Foliar Necrosis and Palm Freeze Damage

Types of Cold Damage

Here is a great explanation on Palm Damage from our reading material here at Edwards Landscape Management. Straight from University of Floridas Ag Dept.

"There are essentially three types of cold weather events that can injure palms. Chilling injury occurs in tropical species at temperatures above freezing and occasionally as high as 50°F. However, the absolute temperature at which chilling injury occurs is less useful as a predictor of damage than the degree of cold acclimation a particular palm has experienced. For instance, a tropical palm acclimated to night temperatures of 70°F, but suddenly subjected to a single night of 45°F, may experience some foliar necrosis (dead tissue) as a result. However, if that same palm had experienced gradually decreasing temperatures over a period of weeks, it may not show any cold injury symptoms until exposed to temperatures in the low to middle 30s°F.

Chilling injury symptoms include leaflet discoloration and/or necrosis (Fig. 1), which occurs within days of the cool or cold weather. Since newly expanded leaves are usually more cold hardy than mature leaves (Larcher and Winter 1981), the youngest leaves may be unaffected or show only mild symptoms. In coconut palms, younger leaves may show reddish blotches on the upper surfaces of the leaflets  while mature leaves may show extensive necrosis from the base of each leaf to its tip ). While potassium deficiency, which is almost ubiquitous in palms in Florida (see Potassium Deficiency in Palms, http://edis.ifas.ufl.edu/ep269), also causes leaflet necrosis, this necrosis is most severe on the oldest leaves toward the leaf tips  Thus, the sudden appearance of extensive leaflet necrosis on mid- and lower-canopy leaves caused by cold temperatures can be fairly easily distinguished from the leaf tip necrosis on the oldest leaves caused by potassium deficiency. "

University of Florida's Ag Extension has been an instrumental part to my companies training and extensive knowledge on everything involving landscaping. Thank you for the hard, studious work you guys put in so that Companies like myself can succeed and ensure Best Management Practices