Ecology of a Compost Tea Catherine Crosby Ph.D. candidate Ph.D. candidate WSU Crop and Soil Sciences
Compost Tea (Compost Extract) 1 part compost : 1-100 parts water Inoculants Growth stimulators, microbe food Plant nutrients, rock powder Aerated or static brew 1hr - 1 wk Dilute or not
What are Aerated Teas? Grown with aeration Contain aerobic microbes More potential for growth (including pathogens)
What are Fermented Teas? Low cost Not aerated, will become anaerobic Community of anaerobes and aerobes (near surface) May have more consistent control of fungal diseases (Scheuerell)
How are compost teas applied? Backpack sprayers for small areas Boom sprayers Fertigation lines Teas must be filtered High pressure can damage organisms
What are Compost Teas used for? Nutrient supplements Soil improvement Plant stimulators Microbial community building Biological control of disease* *The EPA classifies compost tea as an experimental pesticide, id if used as biological i l control. This means compost teas CANNOT be applied to control disease in food systems at this time.
Why do we care about brewing different teas? Designing teas for specific uses Select the microbial community Micronutrient availability affected by ph Salts can negatively impact plants Check the EC of finished teas Stability of chemical properties may indicate Stability of chemical properties may indicate stability in the microbial properties
How can we make different kinds of tea? Change the: Compost Additives Aeration Temperature Time NOTE: If additives are used, compost tea used in certified organic systems must be treated as RAW MANURE: allow 90/120-day harvest interval
What compost is best for tea? High quality is important Tested pathogen free Consistent feedstocks Meets organic standard (for organic systems) Readily available The same compost can still The same compost can still make multiple different teas!
Compost Tea Recipes (1 Liter) Bacterial Tea Compost 50ml Whey powder 5g Glucose 2g Protozoan Tea ¼ tsp Compost Red potato 10g chunk 10g straw (boiled in water) Fungal Tea Compost 50ml Whey powder 5g Straw chopped 50ml Diverse Tea Compost 50ml 1g seaweed powder 2ml humic acids 3 g Azomite rock dust
Do we see differences in tea made from the same compost? Bacteria CFU Log 9 8 7 6 5 4 3 2 1 0 50 million per tsp. a b a a Protozoan Diverse Fungal Bacterial Batch 1 Batch 2 Batch 3 Tea Recipe
Do we see differences in tea made from the same compost? Electrical Conductivity 2 a ds m^-2 15 1.5 1 0.5 d b c Batch 1 Batch 2 Batch 3 0 Protozoan Diverse Fungal Bacterial Tea Recipe
Do we see differences in tea made from the same compost? ph Neutral ph 9 8 7 6 5 4 3 2 1 0 b a Protozoan Diverse Fungal Bacterial Tea Recipe d c Batch 1 Batch 2 Batch 3
Nutrients in Compost Tea Compost teas contain tiny amounts of all macro- and micro-nutrients Total inorganic N anic N mg/l Inorg 3.5 3 25 2.5 2 1.5 1 0.5 0 Protozoan Diverse Fungal Bacterial Tea Recipe Batch 1 Batch 2 Batch 3
What is Biological Control? Also called Biocontrol Using organisms to control other organisms by causing death inhibiting growth inhibiting reproduction Inhibiting pathogenic phase
Disease Suppression Competition Antagonism Inhibitory compounds Stimulate plant resistance responses Interference with disease lifecycle
(1a) Hyphae of the fungus Arthrobotrys coiledarounda a hypha of a pathogenic fungus Rhizoctonia resulting in the death of the latter (1b) Hypha of Sclerotium parasitized (revealed by penetration hole) by a parasitic fungus, Trichoderma (Campbell 1989)
Results with Compost Teas MIXED!! Often do suppress disease Sometimes worsen disease Sometimes enhance plant growth Sometimes no effect
Diseases Controlled with Compost Teas (at least 1 study) Common name Late blight of potato, tomato Gray mold on beans, strawberries Fusarium wilt Powdery mildew on cucumbers Apple scab Bacterial leaf blight on carrots Downy & powdery mildew on grapes Genus Phytophthora Botrytis Fusarium Sphaerotheca Venturia Xanthomonas Uncinula, Plasmopara
Xcc Lifecycle Pathogen contacts leaf surface Production of DF stimulates EPS and pigment pg When population reaches threshold, DSF signals break-up of biofilm Pathogen enters the hydathodes Pathogen travels through the vascular tissue DF DSF
Indicator Strain Overview DF DF DF DF
Diagram of Plating Assay Xanthomonas alone Xanthomonas Plus tea Yellowing indicates pheromone response
Compost Tea Xanthomonas Xanthomonas alone Plus tea Pheromone response Prevents pathogen pheromone functioning
Sterile Tea Xanthomonas Xanthomonas alone Plus sterile tea Pheromone response Pheromone response Allows pathogen pheromone functioning
What is the verdict on Compost Tea? Valuable nutritional supplement Useful part of organic fertility management May provide beneficial microbes More research needed on properties and uses of More research needed on properties and uses of compost teas!
Take home concepts on compost tea Compost tea can be easy to integrate into established systems Use HIGH QUALITY starting materials garbage in = garbage out EPA rules DO NOT allow use of compost teas to control disease at this time
Trying out Teas KNOW YOUR PESTICIDE RULES! Compost tea is classified as an experimental pesticide Can be used as nutrient supplement Follow application guidelines for the compost used If additives used, treat like raw manure
EXPERIMENT! Take notes Replicate!
1 2 Don t Treat Treat Treat Don t Treat 3 4 Don t Don t Treat Treat Treat Treat
Thanks Funded by a USDA special grant for Organic Research administered i d by WSU- CSANR Please ask questions!