Q. Many of my plants including agave, bromeliads, gingers and orchids have tan or white spots on the top of the leaves. The spots are variable in size and are indented. This started several weeks ago.
K. C., Miami Beach
What you are seeing is a physical injury of some sort.
There were several hail storms in southeast Florida in late May and June. Hail damages plants by shredding thin leaves on plants and causing pockmarks on thick-leafed plants such as aloe and agave. Because the leaf tissue has been damaged, the damaged area turns brown or light tan. Although unsightly, this damage does not endanger the plant’s health.
Other causes of physical damage include: spray damage if someone sprayed a pesticide (including herbicides) onto sensitive plants, using an oil spray when the temperatures are high, mower/weed eater damage if mulch or pebbles were flung out from this equipment, something or someone crushing the plants, and other causes.
When using pesticides (insecticides, fungicides, herbicides, etc.), whether they are organic or synthetic products, always follow the label directions. Avoid spraying on windy days. Make sure the problem has been accurately diagnosed and choose the least-toxic product available.
Adrian Hunsberger is an entomologist/horticulturist with the UF/IFAS Miami-Dade Extension office. Write to Plant Clinic, 18710 SW 288th St., Homestead, FL 33030; e-mail email@example.com.