Q. I have a tropical hibiscus plant that has developed white sticky spots on the leaves and stem. We had the plant outside during the summer, and then brought it indoors last fall. What’s going on? A.Q. I have noticed that many trees in the area are turning color as if it were October. What’s going on? Also, we have several pin oaks that look terrible, as if they have some sort of disease. What should we do?
A. Trees that turn color early sometimes are showing signs of stress. The stress may be too much or too little water, herbicide uptake, or they might be under attack by a disease or insect. Regardless, early fall color sometimes is an indication something is wrong. Have the tree evaluated by an arborist, or submit a picture and a sample of the tree to the extension office.
We have received many pin oak samples at the office suffering from iron chlorosis. This condition occurs with many pin oaks in our area because the alkalinity of our soils prevents this tree from absorbing iron properly. Yearly applications of sulfur (at least 1 pound per 100 square feet) can help small pin oaks stay healthy by allowing the trees to absorb iron properly. Large trees need to be treated by an arborist every 1 to 3 years depending on your soil and how bad the tree looks. Arborists sometimes will inject large amounts of sulfur into the root zone, or bypass the soil issue altogether by injecting iron directly into the tree.
Pin oaks are gorgeous trees but unfortunately many pin oaks can develop this problem. Because pin oaks are propagated using acorns, genetic variation results in some trees looking fine, while others suffer from this condition at an early age. It is the luck of the draw. Other oak species don’t have this condition – and might be better choices for landscapes in Allen County.
