Disease Management - Growing Organic Orchard Fruits - page 482

Hydrogen Peroxide
Sometimes described as an organic fungicide, hydrogen peroxide is allowed
for use under the U.S. National Organic Program. At present, two commer-
cially available products are approved by OMRI for plant disease control. In
general, hydrogen peroxide is chemically active and quite effective in killing
microbes under some conditions, making it a useful disinfectant for food pro-
cessing and agricultural equipment. It is also used in disinfecting livestock.
Little is known, as yet, how hydrogen peroxide can be used to control
plant diseases and how effective it is. Controlled tests on treating lettuce leaf
diseases produced poor to mixed results. Hydrogen peroxide is a wide-spec-
trum disinfectant and does not distinguish between beneficial and patho-
genic microbes. Proceed cautiously when testing hydrogen peroxide-based
products, and ensure that any commercial products you apply are approved
for organic food production. Some are reported to contain amendments that
are not approved for certified organic production.
Tetracycline and Streptomycin
Tetracycline and streptomycin are bactericides that are approved under the
U.S. National Organic Plan for plant disease control. Their primary use is
preventing fire blight in pome fruits, but they are also used for a few other
bacterial diseases. The move to include these antibiotics in the allowed list
of synthetic materials was controversial and succeeded largely due to the
importance of apple production and the difficulty of controlling fire blight.
While they have proven valuable for controlling fire blight, there is evidence
that bacteria are becoming resistant to the antibiotics. Use these products
as parts of an integrated program to control fire blight, not as silver bullets.
Microbial Fungicides
OMRI-approved products containing Trichoderma or more generic microbes
are available. Trichoderma is a genus of fungi that includes many naturally
occurring strains found in soil and wood. These fungi are valuable biocontrol