eOrganic authors:
Daniel S. Egel, Purdue University
Lori Hoagland, Purdue University
Ashley Adair, Purdue University
Introduction
One of the primary challenges for organic tomato growers is disease management. To be sure, there are many factors which affect the ability to control tomato diseases. Crop rotation, fall tillage, and sanitation are but a few. For many growers, however, the number of possible products for use in disease management has become confusing. The list below of fungicides and their efficacy should help tomato growers select products to apply to manage disease issues. After the list of products, readers will find a short paragraph regarding the use of fungicides in organic production.
Below is some guidance for reading the fungicide tables:
- The organic listing agency appears for each product entry in the tables below. In addition, see the important information about organic certification after the tables.
- To determine the efficacy ratio, the reports listed in the journal Plant Disease Management Reports were used to determine the number of trials where an organically listed product was used for disease control in tomato. Annual reports from 2007 to 2023 were used. For example, the ratio 5/10, means that in 5 out of 10 trials, the product in question had statistically significantly lower disease than the control treatment where no product was used for disease control. In the remaining 5 trials, the product in question did not result in statistically lower disease than the untreated control.
- Products are listed only if 3 or more trials were performed by researchers. If a product is not listed, it may be that none or fewer than 3 were performed by researchers and listing an efficacy ratio doesn’t make sense. For this reason, very few treatments where combinations of products were compared are listed.
The efficacy ratio is a general guide regarding how the product has performed historically in experimental trials. The ratio will not necessarily predict how the product will work in your situation. In addition, the efficacy ratio was calculated over many different diseases. When the ratio is calculated over specific diseases, the lack of trials needed to draw any conclusions is very obvious. Very simply, more trials are needed.
Nevertheless, the information below can still help growers producing tomatoes organically to make better product choices when it comes to disease management.
Microbial Products
The following products are formulations of live microbes or products derived from microbes. Care must be taken not to tank mix microbial products with products that contain copper, hydrogen peroxide or other compounds that may result in death of the microbial active ingredient unless the label specifies that such applications can be made. Read labels carefully.
| Product/Manufacturer | Active Ingredient | Mode of Action | Effective Ratio | Listing Agency |
|---|---|---|---|---|
| Actinovate-Valent | Streptomyces lydicus strain WYEC 108 | Exclusionism, antifungal metabolites, parasitism | 9/19 | OMRI |
| Effective trials mostly for bacterial diseases, early blight and Septoria leaf spot. Data for AG formulations. | ||||
| Agriphage-OmniLytics | Bacteriophage-beneficial virus | Hyperparasitism | 9/13 | NOP |
| Use for bacterial speck, bacterial spot and bacterial canker. Agriphage is very specific for strains of bacteria for specific diseases. Contact manufacturer for application information. | ||||
| Companion-Growth products LTD | Bacillus subtilis GB03 | Stimulates plant defense response (ISR) | 4/5 | OMRI |
| Some formulations may also supply added nutrients, 2-3-2 | ||||
| Double Nickel 55 WP-Certis | Bacillus amyloliquefaciens strain D747 | Production of lipopeptides | 7/14 | OMRI |
| Labeled against a broad range of foliar diseases. Can be mixed with copper. Do not mix with hydrogen peroxide products. | ||||
| Lifegard WG-Certis | Bacillus mycoides isolate J | Stimulates plant defense response (IR). | 6/10 | OMRI |
| Primarily used for bacterial diseases. Do not mix with copper or peroxide products. | ||||
| Lalstop (previously labeled as Prestop) Lallemand Plant Care | Gliocladium catenulatum strain J1446 | Antagonistic metabolites, outcompetes, predation/hyperparasitis m. | 2/4 | OMRI |
| Labeled for a broad range of diseases. Effective ratio includes a refereed manuscript concerning early blight (Egel et al., 2019; Crop Prot. 122:90-97.) | ||||
| Serenade-Bayer | Bacillus subtilis QST 713 | Stop spores germinating, disrupts cell membrane, inhibits attachment to leaf. | 4/11 | OMRI |
| Labeled for a broad range of diseases. Effective ratio includes all formulations. May be mixed with copper products. | ||||
| Zonix-Stepanbiosolutions.com | Rhamnolipid surfactant | Disrupts spores | 3/10 | OMRI |
| Biosurfactant extracted from bacterium (Pseudomonas aeruginosa). Primarily for late blight and Pythium diseases. | ||||
| Taegro-Novozymes | Bacillus subtilis var. amyloliquefaciens strain FZB24 | Antimicrobial metabolites, competition, induced plant resistance. | 3/11 | OMRI |
Botanical Products
These products are made from extracts of plants.
| Product/Manufacturer | Active Ingredient | Mode of Action | Effective Ratio | Listing Agency |
|---|---|---|---|---|
| Regalia-Marrone Bio Innovations | Extract of Reynoutria sachalinensis | Stimulates natural plant defense. | 6/15 | OMRI |
| Labeled against a broad range of tomato diseases. | ||||
| Sporatec-Brandt | Rosemary, clove & thyme oil | Disrupts the cell wall of spores and hyphae | 4/8 | OMRI |
Inorganic chemicals
Products in this category are ones that can be fabricated from chemicals in the earth’s crust. Oxidate is the sole entry in this category. Although copper products may be considered in this category, they are considered here in a separate sub category. Fungicides that affect multi-sites act on sites in multiple places in the cell. Because multiple sites are affected, it makes it unlikely that insensitivity (AKA fungicide resistance) will develop to the product. This is in contrast to fungicides with one mode of action. The latter products may lead to insensitivity if/when the target organism mutates to a form that is insensitive. The development of fungicide resistance after the use of organically listed products is unlikely.
