Catalpa's showy summer blooms make it a favorite landscape tree.
Catalpa is a tree group divided into two major species. Southern catalpa (Catalpa bignonioides) is the shorter of the two at a maximum height of 40 feet. Its branches reach away from the tree, creating an open canopy. Southern catalpa's light-green leaves grow to 8 inches long and its ornamental flowers develop in clusters. Northern catalpa (Catalpa speciosa ) is a 75-foot-tall tree and hardier than its southern sister. Its footlong leaves develop into a heart shape and share with southern catalpa a vulnerability to fungal leaf spots, which leave brown marks on the foliage.
Instructions
1. Rake and discard all infected leaves as they fall to the ground. Don't compost them. Mature catalpa trees are too tall to make it feasible for you to prune the leaves off the tree. If the infection occurs on a short sapling, trim branches with infected foliage.
2. Control midges, which are mosquito-like insects and their larvae that damage and make catalpa trees susceptible to fungal infections. Choose an insecticide that contains temephos, methoprene or Bacillus thuringiensis var. israelensis (Bti). Read the manufacturer's label of the brand you select and apply the chemical exactly as directed.
3. Increase the water supply to your catalpa tree if it develops brown areas along the margins of its leaves. That's a sign the tree is dehydrated and suffering from leaf scorch, not a fungal infection. Hydrate it to the root zone as often as it takes during hot weather to keep the soil from drying out.
Tags: catalpa Catalpa, catalpa trees, Southern catalpa