Putting a Stop to Pythium: Humic Acid and Kelp Additives Boost ACT's Effectiveness against Damping Off

Compost Tea as a Container Medium Drench for Suppressing Seedling Damping-Off Caused by Pythium ultimum
Phytopathology
June 2004
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          The great state of Oregon has graced us with some insight into combatting damping-off caused by the fungal pathogen, Pythium.  Researchers at Oregon State University wanted to know how to make the most effective (pythium suppressing) compost tea, so they tested several variables: aerated vs. non-aerated, compost type, tea additives, and dilution rates.  The compost types were composted yard waste, vermicompost, and a commercial compost made from manure/agricultural waste.  The additives were soluble kelp, humic acid, rock dusts, and molasses.
             The researchers grew cucumber seedlings planted in an inert growing medium that had been inoculated with Pythium.  The seedlings were allowed to grow for nine days, at the end of which the number of healthy seedlings were counted and compared to the control group (seeds planted in non-Pythium inoculated soil).  The various tea treatments were used to drench the soil medium upon the time of planting. 
          Consistent disease reduction was only observed with the Aerated Compost Tea that had humic acid and soluble kelp as additives (the type of compost did not matter).  Also notable, compost teas made with molasses had inconsistent suppressive effects, with a potential increase in disease.  Dilution rates lowered effectiveness as well.  The take home message: when making a compost tea, be sure you have sufficient aeration, cut back on the molasses, and use humic acid and kelp additives if you want to keep your seedlings happy and healthy. 

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