3.7.91
THE EFFECT OF WATER STRESS OM CANKER AND BUD ROT CAUSED BY T. PARADOXES AND C. RADICOLOA ON DATE PALM (PHOENIX DACTLYLIFERA)

P SULEMAN, A MUSALLAM and CA MENEZES

Deparment of Biological Sciences, Kuwait University 'safat, 13060, Kuwait

Date palm trees (Phoenix dactylifera) were infected with C. radicola and T. paradoxes in one plantation in Kuwait in 1992. A survey of the southern region of Kuwait in subsequent years showed infected date palms in landscapes and nurseries. Laboratory and growth chamber studies with 5-6-leaf seedling plants subjected to water stress resulted in large necrotic lesions, cankers, death of buds and plant mortality. Plants under less water stress had smaller lesions and low mortality compared to those under severe water stress. The extent of tisssue necrosis and size of cankers were inversely related to tissue water potential. In vitro studies using NaCl, nonitol, or agar concentrations to decrease the osmotic- matrix-based water potential of growth medium decreased the growth of both fungi at 4, 3, and 7.5%, respectively. Histological studies showed islands of necrotic lesions mainly in tissues with parenchyma cells. The development of cankers alone was not a good indicator of plant mortality, as many plants died without extensive cankers.