Effekten af varmebehandling af overfladejord i naaletraessaabede over for ukrudt og rodpatogene svampe.
1994
Boedker L. | Noye G.
The effect of heat treatment against root diseases and weeds in raised seed beds under field conditions were investigated in 1992 and 1993. Steam treatment for 5-6 minutes had a good short term effect in 1992 against Polygonum aviculare, Poa annua, Veronica arvensis and a group of other dicotyledons. After four months the steam treatment still maintained a good effect against P annua but showed a reduced effect (60-70%) against dicotyledons in general. A number of different genera and species of fungi were isolated from the root of seedlings. All species of Fusarium and Pythium were pooled in Fusarium spp. and Pythium spp. respectively. In 1992 steam had a only good effect against both Fusarium spp. and Pythium spp. by 12 minutes treatment. In 1993 only Fusarium spp. was prevalent in the seedlings and 2-4 minutes steam treatment was enough to carry out a complete control of Fusarium spp. A desinfection of the seedbed before sowing with Dazomet had only a minor effect against Fusarium spp. Flame treatment was only performed in 1993 with a lower effect against Fusarium spp. compared to steam treatment. However there is an indication of an good effect of both flame- and steam treatment if the soil temperature in a depth of 2,5 cm is raised above 60 deg C. Previous field trials indicate that Pythium spp. is the most important group of soil borne pathogens in raised seedbeds with conifers in Denmark and Dazomet is an efficiant desinfectant. Future trials shall illuminated if a heat treatment has same efficacy against Pythium spp. as Dazomet and can be concidered as an alternative to a chemical desinfection.
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