Earlier cropping of winter-harvested Welsh onion alleviates the severity of allium white rot (Sclerotium cepivorum) in Shizuoka prefecture

Abstract

To estimate the influence of harvest timing on the severity of allium white rot (caused by Sclerotium cepivorum Berkeley) of Welsh onion (Allium fistulosum L.), we compared the severity of white rot during 5 cropping periods. The rate of plant death was significantly lower during the 2 earlier cropping periods (15 June–24 Nov., 30 June–16 Dec.) than during the 3 later periods (15 Jul.–14 Jan., 5 Aug.–28 Jan., 19 Aug.–28 Jan.). The results indicate that earlier cropping allowing harvest in December can avoid severe damage by white rot because of the shorter cool soil period (daily average <15°C).