Submitted to: Spudman
Publication Type: Popular Publication
Publication Acceptance Date: 6/17/2016
Publication Date: 7/15/2016
Citation: Sabba, R., Lulai, E.C. 2016. Understanding pink eye. Spudman. 54(6):18-19.

Interpretive Summary:

Technical Abstract: Pink eye (PE) is a physiological tuber disorder that can result in serious processing complications and storage losses. The earliest external symptoms consist of an ephemeral pinkish discoloration around tuber eyes, predominately at the bud end of the tuber. These pinkish areas can then develop into corky patch lesions later in the season. Tissue just underneath the PE-afflicted periderm characteristically fluoresces under blacklight (UV-A). Recent research in Dr. Ed Lulai’s lab has shown this is due to erratic and incomplete suberization under the PE-compromised periderm, much like the closing layer that initiates in response to wounding. In addition, tissue underneath the periderm becomes brown and necrotic, often with dark, circular inclusions. These areas often became partially surrounded by an internal periderm, which generally does not fully form or completely suberize. At the same time, critically, the native periderm often becomes compromised or lost. The periderm, in particular the suberized phellem (cork) cell layers are the first line of defense from pathogen attack for the tuber. The suberized elements of the periderm (the phellem or “cork”) protect the tuber against both bacterial and fungal invasions. A PE-compromised periderm may allow pathogens inside the tuber, much like an open wound, which likely explains the bud-end rot often associated with severe PE late in the season, or in storage. There is no convincing evidence that PE is dependent upon any pathogen, though it has been associated with high temperatures followed by excessive moisture and with early dying and early vine senescence. Excessive moisture in the soil and heat can lead to hypoxia (deficiency in oxygen available to the tissue) or anoxia (complete loss of oxygen available to tissue) and eventual cell death both within and beneath the periderm of the tuber. Avoidance of early vine death and excessive water in the soil profile where tubers are located are possible approaches to reduce the incidence of PE development in the field.