green Turf Crabgrass Preventer & Lawn Fertilizer (Dimension) (36-3-4)
- Sta-Green Crab Ex (Dimension)
Products with Barricade (prodiamine)
- Penningtons Crabgrass Preventer, a fertilizer with Barricade.
- Ferti-lome All Season’s Crabgrass & Weed Preventer (Barricade) (16-0-8)
Combination products
- Amaze from Green Light is a combination of Surflan (oryzalin) and Balan (benefin). It can only be used in warm season grasses, Bermudagrass,
St. Augustine - Ferti-lome Crabgrass Preventer (Team) (20-0-3) Products with Team, a combination of Balan and Treflan (Chemical name is trifluralin)
Products with Pendelum (pendimethalin) Can be used in lawns
- Scott’s Crabgrass Preventer - (Pendelum) (32-3-8)
- Scott’s Halts
Products with quinclorac are used for post emergence control but quinclorac does have about 45 days of residual control. This is not sufficient for good crabgrass control.
There is one chemical, Tupersan, (siduron) that can be used when seeding new grass.
- Preen New Lawn Crabgrass Control (Tupersan) (11-23-10)
The following describes each chemical with pros and cons (again in the order of choice by The Garden Doc). Descriptions mostly provided by Missouri Botanical Garden
Dimension® (dithiopyr) provides superior pre-emergent control of crabgrass and many other grassy and broadleaf weeds in turf grass and other ornamental plantings. It can be applied several weeks later than other products and still give effective control. It is less of a root inhibitor that some other products so damage to new seedlings is minimal. Barricade® (prodiamine) is one of the longest-lived of the chemicals listed and is sometimes even applied in the fall for pre-emergent control of crabgrass and many other grassy and broad leaved weeds. Since it has a long residual, grass seedling failure from this product is a common pitfall.
Amaze contains oryzalin which has the longest soil residual of these products. Balan gives excellent control of early crabgrass and oryzalin gives very long residual control. However, Amaze can only be used in warm season grasses.
Team® is a product that gives good early control with the Balan and longer acting control with the Treflan. Team is a traditional combination of a 2:1 ratio of Balan to Treflan. This product has a distinctive orange/yellow color but is not as prone to staining as Pendelum.
Pendelum® (pendimethylin) is another commonly used, cost effective pre-emergent crabgrass control. It has similar chemistry to Team. Its granules have a characteristic yellow/orange color and may produce staining on sidewalks and driveways. It is not particularly long lived in the soil. Pendimethylin also acts as a root inhibitor so it may have negative effectives on newly emerged turf grasses. The Garden Docs additional comment – With high rainfall Pendelum can wash out of the crabgrass germination zone.
Tupersan® (siduron) is the only crabgrass pre-emergent chemistry that will allow cool season grasses to germinate. It is pricey and products with Tupersan are often hard to locate. It has a very short residual in the soil, so it must be followed up with another application or Dimension may be used for a follow-up application as long as all of the grass seed is germinated. (The above chemical descriptions are mostly taken from the
The majority of chemicals above come from the family of chemistry called dinotroanilines. The following all have a very yellow color and are very capable of staining. Their staining ability is pendimethylin> trefluralin=oryzalin=benefin> prodiamine. I once dropped some pendimethylin on a white pickup tailgate and the stain drops were there for as long as I had the pickup. Dithiopyr does not stain and is a different class of chemicals. All products need to be activated by applying about 1/4 to ½ inch of irrigation or get lucky and have a good rain within 2 weeks of application.
The length of time each will control crabgrass is oryzalin>prodiamine>dimension>trifluralin>pendimethylin>benefin.
Crabgrass germinates when the soil reaches 50 degrees or warmer for 5 days at the ¼-inch level. This may occur in February in the south and early May in the northern states. A rule of thumb is crabgrass germinates when the forsythia bloom.
Dimension, Barricade and Amaze give season-long control of crabgrass from a single application. You need to select a rate that fits the season in your area.
Do I apply a crabgrass preventer with a fertilizer? Answer is your choice. Often the fertilizer used as the carrier may not be the fertilizer you should choose for your lawns needs. Or you may make the crabgrass application at the wrong time for fertilizer in your area.
Whatever choices you make for crabgrass control, remember to always read and follow the label directions. Many lawn care givers do nothing other than mow the crabgrass which will spread seed and insure a good crop of crabgrass next year and for several years to come.
Discussion on postemergence crabgrass control will come in late spring.
Thank you for goods content
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