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Home  > Question of the Week

Question of the Week

Permalink What can you tell me about organic parasite control in cattle?


Answer: I am pleased to provide you with information on organic parasite control in cattle.


Flies of concern may include members of the family Muscidae that includes house flies, stable flies, horn flies and face flies. Although certain flies favor barns or confinement settings and others are found more in pasture, some eat filth, others such blood and others feed on secretions, all flies reproduce rapidly and can cause trouble that it is worth the effort to prevent. The life cycle is complete metamorphosis: depending on conditions, fly eggs may hatch in a day. Fly larvae (maggots) pass through three larval instars and a pre-pupal stage within about a week, and adult flies begin laying eggs within a couple days.

These flies are pests because at a minimum they cause animals discomfort, and are estimated to reduce weight gain by 25% (18) and decrease milk production up to 15-30% (15) or even 40-60% (18). Flies can transmit all manner of diseases (2) including bacterial diseases such as cholera and anthrax, and eggs of parasitic worms (10). The threshold that indicates a high level of activity for stable flies is just 10 flies per animal. Other flies not discussed here include external parasites that live part of their breeding cycle on/in animals.

The most economic and practical method of controlling flies is to reduce their breeding. The most effective way of reducing fly breeding is to eliminate areas that provide fly habitat where larvae feed and develop in wet or moist manure and other decaying organic matter. Observe the area where flies are a problem and figure out where the flies are breeding. Different flies have slightly different life cycles for breeding as well as different habits for being pests on animals. All the other approaches listed below are complimentary, and will be most effective when used together with good sanitation.

Reduce fly breeding areas around barns and buildings
• Remove or move manure, bedding, waste and other sources of food for fly larvae. For most flies, the breeding cycle may range from 10 to 60 days (shorter in warm conditions and longer when the weather is cool). Move fresh manure, bedding and spilled feed and from barn areas every 2-3 days (10) if possible to break this breeding cycle.
• Keep animal barns and yards dry. Repair any leaky pipes promptly. Address any other sources of water that may help create areas that are ideal places for flies to lay eggs and their larvae (maggots) to develop. Clean drainage ditches. Cover silage.
• Keep drinking water fresh and clean. Dump water where it will be used by plants or dry quickly. Avoid creating places that stay soggy.

Keep flies out
• Ventilate barns to maintain good air circulation.
• Put up physical barriers such as screening on windows, and keep doors closed whenever it is practical.

Reduce Fly Breeding areas in Pasture
• Manage pastures using strategies such as rotational grazing to interrupt pest life cycles. Fly eggs, maggots, pupae and adults all die after a while.
• Disperse, break up and dry out manure paddies by dragging a harrowing. This is especially important early in the season before populations multiply.
• Encourage dung beetles by avoiding pesticides such as synthetic parasiticides (Ivermectin) or using them judiciously. Dung beetles break apart and incorporate fresh manure into the soil, eliminating breeding areas and thus reducing horn fly populations.
• Incorporate pastured poultry into your garden, pasture or farming system to eat fly larvae and help keep populations down. Both domesticated and wild birds in animal pastures, including chickens, ducks, geese, guinea hens, and cattle egrets will pick through paddies and eat fly eggs and larvae. Chickens are even adept at catching adult flies. Eggs or other poultry products may be an enterprise for farm income diversity.
• Compost organic materials using aerobic methods. A hot compost pile (where heat is generated by decomposition) will kill fly larvae, and presents an inhospitable place for adult flies to lay their eggs.

