Grey Mould is No Match for Compost Tea

  Compost teas provide reduciton of grey mold (Botyrtis cinera Pers.) on tomato plants
April 2024
European Journal of Plant Pathology
Link Here

      Yes, we know we have posted about compost tea and its ability to disrupt Botrytis' moldy maneuvers before, but we can't help ourselves to do it again when there's such excellent news out there.  This time the interesting info comes from the polite people of Canada at the Carleton University in Ottawa.  The plant science researchers wanted to see if the different types of compost had an effect on the inhibition of the fungal pathogen Botrytis.
         The composts tested were:  Cow manure, shrimp processing waste, garden/leaves/straw blend, and garden waste.   The scientists performed several telling tests.  In one, the compost teas were sterilized using both hot and cold processes.  The sterilized teas were then applied to colonies of growing Botrytis. .  Guess what, they didn't work.  The teas only had suppressive effects when they were alive (or maybe the sterilization process damaged the anti-fungal compounds produced by the microbes....we'll need more testing).  This tells us that compost tea needs to be fresh and living (or at least no sterilized) in order to get the anti-fungal benefit. 
      In another experiment, the teas were used as a foliar spray on leaves that had been infected with the disease.   They found "When used as foliar sprays, bovine manure (BOV), shrimp (SHR), and garden-leaves-straw (GLS) compost teas effectively reduced disease severity for six weeks"   The greatest delay in infection expansion was found with the Cow Manure, Garden/Leaf/Straw, and Garden Waste composts.  Notably this was done with a 10x dilution (1 gallon of tea in 9 gallons of water, this is TeaLAB's recommended dilution for maximum efficiency).   Interestingly, the cow, shrimp, and garden/leaf/straw teas did not perform any better when less dilute, meaning diluting it is both efficient and effective. 
      Lastly, the microbial populations were counted and identified.  The types and numbers varied between teas, and there was no correlation with the inhibitory effects.  This tells us that whatever type of compost you have, it's going to help reduce Botyrtis disease severity. 
          If you are anything like us here at TeaLAB, gardeners that don't like to see our fruits and flowers wasted to fungal disease, then you're bouncing off the walls right now.  Tell your family, friends, neighbors, community networks, professional associates, person in line behind you at the supermarket:  Compost tea works!!!    Thanks Canadian scientists!  We owe you some delicious, healthy, organically grown strawberries!

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