The potential of biological soil disinfestation to manage Fusarium foot and root rot in Asparagus

In a field experiment on an abandoned asparagus field we studied the effect of Biological Soil Disinfestation (BSD) on survival of buried inoculum samples of three test pathogens (Fusarium redolens f.sp. asparagi (FRA), Rhizoctonia tuliparum (RT) and Verticillium dahliae (VD)) and on the Fusarium infestation level. The BSD treatments involved incorporation of grass into moist soil and covering the soil with airtight plastic. The amount of grass incorporated was varied (42, 62 or 102 tons of grass/ha) as well as the depth of incorporation (40 or 80 cm). It was found that BSD greatly reduced all three pathogens in buried soil samples and that incorporation of 62 or 102 tons of grass per ha to 80 cm soil depth resulted in a significant decrease in soil infestation in the upper 40 cm; in the deeper layer the decrease was lower. Asparagus plants grown from seed in the field for one year showed a strong decrease in Fusarium root rot severity with all BSD treatments. The results clearly show the potential of BSD to decrease soil infestation levels of Fusarium pathogens and to contribute to an enhanced life span of replanted asparagus crop