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Identifying Leaf Spotting Diseases – Denver Tree Care


Leaf Scorch Disease
In Denver’s summer heat, it’s not uncommon for many Denver trees and shrubs to develop brown, dry leaf margins called leaf scorch. This is caused by insufficient intake of water in the harsh conditions in the summer. When there isn’t enough water to reach from the roots to the veins of the leaves, they can turn brown and fall off. There are a few reasons this happens – the first is inadequate root growth, which can be restricted by pavement or construction.

Being deprived of oxygen from excess moisture due to overwatering affects the growth of new roots as well. When no new roots are developing within the overwatered soil, leaf scorch will develop. Heat stress is another way that can lead to discolored leaves or even cell death depending on the severity – preventing a tree from drawing sufficient water into its leaves. 

Once leaf scorch occurs, the best thing you can do is water infrequently and deeply. The leaves themselves cannot be saved, but the plant may recover. To prevent leaf scorch, begin with winter watering once a month without snow cover. Make sure to water in the morning on days when the temperature is above freezing to ensure the plants get the water before it freezes at night and suffocates the roots.

Marssonina Leaf Blight
Marssonina Leaf Spot is a fungus that causes the most common foliage disease on aspen and cottonwoods in Colorado. The leaf spots caused by Marssonina appear as brown flecks surrounded by a yellow ring. When they have a white center, it means that it’s a more immature spot as opposed to severely affected leaves where the spots have come together to form large black dead patches.

When Marssonina affected leaves have fallen, the fungus can survive on them through the winter until they produce spores that are carried by the wind in the warmer weather. The spores then infect emerging, younger leaves. Early infections are rarely serious, but premature leaf loss is common on trees that are infected with a secondary widespread infection.

In the incident of spotted leaves, make sure to call American Arbor Care, your premier Denver tree service, to correctly diagnose the disease. For your leaves and trees look their best, it’s important to take action as soon as you suspect an infection to ensure it doesn’t spread to the rest of the tree or possibly to neighboring trees. 
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