Garden Q&A: Combating lecanium scale on tree bark and debudding veggie plants
By Ellen Nibali
Jun 18, 2020 at 7:00 AM
My oak tree bark is covered with bumps, diagnosed as lecanium scale, sucking the life out of them. Apparently there is a connection with mosquito spraying. We spray because we have an ornamental pond, and we’re afraid it may breed mosquitoes. What do we do now?
We are getting increased reports of lecanium scale infestations, more severe and on many more species of trees than usual. It’s a native scale insect. Normally our insect predators and parasitoids keep their number negligible.
Mosquito sprays are broad spectrum, meaning they take out large numbers of organisms, including beneficial ones. It’s a good example of how dealing with one pest can lead to problems with others. To deal with our native evening-biting mosquitoes, use the usual protections such as repellents (there are safe ones available) and clearing landscapes of standing water such as in rain gutters, indentations on tarps, toys, plant container saucers, etc. Removing breeding sites is especially important when facing the invasive Asian tiger mosquito that bites during the day and needs only about a tablespoon of water to reproduce.
Mosquitoes don’t breed in moving water, so putting a circulating pump in your pond would be helpful. Dragonfly larvae, some tadpoles and fish and other aquatics eat mosquito larvae. Examine a glass of pond water for the small twitchy mosquito larvae to be sure the pond even has a problem. Dropping a mosquito dunk made of Bt, a biological control, into your pond is an easy way to take care of any mosquito larvae there. Search ‘lecanium scale’ on the Home and Garden Information Center website for the scale control options.
When tomatoes and peppers are young, should blossoms and fruit be removed? At what point do you let them be? What about cucumbers and zucchini?
Remove any tomato blossoms that form on transplants prior to planting. After planting in the ground:
1) If plants are stressed and slow to grow, continue to remove blossoms for a week or two until roots establish and plants take off.
2) If the transplants are healthy, there is no need to remove blossoms that form shortly after transplanting.
Pepper plants are slow to establish. Remove blossoms for 2-4 weeks after transplanting. This depends on type of pepper, growing conditions, and size and health of the transplants.
If you direct seeded the cucumber and squash, there is no need to remove blossoms. If you planted transplants and they started to bloom while still in the pot, the blossoms should be removed. Check out Home and Garden Information Center website’s YouTube videos for all aspects of gardening, including debudding vegetable plants.
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.