Resource Guide for Organic Insect and Disease ... - Cornell University

MATERIAL FACT SHEET
Bicarbonate (Potassium or Sodium)
MATERIAL NAME: Bicarbonate (Potassium or Sodium)
MATERIAL TYPE: Mineral
U.S. EPA TOXICITY CATEGORY: III, “Caution”
USDA-NOP:
Considers sodium bicarbonate as non-synthetic and allowed. Potassium bicarbonate is considered
synthetic and is permitted for plant disease control. The related chemical ammonium
carbonate is permitted only for use as bait in traps for insect control. Organic crops destined for
export to Japan may not be produced using potassium bicarbonate (NOP 2000).
MATERIAL DESCRIPTION:
These products rely on a bicarbonate salt (usually potassium bicarbonate) as the active ingredient.
They are promoted for use against powdery mildew diseases. The use of baking soda
(sodium bicarbonate) as a fungicide is not a new idea; in Alfred C. Hottes’ A Little Book of Climbing
Plants, published in 1933, mention is made of using one ounce of baking soda per gallon
of water to control powdery mildew on climbing roses. The author credits the idea to a Russian
plant pathologist, A. de Yaczenski (Williams & Williams 1993).
HOW IT WORKS:
According to the Kaligreen product label, these products disrupt the potassium or sodium ion
balance within the fungal cell, causing the cell walls to collapse.
OMRI LISTED PRODUCTS:
Kaligreen (Otsuka AgriTechno Co.,LTD)
MilStop Broad Spectrum Foliar Fungicide (BioWorks, Inc.)
Monterey Bi-Carb Old Fashioned Fungicide (Lawn and Garden Products, Inc.)
References to OMRI listed products in this Guide are based on the 2012 edition of the OMRI
Product List. Please consult www.omri.org for changes and updates in the brand name product
listings.
Note: Baking soda (sodium bicarbonate) cannot legally be used as a pesticide unless it is an
ingredient in an EPA registered product.
FORMULATIONS AND APPLICATION GUIDELINES:
These products are 82-85% potassium bicarbonate and 15-18% surfactants and other inert
ingredients. The potassium bicarbonate is microencapsulated and used at rates of 1-5 lb/acre.
The pH of the spray solution should be kept at 7.0 or above. Bicarbonate products may be
phytotoxic if used at rates above 5 lb/acre. Several studies have shown much better efficacy
against powdery mildew when oils are added to bicarbonate products, typically at the rate of
0.5-1.0% (Kuepper et. al. 2001, Ziv & Zitter 1992).
REENTRY INTERVAL (REI) AND PRE-HARVEST INTERVAL (PHI):
The EPA Workers Protection Standard requires a minimum of 4 hours before reentering
treated areas for Kaligreen and one hour for Milstop. There is usually a one-day to harvest PHI
requirement. Monterey Bi-Carb Old Fashioned Fungicide is not labeled for use on commercial
farms.
Organic Resource Guide 117