Reduction of fusarium wilt of hydroponically grown basil by Fusarium oxysporum strain CS-20

Abstract

Basil seedlings were drenched with water or Fusarium oxysporum strain CS-20. The following week, plants were placed in hydroponic troughs with a circulating nutrient solution. Since 2% of the seed was naturally infested with F. oxysporum f. sp. basilici, pathogen inoculum was not applied. After 7 weeks, there were significantly fewer dead stems in plants treated with strain CS-20 than in the control treatment. Laboratory experiments were conducted to determine if a different type of seeding medium could retard dispersal of the pathogen. Oasis is a rigid, open-celled foam used as a medium for seeding and for rooting cuttings. Oasis cubes (cubes physically attached to each other within each tray) and wedges (wedges physically separated within each tray) were seeded with basil. The cube or wedge nearest to the center was inoculated with 10 5 propagules of the pathogen or water. After 1 and 2 weeks, half of the cubes and wedges in each of the three trays were destructively sampled. Different trays were used for the 1- and 2-week samplings. For treatments inoculated with the pathogen, the number of colony forming units (cfu) recovered decreased significantly as the distance from the inoculation site increased. Significantly more cfu were recovered from cubes than wedges when both planting media were inoculated with the pathogen, indicating that the cubes were more conducive to pathogen dispersal than the wedges. In the cubes, the pathogen was recovered 13 cm away from the inoculation site at populations significantly higher than the background levels (up to 10 6 propagules/cube).