The Most Common Question about Tree Care in the Twin Cities

The Most Common Question about Tree Care in the Twin Cities

Jim Ostvig answers a lot of questions about tree care as a certified arborist and Minneapolis tree service company owner. He discusses the most common question he receives from clients and provides his answer. Starting in July, property owners begin asking the certified arborists at Ostvig Tree Care, “Why are the leaves on my tree starting to turn brown and fall off?”

In many cases this is caused by one of two leaf diseases: apple scab and anthracnose.

Apple scab infects crab apple, apple and hawthorn trees while anthracnose infects maple, oak and aspen trees.  Both diseases are very similar and infect leaf tissue in the spring when the weather is very wet.  The disease begins to grow on the leaf, turning it brown and causing the leaf to fall off. This typically happens in July or early August.  In some cases, trees can lose up to 50 to 70 percent of their leaf surface.  This is not only an aesthetic problem; the tree loses sugar and starches provided by the leaves that benefit the long term health of the tree.

Both apple scab and anthracnose are very easy to prevent. Trees are treated in early spring when the leaves are about 25 percent out, followed by two more treatments at two to three week intervals. This will help ensure that your trees look great the whole growing season and keep their leaves until they are supposed to turn color in the fall.  The treatment only works as a preventive. Once the leaves begin to fall off in July it is too late to do anything for that growing season.

If you’ve had this problem in the past please give us a call at Ostvig Tree Care and we will help you take preventative measures against these diseases in the future.

Dogwood anthracnose

Dogwood anthracnose as captured by flickr user, NatureServe.