Toxic Chemicals in the Soil Cause Problems for Ornamentals

Q. I have a Mexican Bird of Paradise and ‘Sun Trumpet’ Tacoma plant growing close together. Both have deformed, dwarfed growth, and damaged leaves. The Bird of Paradise feels sticky as well. I tried sprays for insects, including Neem oil, and cut the plants down completely to have them grow back with the same issue. Other plants in the yard are doing fine. Any help is appreciated.

Herbicides applied to the soil or on a hot windy day can result in damage to the leaves and stems of plants. Sometimes plant death.

A. I don’t think these plants are facing a disease or insect problem. 

Soil Contamination Possibly

It is hard to say without guessing, but from your description it sounds like a soil contamination issue. Plant an ornamental grass and broadleaf plant in that area and see if you get the same response. If it were a cooler time of the year, I would tell you to germinate a seed mix with grasses and wildflowers in it.

Brush Killer or Soil Sterilant

            There may be a weed killer applied to this area and responsible for this problem. Some weed killers like dicamba, if applied at a heavy dose or used as a “brush killer”, can damage broadleaf plants like your Bird of Paradise and Tacoma and not hurt grasses. The high rate of this type of herbicide is why some weed killers are labeled as a “Brush Killer”. There are other weed killers sold as “Soil Sterilant” that can persist for years and kill most plants grown in that soil.

Replace Soil or Change Plants

            Some weed killers are difficult to remove by leaching with water. If the ornamental grass isn’t damaged but the broadleaf plants are, then either replace the soil in that area to a depth of about 12 inches deep or only grow ornamental grasses in that spot.