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Home  > Question of the Week

Question of the Week

Permalink What types of microbes are naturally found in sphagnum peat? How do they react to heat? At what temperature do they die? What is the temperature range for peat production?


Answer: It is first important to define the types of peats available in the commercial trade. Peat moss is a general term that includes several grades of peat. The Web site of the Canadian Sphagnum Peat Moss Association (CSPMA) provides a resource room with "Terms and Definitions of Peat and Peat Moss." There can be important distinctions between these different grades and types of peat and peat moss in terms of microbial characteristics.

Terms and Definitions of Peat and Peat Moss
In: Resource Room: Horticultural Teaching Plan, Canadian Sphagnum Peat Moss Association

peat moss or moss peat

sphagnum peat
hypnum peat

reed peat
sedge peat

reed-sedge peat
carex peat

peat humus
fibric peats

hemic peats
sapric peats

sphagnum moss

Characteristics & Qualities of Peat

Characteristics of sphagnum peat and other horticultural peats

Degree of Decomposition

Using Peat

Sphagnum peat moss is a common ingredient in potting mixes and is widely used in horticulture. It is highly valued as an organic media component because it provides porosity and holds moisture. However, it is considered inert and does not contribute mineral elements. Sphagnum peat can support microbial populations introduced by blending with composts and pine bark. In fact, potting mixes containing peat moss, compost, and pine bark are valued for their disease-suppressive characteristics.

The following excerpt from Premier Horticulture describes the microbial characteristics of sphagnum peat moss.

Various reports have confirmed that Sphagnum peat moss has disease suppressive qualities against certain root-rot pathogens. This is due to the presence of beneficial microorganisms. Contrary to popular belief, most peat moss producers do not sterilize or pasteurize their peat-based products for three reasons. First, Sphagnum peat moss is essentially free of pathogens and pests (Tahvonen, 1993). Second, it kills disease suppressive microorganisms found in Sphagnum peat moss (Tahvonen, 1993). Third sterilization is expensive.

Sphagnum peat moss bogs contain many microorganisms including Bacillus, Arthrobacter, Actinomyces, Streptomyces, Penicillium, Cladosporum, Trichoderma, Mucor, etc (Belanger, 1988 and Tahvonen, 1993). Of these, Trichoderma and Streptomyces are quite effective at suppressing certain root disease organisms (Tahvonen, 1993) due to their synthesis of antibiotics. Their presence in Sphagnum moss has been found to suppress Fusarium, Rhizoctonia solani, Phythium, (Tahvonen, 1993 and Chen, 1986) and Alternaria brassicicola (Tahvonen, 1993). The remaining microorganisms suppress root rot pathogens through competition. Simply stated, there is a limited amount of space and resources therefore, if a lot of beneficial organisms are present it is difficult for root rot organisms to establish themselves.

Sources of Sphagnum peat moss vary in microbial populations and composition. Therefore, disease suppression is not always predictable (Tahvonen, 1993). Blonde, fibrous peat from the surface of the bog has higher microbial populations versus darker, decomposed peat from deeper layers in the bog (Hoitink, 1991). Only blonde, fibrous peat, classified as H2 to H3 on the von Post decomposition scale (e.g. PRO-MOSS 'TBK') provides enough beneficial microorganisms to promote disease suppression. Disease suppression lasts about 6-10 weeks (Hoitink, 1997). However, when a plant is planted into a Sphagnum peat-growing medium, populations of disease suppressive microorganisms sometimes increase (Tahvonen, 1993).

Literature Cited

Belanger, A., 1988. Peat A Resource of the Future. Centre Quebecois de Valorisation de la Biomasse, Sainte-Foy, Quebec.

Chen, Y. and Y. Avnimelech. 1986. The Role of Organic Matter in Modern Agriculture. Martinus Nijhoff Publishers, Netherlands.

