November 2013 Newsletter (vol.23)   >>   A Guide to Common Organic Pesticides

 

 

As trends continue to move toward safer and cleaner growing methods, organic pesticides have seen an increase in use. While it can be simple to choose and apply certain organic pesticides, truly understanding where they come from and how they work can be paramount to a successful program. When used correctly, organic pesticides can be just as effective as synthetic pesticides at providing curative and control methods with less harmful effects to plants, animals and people.

 

It is important to note that while organic pesticides are organic, they still carry some level of toxicity. Many organic treatments are chosen specifically due to their toxic levels toward target insects. These pesticides also carry signal words that provide warning and instruction as to the dangers they pose to humans.

 

Keep in mind that while a product may not be toxic to people, it can be extremely harmful to other plants and animals. As with any pesticide, it is extremely important to read and follow the label to ensure effectiveness, safety, and legality. Keep in mind that some products contain organic material but are not organic pesticides. Many pesticides will list an organic ingredient but also contain other chemicals negating them as certified organic. There are also methods of application that can effect whether or not a treatment is considered organic. Products and their guidelines which are certified organic can be found on the Organic Materials Review Institute (OMRI) website at: www.omri.org

 

Some common organic products are microbial or fungal and pertain to certain species found in nature. Bacillus thuringiensis (Bt), Beauveria bassiana, and Spinosad are such materials that have been isolated from soil environments. Bt products such as Dipel Pro DF and Gnatrol WDG focus on leaf feeding insects such as caterpillars and beetles. This product can also be effective against larval stages of mosquito and black flies. Certain strains of Bt attack specific pests so be sure to choose the correct product. Beauveria bassiana is a fungus that creates spores which will attach and kill insects such as thrips, whiteflies, aphids, caterpillars, weevils, grasshoppers, ants and mealybugs. This product, found in Mycotol O, works by initial or residual spray contact and can also have a secondary spread factor if conditions are right. Spinosad is created through fermentation of microbes. When ingested by insects, this product disrupts the nervous system of pests such as caterpillars, thrips, and flies. Monterey Garden Insect Spray is an OMRI approved spinosad spray. Sufficient coverage and application of these materials cause death in target insects within a few days.

 

A few organic pesticides come from plants. Pyrethrum and Neem are botanical compounds with significant use as pesticides. Pyrethrum is found in flowers of chrysanthemum species and has several insecticidal properties. Products such as Pyganic EC 1.4 work as a knock-down contact insecticide that causes paralysis and death of target pests, including aphids, flies, mites and thrips. While there are concerns with resistance to pyrethrum, correct dosage and application can still be very useful in pest management. Neem trees provide an array of natural compounds that can have beneficial properties in inset control. The most significant of these compounds is Azadirachtin which is a growth inhibitor to insects and can also deter feeding and egg-laying. This product can be found in Azaguard and Triact 70 which both carry OMRI certification. Neem trees also provide an oil that is made into an insecticidal spray. This oil is effective against an array of garden and flower pests at immature stages. Contact with the insects is required so good coverage and multiple applications are often necessary.

 

There are also synthetic materials that are certified organic. This group includes Pesticidal Soaps and synthetic Oils. Soap products such as M-Pede are made from salts of fatty acids. They usually have a low phytotoxicity and can be useful against insects and mites. While effective on contact against soft-bodied pest, soaps are generally not allowed to be used on fallow land or on food crops. They are best used to control parameters of growing and production areas. Oils are derived from fish or petroleum and have been used for their insecticidal properties since the 1800s. They have effects on the egg stages of insects and products like Suffoil-X can disrupt the respiratory system of mature insects. Oils can provide both curative and repellent results on an array of pests. It has been noted that oils may be the most widely used class of pesticides to which insects have not built a significant resistance. (Sams and Dayton 2002).

 

These are just a few examples OMRI listed materials that can be excellent solutions to insect problems. They also make great additions to any pest management program and can be used to supplement synthetic chemical treatment. Remember to check out the OMRI website for more information and contact Hummert International for all of your pest management needs.

 

 

Sources:

 

Bextin, B.R. and Thorvilson, H.G. (2002) Filed application of bait formulated Beauveria bassiana alginate pellets for biological control of the Red Imported Fire Ant. Environmental Entomology. 31, 746-752

 

EPA Fact Sheet. Azadirachtin (121701) Clarified Hydrophobic Extract of Neem Oil (025007) source: http://www.epa.gov/opp00001/chem_search/reg_actions/registration/fs_G-127_01-Oct-01.pdf

 

Dow. MSDS for Spinosad Technical. Dow AgroScience, Indianapolis, IN

 

Musser, F.R and Shelton, A. M. (2003) Bt sweet corn and selective insecticides: their impacts on sweet corn pests and predators. J. of Economic Entomology, 96, 71-80

 

EPA 2004 Pesticide Reregistration Status US Environmental Protection Agency. Source: http://www.epa.gov/oppsrrd1/REDs/pyrethrins_red.pdf

 

Caldwell, Brian; et al. 2013 Resource guide for Organic Insect and Disease Management, 2nd Ed. Cornell University

 

Sams, C. and D. Deyton. (2002) Botanical and fish oils: history, chemistry, refining, formulating and current uses. In Beattie, G et al. (Eds.), Spray Oils Beyond 2000 (pp. 78-87) University of Western Sydney Press