Hardiness Zone: 10a
Robert from South Texas
I'm sorry that I can't tell you what the exact problem is from your pictures. What I can tell you is that mango trees tend to fall prey to certain fungal diseases. The most common is anthracnose. Unfortunately, Kent mangos happen to be a variety that is very susceptible to anthracnose. Young leaves are particularly susceptible, especially in wet conditions, but the disease also attacks flowers, twigs, and young fruit. Symptoms appear as black spots on the leaves, or sunken black lesions on the fruit.
Verticillium Wilt is another type of fungus that can attack mango trees, especially if they are planted on sites where vegetables were previously grown. This soil-borne fungus is capable of surviving in a dormant state in the soil for as long as 15 years before becoming active. The fungus blocks the vascular system in plants, which sends them into a slow decline. Symptoms include leaves wilting and dying, often only on one side of the tree. Because the dead leaves tend to remain attached, the tree develops a burnt or "fired" appearance.
Deficiencies in manganese and iron can also result in mango decline.
I hope this information gives you some place to start.
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Yours looks almost exactly like mine, which is also a Kent. It seems strange for a fungus--only certain leaves are affected. They just turn completely brown, and then fall off.
By Jack C. (Guest Post)04/27/2008
From the photo you have provided it looks like you have a fungus either below the surface(root fungus) and/or on the tree. Try spraying you entire tree and on the ground heavily all around the roots with liquid copper. 4 tablespoons per gallon for mango trees in a garden sprayer. Repeat the spraying again 7 to 10 days later and if needed again in another 10 days. This process will not hurt your tree and do not be too concerned if your tree starts to drop the brown leaves (this is good!). If you have new leave shoots coming out, try to avoid a heavy application on the new shoots and fruit if any.
If liquid copper does not work then try a little more potent fungicide such as Dithane M - 45. Hopefully the liquid copper will work as it is less evasive.
Good luck, I hope it works out for you.
Best Regards, Jack C.
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