The lush scent of the orange flowers may call to obey tropical lands, but orange trees (Citrus spp.) Are not merely for Florida and the south of Spain. Many orange tree cultivars prosper in U.S. Department of Agriculture plant hardiness zones 9 through 11. Like other citrus trees, orange trees may catch many different fungal, viral, mycoplasma and nematode diseases and while some might be treated, others don’t have any cures. The best defense against orange tree diseases could possibly be good citrus management practices all year round.
Diagnose fungal diseases such as anthracnose and gray mold (Botrytis cinerea) identifying velvety mats of sporulating tissues which induce invading to die back and fruit to come up with ridges and drop. Spray the tree thoroughly with copper and benzimidazole fungicides according to label instructions. Reapply if required. Lower your orange tree’s susceptibility to fungal disease by protecting the tree from mechanical injuries and pruning to enhance air movement.
Treat citrus plant parasitic-nematode diseases by combining a broad-spectrum insecticide/nematicide featuring Oxamyl into the irrigation water provided to the tree. Use according to label instructions, but never apply over the maximum recommended, about 4 quarts per acre per month.
Diagnose psorosis by noting that a gradual decrease caused by flaking of the bark which develops into an infection. Treat it by scraping away the infected bark area with a sharp, sterilized knife and allowing the wound to callus over. Both psorosis and nematode diseases are transmitted by grafts and both can be avoided by buying certified disease-free citrus plants for your own orchard.
Apply a fungicide wash featuring copper sulfate to treat fungus- and mold-based diseases. Mix the fungicide with water in accordance with the label instructions and washing the tree twice per year, in fall and spring. Check your irrigation and drainage system to stop over-watering which may be a element in fungal infections. Orange trees require moist but well-drained dirt to thrive.
Treat black rot, also called Alternaria rot, by removing affected fruit from the site. This fungus grows on dead citrus tissue during rainy weather causing fruit drop and rotten, dark spots on the fruit. Not all the fruit will be affected and you are able to eat those oranges which aren’t. Avoid the disease in the future by applying good cultural practices including good tree maintenance and irrigation. It is very important to prevent all wounds or other harm to fruit that provides the fungus a means to enter the tree.