Compost Tea for Disease Management in Horticultural Crops

2004 Annual Report for LNE03-181

Project Type: Research and Education
Funds awarded in 2003: $147,956.00
Projected End Date: 12/31/2006
Matching Non-Federal Funds: $6,933.00
Region: Northeast
State: Pennsylvania
Project Leader:
Paul Hepperly
The Rodale Institute

Compost Tea for Disease Management in Horticultural Crops


The goals were to: 1)evaluate aerated compost tea (ACT) for its ability to enhance the health of horticultural crops and 2) to educate potential users on its production, application, and efficacy.

Field trials were done at The Rodale Institute® and at 3 collaborating farmer vineyards. Compost tea information was outreached in farmer field days (2 this year), by Fact Sheets (2) directed toward extension agents, farmers, growers, landscapers, and the general public and information was outreached on line through web publications.

Specific experiments were established to test the efficacy of ACT. Wine grapes, potatoes and pumpkins were used to evaluate ACT for crop health effects.

As in 2003, results in 2004 were mixed. Results were positive in pumpkins and no differences were noted in grapes and potatoes. This is the reverse of the results found in 2003 for the same crops.

Grape and Potato Trials: No positive effects in health or yield were identified in 2004 at any of the 4 sites (3 grape and 1 potato).

The 2004 season was very conducive to severe disease from a number of grape pathogens including those causing powdery mildew, downy mildew, gray mold, black rot, and leafspot diseases.

On potatoes all treatments were defoliated prematurely by late blight and no differences in yield or quality measurements were detected among treatments.

Pumpkin Trials: Powdery mildew early severity was reduced 80% (P = 0.05) for ACT compared to the nontreated control. ACT yielded more than both the Nutrient treatment and Nontreated by 1,700 and 5,000 lbs/acre but the difference was not statistically significant. Serenade and milk and compost tea and the same also reduced powdery mildew severity about 70 to 90%. ACT reduced both the number and size of powdery mildew colonies.

Milk and Serenade with compost tea provided over 80% control of powdery mildew and provided downy mildew control not given by ACT. Although compost tea alone was not a viable solo treatment the ability to get excellent and broad control with biocontrol agents deserves more attention. Downy mildew was the most destructive disease in 2004 on our pumpkins.

Soil Foodweb and Microbiological Analyses:We found that eliminating molasses from CT preparations effectively eliminated E. coli and enteric bacteria that were previously encountered in 2003.

We confirmed that active and total bacterial biomass and leaf colony counts reached thresholds believed to promote effective biocontrol according to Soil Web publications in all cases.

Overall Conclusions:Variable results obtained in relation to enhancing plant health. Over 2 years about 60% of the time yield and/or quality was positively affected (3 of 5 comparisons) and only in about 40% of the time was disease reduced (2 of 5 comparisons).

While ACT cannot be viewed as a panacea for plant health, it also is not without demonstrateable if unpredictable benefits. Because of its variable response, more work is needed before it can be recommended without reservations and with good probability of beneficial effects that are economically viable.

We recommend further investigation be aimed at improving overall efficacy of biologically based management systems by combining tactics as we did with serenade, milk, and compost tea combination.

Several approaches and tactics as part of integrated disease and health management seem in order and need more development and validation at this point.

Objectives/Performance Targets

1) Of 30,000 people exposed to and 120 people engaged in this SARE project, 50 farmers will adopt ACT within two years.

2) 15 vineyard managers will incorporate ACT into their management practices within one year of the field day. 10 will permanently adopt ACT and serve as a model of other vineyards.

3) At lease 10 extension agents will permanently incorporate ACT practices into their recommendations upon review research and attending field days. They will be able to easily provide information, research results and contact information for equipment and ingredient suppliers.


Compost tea information was posted on website. Interested farmers visited the site and read the information.

Compost Tea Production, Application and Benefits Fact Sheet was developed by Matthew Ryan.

On Farm Composting FAQ Fact Sheet developed and distributed.

A summary poster on ACT tests was developed and displayed for the SARE conference in Burlington Vermont during October 2004.

In July 2004 we hosted a field day at the Rodale Institute where 200 participants saw the field trials and had the compost tea process explained in detail. Results on pumpkins and potatoes we seen hands on in the field.

In August we participated in The Pennsylvania Association of Winegroweres field day on our cooperator Phil Roth’s farm in Adams County