Wednesday, June 20, 2018
Home and Garden

Ask Dr. Hort: Yellow-tipped palm needs potassium

Palm tree needs more potassium

Q: My areca palm seems healthy, however, many of the fronds have yellow tips. It gets water twice a week and has been fertilized with the 8-0-12 with micronutrients about 1 to 2 cups four times a year. Do I need to give it more?

Also my hibiscus grow and bloom, but get many yellow leaves. What can I do? Paul Hohman

A: The picture of your areca, Dypsis lutescens, is still showing signs of potassium deficiency despite using a quality palm fertilizer, so it must be in the rate. Areca palms by nature have a yellowish cast, but the browning (necrosis) of the older frond leaflets is symptomatic of potassium deficiency. Apply 10 pounds, 3 times per year, February, May and October, broadcast evenly over the entire front because the clump is mature so roots are all over that area.

Aphids infest milkweed plants

Q: I have some milkweed, and they are beautiful now. I do have a problem with aphids though. They are all over the plants. I have been spraying with a plant oil as per directions. But this is also affecting the monarchs landing on the plants to lay their eggs. What can I do or should I do nothing more? I saw 2 small caterpillars this morning but this time last fall the plants were loaded with caterpillars with no aphids. Mary Benson

A: You are right, the oil will affect the monarch babies on your milkweed, Asclepias curassavica. The yellow aphids, though in mass, do very little harm, mostly leaf distortion, so you can let them be.

If you must get rid of them, use a pistol grip trigger spray nozzle on the end of the hose and blast them off (it's also a great tension reliever). It really works. Or you can cut off the tips of the branches and toss them into the compost pile.

Another critter that you may see is the milkweed bug, black and orange, up to 3/8 inch long, don't worry about them either.

Milkweeds are amazing plants, bugs are sucking on it, chewing on it and yet it re-leafs and flowers over and over again, yet another lesson in nature.

Thatched St. Augustine lawn needs verticutting

Q: I have been told I have a heavy thatch buildup plus compacted soil in sections of my St. Augustine grass. The advice I got from the lawn guy was to use a pitchfork to loosen it up.

What is the best tool for the job? I have sprinkler pipes about 10 to 12 inches deep. Tim Gromlovits

A: Heavy thatch in St. Augustine grass is the result of overwatering and overfertilizing the turf. The faster that you grow your St. Augustine grass, the more it thatches, creating a several-inch dead zone between the living grass and the soil, which impedes water penetration resulting in yet more irrigation.

The advice from your lawn guy was accurate, but the tool is questionable. Ideally, verticutting is the proper procedure, but needs to be done by a professional so that your yard doesn't look rototilled when finished. It is a renovation procedure so the turf looks a little rough for about six weeks, but the results are worth the procedure: no more spongy lawn; watering, disease and insect problems are reduced; fertilizer is better utilized; and it is much easier to mow.

With a 5,000-square-foot St. Augustine lawn, thatched up 3 to 4 inches, it is not uncommon to take off three pickup-truck loads of thatch.