Fly traps: many possible designs and variations are allowed for use in organic production
• Indoor traps include sticky traps or fly tape. Place these near beams and walls so they do not catch bats, and away from any barn swallow nests. Pheromone traps may be more effective against certain species of flies.
• Outdoors-an inverted cone traps consist of a cone with a hole in the top that opens into a space enclosed with screening from which flies cannot escape. Smelly bait under the cone will attract flies so they fly up through the hole in the top of the cone into the enclosed space where they die. These traps should be placed in full sunlight, sheltered from strong winds, and within 6 feet of active breeding areas, such as at the ends of barns manure piles or calf hutches.
• Walk-through traps can help reduce flies—especially horn flies--on larger animals. Strips of canvas dislodge flies from animals’ backs and sides. Attracted to the light, they fly up and become trapped between two layers of screened mesh. Plans are available from various sources including ATTRA. Please note that some plans for walk-through fly traps recommend the use of treated lumber. Organic producers must find alternatives to using this prohibited material. Please see ATTRA’s publication entitled Organic Alternatives to Treated Lumber. Walk-though traps can be placed anywhere where animals must pass, such as the entrance to the milking barn, and to sources of water. While cattle may need to be trained to walk through such an unfamiliar space at first, they may later walk through to achieve its benefits even when it is freestanding in a pasture.
• Use bug zappers to kill adult flies. These are most effective when the bulbs are replaced frequently enough to keep the ultraviolet wavelength attractive to insects. Keep records of their date of installation; a light that appears all right to the human eye may not maintain that proper wavelength.

Biological control
• Recognize and encourage predators: Hister beetles are small, shiny black beetles that eat fly eggs—one beetle can eat as many as 24 eggs per day. Predatory mites also eat fly eggs and small maggots (15).
• Release fly parasites such as parasitic wasps. The Cornell website on biological notes the use of the parasitic wasp Muscidifurax raptor for control of the housefly Musca domestica and stable fly Stomoxy calcitrans, as well as different types of bacteria, fungi, and nematodes for flies. The wasp Muscidifurax raptor may be most effective in hot and humid conditions. Other wasps or mixtures of wasps may be more effective in other areas. Consult with an insectary or supplier of beneficial insects about which parasitic wasps are most appropriate for your species of fly, type of livestock and region. A supplier should also be able to provide recommendations on the best conditions, locations, frequencies, and numbers of releases. Remember to protect these beneficial insects from getting too hot, cold, wet or dry. Releases may be most effective when done weekly, and will probably need to be done every year because their numbers decline in winter.

The ATTRA publication Farmscaping to Enhance Biological Control includes a description on page 7 of birds and bats as insect eaters (biological control agents), and its Sources of More Information section includes sources of bat houses. Please see also the article (C ) that describes one person’s experience with using releases of parasitic wasps for fly control around goats. Release of predators is reported to be quite cost-effective.

• Provide habitat for bats, and birds such as purple martins (in the parts of the country where they live). Several species of bats and birds will inhabit appropriately constructed and well-placed nest boxes or other types of enhanced or artificial housing, and help by eating flies.

Allowed pesticides

Some pesticides are allowed for use in organic production a complement if other methods are unsuccessful or insufficient. Such materials should be used to complement, not substitute for other methods as listed above. Before you use any organic or biological pesticide, you must include it in your organic system plan that is approved by your organic certifier. Botanical and allowed synthetic pesticides may be found in various product formulations at feed stores and farm coops. Organic or natural materials often have inert ingredients or synthetic carriers that are not allowed. Botanical pesticides also need to be labeled for use on cattle or other animals where you intend to use them. All synthetic pesticides, including insecticidal ear tags, are prohibited in organic production. It is good to check with your veterinarian to see if she or he has any experience in administering organic pesticides in animal production.


Lice are classified into two main orders, described in more detail below. Both orders are fairly specific in their host relationships. They spend their life cycle on their host, and are spread by direct contact.

Chewing lice (Order Mallophaga) feed on feathers, hair, skin, and other external tissues of animals. They are often referred to as bird lice, because they thrive in bird feathers and may puncture the skin at the base of feathers. Bovicola bovis is the species that most often affects cattle.

