If so, how much of the product would I need to treat an 18" hemlock?
Yes, you can use Criterion to treat a hemlock for the woolly adelgid. You should follow the soil drench instructions on the product label. You should apply 1 pouch or 1.6 oz of criterion for every 24 to 48 inches of trunk diameter. You should apply the pouch in at least 10 gallons of water to apply the drench. It really does not matter how much water you use, it just matters how much product you are applying over the area. The more water you apply it with the deeper the ground will soak it up. Slightly less than 1 pouch should be used for an 18" wide hemlock.
Answer last updated on: 06/26/2011