Possible causes are, lack of nourishment, excessive nitrogen, excessive soil dryness, overwatering, and syringing with cold water. Corky scab causes irregular, rusty or corky spots on stems. Older parts of the plant may have many spots while young shoots have none. Severe attacks may destroy entire shoots. Mild attacks may decrease flower production.
Epidermal cells dry then the epidermis breaks open and curls.
Increase light exposure and decrease humidity. Glassiness symptoms are dark green translucent spots. Slight pressure crushes the epidermis then the tissue beneath rapidly turns black. The shoots above the infection may be killed. Mild attacks cause corky layers or spots.