Sucking lice (Order Anoplura) are blood-sucking insects that are found on mammals only, not on birds. Important parasites, they live on mammal blood and can transmit diseases. Legs are good at grasping the hair of their hosts. Their mouthparts have styles that pierce the skin and small hooks hold on while they are feeding. Please see the more detailed description of the life cycle of lice in the article (B) about lice on goats.
According to Organic Valley Co-op, in a webpage entitled Controlling External Parasites on the Organic Farm (5), important lice pests of cattle include one species of chewing louse and four species of sucking lice. They affect cattle by causing irritation, blood loss, loss of appetite, and decreased gain. Factors associated with infestations are close confinement and cold weather. Control measures are similar for chewing and sucking lice. The life cycle of cattle lice is about 24 (3) to 30 (12) days. Reproduction increases in winter, such that young dairy animals can be heavily infested with lice (3). Eggs hatch in about 7 days (10). Because most treatments will not control eggs, they will need to be repeated to kill the new eggs that hatch out. Check animals at 14-day intervals to determine if the infestation has been eliminated or brought under control (3).

Prevention is the most important. If an infestation appears, treat it promptly with the control options that are allowed in certified organic production. Most of the ideas below come from the Organic Valley reference (5).

• Prevent infestations by isolating and observing any new animals for three weeks.
• Prevent direct contact between healthy animals and those that are infested with lice.
• Provide good quality feed with appropriate mineral supplements. Offering minerals free-choice allows cattle to meet their own needs (5). Provide free choice kelp to young stock in winter to reduce lice (9).
• Reduce animal stress by following all the requirements in the organic standards, especially including access to the outdoors, pasture for ruminants, fresh air, direct sunlight, shade, shelter and the opportunity to exercise.

• A thin coat of vegetable oil in the affected area will suffocate insects (5) and can probably kill insect eggs. Another resource suggests raw linseed oil applied with a stiff brush (8). The application technique sounds effective for application. Since the effect of oil is physical, any natural vegetable oil should work and be allowed.
• Soap dissolves the waxy cuticle (5)(9) or exoskeleton of lice. Repeat in one week to get the lice from newly hatched eggs. Please note that this is not a recommendation for special lice shampoos. Any type of soap will harm insects. Just choose one that will not be too irritating to your animals.
• Liquid enzymes dissolve the insect’s exoskeletons (5). Be sure these are natural enzymes derived from non-pathogenic bacteria or fungi, or from edible, non-toxic plants, and not genetically modified (11)
• Diatomaceous earth has naturally pointed edges that pierce insects’ exoskeletons (5). Be sure to use natural, non-heated forms (11), not the type that is sold for pool filtration (5).
• Use garlic powder as a topical treatment and feed as a tincture. Garlic containa allicin that acts as an insect repellant and antimicrobial (5).
• Rub white hellebore root on the affected area, or make a liquid mix of 4 quarts boiling water and 4 oz. white hellebore and wash the animal’s effected parts when the mix has cooled down (7).
• Various other herbal preparations are described in (8) including pyrethrum powders; Essential oils such as anise, camphor, eucalyptus, pennyroyal, pine rosemary & sassafras: 1 part of each with 2-3 parts olive or other oil. Rub in well. (Grainger and Moore, 1991); Wash morning and evening with powdered lobelia seeds (2 oz. in 1 qt. boiling water). Let stand a few hours and apply with sponge. (Dadd, 1897, p. 196); Raw linseed oil applied with a stiff brush (Alexander, 1919, p. 74 and Udall, 1943). Please check with your certifier to be sure all of the ingredients mentioned in these treatments would be allowed.

The website of Farmer Research in the Northeast describes the problem of lice as follows, and proposes a research project. The results are not yet posted. You may wish to contact this group to follow up on what they have learned.

“The proposed research project will test three different treatments for lice infestations in dairy and beef heifers. This is a problem with livestock in the winter, especially pubescent and young adult animals. The usual treatment for organic farmers is to wait until the animals can go out in the spring sun and the condition clears up. But when the condition is more pronounced it can cause reduced weight gain and irritation to the animal’s skin to say nothing of their increased stress level. This increase in stress can be debilitating, leading to other health problems. At the last Animal Health Study Group meeting we had, lice was listed as one of winter’s problems. Also whenever I visit livestock farmers in the winter this problem is expressed. The producers requested a study of some treatments for lice that would be permitted in a certified organic system. The proposed study will compare three treatments and a control. The treatments include a homeopathic remedy (30c Stapysagria), a powder of four parts neem and one part turmeric, and Pyganic, a commercial product that recently became labeled for livestock treatment. Each farmer will also keep at least two control animals. Treatments will be given weekly and repeated three times after the lice infestation is recognized in the winter of 2004-2005. Results will be tabulated in the next week. If there are no positive responses from the treatment, then the protocol will be repeated.”


