Ask the gardening expert

Published:

 

An email came into the answer clinic last week with the following question: "I use a trail that has patches of poison oak. I have heard that there is a plant with orange leaves that grows next to poison oak that can actually be used to treat it. Any info on this?" How did the master gardener on duty respond?

The master gardener gave the following answer: "Poison oak does not have any native leaf treatment. If you are exposed to the leaves of poison oak, the best advice is to wash the exposed areas with hot soap and water within one hour after exposure. If the skin does react, use a soothing lotion such as calamine lotion to calm it down and reduce the itching. However, if you are severely allergic, you may need to see a dermatologist for prescription creams or other medications. The best prevention is to wear clothing to cover the skin when gardening, wear gloves, and avoid the plant."

I remember one time you said you were able to save two trees that you planted on a hillside. You had a solution for watering them and keeping the roots damp. Could you remind me?

Yes, I'm happy to since we are coming into the time of year where we need to remember to keep recently planted trees and shrubs from becoming too dry. My customer wanted a series of variegated maple trees running down a steep hill. We made a simple series of 3-inch PVC tubing. We cut them at about 4-feet tall, we drilled small holes at the bottom third of the pipe, and placed a cap on the end. This allowed water to seep out at the root zone and not rush down the hill.

I had seen a photo and story about them in a landscaper magazine sometime before, and was glad to get a chance to try making them. The story called them "water cannons." We put them in as we planted, and since it was such a steep hill, we placed one on both sides of each tree. Later, we made these shorter, hoping they would attract less attention (at first they were noticeable, and things ended up in the tubes other than irrigation water). But after lowering the tube, they were less noticeable, and for the most part were left alone. We felt they were successful, and all the trees are still doing quite nicely. The neighborhood bought a small, retired water truck that served them well.

There is scale on my jade plant. What can I do about it? The person I got it from told me I need to throw the plant out, because I could never get rid of all of them. I like the plant and want to keep it. Do you know of a garden pesticide to kill the scale?

Your friend is nearly right. It will be a chore getting rid of scale, but it can be done. You'll need to wash the plant often, several time a week. Remove every scale using insecticidal soap. I'd suggest repotting it; fresh soil, new pot. I've treated small infestations of scale with cotton swabs dipped in rubbing alcohol. Whichever treatment you choose, it will need to be repeated often. I am of the opinion that you're in for a big job. So unless the plant is a wonderful specimen, I'm guessing you'll wonder if it's worth it after all, and if the person who gave it to you is about right.

Celeste Lindsay is a WSU-certified master gardener. Send questions to mslindsay8@gmail.com.

More Like This