(1) On 9th May, 1952, there was a destructive frostdarnage in Fukushi-ma prefecture. A few parts in this prefecture suffered additional frostdama-ges vocally on 17th, 22nd, and 26th, May. (2) 3.n the Fukushima Basin mulberries, pears and peaches only sufferd the first frostdamage of the year. The distribution of several grades on in mulberrydamage is mapped in Fig. 1. The distribution of “Super high” and “high” grades is found in two belts; one is in the flood-plain of River Abukuma situated on the north-eastern lovvest part of the basin, and the other on the gentle slope of the young compound fans in the south-western part of the basin. The pattern of this distribution relates closely to that of the minimum temperature, since the time of mulberries germination. is almost similar th rdughout the basin floor. The form er is so. low in its height that cold air settles early in the morning, and the latter is a stagnant part of the cold air, caused by windbreaks maide of dense cryptimerias and bamboos, and by other reasons. (3) The distribution of frotdamage in Fukushiia prefecture.
In the Abukma valley, and on the Abukuina plateau, or Nakadori, there is almost always a tendency of suffering severer frostdaznage than in Aizum and Hamadori. Although the minimuin. temperature is lowest in the south-wastern part of the prefecture there is no frostdamage of mulberries untill early in May. Since Aizu is a mountainous, snowy province, mulberry buds are later than in the other pprovinces, and there is also few frostda-mage in April and early in May. In Hamadori or the littoral province it is as warm as in the Fukushima Basin, but the littoral has longer frostless period owing to oceanic influences. In spring, 1952, and 1941, etc, the middle Abukuma valley and. the plateau suffered severe damages, while there Little or no daiiiage in the gorge and its outlet on the south-easten manin of the Fukushima Basin. since the Surimagi and Okawa Valley also have gorges at the lower parts, and bear some resemblanees to the middle hukilnza Valley, severe frostd.ainage sometimes occurred in the upper part but a little or no frostdauiage occurred in the gorge and its outlet. (a) In the gorge the canyon wall is so steep that the Katabatic wind hlows as soon as tre air cools down. By the drainage of the speedy air, the cool air mingles with the warmer air of the upper. layer. (b) cold airsaagniates on, the Wide, gentle slope of the upper valley, and through a narrow steep floor of the gorge, it is drained off as fast as a rapid stream in the canyon. it mingles With. warm. air, and they blow down towards a gorge outlet. That is one of the reasons why frostdamage is not so severe in the gore and its outlet. (4) On the flood-plain of the Abukuma-River in the Fuku sima Basin, the frostdamage occured in 33 years out of 52 years from 1889 to 1941. Among these 33 years, very great damages were made in 9 years. In spite of the frequent damages one of the most integrated sericuture region of Japan, located on the flood-plain in north-eastern Ft kusinia Basin did not move towards a frostless region on. the slope of its surrounding mountain. Where the latest frost occurs in June or at the latter part of May, silkworms of summer or autumn are mainly reared. (5) The method of protection front frostdainage is has made no progress in this region. The difficulties of prevention increased rather than before the war owing to the dispersion of mulberry fields, resultedf rom the expansion. of fields for food production during the wartime, and to other various reasons. Whereas such sensitive crops, as pears and some sort of vegetables came to be raised. in the re ion where the damage e was repeated in almost every season, thus resulting in suffering severer damage. (6) With a few e ceptions. the people are not adequately utilizing the frmtle s belts of a temperate zone on the slope of surrounding mountains and of isolated hills.