1) Fanatico, A. 1996. Alternative Fly Control. Butte, MT: National Center for Appropriate Technology. (out of print)

2) Macey, Anne, Ed. Canadian Organic Growers, Inc. 2000. Organic Livestock Handbook, Fly and Rodent Control chapter, pages 50-63.

3) University of Nebraska at Lincoln, Dairy Cattle Insect Management: Fly Control and Cattle Lice sections.

4) Biological Control: A Guide to Natural Enemies of North America

Note: This site provides photographs and descriptions of over 100 biological control (or biocontrol) agents of insect, disease, and weed pests in North America. It is also a tutorial on the concept and practice of biological control and integrated pest management (IPM). Excellent photos and lifecycle descriptions.

5) Organic Valley Co-op. Controlling external parasites on the organic farm.

6) Farmer Research in the Northeast. Faciliator: Diane Schivera. Organic Lice Control for Heifers

7) Dr. H.J. Karreman, DMV. January 2002 Newsletter. Penn Dutch Cow Care

8) Dr. Hubert J. Karreman, VMD. Treating Dairy Cows Naturally.

9) Paul Dettloff, DVM. Alternative Treatments for Ruminant Animals

10) Little, V.A. 1963. General and Applies Entomology. Harper and Row Publishers.

11) Organic Materials Review Institute (OMRI). June 2004. OMRI Generic Materials List, under Livestock Production Materials: enzymes.

12) Those Pesky Lice! By Cheryl K. Smith. Dairy Goat Journal May/June 2005

13) UC IPM Online. April 2004. Pests of Homes, Structures, People and Pets: Flies

14) Integrated Pest Management for Fly Control in Maine Dairy Barns. University of Maine Cooperative Extension Bulletin #5002.

15) Integrated Management of Flies in and around Dairy and Livestock Barns, DAIRY MANAGEMENT Pest Management Fact Sheet, 6/1994.

16) Make Your Own Fly Trap
Horse Talk New Mexico Horse Directory

17) David Shetlar, PhD. The Ohio State University, photos of Old Fly Traps.

18) West Virginia University Extension Service. October 1995. Stable Fly Biology and Management.



Permalink What can you tell me about flame weeding?

Virgin Islands

Answer: I am pleased to provide you with information on flame weeding.

Flame weeding is a non-chemical weed control technique common among organic farmers. Flame weeding, also called flame cultivation, is dependent on propane gas burners to produce a carefully controlled and directed flame that briefly passes over the weeds (Diver, 2002). The intense heat sears the leaf, causing the cell sap to expand and disrupt cell walls. Foliage that retains a thumb print when pressure is applied between your thumb and finger has been adequately flamed. The flamed weeds soon wilt and die, usually in one to three days.

Weeds are most susceptible to flaming when they are seedlings, 1 or 2 inches tall. Broadleaf weeds are more susceptible to lethal flaming than grasses. Grasses develop a protective sheath by the time they are approximately 1 inch tall and may require a second flaming. Repeated flaming can likewise be used to suppress perennial weeds such as field bindweed.

Flaming on dry, sunny days is recommended (Daar, 2002). Weeds growing in dry areas tend to respond more quickly to flaming than those growing in moist habitats, perhaps because available moisture gives plants more resistance to the heat. When dealing with large areas of weed growth, work in sections, so that areas where weeds have not been flame-killed provide effective fire breaks - just in case some unseen dried material becomes ignited. Green plants undergoing flame-treatment rarely ever ignite.

