How to Control Fungi on an Orange Tree

Orange trees along with many other varietals of citrus trees are vigorous producers of fruit but are also very susceptible to a wide range of diseases and infections that can spread quickly through orchards and even residential communities. Fungal diseases are one of the most common afflictions of citrus. Some fungal infections can be treated or managed without chemical intervention where biological and environmental factors can be altered to correct the problem. When chemical intervention is required, the manufacturer's label instructions are the ultimate guide to treatment dosing and application guidelines.

Things You'll Need

• Clean, sharp secateurs or loppers
• Ziploc bags
• Fungicide for fruit trees
• Insecticidal soap

Instructions

1. Collect a fresh sample of a leaf, branch, bark or fruit from your diseased tree that you can use a reference in research on the Internet or take to your local garden shop and for identification.

2. Treat a Melanose fungal infection in mature orange trees by heavily pruning away the dead and infected wood, using clean, sharp pruning loppers. Pruning is the only completely effective method of control for this common fungus.

3. Eradicate Greasy Spot fungus with a fungicide spray such as captan powder diluted with water. Start treatment at the very first visible signs of the fungus, as it becomes apparent many months after infection.

4. Stop the growth of Sooty Mold fungus that blackens the leaves of orange trees with a slightly gritty dark coating, by eliminating the insects on whose secretions the mold thrives. Treat whiteflies and aphids by spraying the tree with horticultural oil to kill the bugs and loosen mold so it can be sprayed off with a garden hose. You can use an insecticidal soap with pyrithrens or an insecticidal spray containing acephate-bifenthrin.

5. Get rid of Diaporthe citri by applying fungicides containing copper sulfates or captafol.

Tips & Warnings

• Pruning is the only completely effective method of control for a Melanose fungal infection.

• Always wear a face ventilator when working with garden chemicals---during preparation and mixing as well as curing application.

References

• University of Florida
• Purdue University
• Colorado State University

Resources

• ForestryImages.org