Hoitink, H.A.J., Y. Inbar and M.J. Boehm. 1991. Status of Compost-Amended Potting Mixes Naturally Suppressive to Soilborne Diseases of Floriculture Crops. Plant Disease 75(9): 869-873.

Hoitink, H.A.J., A.G. Stone and D.Y. Han. 1997. Suppression of Plant Diseases by Composts. HortScience 32(2): 184-187.

Tahvonen, R. 1993. The Disease Suppressiveness of Light Coloured Sphagnum Peat and Biocontrol of Plant Diseases with Streptomyces sp. Acta Horticulturae 342: 37-42.

Disease Suppression Associated With Sphagnum Peat Moss
Premier Press, Summer 2000, Vol. 7/No. 2

The following excerpt from the inactive ATTRA publication Disease Suppressive Potting Mixes addresses the use of peat moss in disease suppressive potting mixes.

Disease-supressive potting mixes are developed by (a) incorporating suppressive organic amendments such as certain types of peat moss and good quality composts, (b) inoculating composts and/or potting media with microbial biocontrols such as Trichoderma, Gliocladium, Bacillus, and Pseudomonas, or (c) inoculating potting media with plant-health promoting microorganisms such as mycorrhizae.

Dr. Harry Hoitink (2), a plant pathologist at Ohio State University , has pioneered much of the work with disease suppressive composts. Dr. Hoitink started working with composted bark as a disease-suppressive ingredient in nursery mixes in the early 1970s. The research program at Ohio State University has been so successful that methyl bromide has not been used in the Ohio nursery industry in two decades (1).

Through research, Hoitink and others have determined that pathogens such as Pythium are suppressed by general competition, while others such as Rhizoctonia require specific microbial antagonists. Light peat moss, or sphagnum peat, is known to be suppressive against Pythium for about six to seven weeks. However, dark peat moss that comes from deeper layers in the bog does not exhibit suppressiveness and may in fact be conducive to pathogens. Apparently, sphagnum peat contains naturally occuring microflora. As long as a plethora of microflora are present, they compete for nutrients with pathogens such as Pythium and Phytophthora through a process known as "general suppression". Thus, when sphagnum peat is used in potting mixes to start plugs and transplants, it often doubles as a natural disease suppressant for the lifetime of the seedling. Likewise, microflora-rich composts are generally suppressive to Pythium and Phytophthora.

However, to provide reliable control of Rhizoctonia, inoculation of compost piles after the thermophyllic stage with known antagonists such as Trichoderma and Flavobacterium is required. Earthgro, a Lebanon, Connecticut, compost company that manufactures potting mixes, specializes in microbial inoculation for control of Rhizoctonia.

There is a peat humus product brand-named Alaska Humus that is sold as a substrate for the production of "compost teas" in farming and gardening. The company claims that Alaska Humus contains an estimated 35,000 species of bacteria and 5000 species of fungi; apparently this estimate is based on molecular analysis.

The Web site of the Canadian Sphagnum Peat Moss Association (CSPMA) contains resources you may find helpful. In particular, see the list of peat moss association members, which provides Web address contacts for prominent horticultural suppliers of peat moss-based potting mixes, such as ASB Greenworld Ltd., Conrad Fafard, Inc., Premier Horticulture, The Scotts Company, and Sun Gro Horticulture. These companies may be a source of technical information.

Most of the scientific literature on microbial ecology of peat moss and peat bogs deals with methanogenic microbes. Some research concludes that 70% of the methane released into the atmosphere is of biogenic origin, and Northern peatlands are the source of 40 to 60% of the global methane budget. Several papers are cited below.


Canadian Sphagnum Peat Moss Association -- CSPMA
7 Oasis Court
St. Albert
Alberta , Canada T8N 6X2
780-459-0939 FAX

Alaska Humus Company
711 M Street , Suite 102
Anchorage , AK 99501
907-258-1525 FAX
[Contact: Jeff Lowenfels]

Upton M., B. Hill, C. Edwards, J.R. Saunders, D.A. Ritchie, and D. Lloyd. 2000. Combined molecular ecological and confocal laser scanning microscopic analysis of peat bog methanogen populations. FEMS Microbiol Lett. Vol. 193, No. 2 (Dec. 15). p. 275-81.

