Black Mold & Mesquite Trees

Cotton Root Rot

• Attacking more than 2,000 species, cotton root rot is one of the most destructive diseases to plants and trees. This fungus typically presents itself from June through September with yellowing of the mesquite leaves. The fungus travels through the tree, down to the roots, turning the plant brown before it develops a white “cotton” color, eventually turning black. If left untreated, the cotton root rot continues to infect the tree and eventually kill it. The root rot is not a treatable condition and instead take preventive measures to keep the cotton root rot at bay. One way to help prevent cotton root rot is to keep the soil pH level below 7.2.

Leaf Spots

• During the summer months, mesquite trees may begin to black circular or oval dead spots on the leaves. Generally, the fungus that causes leaf spots are not harmful to the tree. If, however, the leaf spot fungus attacks the tree early in the growing season it can weaken the tree making it more susceptible to other diseases and pests. Treating the leaf spots is not necessary since most winter weather stops the fungus development. Only apply a protective fungal spray if the tree’s health is at stake. You can help prevent future leaf spots by applying preventive measures such as removing diseased and weak limbs from the mesquite tree with a pair of clean and sharp pruning shears.

Spongy Yellow Heart Rot

• When the mesquite tree becomes damaged or harmed -- such as from a broken limb or insect borrowing -- the fungus will enter through the damaged bark. The fungus will attack the interior of the tree creating brown to black or yellow spongy masses on the tree. According to the University of Minnesota, there is no chemical control of spongy yellow heart rot. However, removing dead or dying limbs, pruning the tree properly and avoiding damage to the tree will help prevent future heart rot infestation.

Considerations

• When working with protective fungal spray of any kind, wear chemical-resistant rubber gloves and safety goggles to prevent skin and eye irritation. If the chemical does come in contact with your skin or eyes, flush immediately with cool water for 15 minutes. If irritation continues, seek immediate medical condition. Apply the spray on a warm day when the wind is calm and there is no rain in the forecast.