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Plant Diseases/Autumn Blaze Maple Leaf Rigid and Deformed

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Hello Jim,

I have two Autumn Blaze Maple trees in a row on a side of a hill about 20 feet off or a paved driveway. There is a huge 35 year old Sugar Maple in the same row to the south of the two Autumn Blazes. The Autumn Blaze closest to the Sugar Maple is shaded part of the day by the Sugar maple and does not have deformed leaves.

I planted the two autumn blazes in the fall of 2010 at 3.5 inch calipers. Now they are 4.5 inch heading towards 5 inches. I feed them once a year with Jobes tree spikes and also water them every 4 days when dry outside. I also treat them with Bayer Tree and Shrub every late spring to protect their health.

This year in southeastern PA we have had a HOT heatwave month of July. I notice on the north side of one of the autumn blaze maples that that last 8 to 12 inches of leaves on some of the newer branches have deforming leaves. This maple is not shaded from any sun.

The leaves are very rigid and curling up. They are more firm than the fake leaves on decorative trees for inside a building. The leaves are pale green in color. I snapped a photo of one branch.

Is this the result of disease or is 3 weeks of upper daytime highs near 100 and nighttime lows in the upper 70s to lower 80s and HIGH humidity making the tree leaves dry up? Will this damage the tree permanently?

The Autumn Blaze that is shaded by the huge Sugar Maple does not appear to have any leaf deformations.

I am attaching an image.

Thank you very much for your insight.

Appreciatively Yours,

Mike

Answer
This is called leaf scorch. Leaf scorch is a noninfectious condition caused by an unfavorable environment. There is no chemical control for leaf scorch, so the most effective defense is good management. Leaf scorch typically appears following periods of extended dry, hot weather and occurs because tree roots are unable to adequately supply leaves with water. When water is lost from leaves faster than it can be replaced from the soil, leaves become dry and scorched. It's not unusual for scorch damaged leaves to drop from trees.

Young trees transplanted within the past few years are especially vulnerable to weather stress injury and should be watered with the equivalent of a one inch rain per week. As a general rule, water each week it does not rain. Water deeply to encourage deeper root penetration. Don't wet the foliage, and water in the afternoon to give the surface of the soil time to dry during the afternoon. Place a pan under the tree and turn the sprinkler on and when the pan has 1 inch of water in it stop. Do this only if it does not rain for a week. Over watering can be as bad as too little water. You want to train the trees roots to grow deep. IF you have not done so mulch around the tree with not more than 3 inches deep of organic mulch not piled up on the trunks--pine straw is good. This will help hold moisture around the roots.

Do not fertilize after June,  because some plants will then develop young, soft growth that will scorch easily in hot August winds.

Finally, if scorch occurs, resist the urge to continually apply more water. Just keep up with the deep and infrequent schedule. In some years, especially if conditions are especially hot and windy, some scorch is likely. Donít panic and kill off your trees with an excess of kindness by over watering.

Forgot to say this will not kill the tree. The drying leaves will more than likely drop off but usually new ones will sprout back. Your tree will be fine.  

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Jim Hyland

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30 years experiance in the ID and management of forest diseases and ID of landscape tree diseases.

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