Organic And Biological Control Of Plant Diseases
Gary W. Moorman, Professor of Plant Pathology
‘ORGANIC’ methods involve growing and maintaining healthy plants without using synthetic (man-made) fertilizers, pesticides, hormones, and other materials. In organic disease control, natural materials (things found in nature or that exist in the environment) can be used to inhibit or prevent the activity of plant pathogens. Sources of information on what are considered to be an organic control material include the Organic Materials Review Institute website (http://www.omri.org)
and the National Organic Program of the US Department of Agriculture
What is considered ‘organic’ is not well defined. For example, chemicals extracted from plants are considered to be ‘organic’ even though they are concentrated by man-made processes. Also, salts of copper and iron are found in nature, processed for use, and termed ‘synthetic’ but are allowed to be used with some restrictions (used in a manner that minimizes accumulation in the soil) and are considered to be ‘organic.’ For some specific materials, see http://www.omri.org/omri-lists .
Below is a partial list of organic materials and the pathogens listed on their labels as being controlled. This list may not comply with all the requirements that must be met in order to be ‘certified organic.’ You, the user of the information provided here, must find out if the material can be applied and be ‘certified organic.’
| Organic control material | Target pathogens on one or more of the product labels |
|---|---|
| Copper | Alternaria, Erwinia, Pseudomonas, Xanthomonas, Cercospora, Colletotrichum, Cladosporium, Powdery mildew, Downy mildew, Phytophthora, Pythium, Mycosphaerella, Phomopsis, Taphrina, Elsinoe, Gnomonia, Fusicladium, Nectria, Phyllosticta, Diplocarpon, Albugo, Guignardia, Botrytis, Exobasidium, Entomosporium, Exobasidium, Pestalotia, Phoma, Cristulariella |
| Oils derived from plant extracts | Powdery mildew |
| Potassium bicarbonate | Powdery mildew |
| Potassium silicate | Powdery mildew, Pythium, Botrytis, Fusarium |
| Sulfur | Powdery mildew |
‘BIOLOGICAL’ control of a plant disease involves the use of one living organism to inhibit the activity of a living plant pathogen. Biological control agents (BCAs) are registered for use by the Environmental Protection Agency (EPA) and have labels very similar to those for chemical pesticides. BCAs can be hazardous to the applicator and all safety equipment recommended on the label should be used. BCAs may have to be applied more than once in order to maintain adequate protection. Follow the label recommendations for the amount to use, the method of application, application intervals, and the restricted entry interval (REI). BCAs can be used on the same crop with chemical pesticides with some precautions. In general, a BCA should be applied 10 days before or 10 days after applying a chemical. Always consult the product label of the BCA to determine whether or not it can be applied in conjunction with a chemical pesticide. Below is a partial list of BCAs and the pathogens listed on at least one of the product labels as being controlled:
| Biological control agent (type of organism) | Trade Name (IPA reg. no.) | Target pathogens on one or more of the product labels |
|---|---|---|
| Agrobacterium radiobacter (bacterium) | Galltrol A (strain 84) (40230-1) | Agrobacterium tumefacians (crown gall) |
| Ampelomyces quisqualis (fungus) | AG10 (55638-16) | Powdery Mildew |
| Bacillus subtilis (bacterium) | Companion (GB03 strain) (71065-1) | Pythium, Fusarium, Phytophthora, |
| Serenade (69592-4) | Rhizoctonia, posdery mildew | |
| Rhapsody (QST 713 strain) (69592-10) | Colletotrichum, Erwinia, Pseudonomas,Xanthomonas, Diplocarpon, Cercospors | |
| Cease (69592-19-68539) | Venturia | |
| Candida oleophila | Aspire (55638-29) | |
| Gliocladium catenulatum (fungus) | primastop | Pythium, Rhizoctonia, Botrytis |
| Steptomyces lydicus (actinomycete, fungus-like bacterium) | Actinovate (73314-1) Actino- Iron (73314-2) | Pythium, Fusarium, Phytophthora, Rhizoctonia, Botrytis ,powdery mildew, downy mildew, Sclerotinia, Verticillium. |
| Steptomyces griseoviridis | Mycostop (64137-5) | Botrytis, Alternaria, Phomopsis, Pythium, Fusarium, Phytophthora |
| Trichoderma harzianum (fungus) | PlantShield (68539-4) or RootShield | Pythium, Fusarium, Phytophthora, Rhizoctonia, Botrytis ,powdery mildew, downy mildew, Sclerotinia |
| Trichoderma virens (fungus) | SoilGard (70051-3) | Pythium, Fusarium, Phytophthora, Rhizoctonia, Botrytis ,powdery mildew, downy mildew, Sclerotinia |
DISCLAIMER
Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
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