Question
I have black spots on many of the leaves of my yellow tabetuia tree. What should I do?

Answer
Fungi : Leaf Spots

Leaf spots are caused by fungi or bacteria. Brown or black spots and patches may be either ragged or circular, with a water soaked or yellow-edged appearance. Insects, rain, dirty garden tools, or even people can help its spread.

Prevention and Control: Remove infected leaves when the plant is dry. Leaves that collect around the base of the plant should be raked up and disposed of. Avoid overhead irrigation if possible; water should be directed at soil level. For fungal leaf spots, use a recommended fungicide according to label directions. Spraying fungicides depends on the size of the tree. Large trees are hard to spray.

Control - chemical. If the tree is a valuable specimen and despite the use of good cultural practices the leaf spot disease continues to be detrimental to the health of the tree, fungicide sprays should be considered. Professional landscapers have access to a wider range of effective chemicals than do homeowners.

---Use protectant fungicides such as Captan, Chipco 26019, Daconil 2787, fixed copper, Fore, Manzate, Syllit, and Ziram to control a wide range of leaf spot diseases.

---Use systemic fungicides such as Banner Maxx, Bayleton, Benomyl, Cleary's 3336, Eagle, Immunox, or Rubigan to target certain specific diseases.

---Fungicide mixtures may include active ingredients with both protectant and systemic activity which may be advantageous.

---Bacterial leaf spot diseases are more difficult to manage, but fixed copper chemicals such as Kocide, Champion, or Bordeaux mixture are most often used.

Choose fungicides and bactericides that have the tree and the disease listed on the label. The timing of sprays for leaf spots is critical, and applications often will need repeating. It is almost always better to control the disease early rather than later in the season. Be sure that the spray equipment that is being used thoroughly covers all surfaces of the foliage.