Managing worms and moths

Credit: Flickr / karomanah 1980

Q: Hello to all of you. I really need your help. Some of my columnar crabapples, a ninebark, verbena, and some roses are covered in green leaf rollers. I have handpicked and squeezed them, opened the delicate new emerging leaves, accidentally torn many, cried, and used Btk spray. I can’t seem to get rid of them. Short from using a flame thrower, is there a good chemical that I can use. Help please.  

Winter moth (Operophtera brumata) and Bruce spanworm (O. bruceata) are very common on a wide variety of plants. Use a sticky band (saran wrap coated with Tanglefoot) on the tree trunk of your columnar crabapple by Thanksgiving Day to catch the migration of female moths (unable to fly and therefore must climb up plants to mate and lay eggs).

A thorough spraying of dormant oil during the winter months may smother some of the overwintering egg masses. Spray, if required, before leaves curl up. In the case of Btk, the insect must consume the sprayed plant foliage. Pyrethrin spray must come in direct contact with the insect in order to be effective. Handpicking can also be utilized especially if plants are accessible.

The good news is that even if you leave things as they are, there is only one generation feeding on your plants—any leaves produced later will have minimal damage.