The damage from last week’s freeze events has become more evident over the past few days. In past frost events, typically the stem is the most affected by frost, either resulting in kinking or splitting. This can weaken the top and result in a variable canopy but doesn’t kill the top entirely unless the freeze is severe. This year the damage seems to be more to the leaves and less to the stems (Figures 1), even though the leaves had not unfolded yet when the freeze occurred. Frost blankets (row covers) helped reduce the damage considerably. In some lower areas without protection, both stems and leaves will be affected.

Figure 1. Damage to unprotected ginseng caused by the freeze events is focused on the leaves more than the stems (photos courtesy of OGGA).

It is likely that stems on these affected plants will eventually die as well over the next few weeks without the leaves to provide energy to the stem. This would lead to a long period of dead or dying tissue in the garden. This tissue will be highly susceptible to both Alternaria and Botrytis, so gardens will need to be consistently protected for the next few weeks for both diseases, especially considering warm and humid weather is in the forecast beginning this weekend.

Slugs and cutworms will also be very active in this weather and controls may be necessary. It is also important to start scouting now for leafrollers, even though the damage may not be seen for a few weeks. The earlier you can catch the small caterpillars beginning to fold up leaves, the better chance you have to control them. Once they are in their rolled-up homes, they are very difficult to control.