Helena Crossbow Herbicide does not specifically list Catalpa on the label as a controlled tree. We would recommend checking directly with Dow to confirm if it is effective for your target tree. You can reach Dow at 800-992-5994.
Since an herbicide like Crossbow could kill the desirable trees, too, the best option would be cutting the ivy and then treating the fresh cuts by brushing on the herbicide directly.
To kill Hemlock trees you want to take hatchet or something like that and make chops into the trunk. Then you would apply the Crossbow undiluted by spraying or painting on the cuts.
The best method to remove woody plants and shrubs is to first cut down them down to their stump and apply Helena Crossbow Herbicide on the fresh cut or spot treat as best as you can. If enough of the solution contacts the young trees roots it could injure them.
Crossbow Herbicide could affect desirable woody and viney plants that are sprayed with it. You should avoid spraying desirable vines and trees. We suggest spot treating the target plants and spraying when conditions are calm.
Do not apply Crossbow Herbicide to, or otherwise permit it to come into direct contact with cotton, grapes, tobacco, vegetable crops, citrus, flowers, fruit or ornamental trees, or other desirable broadleaf plants and do not permit spray mists containing it to drift onto them.
Crossbow Herbicide could possibly harm holly but it is not labeled for this plant so we cannot recommend it for controlling/killing it. Holly shrubs would need to be treated like trees, in which case you would cut the shrubs down to stumps and then treat the fresh cuts. Crossbow Herbicide is labeled for the control of most kinds of unwanted trees. On page 5 of the label you can find directions on how to use for conventional basal bark and stump applications.
In order to kill a tree that size, you would get the best results cutting the tree down to a stump and treating the fresh cut stump directly. If the trunk diameter is less than 6-8 inches, then you could potentially do a basal bark treatment with Crossbow Specialty Herbicide.You would mix 1.25 to 5 ounces per gallon of solution, mixing in diesel No. 1 or 2 or kerosene, then spraying the basal part of the tree up to a height of 15-20 inches off the ground. If you do not need this much product, then could also use Fertilome Brush Killer and Stump Killer.
