The Bay Gardener by Dr. Francis Gouin

Your Sycamores Are Not Dying

But thanks to sycamore anthracnose, they are suffering and won’t fill out until this summer

During the past weeks, a number of Bay Weekly readers have expressed concern that something is killing the sycamore trees in their yards and in forests. The defoliation and the dead leaves that are dropping to the ground are due to a disease called sycamore anthracnose.

This disease occurs only when we have a cold, wet spring like this year. The fungus that causes this disease attacks the newly emerging growth at the tips of the branches. Just as the first young leaves begin to mature, they are killed by the fungus, causing them to curl and turn brown before falling to the ground. This gives the appearance that the tree is dying.

Since only the outermost three to five buds on last year’s growth are the first to start growing in the spring, there are older buds farther down on that same stem that are capable of growing. Because these lower buds are older, they are not able to start growing until the buds at the ends of the branches have been completely killed. This phenomenon is known as apical dominance.

When the weather is warmer and drier, those older buds will start growing and the trees will again appear normal. However, if you examine the ends of the branches closely, you will notice that each branch has dead tips that will often persist for several years.

Sycamore anthracnose can be prevented by spraying the trees with a copper sulfate solution prior to the period of infection. Since it is difficult to predict when the infection will occur, and since sycamore trees are tall, spraying is expensive and difficult.

The most effective means of preventing this disease in the home landscape is to plant only the London plane tree (Platanus acerifolium). The London plane tree has foliage similar to that of sugar maples with a bark similar to our native sycamore.

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Tending to Compost

Q Is there any way that’s easier to turn compost? Gadget, technique? I’m manhandling a pitchfork to turn the heavy load. As to water: Don’t have to worry of late, but how often do you suggest wetting the compost pile? Every day? Every two days?

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A Turning the compost pile with a pitchfork is not only good exercise but it is cheaper than going to the health center and paying to use a rowing machine or treadmill. Using a long-probe thermometer is the best way of knowing when to turn. When temperatures start dropping, it is time to turn.

Keeping the compost pile wet is, however, more important than frequent turning. The only way to determine when to add water is by feel. If the compost feels like a wet sponge, there is sufficient water. If it feels dry, add water. If you squeeze it and water runs out, there is too much. I still have all my fingers after handling compost of all types for 40-plus years.