Gj. Van Os et al., Effects of soil fumigation and flooding on suppression of Pythium root rotin ornamental bulb culture, EUR J PL P, 105(8), 1999, pp. 791-800
The effects of flooding and soil fumigation with cis-dichloropropene or met
hylisothiocyanate (MIT) on disease suppression against Pythium spp. were te
sted in pot and field experiments in sandy soil. Disease suppression was re
duced by both flooding and fumigation treatments, resulting in severe infec
tion in Iris and Crocus and reduction of bulb yields. It is demonstrated th
at the disease suppression has a biological nature, and that disease severi
ty is more related to effects of the soil treatments on the soil microflora
than to the initial inoculum density of Pythium. After flooding, disease s
uppression was restored within the experimental period of two years, wherea
s after fumigation, disease suppression was only partially restored. The ef
fect of repeated fumigation in two consecutive years on the disease suppres
sion was less severe than the effect of a single fumigation treatment prior
to cultivation of a susceptible crop.