How to Troubleshoot a Diseased Linden Tree

To treat your linden tree for diseases, you must first make an accurate diagnosis of what disease is affecting your tree. Several diseases are common in linden trees, such as powdery mildew, sooty mold, anthracnose cankers and leaf spot. Your linden tree may also suffer from environmental stressors, which can often appear as symptomatic to diseases. The most common environmental diseases are micronutrient chlorosis and winter damage due to frost or freezing. Consider all possible causes when studying your linden tree’s symptoms before proceeding with a treatment plan.

Rake

Fungicides

Garden hose

Insecticide

Pruning tools

Tree fertilizers

Powdered iron, zinc and manganese supplements

Mulch

Denatured alcohol

Diagnose powdery mildew disease on linden trees by looking for a white to grayish powder-like coating on the leaves and stems. Powdery mildew begins forming as separate spots of mold on the leaves until it covers the entire leaf.

Look for black strand-like mold growing on the linden tree’s foliage to diagnose sooty mold disease. Sooty mold is a fungus that grows on honeydew, a sticky liquid substance secreted by aphids, scale, whiteflies and mealybugs.

Identify anthracnose cankers on your linden tree by looking for discolored callus tissues growing on the woody parts of the tree, as well as browning leaves and premature leaf drop.

Look for brownish circular spots on the leaves to diagnose leaf spot. The brown spots will have a darker ring around the outer border and can cause premature leaf drop.

Diagnose micronutrient chlorosis in your linden tree by looking for yellowing of the leaf areas between the veins, either on the entire tree or localized to one side. Micronutrient chlorosis is caused by manganese, iron or zinc deficiencies.

Treat powdery mildew on your linden tree by raking away and destroying all fallen leaves and spraying the tree with an approved fungicide during the growing season. Ensure that the fungicide is designed to kill powdery mildew and is safe to use on lindens.

Get rid of sooty mold disease on your linden tree by spraying away the mold with a garden hose. Then, treat the insect infestation to prevent recurrence of the fungal disease by spraying the tree with an appropriate insecticide according to the directions on the label.

Troubleshoot canker diseases infecting your linden tree by raking away and destroying all fallen leaves, pruning away all diseased branches and stems, and carving the callused canker growths from the tree. Boost the linden tree’s strength by watering it during dry spells and fertilizing it in the spring or late fall.

Control leaf spot by raking away and destroying all fallen leaves. Fertilize your linden tree in the spring to build its resistance to the disease, and water the tree generously during droughts or dry spells.

Treat your linden tree for micronutrient chlorosis by first taking a soil or leaf sample and testing it to determine which nutrient is lacking. Then, apply the needed nutrient in powder form by boring holes into the soil around the tree and inserting the powder.

Frost or freeze damage can also harm your linden tree. Prune away all damaged or dead areas of the linden tree in the spring, after the new growth just begins to emerge. Feed your linden tree a high-nitrogen fertilizer in late summer and spread a 2- to 3-inch layer of mulch around the base of the tree in autumn to protect the roots from freezing temperatures.

Always disinfect your pruning tools before and after using them on diseased trees. Dip the tools in a solution of three parts denatured alcohol and one part water.