Temporal changes of the frequency of spring frost damages in the main fruit growing regions in Western Hungary and in East Hungary

Among the climatic risks of horticultural production, the spring frost damages are the most important, consequently its quantifi cation is highly justifi ed. The severity of the damage claims a physiological approach by the LT50 function. The present study attempts the use of the function to distinguish between frost-susceptible, medium tolerant and frost tolerant apricot and peach varieties. The tests of measuring the severity of spring frost damages should be extended also to other fruit species. Apricot and peach are indeed relatively susceptible fruit species; therefore the experiments are initiated with those. Two Transdanubian and other two TransTisza growing sites have been selected for the meteorological study, how we could calculate the probability of the damage at least on the 50% level. As by knowing the frequency of climatic risks would help to determine the risks of production. The growing sites and varieties of peach and apricot plantations have been thoroughly elaborated by Timon (2000), Zayan (1981) and Salary (2001). Earlier studies proved that the most affl icted period is between April 11 and 15 almost on all growing sites (Liatos et al, 2005a). The probability of frost damage was 12–14% on almost all growing sites: Martial, Szeged–Szatymaz and around the Lake Balaton. At Szeged–Szatymaz, in the following period (April 16–20) the risk was still about 10 %. During a later period, April 26–30 and May 1–5, the threat is 2–4% at the Mátra–Bükkalja region only. Earlier, it was stated that at Mátra-Bükkalja the risk was double as severe as around Buda during the period April 11–20. The dates of bloom become later in south-north direction. At Mecsekalja (south), the bloom is earlier by 8 days than Temporal changes of the frequency of spring frost damages in the main fruit growing regions in Western Hungary and in East Hungary