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My Avocado Plants Have Brown Spots on the Leaves

By Irum Sarfaraz
Healthy avocado trees produce a prolific harvest.

Avocado is a native fruit of tropical America and thrives in subtropical and tropical weather. The evergreen tree grows up to 30 feet tall with 3- to 16-inch-long, leathery, elliptical foliage. A fungal disease leads to brown spots on tree foliage.

Identification

Avocado is susceptible to anthracnose, a fungal disease caused by Colletotrichum gloeosporiodes. The fungal spores are most active during humid and wet weather. Cooler temperatures less than 59 degrees Fahrenheit stop the spread of disease.

Damage

Initial symptoms of anthracnose include the appearance of yellow spots on foliage. As disease progresses, the spots turn brown and enlarge in size, covering the entire foliage surface. There is necrosis or dark borders on margins, veins and tips of foliage. New shoots display purple or brown spots and infected flower heads die. Lesions also spread to fruit.

Management

Prune and remove all infected tree areas. Keep the growing area clear of fallen foliage to keep fungal spores from spreading. Thin the canopy to let light and air into the inner tree. Chemical control options include the use of copper hydroxide sold under various trade names.

 

About the Author

 

Irum Sarfaraz is a freelance writer with over 20 years of nonfiction writing experience in newspaper op-eds and magazine writing, book editing, translating and research writing. Sarfaraz is originally from Pakistan and has been published in both American and Pakistani newspapers and magazines. She holds a Bachelor of Arts in English literature, and diplomas in nonfiction writing.