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Home  > Question of the Week

Question of the Week

Permalink I am building a new lambing barn. What are some resources for building energy efficient barns?


Answer: Thank you for your recent request for information from ATTRA, the National Sustainable Agriculture Information Service regarding energy efficient lambing and lactation barns. Using passive ventilation and lighting methods, like we talked about, can certainly reduce your operating energy costs.

There are a number of construction designs available for lambing and lactation barns. The expandable lambing unit (Canada Plan Service, M-4312) may be a good option for you to expand over time, as we discussed. You will need to make some modifications to this to achieve passive ventilation and lighting.

Scan through the article “Natural Ventilation”, by Andy Walker. The Design Recommendations of this short publication are very helpful, although not all are relevant to agriculture buildings. I’ve referenced several other sets of plans for you to consider as well.

Some of the least expensive daylighting options include integrating polycarbonate corrugated roofing into your metal roofing so that it brings in natural light. You may also want to use casement windows that will be used for both ventilation and light. “[I]f the wind blows from east to west along a north-facing wall, the first window (which opens out) would have hinges on the left-hand side to act as a scoop and direct wind into the room. The second window would hinge on the left-hand side so the opening is down-wind from the open glass pane and the negative pressure draws air out of the room.” (Walker, Andy)

In addition to the ATTRA publication on efficient buildings, I would also recommend eXtension resources on farm building energy efficiency available online at

More plans and resources are available from Iowa State Extension, online at Another good source is

Keep in mind that your latitude is 38 degrees. Therefore, adjustments in passive heating depend on what time of year you need heat (tilted flatter during the summer to optimize for solar collection and steeper during the winter to optimize for solar collection).


Sheep Housing. Plan 4000. Canada Plan Service.

Expandable Lambing Unit. M-4312. Canada Plan Service.

240 Ewe & Lambing Barn. MWPS-72506. Midwest Plan Service. Cooperative Extension Service.

500 Ewe and Lamb Feeding Barn. MWPS-72507. Midwest Plan Service. Cooperative Extension Service.

Walker, Andy. Natural Ventilation. National Renewable Energy Laboratory.

Solar Ventilation Wall with Heat Storage. Plan 9732. Canada Plan Service.

Passive Solar Design in Wisconsin. Renewable Energy. Focus on Energy.

Darby, D.E., Borg, R. Hot Water Heating. 9735. Canada Plan Service.

A Consumer’s Guide: Heat Your Water With The Sun.

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Permalink What information can you give me on growing rosemary commercially?


Thank you for requesting information from ATTRA on field production of rosemary in Florida—as raw material for your nutraceutical extraction facility and for sales to the herbal and spices industry.

Referenced below are some information resources to aid in decision making on this enterprise.

Spain, France and Egypt are the largest producers of rosemary. Most of the rosemary for oil production is grown in France, Spain, and Tunesia. Within the past 15 years, Australia, Canada, New Zealand, and South Africa have investigated the feasibility of growing rosemary commercially. Referenced is a feasibility study on greenhouse production of rosemary for the nutraceutical industry, prepared for the Ministry of Agriculture and Rural Development, Province of Alberta, Canada.

Arthur O. Tucker, research professor at Delaware State University, co-authored The Big Book of Herbs. The section on rosemary provides an extensive description of cultivars. In zone 9a/b you have a wider range of cultivar choice than further north.

University of Florida Extension has published a pest management profile for herbs, noting that 1. field production is concentrated in south Florida, and 2. fewer than 500 acres total (distributed between greenhouse and field) of all herb crops were being grown in 2005. Tucker notes that rosemary is susceptible to spider mites, mealy bug, whitefly (primarily in greenhouse production), and thrips. University of Ohio Extension notes problems with aphids, scale, root rot, and botrytis, as well. Web blight from Rhizoctonia solani may produce interior twig and branch blight. Root rot results from poor drainage. Pseudomonas syringae infection may produce a systemic “stem knot” that is difficult to control. Tucker’s suggestions for control rely primarily on sustainable strategies (p. 514), rather than chemical treatments.

Bandara, Manjula. 2010. Rosemary Nutraceutical Industry Feasibility Study. Ministry of Agriculture and Rural Development, Province of Alberta, Canada. 4 p.

Mossier, Mark A. 2005. Florida Crop/Pest Management Profile: Herbs (Basil, Cilantro, Dill, Mint, Parsley, Rosemary, Sage, Thyme). University of Florida IFAS Extension. 7 p.

Staff. 2009. Rosemary Production: Production guidelines for rosemary. Agriculture, Forestry & Fisheries Department, Republic of South Africa. 26 p.

Tucker, Arthur O. and Thomas DeBaggio. 2000. Rosemary, Rosmarinus officinalis. The Big Book of Herbs. p. 512–527.

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Permalink What are some resources for vegetable production and planting guides?