Most flame weeders are designed to not radiate large amounts of heat. Their purpose is to sear the leaves of plants (weeds) in order to change the protein structure of the plants. As a result, stress is what kills the weeds, not torching them. Due to the design and purpose of flame weeders, there is generally not enough heat produced to penetrate the soil and effect soil life. As stated above, timing is everything.

While most articles focus on the weed control benefits of flaming, this technique also has other pest control applications (Daar, 2002). For example, potato plants up to eight inches (20.3 cm) tall can be flamed to kill Colorado potato beetles, Leptinotarsa decemlineata, without causing undue damage to the potato plants. Flamers can also be used to incinerate fallen fruit and mulch that harbors over-wintering spores that cause powdery mildew, brown rot, and other plant diseases. Given their versatility, flamers appear to be very useful garden tools - particularly for those seeking alternatives to toxic materials.

ATTRA offers two publications on flame weeding; one for vegetable crops and the other for agronomic crops.


Daar, Shelia. 2002. “Flame Weeding in the Garden.” Brisbane: Gamaco Pty Ltd.

Diver, Steve. 2002. Flame Weeding for Vegetable Crops. Fayetteville: ATTRA.



Permalink What information can you give me on erosion control for pastures?


Answer: I am pleased to provide you with information on basic erosion control measures for pastures.

Erosion Control Measures (Moench and Fusaro, 2008)

Reseeding; Seeding Tips for Hand Planting Small Areas

1. Roughen the soil surface to provide a better seedbed by breaking through the hydrophobic layer. A steel rake works well for this, or, depending on the slope, a small tractor drawn harrow could be used.
2. Broadcast the seed (a "Cyclone" seeder works well). Seeding rate depends upon the variety of seed sown. A good estimate is 10 to 20 pounds per acre of grass seed with another 10 to 15 pounds per acre of the nurse crop. Spread straw over seeded areas to prevent erosion.
3. Rake or harrow in 1/4 inch to 3/4 inch deep.
4. If the area is small enough, roll or tamp the seed down to ensure good soil/seed contact.
5. Spread weed-free hay straw. If the area is small, crimp the hay in with a shovel. (This will help keep both soil and seed in place during wind and rain.)
6. Control weeds as needed by cutting off the flower before it can seed.

Contour log terraces
Log terraces provide a barrier to runoff from heavy rainstorms. Dead trees are felled, limbed, and placed on the contour perpendicular to the direction of the slope. Logs are placed in an alternating fashion so the runoff no longer has a straight downslope path to follow. The water is forced to meander back and forth between logs, reducing the velocity of the runoff, and giving water time to percolate into the soil. Logs should be 6 to 8 inches in diameter (smaller logs can be used) and 10 to 30 feet long. The logs should be bedded into the soil for the entire log length and backfilled with soil so water cannot run underneath; backfill should be tamped down. Secure the logs from rolling by driving stakes on the downhill side. It is best to begin work at the top of the slope and work down. (It is easier to see how the water might flow by looking down on an area to better visualize the alternating spacing of the logs)

Straw Wattles

Straw wattles are long tubes of plastic netting packed with excelsior, straw, or other material. Wattles are used in a similar fashion to log terraces. The wattle is flexible enough to bend to the contour of the slope. Wattles must be purchased from an erosion control material supplier.

Silt Fences
Silt fences are made of woven wire and a fabric filter cloth. The cloth traps sediment from runoff. These should be used in areas where runoff is more dispersed over a broad flat area. Silt fences are not suitable for concentrated flows occurring in small rills or gullies. Silt fences are made from materials available at hardware stores, lumberyards, and nurseries.

Straw Bale Check Dam

Straw bales placed in small drainages act as a dam - collecting sediments from upslope and slowing the velocity of water traveling down slope. Bales are carefully placed in rows with overlapping joints, much as one might build a brick wall. Some excavation is necessary to ensure bales butt up tightly against one another forming a good seal. Two rows (or walls) of bales are necessary and should be imbedded below the ground line at least six inches.

