Gnats, Spider Mites, Bamboo Mites, Tree Wrapping

Q. How do I organically control spider mites on indoor plants? – D.M., Dallas
A. Cover the potting soil with a thin layer of horticultural cornmeal and spray the foliage with seaweed or natural products that contain seaweed. Dr. T.L. Senn at Clemson University proved years ago that seaweed is an effective control of spider mites, whiteflies and other insect pests.

Q. I have a terrible problem with little black gnats in my house plants. I used the horticultural cornmeal. It helped for a few days, but they came back. Should I keep applying the cornmeal? It seems to cause the soil to form a crust on the surface when I water. Does this mean I have used too much? How much should I use? Also, should I put a tablespoon of baking soda per gallon of water when I water these plants to get rid of fungus in the soil? – A.C., Dallas
A. Sounds like you used too much. The cornmeal should be a light coating on the soil and gently worked in. Cutting back on the watering is the long-term solution. Interior plants should be near wilt before adding more water. The cornmeal will be all the fertilizer the plants need for at least a month. Instead of baking soda use an ounce of apple cider vinegar per gallon of water.

Q. I have recently purchased three bamboo plants Phyllostachys pubescens moso and have been informed that I should treat them for bamboo mites. The recommended treatment according to the bamboo seller is either Isotox or Orthene’s systemic poison. In researching on the internet I’ve stumbled upon the American Bamboo Society. Their recommendations are using an insecticidal soap such as Safer or Talstar-10 wettable powder. I wonder if garlic/pepper tea with other additives would be effective without harming the environment or me? Do you have any suggestions or educated guess you can offer? – D.F., Dallas
A. All these recommendations except for Safer soap are irresponsible. They are toxic materials that will kill more beneficials than pests. The soap just wouldnÂ’t work very well. Assuming your plants have mites in the first place, seaweed drench and foliar spray is probably all thatÂ’s needed. All bamboos respond to organic fertilizers and healthy soil.

Q. I’ve been told that my new red oak trees need to have paper wrap applied to the trunks to prevent borers. Is there any way to avoid having to do that? It really looks bad. – E.L., Dallas
A. The way to avoid that ridiculous advice is just ignore it. No competent arborist recommends wrapping paper, gauze, burlap or anything else around the trunks of trees. Not only does the artificial covering not benefit the tree from an insect control standpoint, it doesnÂ’t help in any way. On the contrary, wrapping tree trunks causing injury. It gives insects and disease pathogens a nice dark, protected place to hang out. When the wrapping is removed, the trunk will resemble your finger when a bandage has been left on too long. I have planted many thousands of trees since 1970 and none of them have had their trunks wrapped.

By the way – those same misguided folks will also recommend staking and thinning out newly planted trees. Two more bad ideas.

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