Monday, November 5, 2007
47-4

Evaluating the Impact of a Severe Frost Event on Cold Sensitive Crops on a Research Station.

C. Lynn Morrison, Thomas Ortega, Sue Lee, and Stephen Cockerham. University of California-Riverside, University of California-Riverside, 1060 Martin Luther King Blvd., Riverside, CA 92507

Temperatures spiked at 5.6oC (22oF) three nights in a row. Damage included broken irrigation lines, valves, and filters. Early estimates of lemon fruit loss was in excess of 50% and navel orange fruit loss about 40%. Each had mature fruit that was being harvested at the time of the frost. Although damaged fruit does not show up for several days, fruit was assessed by cutting and noting ruptured vesicles. The losses of other citrus fruit not ready for harvest is less easy to measure. Long term damage is evaluated for the slow leaf emergence in the spring, bud damage, loss of young tissue, and slow fruit development. Young citrus and avocado trees planted in the early fall prior to the mid-winter frost event have exhibited considerable stunting of growth and approximately 50% mortality requiring replacement of the lost trees.