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| 1 Crop Production |
| 1.2 Crop Production Aids |
| 1.2.7 Plant Disease Control |
| Organic farming places significant emphasis on creating healthy soils with the use of compost and green manures, rotating crops (including underseeding and intercropping), and integrating crops with livestock. These management practices along with proper nutrient and soil management lead to healthy plants and a first-line of defence against diseases. However, at times disease pressures become too great and organic producers may have to be proactive or reactive and use products that may deter the prevalence of some plant diseases. |
| 1.2.7.1 Chitin (CGSB Under Review) |
| Chitin is a natural polymer that is found in crustaceans, such as crabs, lobsters, and shrimp as well as other organisms, such as insects, worms, and fungi. When added to the soil ecosystem, chitin (also referred to as chitosan) promotes the growth of chitin-degrading bacteria. These bacteria, in turn, create a hostile environment for pathogenic fungi and parasitic nematodes. Chitin also acts directly on plants to promote tissue repair and disease resistance.
There are currently no chitin based products registered in Canada as a pesticide. |
| 1.2.7.2 Compost Tea (CGSB Restricted) |
| The disease suppressive characteristics of compost have long been known and therefore the liquid extracts from compost, known as compost teas are being used to battle plant disease while stimulating plant growth. Beneficial organisms including bacteria (primarily from the genera Bacillus, Pseudomonas, and Penicillium) along with some yeast and fungi form a physical barrier against disease causing agents and provide a competitive environment in which the pathogenic species lose out. In addition, compost teas stimulate plant growth, translating into a healthier plant, which is more resistant to attack from disease. Compost teas have shown effectiveness in the control of late blight, grey mould, downy and powdery mildew, fusarium wilt, and apple scab.
Commercial compost tea brewers are now readily available along with recipes. Care should be taken when adding amendments such as molasses to stimulate the microbial population within the brew. This can encourage the regeneration of pathogens that were initially eliminated in the composting process. Written documentation of off-farm components of the tea is required. Once brewed, compost tea has a short shelf life. Claims range from 4-8 hours in batches under 20 gallons to 10-24 hours in larger batches. This is because available oxygen is used up and the tea turns anaerobic, killing the beneficial bacteria. As is the case with composted manure, compost teas can be sources of pathogens unless they have been exposed to adequate temperatures and for the durations stated in the standards (50C for at least 2 weeks). This potential health threat is increased when improperly brewed compost tea is applied directly to the edible parts of crops. There are currently no compost teas registered in Canada as pesticides. |
| 1.2.7.3 Copper Products (CGSB Restricted) |
| Copper is an essential plant micronutrient with a wide range of other agricultural applications; however, as is the case with many plant nutrients, an excess of copper can be toxic to plants and other organisms. Fungi are particularly susceptible to copper and for this reason, copper is frequently used as a fungicide and wood preservative. Many invertebrates, algae, and bacteria are also sensitive to copper and it has can be used against these pests as well. Because copper is a mineral element, it can accumulate in soils. Low levels do not pose a risk to soil life and may even enhance plant growth if soil copper levels are deficient; however, higher levels can be detrimental to soil life, particularly earthworms. They can also be toxic to fish. Copper compounds must also be handled carefully since they can present a health risk for humans.
Copper is a restricted input in organic systems. Its use must be monitored to avoid build up of copper in soil. Many certifying bodies, particularly in Europe, are beginning to re-assess its use in organic systems. There are many forms of copper available for use. Copper sulphate, often referred to as "bluestone", is the most common form of copper allowed for use in organic systems. It is a finely ground powder that dissolves relatively quickly in water and should be stored in a dry place to avoid clumping. Copper sulphate is frequently combined with hydrated lime to make what is known as a Bordeaux Mixture. Because hydrated lime is not permitted under organic standards, Bordeaux mix is frequently prohibited for use in organic systems. Other approved forms are copper hydroxide and copper oxychloride. Prohibited forms of copper are copper ammonia base, copper ammonium carbonate, copper nitrate and cuprous chloride. As a fungicide, copper is now being replaced by newer biological agents, such as Bacillus subtilis, which directly kill fungal pathogens, or by fish emulsions and compost teas, which act to stimulate a plant’s own defence against pathogens. Copper products are readily available at farm supply stores. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | Parasol WP | NuFarm Agriculture Inc | R | 24671 |  |
United Agri Products | R | 24671 |  |
Kocide DF - Copper Hydroxide 64.1% | DuPont Canada | R | 24538 | |
DeeCop - Copper Sulphate | Nu-Gro Corporation | R | 14160 | |
Garden Doctor - Copper Sulphate | Nu-Gro Corporation | R | 17424 | |
Guardian - Copper Sulphate Dust | White Rose Nurseries | R | 22935 | |
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| 1.2.7.4 Essential Oils (CGSB Allowed) |
| Essential oils, or 'essences' as they are also called, are highly concentrated substances extracted from various parts of aromatic plants and trees. They are usually captured by steam distillation. Unlike ordinary vegetable oils, such as corn and olive, plant essences are highly volatile and will evaporate if left in the open air. Essential oils are frequently combined with carrier oils in order to stabilize them. Essential oils are used against plant pests and disease; however, there are no essential oils registered for use in disease prevention in Canada. |
| 1.2.7.5 Hydrogen Peroxide (CGSB Allowed) |
| Hydrogen peroxide is registered for use as a fungicide only as a treatment for potato storage.