Answer: Thank you for your recent request for information from ATTRA, the National Sustainable Agriculture Information Service. I am pleased to provide you with information regarding vegetable production and planting guides.

North Carolina State University Growing Farmers web site has a lot of information on farm record keeping and yield charts. The most helpful one for you would be their Planning Spreadsheets for CSA and Farmers' Markets. This is a tabbed spread sheet that includes yield and planting information for a typical CSA. The Field Production Info sheet might be most helpful to you. You can access this and other helpful record keeping templates at the following link.

Another very helpful vegetable planting guide is available from Kansas State University Extension Service. It includes information on days to harvest, days to germination, optimum germination temperature, space and depth requirements and amounts per person. While it is written for the Kansas climate, much of this information is adaptable to your situation. The link to this guide is listed below.

Kansas State University Hort Report
Vegetable Garden Planting Guide
By Charles Marr (1992)

Another yield chart that I refer to often is the Johnny’s Selected Seed yield chart for direct seeded and transplanted vegetables. It is broken down into 100’ rows and acre yield estimates. This is also included in their annual catalog. I find it helpful to take this out, laminate it, and refer to it while planting throughout the season.

Finally, these guides are meant to be a rough guide for your planning your vegetable plantings. Your own microclimate and farming practices will affect the yield and days to maturity of vegetable crops grown specifically on your farm. I encourage farmers to develop their own template and record exactly when their crops mature and their yield. This can help with planning and succession planting for the following season.

I have also listed a link to the ATTRA publication, Scheduling Vegetable Planting for Continuous Harvest. This publication has a record keeping template that you can fill in based on the information from your own farm.

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Permalink What are some options for snail and slug control?

New York

Answer: Thank you for your question on snail and slug management. This letter provides information about control options for both snails and slugs.

Snails and slugs are one of the more common and serious pests in the vegetable garden. These soft-bodied insects are mollusks and feed on decaying plant debris and on a number of vegetable, flower, fruit and herb species. Although slugs have a range of favorite foods, including cabbage, cereals, lettuce, green vegetables, strawberries and root vegetables, slugs will attack any and all seedlings, even if the mature plant is unpalatable (1). Crop damage from slugs is greatest at the seedling stage.

Lacking a protective shell cover, slugs prefer to stay out of the sun hiding under rocks and boards, mulch, compost piles and other garden debris during the day. They forage only at night and on wet, sunless days, and are easy to identify by the telltale trails of silvery, sticky mucus they secrete to smooth their path. In most cases, it is temperature, not light, that will most influence slug feeding.

Compared to snails, slugs spend more time on the ground or in the soil. Lacking a shell, they require more contact with moist environments to avoid desiccation. Conditions that favor slug development include the following (2):
• No-till practices that provide crop residue on the soil surface for slug habitat
• Dense weed cover, or addition of organic matter such as livestock manure
• Mild winter temperatures that enhance overwintering success
• A prolonged period of relatively cool temperatures (6368° F) combined
with evenly distributed rainfall that maintains wet soil moisture conditions
• Either heavy-textured soils or coarse-textured soils, neutral to high pH, and
excessive nitrogen levels.

Referenced in this letter are lists of articles that describe the biology and control of this mollusk. Not all slugs are pests. Native species like the banana slug recycle nutrients, produce humus and build soil. Other insects and birds prey on them for food. Species that attack garden or field crops are those that were inadvertently introduced from Europe like the gray garden slug (Deroceras laeve), the spotted garden slug (Limax maximus), the tawny garden slug (Limax flavus) and the European black slug (Arion ater ater).

Slug biology and habits must be understood in order to implement an effective management program. Correct identification and regular monitoring are necessary to assess the severity of the infestation and determine what kind of controls to most appropriately implement. The trick is to find weak points in the slug life cycle at which management measures can be most effectively applied. For example, baiting is most effective when the slugs emerge to mate and lay eggs (see the article Stopping Slugs and Snails by Joel Grossman).

Management measures for slugs generally fall into two general categories: proactive and reactive. (Biological controls may be either proactive or reactive, depending on the context of their implementation). Proactive, or preventative measures are various cultural controls that can be taken prior to an outbreak of slugs in order to decrease the chances of an economic infestation developing. These are often manipulations of the farm ecology that somehow increase the environmental pressure against an organism. A program that integrates preventative and reactive measures will be the most likely avenue to successful slug management.


Recent research in Switzerland (3) found that slug damage to lettuce plots that were watered in the morning was significantly less than slug damage to plots that were watered in the evening. Evening watering creates a very slug-friendly environment. Drip irrigation may be of some benefit (compared to overhead irrigation), since its use will decrease the general moisture of the crop environment.

