Early tree defoliation

Farm Forum

I have been receiving a large amount of phone calls in regard to cottonwood trees that have leaves turning brown and falling to the ground. This has been happening now for about 2-3 weeks. In many areas of the county, there are large cottonwoods that are completely defoliated. Luckily, most of these trees will not be negatively affected by the early loss of leaves. The wet spring we experienced this year created conditions for multiple leaf diseases to set in on cottonwood trees. Once these leaf diseases are established, there is no recommended control. Native cottonwoods are more tolerant of these diseases then the hybrid, seedless cottonwoods. Although there are large cottonwoods growing in Aberdeen, this is a tree recommended for planting in rural areas only. I always recommend planting native cottonwood over hybrids as they will live longer, have less disease problems and thrive in various conditions. Other poplar species are affected as well, such as aspen and balsam poplar. If you have poplars that have completely defoliated, refrain from cutting them down as they will put new leaves out next season.

Remember to water your trees until the ground freezes. With the lack of fall rain, our trees need supplemental water to ensure successful winter dormancy. Trees that go into winter with a lack of soil moisture are prone to winter injury, desiccation and death. Avoid fertilizing until after a hard freeze and if you are fertilizing your lawn, your trees do not require additional fertilizer. It’s always better to have your soil tested for nutrient deficiencies before fertilizing. Soil testing labs can be found at http://bit.ly/1N28p0D.