Information Sheet - Amgrow Metric Herbicide - 220727

Metric® Herbicide Product Information

What Is Metric Herbicide?

Metric Herbicide is a unique selective turfgrass herbicide containing 400g/L of the active ingredient Metribuzin.

It is the first Metribuzin-based herbicide in Australia to be registered for the control of crowsfoot grass in common couch grass turf surfaces and is labelled for use in Qld, WA, NT and the ‘Northern Rivers’ region of NSW only.

Metric Herbicide at a Glance

Features of Metric Herbicide

• Exceptional performance in crowsfoot control
• First Australian turf-registered metribuzin based herbicide
• Superior control of large ‘difficult to kill’ crowsfoot plants
• Low active ingredient output due to low use rate
• Easy to use liquid formulation
• Unique mode of action for crowsfoot control, ideal for combating resistance

Metric Herbicide Mode of Action

Metribuzin, the active ingredient in Metric Herbicide is a Group C herbicide and a member of the Triazinone chemical family. Group C herbicides are classified as photosynthesis inhibitors with metribizin classified more specifically as a PS II inhibitor. PS II inhibitors act by binding to the QB binding protein, blocking the mobile electron carrier and disrupting photosynthesis and reducing the amount of energy being generated.

Plant uptake of metribuzin occurs through both foliage and the roots, with the active ingredient carried upward within the plant via the xylem, directly to leaf edges where symptoms first appear.

Weed Control with Metric Herbicide

As with most herbicides Metric will perform best on younger, actively growing weeds. Adequate soil moisture has been shown to play a role in achieving good control of target weeds.

[Chart: Crowsfoot Grass Population (%) over 0 DAT, 7 DAT, 14 DAT, and 21 DAT. Lines represent Untreated, Metric 1L/Ha, 22.5g/L Foramsulfuron @ 2L/Ha, and 375g/L Diclofop Methyl 1.5L/Ha.]

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Turf Tolerance with Metric Herbicide

Following an application of Metric Herbicide slight discolouration of the turf couch turf surface may be observed. At the label rate of 1L / Ha any discolouration that may be observed will peak around one week after application and begin fading to disappear by three weeks after application. If the label rate is exceeded a greater level of discolouration can be expected.

Some factors influencing the plant safety characteristics of Metric Herbicide include:

• Soil pH: Metric is more readily soluble at a soil pH above 7.2, thus the active ingredient becomes more available for plant uptake increasing both weed control as well as the chance of turf discolouration to occur.
• Shade Stress: As a PS II inhibitor, Metric disrupts the plants’ ability to generate carbohydrates through photosynthesis. Consequently, if the plant is already in a state of shade stress any discolouration may be exacerbated.

Common couch grass couch grass (Cynodon dactylon) within a plot was rated for discolouration (yellowing) of the treatments and rated on a 0 to 10 scale. 0 being no effect, 10 total chlorosis.

[Chart: Turf Discolouration with Metric Herbicide (Cynodon dactylon) at 6 DAT, 15 DAT, and 22 DAT for Untreated Control, Metric 1L/Ha, Metric 1.5L/Ha, Metric 2L/Ha, and Metric 4L/Ha.]

Metribuzin and the Environment

Although it is classified as highly soluble in water, metribuzin is almost immobile in soils with a high organic matter content however higher soil pH increases its mobility. Once applied to the turf metribuzin has a soil half-life of between 11 and 10 days making it a non-persistent chemical.

Application Information

Apply at a volume of 400 to 800 L of water per hectare. Higher volumes should be used for severe weed infestations to ensure adequate spray coverage. Good weed coverage with the spray is essential for optimum weed control. Avoid overlapping of spray runs. Avoid application under conditions when uniform coverage cannot be obtained or when spray drift may occur.

Read the full label and leaflet for complete application details and general instructions.