Basiliko, N., J.B. Yavitt, P.M. Dees, and S.M. Merkel. 2003. Methane biogeochemistry and methanogen communities in two Northern peatland ecosystems, New York State. Geomicrobiology Journal. Vol. 20, No. 6 (November-December). p. 563-577.

Krumholz, L.R., J.L. Hollenback, S.J Roskes, and D.B. Ringelberg. 1995. Methanogenesis and methanotrophy within a Sphagnum peatland. FEMS Microbiol Ecol. Vol. 18. p. 215-224.

Lloyd D., K.L Thomas, A. Hayes, B. Hill, B.A. Hales, C. Edwards J.R. Saunders, D.A Ritchie, and M. Upton. 1998. Micro-ecology of peat: Minimally invasive analysis using confocal laser scanning microscopy, membrane inlet mass spectrometry and PCR amplification of methanogen-specific gene sequences. FEMS Microbiol Ecol. Vol. 25. p. 179-188.

McDonald, R., M. Upton, G. Hall, R.W. Pickup, C. Edwards, J.R. Saunders, D.A Ritchie, and J.C. Murrell. 1999. Molecular ecological analysis of methanogens and methanotrophs in blanket bog peat. Microbial Ecol. Vol. 38. p. 225-233.



Permalink Where can I find information about product liability for my eggs, broilers, and beef?


Answer: From Dr. Neil Hamilton's The Legal Guide for Direct Farm Marketing, the section on products liability coverage:

The issue of whether products liability insurance is commonly available in the context of direct farm marketing is somewhat confusing. Many farmers believe that their typical farm liability insurance policy will provide them with "products liability coverage." In most situations this is probably not true. Farm liability coverage applies in situations when people are injured while on the farm premises. This is a different issue than someone being injured by a product which was purchased on the farm. The classic form of products liability insurance is the type of coverage a manufacturer acquires to apply when a person was injured using a product purchased from the manufacturer. The insurance policy is written on an individual basis and the cost of the insurance is a function of the type of product being sold, the process under which it is manufactured, and the type of risks associated with using it.

As it relates to the sale of food such as fresh produce and meat, the main concern about product liability is what happens if someone becomes ill from eating the food. Would a farm liability policy apply in this situation? The best answer is that it probably would not because it was not the type of activity or injury which the insurer was covering. This injury is not connected to the use of the farm premises. If the farm operation has an additional "excess liability policy" sometimes referred to as an umbrella policy, the answer could be different. It will all depend on the language of the policy and whether the injury involved can be shown to have been within the parties' expectations about the coverage. If you have concerns about this issue, the best advice is to ask your insurance agent how your current liability policy would apply in such a situation. If the answer is no, then you should ask whether such "products liability" insurance is even available for the products you sell.

See Resources (below) for links to Liability Concerns for Farmers Involved in Direct Marketing of Farm Products, the publication Food Product Liability Insurance, and the article "How much insurance is enough?" These provide information on many aspects of liability insurance.

Before 2001, the North American Farmers' Direct Marketing Association offered liability insurance for their members. They no longer provide this service, but they have a list (exclusively for their members) of insurance companies providing liability insurance policies for direct marketing operations

A part of the publication Risky Business? answers the common question: "What if a customer gets hurt while on my farm or gets sick from eating my farm products?" It discusses insurance, but also suggests organizing your farm business as a corporation to limit liability. The Midwest Plan Service Catalog page lists several publications that discuss farm corporations and planning financial organization structure for farms.

Your local Extension should be able to put you in touch with the Nebraska Farm Management Extension Specialist in your area. They could help you decide if a corporation or limited liability corporation (LLC) would fit your situation.

