Effect of Compost Teas in Controlling Late Blight Damage to Tomatoes in Pennsylvania

Final Report for FNE98-221

Project Type: Farmer
Funds awarded in 1998: $500.00
Projected End Date: 12/31/1998
Region: Northeast
State: Pennsylvania
Project Leader:
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Project Information


Mr. Kretschmann is an organic vegetable farmer. He was interested in seeing whether foliar application of water extracts made from compost would be an effective method of controlling fungal diseases. He also wanted to know whether the age of the compost might have any bearing on its efficacy.

He made composts out of leaves and chicken manure, extracted them with water, then sprayed the extracts weekly on his tomato plants. Some extracts came from a compost pile that had been made the previous winter, and some from a pile made the winter before that. The experiment was run in triplicate, and with untreated controls, on field-grown tomatoes.

Mr. Kretschmann observed Septoria leaf spot and early blight on all plots. He also reports some small incidence of late blight. By the end of the season almost all plants were affected. Disease incidence may have been slightly lower among those plants treated with extracts made from the younger compost, but the effect would probably not be statistically significant. He did, however, make the serendipitous finding that of the two tomato varieties he was growing-- Belstar and Sunbeam-- the former was distinctly more susceptible to fungal disease.


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  • Lee Miller


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.