Abstract:
Tipburn is a widespread physiological disorder of cabbage and
lettuce, caused by calcium deficiency. Symptoms of tipburn are
necrosis on margins of outer and inner head leaves in lettuce,
whereas in cabbage it is only on margins of inner leaves. Tipburn
on outer leaves may develop early, but symptoms remain the same until
harvest. Tipburn is more serious when it occurs on the inner leaves
as heads approach maturity.
In search of tipburn control, foliar calcium (Ca(N0₃)₂ and
CaCl₂) sprays were applied to the entire leaves to increase calcium
content, and foliar Folicote antitranspirant spray was applied to
outer frame leaves to reduce transpiration, stimulate root pressure
flow and increase movement of calcium to inner leaves.
Foliar sprays of antitranspirant, calcium, and combined sprays
of antitranspirant and calcium resulted in a degree of tipburn
control and in an increase in calcium content of inner leaves, but
failed to adequately control tipburn. Most effective was a combined
spray of antitranspirant and CaCl₂, next were CaCl₂, combined
spray of antitranspirant and Ca(N0₃), then antitranspirant alone
and least effective was Ca(N0₃)₂.
Foliar sprays of antitranspirant, calcium, and combined sprays
of antitranspirant and calcium resulted in slightly higher head
temperatures in cabbage and lettuce, and a tendency to increase
uptake of some mineral elements such as K, P, Mg, and B.