You should contact insurance agents working with business insurance. These agents should be able to help you find a policy to cover your value-added business.


The Legal Guide for Direct Farm Marketing. 1999. By Neil D. Hamilton. 240 p.
$20 plus $3 shipping.

Order from:
Drake University Law School
Agricultural Law Center
2507 University Avenue
Des Moines , IA 50311-4505

Anon. No date. Risky business? New England Small Farm Institute, Belchertown, MA. p. 1-2. 6-7.

Holland, Rob. 1998. Food product liability insurance. Agricultural Development Center - University of Tennessee. ADC Info# 11. Sept. 2 p.

Midwest Plan Service. 2005. Farm business management. Catalog. 4 p.

North American Farmers' Direct Marketing Association. 2005. Liability insurance and NAFDMA services. 5 p.

Pugh, Carolyn J. 2003. Liability concerns for farmers involved in direct marketing of farm products. Agricultural Law Research and Education Center - Pennsylvania State University. August. 10 p.



Permalink From a baking perspective, what is the difference between winter and spring wheat?

New York

Answer: The two Web sites cited below have all the information you should need about the six main classes of wheat and their different baking characteristics.


Anon. 2005. Flour. & 6 p.

Kansas Wheat Commission. 2003. Classes. 2 p.



Permalink Would a hybrid-poplar plantation be feasible in my area?


Answer: As usual, the main key to profitability is the market. Is there someone who will buy the poplars within a reasonable trucking distance of your location? You may have to sell to local pallet producers.

However, Missouri has several excellent resources that can help you in your overall evaluation of a hybrid-poplar plantation. A Missouri Extension publication on the Web that should be helpful is Forestry Assistance for Landowners. The entire publication can be found at

In addition, the Missouri Center for Agroforestry has included the subject as one of its eleven research clusters. You may wish to contact them for consultation. Following is the description from their Web site, located at

Fast growing hardwoods biomass research cluster. Focus is to quantify growth of Populus clones, and other species, for biomass production, flood tolerance and levee protection.

Biomass opportunities in the floodplain. Collect above-ground biomass weights (mt/ha) from 92 cottonwood clones. The information will be input into a database for future analyses. Data on heat content (GJ/mt) will also be determined.

The development of fast growing energy plantations for bottomland sites in Missouri using elite Populus deltoides clones.

Physiological and morphological determinants of biomass productivity of poplar clones leading to an assessment of the carbon budget for cottonwood clonal stands.

Minnesota has also done considerable research. In Minnesota, the native stands of aspen were exhausted, and the state encouraged plantings of hybrid poplar to replace them. In this case, the processing infrastructure was already in place. Hybrid Poplar Profits, by Erik Streed, although it is several years old, might be helpful in your market analysis.

Another University of Minnesota publication, Discovering Profit in Unlikely Places: Agroforestry Opportunities for Added Income, devotes a chapter to "Woody Crop Plantations." You may view the entire publication at

Three other Web locations that might be of interest:

Short Rotation Woody Crops Operations Working Group

Hybrid Poplar Research Program

National Agroforestry Center's publication Opportunities for Growing Short-Rotation Woody Crops in Agroforestry Practices (PDF / 147 kb)

The Poplar-Willow Technology Network is linked to the National Agroforestry Center's site. It is described as "a national network of experts to provide technical support for individuals, private companies, city, county, state and federal agencies interested in using fast growing tree species for wastewater treatment and other similar types of tree-related environmental projects." Two sources of tree materials in Missouri were listed on this site.

Cutting suppliers/nurseries:

Ripley County Farms, Doniphan, Missouri, 573-996-3449 E-mail:

River Valley Tree Service, East Prairie, MO, 573-649-3355, 573-380-1145


Alig, Ralph et al. 2000. Economic potential of short-rotation woody crops on agricultural land for pulp fiber production in the United States. Forest Products Journal. May. p. 67-74.

