PPDL Picture of the Week
February 27, 2017
Warm Weather May Cause Problems for Ornamentals
Kyle Daniel, Nursery and Landscape Outreach Specialist,
Horticulture and Landscape Architecture
The last few days, and coming week, temperatures across
Indiana and the Midwest are abnormally high for February. The southern part of the state should expect
temperatures in the 70’s, while the northern parts are expecting upper 60’s. Though the temperatures are a welcome reprieve
from a ‘typical’ winter for us, most plants can have serious problems due to
breaking bud too early. Most of Indiana
has accumulated greater than 900 chilling hours, which fulfills dormancy
requirements for most ornamentals.
Temperatures play a key role in de-acclimation from dormancy in the
spring. When an extended time of warm
temperatures occur, and chilling hours have been met, bud break begins to
occur, as well as phloem begins to move within the vascular tissue. If temperatures cool, the bud swell can be
suspended, but it appears the long term forecast calls for temperatures around
50 for most of the state. When bud break
occurs followed by cold temperatures injury can occur, such as bud kill. Since phloem may be active, bark splitting or
cracking may also occur on thin barked trees if a cold period occurs after
extended warm temperatures. At this
point it is too early to determine whether any damage will occur, but you
should be inspecting plants as bud break occurs. Damage may not be visible on the outside of
the plants, but necrotic (dead/dying) tissue will be evident in the vascular
tissue. Pruning out dead branches of trees and shrubs may be required this
spring after damage has been assessed.
If you have any questions, please contact Kyle at daniel38@purdue.edu.