There are two treatment methods. One is an application as a spray treatment for newly harvested potatoes before storage. The other is as a direct injection into the humidification water for post-harvested potatoes in storage. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | Oxidate - hydrogen peroxide 27% | BioSafe Systems | R | 27432 |
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| 1.2.7.6 Potassium Bicarbonate (CGSB Allowed) |
| Potassium Bicarbonate is used to control or suppress Powdery Mildew on tomato, sweet pepper, cucumber, pumpkin and ornamental crops in greenhouses. It is a contact fungicide which must be applied with sufficient water to ensure complete plant coverage.
Potassium Bicarbonate acts by inhibiting the growth of the fungus' cell wall. It controls and prevents Powdery Mildew. In the US it is also registered for the control of a variety of other foliar diseases. Potassium Bicarbonate is best applied at the first onset of disease. Spray intervals are generally 7 days for vegetables and 7-14 for ornamentals. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | MilStop | BioWorks Inc | R | 28095 | |
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| 1.2.7.7 Sodium Bicarbonate (CGSB Allowed) |
| Sodium bicarbonate, commonly known as baking soda, has been found to possess fungicidal properties. It is best used as a preventative or as treatment at first signs of any of the diseases. Sodium bicarbonate is commonly used on anthracnose, early tomato blight, leaf blight and spots, powdery mildew.
Sodium bicarbonate is not registered in Canada as a fungicide. |
| 1.2.7.8 Sodium Carbonate Perohydrate (CGSB Restricted) |
| The EPA approved an application to register this new active ingredient as an algaecide and fungicide for use in ornamental plants and turf; however, it is not currently registered for use in Canada. |
| 1.2.7.9 Streptomyces griseoviridis (CGSB Allowed) |
| Streptomyces griseoviridis is a naturally occurring soil bacteria. The microbe deprives pathogen fungi of living space and nourishment by colonizing plant roots in advance of fungi. In addition the microbe secretes various enzymes and metabolites which inhibit pathogen growth. Streptomyces griseoviridis has been shown to promote the growth and yield of plants even in healthy crops.
Streptomyces griseoviridis is used for the control of damping off, root and stem rot, and wilt caused by Fusarium in greenhouse ornamentals and vegetables such as cucumbers, tomatoes and peppers. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | Mycostop - Biofungicide | Koppert Canada | R | 26265 | |
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| 1.2.7.10 Sulphur Products (CGSB Restricted) |
| Sulphur is an effective organic fungicide. Fungi absorb the sulphur, which then disrupts electron transfer. This results in the sulphur being converted to hydrogen sulfide - which is toxic. Sulphur also forms a protective layer that inhibits spore germination. The use of sulphur as a fungicide is restricted to foliar applications.
Sulphur applications delayed significantly after the onset of disease symptoms are less effective. Sulphur has been effective in controlling apple and pear scab, powdery mildew, rust mites, brown rot, grape erineum mite, leaf spot, cane spot, cane blight and rust blight. Sulphur can cause severe damage to plants, especially in hot weather. Tomatoes, grape, cranberry and melons producers should be particularly cautious. Do not apply within 30 days of an oil application. Adding lime to sulphur enhances its fungicidal properties. Lime causes a chemical change that permits the sulphur to penetrate the leaf tissue. Diseases such as brown rot, leaf spot, mildew, and both apple and pear scab have been controlled by the use of lime sulphur. The use of lime sulphur is restricted and certification bodies may require a leaf tissue analysis prior to authorizing its use. Lime sulphur is primarily used as a dormant spray to clean up overwintering insects, mites and fungal diseases on fruit trees and small fruit. Do not spray when foliage is wet. Lime sulphur may cause leaf yellowing and defoliation. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | Lime Sulphur 22% | United Agri Products | R | 16465 | |
Kumulus DF | BASF Canada | R | 18836 | |
Sulphur DF | Wilbur Ellis | R | 23171 | |
Bartlett Wettable Sulphur | N. M. Bartlett Inc. | Y | 873 | |
Wilson Professional Lime Sulphur 23% | Nu-Gro Corporation | Y | 25356 | |
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| 1.2.7.11 Trichoderma Harzianus (CGSB Allowed) |
| Trichoderma harzianus is a naturally occurring fungus that is used in the suppression of root diseases, such as Fusarium, Pythium, Rhizoctonia and Sclerotium. It also helps to protect tree wounds from decay and enhances plant tissue development through auxin release. It is also used for disease suppression on crops and suppression of post-harvest diseases on fruits and vegetables. |
| Products | Sources | PMRA | PCP# | OMRI | Origin | Trianum-G | Koppert Canada | R | 27116 | |
Trianum-P | Koppert Canada | R | 27116 | |
Rootshield Drench | Sun Gro Horticulture | R | 27115 | |
Rootshield Granules T-22 | Sun Gro Horticulture | R | 27116 | |
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