Anon. 1990. Short Rotation Intensive Culture. Energy Information Center, Minnesota Dept. of Public Service, St. Paul, MN. 8 p.

Godsey, Larry D. 2001. Tax Considerations for the Establishment of Agroforestry Practices. 3-2001. University of Missouri Center for Agroforestry, Columbia, MO. 12 p.

Godsey, Larry D. 2002. Funding Incentives for Agroforestry in Missouri. 5-2002. University of Missouri Center for Agroforestry, Columbia, MO. 24 p.

Kuhn, Gary A. and W.J. Rietveld. 1998. Opportunities for Growing Short-Rotation Woody Crops in Agroforestry Practices. AF Note #10 Agroforestry Notes. USDA Forest Service Rocky Mountain Research Station and USDA Natural Resources Conservation Service. 4 p.

Rhoads, Julie L., and John P. Slusher. 1999. Forestry Assistance for Landowners. G5999. University of Missouri Extension Publication, Columbia MO. 5 p.

Streed, Erik. 2002. Hybrid Poplar Profits. University of Minnesota. 6 p.



Permalink Is 'Hialeah' green bean seed available untreated; is it a genetically-engineered variety; and does the Plant Variety Protection Act (PVP) prohibit anyone from saving seed from it?


Answer: 'Hialeah' was specifically developed for disease resistance under Florida growing conditions, upright plant habit/uniform maturing (to facilitate one-pass harvesting), and abundant yield. In 1989 it was introduced as a newer version of 'Gater Green,' another Florida commercial standby. Still newer versions have since been introduced for the Florida commercial winter vegetable grower. The following is from the online version of Vegetable Cultivar Descriptions for North America.

Hialeah (FM216)-- Breeder: Dr. G. Emery. Vendor: Ferry-Morse. Characteristics: Gatorgreen pods on an upright plant habit, excellent concentration of maturity and yield potential. Resistance: bean common mosaic virus. Similar: Gator Green 15. PVP. 1989.

To address your specific questions:

According to NCAT agriculture specialist Nancy Matheson, any commercial seed company can supply untreated seed, upon request, but they may not feel it's worth their while. The companies that stock 'Hialeah' cater to large commercial growers, for the most part, although the originator of 'Hialeah,'Ferry-Morse, sells seeds by the retail packet in supermarkets and hardware stores.

'Hialeah' is a conventional hybrid, not a genetically engineered variety. "Seeds saved from hybrids will either be sterile or will begin reverting to one of the parent varieties during succeeding generations," according to Suzanne Ashworth. This even applies to self-pollinated legumes such as Phaseolus spp.

The Amended PVP Act (October 6, 1994) removed the farmer's right to sell or trade seed descended from a PVP variety to his neighbor. In summary:

The seed you buy of a PVP protected variety includes the right to use the genetics of that variety on your farm, just as you would use computer software, for example; it does not include the right to reproduce the product to sell for planting to someone else.

Farmers can produce and replant seed of a protected variety on the farm where the seed was produced, but cannot sell, trade, or transfer the seed by any other means to any one else for planting purposes. (Resource Seeds, Inc., p. 2)

For a list of seed suppliers for organic production, see ATTRA's Suppliers of Seed for Certified Organic Production.


Nienhuis, James, Michell E. Sass, and James R. Myers (ed.). [n.d.] Vegetable Cultivar Descriptions for North America. Bean--Green. University of Wisconsin, Oregon State University.

Ashworth, Suzanne. 2002. Seed to Seed: Seed Saving and Growing Techniques for Vegetable Gardeners. Seed Savers Exchange, Decorah, IA. p. 14, 126.

Janice M. Strachan. [2004]. Plant Variety Protection: An Alternative to Patents.

Resource Seeds, Inc. [2004]. PVP - U.S. Plant Variety Protection Act as Amended 1994. [See Resource Seeds, Inc. / PDF Library / PVP Information for Growers]



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