| Product/Manufacturer | Active Ingredient | Mode of Action | Effective Ratio | Listing Agency |
|---|---|---|---|---|
| Oxidate-Biosafe Systems | Hydrogen peroxide + peroxyacetic acid | Multi-site | 6/11 | OMRI |
| When applied properly, Oxidate works to kill microbes it comes into contact with on the plant surface. However, after Oxidate dries on the plant surface, there is no residue. Therefore, frequent applications may be warranted. Consult the label carefully before mixing this product with a copper product. | ||||
Copper Products
These products are also inorganic chemicals. Copper compounds are effective because they disable proteins of the cells they come into contact with. However, they do not enter into the plant and thus have no effect on existing infections. Copper may be toxic to the plant under some circumstances and may affect the environment adversely if overused.
| Product/Manufacturer | Active Ingredient | Mode of Action | Effective Ratio | Listing Agency |
|---|---|---|---|---|
| Badge-Gowan | Copper oxychloride-copper hydroxide | Multi-site | 7/10 | OMRI |
| Copper hydroxide includes small particles and thus the rapid release of copper ions. Copper oxychloride includes slightly larger particles that are released slower. Includes SC and X2 formulations. | ||||
| Cueva-Certis | Copper octanoate | Multi-site copper soap | 3/10 | OMRI |
| Contains a relatively low metallic copper-10% compared to Champ WG (77%) or Kocide 3000 (46.1%) for example. | ||||
| Champ WG-Nufarm | Copper hydroxide | Multi-site | 3/8 | OMRI |
| Copper hydroxide includes small particles and thus the rapid release of copper ions. | ||||
| Kocide 3000-O DF-Certis | Copper hydroxide | Multi-site | 3/3 | OMRI |
| Copper hydroxide includes small particles and thus the rapid release of copper ions. | ||||
Mixtures
The following tank mixes were trialed.
| Product/Manufacturer | Active Ingredient | Mode of Action | Effective Ratio | Listing Agency |
|---|---|---|---|---|
| Cueva + Double Nickel | Copper octanoate Bacillus amyloliquefaciens strain D747 | Multi-site Production of Lipopeptides | 2/3 | OMRI |
| Cease + Milstop | Bacillus subtilis QST 713 Potassium Bicarbonate | Competition and lipopeptides | 3/6 | OMRI |
Effective Application of Fungicides in Organic Production
Regardless of what type of fungicide is used, it is always better to make applications before foliar disease is observed or soon after. Once applications have begun, maintain a 7-14 day schedule. Apply more frequently during wet weather. Read the label and other literature to understand how individual products work. Microbial products may require frequent applications to maintain leaf populations. Product labels for products that turn on plant defense reactions may specify application frequencies to maintain protection. Fungicides that rely on metabolites may require frequent applications to combat plant pathogens. Similarly, products that work by hyperparasitism may need regular applications of the product to lessen pathogen populations. Copper products may vary with the active ingredient as to stability of the product on the leaf surface. Products with the active ingredient hydrogen peroxide essentially leave no residue after drying and therefore require very frequent applications.
Since leaf wetness promotes most foliar diseases, it is best to apply fungicides before wet weather. However, many organic products lack the stickers that allow residues to be maintained during rains. Therefore, some products may have to be reapplied after a heavy rain.
In most cases, it is best to apply the highest rate of a product unless your experience indicates otherwise. Likewise, increased gallonage, or gallons per acre, are usually to be preferred up to about 50 gallons per acre.
There is no reason to expect that new and different equipment is needed to apply organic products vs synthetic products. Plan to dedicate a set of equipment for applying only organic products.
As a rule, avoid fungicide applications during very hot and sunny conditions.
IMPORTANT: Before using any pest control product in your organic farming system:
- Read the label to be sure that the product is labeled for the crop and pest you intend to control, and make sure it is legal to use in the state, county, or other location where it will be applied,
- Read and understand the safety precautions and application restrictions, and
- Make sure that the brand name product is listed in your Organic System Plan and approved by your USDA-approved certifier. If you are trying to deal with an unanticipated pest problem, get approval from your certifier before using a product that is not listed in your plan—doing otherwise may put your certification at risk.
Note that, although OMRI and WSDA lists are good places to identify potentially useful products, all products that you use must be approved by your certifier. For more information on how to determine whether a pest control product can be used on your farm, see the related article, Can I Use This Input On My Organic Farm?
References and Citations
- Egel, D.S., Hoagland, L., Davis, J., Marchino, C., Bloomquist, M. 2019. Efficacy of organic control products on common foliar diseases of tomato in the field and greenhouse. Crop Prot. 122:90-97. https://doi.org/10.1016/j.cropro.2019.04.022
- National Organic Program (NOP) https://www.ams.usda.gov/rules-regulations/organic/handbook
- Organic Materials Review Institute (OMRI) https://www.omri.org/
- Plant Disease Management Reports (PDMR) https://www.apsnet.org/publications/Pages/PDMR.aspx