Plant Species for Reseeding (ATTRA)

Combine bunchgrass species with a diversity of forage species, including plants with prostrate growth habit to provide both good water infiltration and protection against erosion and soil compaction. In your region of the country, I suggest considering the following species:

Cool Season Grasses
These species can be fall or spring planted with a Brillion seeder or drill. If broadcasted double the seeding rate. Decrease seeding rate if mixing with other grasses and legumes to a total seeding rate of about 15 pounds per acre.
1. Orchardgrass 10 to 15 lb/ac
2. Timothy 3 to 6
3. Kentucky bluegrass 10 to 15

Cool Season Legumes

These species can be fall planted or spring frost seeded in northern regions. Plant in a mix with cool season grasses at about 5 to 10 pounds per acre for alfalfa and red clover, 1 to 2 pounds per acre for white or ladino clover.
1. Red Clover
2. White Clover
3. Alfalfa

Warm Season Grass
You might consider planting hairy crabgrass at about as a warm season grass alternative. Broadcast in early spring or plant with a wheat or ryegrass nurse crop, just be sure to mow off the wheat or ryegrass when it gets warmer to allow the crabgrass to emerge and take root.

Referenced below is a paper from New Zealand on erosion control for pastures as well.


Hicks, D.L. 1995. Agricultural Practices Which Control Erosion, in Soil Erosion on Farmland. Wellington, NZ: MAF Information Services.

Moench, R. and J. Fusaro. 2008. Soil Erosion Control after Wildfire. Colorado State University Extension.



Permalink What information can you give me on over-wintering nursery crops?

North Carolina

Answer: I am pleased to provide you with information regarding over-wintering your nursery crops.

Winterization of your nursery crops depends on what they are planted in. Bare root crops and burlapped roots are the most susceptible to winter damage and obviously those in the ground are the least susceptible and need very little preparation. I recall you saying that your crops are overwintered in plastic pots, which is one of the most common planting methods for nursery crops. I found a newsletter article from NCSU regarding overwintering nursery crops. This information would be most applicable to your situation, see the article titled, “Preparing Nursery Plants for Winter”.

The key to overwintering is to acclimate your plants so that they are dormant and remain dormant during the winter. Protection from dessication from wind as well as occasional watering is also important. Once plants are dormant they are ready to be protected. Before they can be covered, however, they need to be properly prepared by following these guidelines:

• Containers should be well watered before going into cover.
• Containers should be placed on a clean, level surface that is not subject to flooding. Growers often use gravel and/or landscape cloth as surfaces for Quonset greenhouse structures.
• Foliage should not be overly wet right before covering.

Ideally, the best possible protection is to cover plants once they reach a state of dormancy, and then keep temperatures cold enough to maintain this dormant state until covers are removed in the spring. Once plants are covered up, they cannot be ignored. Houses must be scouted periodically to track environmental conditions, plant quality and any pests. Overwintering structures are natural havens for rodents, and it is necessary to use rodent bait stations to prevent excess rodent feeding on roots and bark. Watering needs must be monitored frequently, especially if temperatures inside the poly house warm up on sunny days.

Plants will dry out under cover, especially evergreens. Plants on the edge of the poly houses may be particularly susceptible to drying out. Before covering, consolidate plants as close as possible and water well. Moist media freezes slower and releases heat compared to dry media offering protection to the roots. The moisture level of the media should be checked during the winter and irrigated if necessary. This will also increase the relative humidity, which helps guard against desiccation. Structureless systems will not need watering if sealed properly.

Since your climate is sporadically warm, I advise you not to use clear plastic over the winter. Many nurseries overwinter their nursery crops with a white poly cover to prevent solar heat up and desiccation.

Visit this site for a table of minimum temperatures in preventing over-wintering damage with specific crops.

Below you will also find further information about overwintering your container ornamentals. I have referenced a fact sheet from UMASS Extension as well as another more applicable to your climate from the University of Kentucky Extension Service.

Overwintering Nursery Crops
Winston C. Dunwell & Robert E. McNiel
University of Kentucky
Department of Horticulture

UMASS Extension. (no date). Overwintering Container Grown Ornamentals. UMASS Green Info Fact Sheet.



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