January 23, 2016

1 - Some indoor plants are attacked in winter by insects which may be treated with oil spray or rubs that are safe for people.

Yard and Garden January 23, 2016

Q.

A co-worker of mine is having problems with pests on her Hoya plant. Here is her note: "My Grandmother owned this plant for many years and I would always fawn over it when I went to see her. About four years ago "Granny" passed away and the plant moved in with me. I can still remember the amazement I felt when I first saw it bloom. I had never seen it in bloom at my Granny's house and had no idea just how gorgeous this plant was. I've kept it in my office for nearly the entire time I have owned it. It sits on a cabinet in front of a south facing window. A couple of months ago I started to notice that the leaves were looking a little yellow and the shoot that the blooms appear on seems ashy and dry. When I took a closer look I noticed the little yellow bugs covering several of the leaves. I have a cactus growing right next to it and the cactus appears to be unscathed. What are these, and how can I get them off of my beloved Hoya plant?"

- Ana H.

Las Cruces

A.

It looks like scale insects are present. These are common pests on hoya and other indoor plants. There are also aphids. Check to confirm which by rubbing the stem and leaf gently. Scale insects are tightly attached and covered with a protective waxy coating while the aphids are soft-bodied insects that are easily rubbed off and smashed while you are rubbing the plant. In either case, treating with oil should help. Horticultural oil can be mixed with water and sprayed (protect any fabrics and other furnishings from the spray). Neem oil (check label for scale insects) can also be used; it is available at a lot of garden stores. These are safe for humans indoors, but be sure to follow directions. Some people will dip a Q-tip in vegetable oil and rub it over the scale insects. Sometimes this rubs the insects off, other times the oil coating just smothers them. Frequent retreatment is advised. Treat the stems, top and bottom of leaves and watch for reappearance in the event they are on the stem or roots below the soil. The cactus may get these insects, or, perhaps not. Watch the cactus carefully; scale insects may also attack the cactus.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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