Rototilling the ground during warm weather in early spring will reduce slug populations through physical destruction and exposure of slugs and slug eggs to predators and the weather. Three passes of a rototiller in an area may decrease slug population by 75% (4). The downside is that the cultivation will expose the organic matter of the soil to an increased rate of oxidation.

Biological Control

A posting on the Gardening in Harmony website message board noted that:

Rhode Island Red hens are great slug hunters, they eat virtually all the slugs they can find. Other chickens don't seem to care for slugs very much. My number one vote is for ducks! They devour slugs like mad. I have heard it said that they will eat half their body weight in slugs a day. Here is a quote that says it all: "You don't have a slug excess, you've got a duck deficit!" Bill Mollison, Permaculture expert. I have several friends with organic farms who put their ducks on slug patrol with great success! (5).

Khaki Campbell or Indian Runner duck varieties are especially good snail and slug hunters (6). A word of caution about ducks and chickens. Ducks are browsers and may eat the salad plants, particularly if they are young. Chickens may take a few bites out of the foliage as well. Of greater concern may be the presence of duck or chicken feces contaminating the lettuce leaves. One option is to use these animals to control slugs (and snails) after harvest. It may be worthwhile to experiment with ducks or chickens on a small scale to observe the practicality of integrating them into your farming system as slug controls.

Other biocontrols include various species of ground beetles in the genus Scaphinotus and other genera. These beetles are not available commercially and must be conserved through habitat manipulation. However, the habitat that favors Scaphinotus spp., such as mulch, may also favor slugs.

Some research has been done using parasitic nematode, Phasmarhabditis hermaphrodita, as an applied biocontrol for slugs. Field research in 2004 reported that slug damage on Chinese cabbage was reduced by about one-third by the nematode treatment (Vernavá, et. al., 2004). Sources for these nematodes are provided at the end of this letter. The same research (Vernavá, et. al., 2004) found that slug damage was significantly (c. two times) greater after red clover or vetch than after ryegrass. Damage on plots without cover crop was intermediate and not significantly different from either extreme.

Harvestmen (Opiliones) prey on slugs. The sciomyzid flies, Tetanocera plebeia Loew and Tetanocera valida Loew prey on brown slugs (7). Other general predators include birds (up to 6 percent of the diet of starlings), moles, toads, shrews, rove beetles and firefly beetles (8).

Treatment: Barriers and Baits

Reactive measures generally take the form of some kind of treatment. A variety of baits, traps and barriers have been tried with varying degrees of success. Barriers reported to be effective against slugs and snails include sand, diatomaceous earth, ashes, crushed eggshells and others (9). Rain or moisture will decrease the effectiveness of many of these. Another technique, supposedly very effective, is to surround the plant, bed or garden with a 6" wide copper foil barrier. The mollusks get a mild shock when they encounter the metal and stay away. Wooden surfaces treated with copper sulfate also act as a slug barrier. (8). Copper sulfate is toxic to slugs as are inorganic salts of aluminum and iron. There have been some observations that aluminum sulfate, which is commonly used as a soil acidifier, repels slugs well at the rate of 510 lbs per 1000 square feet. However, noting that the compound is inactivated very quickly when in contact with wet soil, researchers speculate that its effectiveness could be enhanced by application to inert materials like plastics that surround the plants (10). Another method of protecting barriers consisting of aluminum and iron ions is to combine (chelate) these ions with an organic compound to protect against environmental degradation and inactivation (1).

Other options include use of pennyroyal as a slug barrier or perhaps a mulch. Pennyroyal and some other mint oils contain pulegone, a toxic monoterpenoid that acts as a feeding deterrent (11). Sources of mint oils are provided below.

Research in Great Britain in 2003 investigated the repellent and irritant effects of cinnamamide, copper ammonium carbonate, a mulch, a horticultural ground-cover matting impregnated with a copper formulation and urea/formaldehyde. In the no-choice experiments the products had a stronger irritant effect on the snails than on the slugs. All products tested except the mulch significantly reduced the locomotor activity of both the slugs and snails. The most effective product, cinnamamide, reduced snail locomotor activity by 94% and track length by 96%. The overall repellent effect of the treatments in the choice experiments was stronger in the slugs; where presence, locomotor activity and track length in the treated area were significantly reduced by all products. The avoidance of treated areas exceeded 95% with the mulch (for slugs) and with copper ammonium carbonate (for snails) (12). An earlier study in 2002 lab-tested 4 materials, metaldehyde, methiocarb, cinnamamide and 3,5-dimethoxycinnamic acid (DMCA), as a seed treatment on oilseed rape against slug damage. The researchers found that all doses of cinnamamide and DMCA were phytotoxic to the young plants, and that all compounds reduced slug damage, but metaldehyde and methiocarb consistently performed better than cinnamamide and DMCA (13).

