The Q&A Archives: How to stop our Catalpa & Cottonwood trees from dying?

Question: We have several Catalpa & Cottonwood trees on our property that are 4 to 5 years old. We lost all but one of the cottonwoods; the leaves start out dark green, turn to a pale-bright yellow with brown spots, die, and fall off leaving the tree almost bare by end of July. The Catalpa's were doing great until this year, now many of their leaves are turning a pale-bright yellow with browning at the ends. This has been a very hot summer with 20+ days over 90.(We live in Colorado east of Denver about 75 miles) We now notice some of our Maple trees that were planted last fall doing the samething with leaf color. We've had the extension people out twice & they can't agree on what the problem is over/under watering, disease...was hoping you might have a clue. I did read about a disease that can get into stressed trees & clog their

Answer: It is really difficult to diagnose a plant problem without being able to see the plant. If you have already had extension professionals out and they cannot come to any conclusion, I?m not sure I can, either. I do know this: plants under stress are more likely to develop insect and disease problems than those that are not stressed. So, environmental/cultural issues enter into the picture. Diseases are generally host specific so if your cottonwoods developed a disease, it would not necessarily spread to your catalpa or maples. Insects can be vectors of diseases (spread disease pathogens from one plant to another) but they would do so only if the insect population moved from the same species of trees to other trees of the same species. There is a disease maples are susceptible to called verticillium wilt. It is not curable and it is unusual, but it does happen. You can check for sure if your maple has this by cutting off a branch and looking at the wood. If it has the disease you will see a definite olive-black streak within the wood, running the entire length of the branch.

While I can?t positively diagnose the problems with your trees, I can offer some guidelines to help keep your remaining trees healthy. Deep watering is essential, especially in hot, dry weather. Feeding each spring will ensure healthy new growth. Rake and destroy any fallen leaves in the fall, to remove insect eggs and disease pathogens from the landscape. Keep lawn mowers and weed whackers away from the trunks of your trees to minimize injury.

Best wishes with your trees!

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