Issue 4, June 1, 2021
Watering during drought can reduce stress in trees, potentially reducing long-term injury from frost damage and diseases
Don’t fret, but some trees may be showing damage from the late frost we received in May for several months to come. Some additional watering during the hot dry months of summer, and the affected trees will be well on their way to being beautiful specimens.
Maples, redbuds, crabapples, flowering cherries, ginkgos and magnolias may are a few examples of trees that may have experienced some damage. Frost damaged leaves often shrivel, turn brown or exhibit black spots with chlorosis. Some leaves may have already dropped off the plant. Fortunately, these frost-damaged trees will produce new leaves to replace any that were lost.
Some branches may be slow to leaf out. Do bark scratch test before removing “dead” branches. A live tree will be green underneath the bark, while a dead branch will be brown.
Symptoms from other diseases may start to appear as the season progresses. Diseases like anthracnose thrive under cool, rainy spring weather. Disease symptoms can be hard to distinguish frost damage and may need to be sent to the University of Illinois Plant Clinic to get proper identification.
It is important to know diseases cannot be cured, but they can be prevented. Diane Plewa, University of Illinois Plant Clinic Diagnostician, says, “Diseases are more prolific in stressed trees and most of the stress comes from nutritional deficiencies, drought, improperly planted trees, improperly mulched plants. “ If homeowners don’t address issues causing tree stress, reduction of disease symptoms may be impossible. Check out these blog posts on diseases that will likely appear soon on Illinois trees. Richard Hentschel talks about diseases symptoms expressed in the late summer following a cold wet spring and Flowers, Fruits and Frass blog highlights
Tips for watering stressed trees during drought
- Check the rain accumulation in your area, https://stateclimatologist.web.illinois.edu/current-conditions/. Most established trees need 1 inch of water a week and 2 inches if it is hot and dry.
- Newly planted trees or shrubs require more frequent watering than established trees. They should be watered daily the first few weeks after planting and at least weekly for the first season of establishment. Check to see if the root ball is dry a few times a week.
Author:
Kelly Allsup