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HEAT Injury to high field temperatures other than drought stress may also be associated with sunlight. Leaves become sun-scalded, turning brown and loosing their rigidity. Affected areas are moist and feel like thin, smooth, soft leather or membranous like a bat's wing, then become brittle upon drying out. Stems are affected by high soil temperature at soil level. This is especially true with small plants. The stem becomes girdled and the surface turns tan to white. It also becomes prone to rot organisms especially blackleg and stem canker. Tubers exposed
to high soil temperatures will become soft and be partially cooked.
The inside will hollow out and the large cavity will have a dark border.
This defect is call internal heat necrosis. When exposed to sunlight
at high temperature, tubers turn dark green, dry up and become hard.
This is a severe form of tuber greening called sunburn.
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