Beer baits are often recommended but must be closely spaced in order to be effective. The slugs are attracted to the yeast products, not to the alcohol or hops. Recommended spacing is one bait per 10 sq. feet. To create your own slug bait, add 1Tb of granulated yeast in three cups of water and 2 Tb of sugar. Put it in a pan with the edge at least ½" above soil surface to keep beneficial insects from inadvertently falling in.

Baits made with iron phosphate (i.e., Sluggo and Escar-Go) are an environmentally friendly way to manage snails and slugs. Use of Sluggo is allowed under the National Organic Standards since 2006. If your farm is organic, or transitioning to organic, before using other materials it is important to discuss this material with your certifying agency prior to use. Organic standards does not allow use of synthetic forms of iron phosphate, which may leave the door open for the use of mined iron phosphate. However, “inert ingredients” make up 99% of the formulation of these products, and it may be that the composition of the inerts must be determined and pronounced “allowable” before these products are declared allowable for use in organic production systems.

In summary, the slugs and snails have several weak links in their life cycles that can be exploited to manage these populations. These organisms seek moist environments, so actions to reduce moisture, particularly during the night, will provide some relief from this pest. Morning (vs. evening) irrigation, use of drip irrigation, and use of raised beds all may help reduce slug populations. The penchant of slugs to seek protected environments might be taken advantage of by providing such environments in order to trap them. For example, long sheets of plastic laid in between rows might be an attractive shelter in which slugs will congregate come daylight. The plastic sheets could be collected during the day and the slugs harvested.

Weaving the options available to you for slug control into an integrated pest management program that fits your operation requires creativity, flexibility and a willingness to experiment, observe the results and experiment again.


1) Quarles, William. 1997. Slugs and snails in gardens and fields. Common Sense Pest Control. Winter. p. 515.

2) Van Dyke, J. 1998. Slime trails in the moonlight. Iowa State Dept. of Entomology Website.

3) Speiser, B., and M. Hochstrasser. 1998. Slug damage in relation to watering regime. Agriculture, Ecosystems and Environment. Vol. 70. No. 23. p. 273275.

4) Symondson, B. 1990. Slug control. Webpage at

5) Michaels, F. 2001. Organic slug and snail control.

6) Judi. 1999. Posting on Gardening in Harmony message board.

7) University of Florida Institute of Food and Agricultural Sciences, Mid-Florida Research and Education Center (MREC) Webpage. Derocerus slugs.

8) University of Florida Institute of Food and Agricultural Sciences, Mid-Florida Research and Education Center (MREC) Webpage. Introduction to Slugs and Snails.

9) Organic Gardening (eds.) 1997. 18 nifty ways to negate slugs and snails. Organic Gardening. May-June. p. 4648.

10) Anon. 1990. Iron and aluminum molluscicides. Hortideas. September. p. 102.

11) Quarles, W. 2000. Mints and pest control. Common Sense Pest Control. Vol 16. No. 2. Spring. p. 1719.

12) Schuder, I., et al. 2004. The Behavioural Response of Slugs and Snails to Novel Molluscicides, Irritants and Repellents," Pest Mgmt. Sci., 60(12), 1171-1177, December 2004.

13) Simms L.C.1; Mullins C.E.1; Wilson M.J. 2002. Seed dressings to control slug damage in oilseed rape. Pest Management Science, July 2002, vol. 58, no. 7, pp. 687-694(8)

Suggested Further Reading:

Grossman, Joel. 1991. Stopping slugs and snails. Fine Gardening. November-December. p. 5659.

Organic Gardening (eds.) 1997. 18 nifty ways to negate slugs and snails. Organic Gardening. May-June. p. 4648.

Quarles, William. 1997. Slugs and snails in gardens and fields. Common Sense Pest Control. Winter. p. 515.

Long, Becky. 1996. Coping with slugs and snails. Journal of Pesticide Reform. Spring. p. 2223.

Lynas, Bryam D.T. 1992. More on iron sulfate as a molluscicide. Excerpt from a report. Hortideas. April. p. 43.

McLeod, Edwin J. No date. Snail and Slug Biology and Management: A Review. Organic Agriculture Research Institute. 6 p.

Verbena, Melissa and Jean Yates. 1991. Success secrets of super slug slayers. Organic Gardening. April. p. 44, 4648.

Vernavá, M.N., Phillips-Aalten P.M., Hughes L.A., Rowcliffe, H., Wiltshire C.W., and D.M. Glen. 2004. Influences of preceding cover crops on slug damage and biological control using Phasmarhabditis hermaphrodita. Annals of Applied Biology, December 2004, vol. 145, no. 3, pp. 279-284(6)

Selected Sources for slug control products:

Slug Bait

Gardens Alive (EsCargo)

Peaceful Valley

Predatory Snail (Rumina decollada, for brown garden snail)

800-827-2847 or 520-825-9785

Peaceful Valley


Copper Snail Barrier

Harmony Farm Supply

Peaceful Valley

The Green Spot


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