Mesotrione: Eliminating Weeds During Spring Seeding

Establishing pre-emergent control over weeds will make caring for customers’ lawns and sports fields easier as the year progresses. Doing this during spring seeding, however, can be difficult. Weeds normally germinate and grow faster than newly planted grass seed, and many pre-emergent herbicides like dithiopyr and prodiamine cannot be used immediately after seeding, as they would hinder seed from germinating properly, preventing new establishment. That means applications have to wait until around a month after seeding, which gives weeds plenty of time to grow—not something lawn care customers or sports turf managers want.

Mesotrione is different. It can be applied immediately.

What is Mesotrione: How it Works on Newly Seeded Grasses

Pre-emergent control over weeds on newly seeded areas, including hard-to-kill weeds like goosegrass and crabgrass, can be accomplished with mesotrione.

Mesotrione, unlike other pre-emergents, lets cool-season grass seed germinate while it works to prevent annual grassy and broadleaf weeds from germinating. It also has post-emergent qualities and can kill existing  grassy weeds. Unfortunately, warm-season grass growth is inhibited by mesotrione, so only use it when seeding with cool-season grass seed. It can be used when overseeding and on bare-ground areas.

Standalone Products or Starter Fertilizer

Mesotrione can be applied either through a liquid formulation like ArmorTech Trione, or through a starter fertilizer containing mesotrione, like The Andersons 21-22-4 with 0.08% mesotrione.

With a mesotrione-infused fertilizer, weed control and starter fertilizer come in the same package. A liquid formulation like Trione should be used in conjunction with a starter fertilizer to ensure the new grass will be able to easily access nutrients.

Although using these products may result in a small increase in input costs, they will undoubtedly keep weeds away and customers, crews, and players happy. 

What Weeds Does Mesotrione Kill?

ArmorTech Trione specifically provides pre-emergent control of 24 types of weeds, including crabgrass and creeping bentgrass, and suppresses Poa annua.

Mesotrione Applications

Apply ArmorTech Trione to the soil surface at a rate of five to eight fluid ounces per acre in at least 30 gallons of water before or after seeding. Weeds absorb mesotrione through the roots, so the product must be watered in. If a rain event does not occur within 10 days of application, irrigate with 0.15 inches.

For starter fertilizers with mesotrione, follow the label and SDS for product-specific application information.

Mesotrione herbicides are typically effective for up to six weeks. Additional applications may be required, but rates and timing will vary based on the turfgrass it is applied to and restrictions. 

Learn more about the benefits of mesotrione from your ATS rep.