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Home  > Question of the Week

Question of the Week

Permalink How can I treat my layer flock organically for parasitic worms?

Answer: A great resource for organic treatments of common health problems of poultry flocks is Karma Glos's Remedies for Health Problems of the Organic Laying Flock, available at This compendium lists various styles of treatments, as well as preventative measures. The treatments for worms begins on page 56. Another useful resource is an article that was published in the October/November 2009 issue of Backyard Poultry Magazine entitled "Fall Season Herbal Wormer and Alternative," by Susan Burek and Laura Corstange. This article explains the different properties of alternative worm treatments and how they help in treating these internal parasites.

It is uncommon, but possible, to find worms inside an egg. For this to occur, the worm actually travels out of the intestine and then up into the oviduct where the egg is formed and gets trapped inside. Candling will help detect this occurrence and any such eggs should be discarded.

The meat from infected chickens should be fine to eat. According to Gail Damerow author of The Chicken Health Handbook, most worms that prefer poultry do not invade humans, and if an infestation does occur, there are often few or even no symptoms. Also, since the worms are in the digestive tract, the meat shouldn't be contaminated as long as it is processed in a sanitary manner. There seems to be more of a danger of ingesting worm eggs through contact with contaminated manure and then forgetting to wash hands before eating. It is also important to remember that heavy infestations of worms can impair a chicken's immune response, and make them more susceptible to other diseases. Because of this, it is important to observe the birds and watch for additional symptoms of disease which may result in their meat needing to be discarded rather than eaten.

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Permalink What can you tell me about organic control of the cherry fruit fly? Is there a role for gypsum applications?

Answer: The major insect pest of cherry is the cherry fruit fly (Rhagoletis cingulata and R. fausta). Failure to adequately control this pest can cause severe crop loss due to the presence of fruit fly larva (maggots) in the cherries at harvest. Both federal (USDA) regulations and consumers demand a zero tolerance for maggots in fruit at harvest.

Spinosad, derived from a naturally-occurring bacteria, is quite effective at controlling the fruit fly, and it is approved for use as an organic pesticide in cherry production. It has been used in combination with bait as well as applied as a foliar insecticide. The bait-plus-spinosad product (GF-120NF) is an attractive substance that is lethal to flies that feed on it while "grazing" on the tree. This bait is "squirted" and spattered on the trees weekly at 20 fluid ounces per acre diluted in about 1.5 to 2 gallons of water per acre (it should NOT be applied with an air-blast sprayer). EntrustTM is a spinosad-based product that kills flies both by contact and residue, and, unlike GF-120NF, it can be applied by air-blast sprayer. Sprays of Entrust every seven to 10 days beginning with fruit fly emergence have provided excellent fruit fly control.

Regarding gypsum as a possible fruit fly control, there seems to be no research references on this topic. However, the fact that the cherry fruit fly maggot falls from the fruit, burrows into the soil, pupates in the soil, and then re-emerges from the soil as an adult could lead one to think that some sort of manipulation or treatment of the soil could result in significant mortality to the fruit fly. That might be the case, but it doesn’t seem to me that gypsum would be the best candidate for this. Gypsum (calcium sulfate) is pH neutral, so it probably would not alter the pH enough to be deadly to the pupae. Besides, if some soil amendment did alter the soil pH enough to affect the pupae, it might also be deleterious to the trees. And applying enough gypsum to the soil surface so that it might present some sort of abrasive barrier (like diatomaceous earth) to the entrance and exit of the fruit fly from the soil seems unlikely due to the inevitable weathering of the gypsum by wind and rain.

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Permalink What can you tell me about the use of treated lumber in organic operations?

Answer: The USDA National Organic Program (NOP) Regulations state that producers must not use lumber treated with arsenate or other prohibited materials for new installations or replacement purposes in contact with soil or livestock. The key words here are “in contact with.”

Many certifiers realize that zoning regulations and federal conservation programs may prescribe treated wood for specific applications, and some certifiers will allow treated wood for some purposes, as long as the necessity of its use can be substantiated and documented on the farmer’s organic system plan. Also, the farmer must verify that effective barriers are in place to ensure that no contact is made between crops or livestock. An example of where some certifiers allow treated wood is in fence posts for pastures.

It is important to understand that the NOP Regulations are quite clear about preventing contact between treated wood and crops or livestock. The certifier must be sure that organic integrity is maintained and is responsible to the NOP for ensuring that integrity. Therefore, there must be a seamless audit trail and justification of materials use in the farmer’s organic system plan to substantiate the use of any material, especially those that come into question like treated wood. The main thing to remember is that the organic certifier has the responsibility to review and approve or disapprove the use of materials under the authority of the NOP Regulations.

For more information, see the ATTRA publication Pressure Treated Wood: Natural and Organic Alternatives at This publication includes a discussion of currently used materials, lumber treatments using less-toxic materials, decay-resistant lumber species, and an explanation of the National Organic Program Regulations.

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Permalink What can you tell me about liquid copper as an organic fungicide?

Answer: Copper fungicides can be highly effective against disease and can extend the growing period, especially if applied before plants are infected with pathogen spores. However, copper fungicides can accumulate in the soil and cause health-related issues to plants and animals, including humans. Due to the effectiveness of cooper fungicides, in addition to the limited alternatives for specific diseases targeted by copper fungicides, such as Late Blight, copper fungicides are allowed for use in organic production systems.

Copper fungicides are classified as a synthetic on the National Organic Program National List. According to the National List (Subpart G), copper-based materials used as plant disease control must be used in a manner that minimizes accumulation in the soil and shall not be used as an herbicide. As a result of this classification, it is required by the certification process that before a copper fungicide is applied, farmers must first implement all available preventative and alternative practices and must show that such practices are ineffective. For many diseases, alternative practices include planting disease-resistant cultivars, destroying infected plants, managing irrigation, and implementing wide-row plant spacing.

If it is shown that all alternative practices prove ineffective, the use of any copper fungicide must be listed in the Organic System Plan and approved by the certifier. It is also recommended that frequent soil tests be performed to monitor cooper concentrations in the soil.

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