FROST DAMAGE IN LEMON ORCHARDS IN THE PROVINCE OF MURCIA

Every few years frosts affect the cultivation area surrounding Murcia (Spain). The most important frosts in recent years occurred during the winter of 1994-95 and the latest ones in 2004-05, 2010-11 and 2011-2012. In this work we describe and compare the effects of the last two frost periods on fruit and vegetative damage in lemon trees cultivars (Citrus limon Burm. f.) and grapefruit (Citrus paradise Macf.) in the above mentioned area. During the season of 2010-2011, frost damage was more severe than in the current year 2011-2012. Temperatures in citrus fields reached -6.63°C with 10 hours of temperatures below 0°C. Frost-induced damage in fruits and vegetative tissue in orange and mandarin cultivars was scarce but more frequent in grapefruit and severe in lemon trees, two last cultivars grafted on Citrus macrophylla. Among lemon cultivars studied, the most sensitive to frost was Messina. The risk of frost in the citrus area of Murcia for a critical temperature of -3°C was also studied. The probability of frost damage is 2% on the coast and 60% in the inland valleys of Murcia.