Typical water stress symptoms include reduced growth and necrosis of leaflet tips, spreading to the entire leaf as severity increases (Fig. 1). Oldest leaves are usually the first to show symptoms, but eventually newly emerging leaves may also wither and die. Death of the meristem may follow. Water stress in some species is indicated by leaflets folding about the midrib or wilting. In mature palms, shriveling or collapse of the trunk may also occur (Fig. 2).
Boron or other chemical toxicities, high soil soluble salts, and potassium deficiency can cause similar symptoms. Leaf, and/or soil analysis may help eliminate these other possibilities.
Water stress occurs when water is limiting or the root system is incapable of taking up sufficient water.
Water stress is fairly common in container-grown palms but is less common in landscape or field situations due to the more extensive root systems of the latter. Wilting caused by water stress may be apparent on palms growing in wet soils due to root rot diseases, poor soil aeration, or vascular wilt diseases. Palm species native to dry climates are usually more drought tolerant than those from tropical rain forests that lack a distinct dry season. Palms in general are fairly tolerant of drought once established in the landscape.