Recent major citrus freeze damage in Louisiana prompted expanded research in frost protection methods. Tests with tree enclosures and water and protection of the tree trunk and main scaffold limbs with water were initiated in 1987 and 1988 and data were taken during the Christmas freeze of 1989. The morning low air temperature was below -8-degrees-C for 3 consecutive days and a wind of approximately 13 m s-1 was present during the first 2 days. The trees were Satsuma-mandarin orange and navel orange. The five treatments in the tree enclosure-water trials were without and with water and/or enclosures or an enclosure with a low rate of water application. The scaffold branch protection trials consisted of protected and unprotected treatments. At the coldest air temperature, -12.0-degrees-C, the temperature near the tree in the enclosure-with-water, high rate of application, was -2.4-degrees-C. The temperature modification provided by the high rate of water application on the three mornings was 6.6, 9.6, and 10.3-degrees-C. No significant tree damage was observed in the enclosures with water. The scaffold branch trial had limited success owing to the small size of the tree trunks and improper height adjustment of the spray nozzles.
