Monday, March 16, 2009

Edema

Under certain conditions plants in greenhouses or even in the open field, may absorb water through the roots faster than it can be transpired through the leaves, with the result that dropsical swellings or blisters occur on the leaves and more succulent stems. There is also a deformation of the foliage, much like the leaf-curl produced by over-feeding. This trouble, known as edema, occurs when the soil is warmer than the air, or during periods of moist, warm, cloudy weather, which checks transpiration. The grower should cease pruning, and withhold water, and in the field cultivate deeply. In the greenhouse, adequate ventilation should be given, keeping the house dry rather than moist.