Integrated Pest Management

B.C. Pest Monitor — Former Newsletter of IPM in British Columbia

Vol. 1 No. 2 November 1992

Using Sheep for Vegetation Management in British Columbia

Sylvia von Schuckmann, Integrated Management Branch, BC Environment

Over the past eight years, interest has grown in using sheep to graze vegetation around young crop trees in British Columbia forest plantations. Reducing competing deciduous plants and grasses makes more light, moisture and nutrients available to the tree seedlings. Because the use of herbicides is controversial, sheep have been widely promoted through the news media as a "green", biological control alternative. Using sheep in grazing contracts could also provide another source of economic returns to the sheep industry, while generating employment. How practical is this alternative for vegetation management? The following article addresses this question by examining some of the issues around using sheep and the factors that must be considered in determining whether sheep are the best option.

History and Current Status

Treatment can be one or several of the following methods coordinated into a management program:

Sheep were first used experimentally in the central interior Cariboo region of B.C. in 1984. Since then, other trials have been undertaken in all areas of the province. The Cariboo trials were carried out by the Ministry of Forests in cooperation with the B.C. Sheep Grazing Association. They measured how well the sheep used the forage, vegetation removal, amount and type of seedling damage, and the growth of tree seedlings. Results from these and other trials have been promising, but variable, and long term monitoring is still needed to measure the response of the crop trees.

The early trials also identified the need for careful management to reduce the high loss of sheep to predators and to improve sheep health. Although carnivore populations pose a risk to sheep grazing forest plantations, sheep producers do not consider predator kills excessive when compared to predator losses on farms. Predator interactions with livestock, however, concern wildlife managers because in the past they have often resulted in the destruction of carnivores and some predator populations have declined. The greatest concern is the safety of grizzly bears, although black bears, wolves, cougars and coyotes are also at risk. Grizzly populations are sparsely distributed, have low reproductive rates and cannot withstand additional mortalities. Sheep grazing may displace grizzlies from critical habitats, impairing the survival of adults and cubs. If the bears become used to domestic sheep on their ranges, they may adapt to this unnatural food source, perpetuating future problems.

Avoiding conflicts with predators is an issue with important implications for the economics of grazing and the success of the project. For example, persistent attacks by bears have forced cancellation of a few grazing projects. Whether attacks could increase in the future as predators become used to sheep, whether experienced dogs can provide sufficient protection for a flock and how to best dispose of sheep carcasses to avoid attracting predators are questions for further study. In 1991 and 1992, BC Environment and the Ministry of Forests jointly funded a project to monitor the impacts of sheep grazing projects on large carnivores and the use of dogs to deter predator attacks. Initial work in 1991 documented conflicts between sheep and large carnivores; of five sites studied in 1992, four sites had from one to several dozen sheep killed by predators.

Provincial agriculture and wildlife managers are also concerned about the effect of herding sheep onto the natural ranges of wildlife. Wild sheep and mountain goats are most at risk from infectious viral, bacterial and parasitic diseases that may be present in commercial sheep flocks. Some diseases can be transmitted to native wildlife and could potentially decimate wild sheep and goat populations. There has been very little research in B.C. on wildlife health and the potential danger of transmitting diseases to wildlife is not well understood. The activities of hundreds of sheep can also degrade wildlife habitat, soil and watercourses and displace other animals from their preferred ranges. Grazing can also reduce plant species important for forage and protective cover, thus reducing biodiversity.

In recognition of the complex nature of sheep health, disease transfer, and predator issues, the provincial ministries responsible for agriculture, environment and forestry formed an interagency Sheep Vegetation Management Committee in January 1992, to cooperatively develop standards for the use of sheep on forest lands. The committee is developing a set of comprehensive guidelines for use by all agencies and the sheep industry. Guidelines cover project planning, health management of sheep and on-site management. A key component of the guidelines is the Health Protocol developed by Dr. Henry Lange (B.C. Agriculture, Fisheries and Food) in collaboration with Dr. Ray Fenton (Alberta Agriculture) and the B.C. and Alberta sheep industry.

Choosing Appropriate Sites for Sheep

Sheep grazing is only one of many vegetation management tools available to foresters who must take into account costs, impacts on people and the environment and the effectiveness of the management method they choose under the local conditions. Factors that must be weighed when considering the sheep option include:

• Crop Species: Species, age and condition of the crop tree seedlings must be assessed. Under certain conditions, such as when there is a limited amount of preferred or palatable forage, sheep may eat any species of tree. Pine is most susceptible to browsing, but douglas fir is sometimes eaten, particularly in the same year it is planted and during flushes of new growth.
• Competing Vegetation: The type of vegetation on the site must be suitable for sheep. There must be sufficient palatable and nutritious vegetation to ensure that sheep remain healthy. Sheep prefer young fireweed, clovers, grasses and thimbleberry, but do not normally eat all deciduous species on the site. Vegetation over a meter in height is a problem because sheep cannot nip the growing tips on higher vegetation, therefore may not reduce the competing vegetation sufficiently to benefit the crop trees. Tall vegetation also makes it difficult to see and herd sheep and increases the danger of predator attack.
• Physical Characteristics: Physical characteristics of a site may preclude the use of sheep. Wet sites can spread hoof diseases and cause lameness. Sheep trampling may also compact the soil on such sites. Obstacles, such as excess slash left on the ground, make it difficult to herd sheep through the plantation and increase the risk of injury to the animals. Large obstacles impair the ability of shepherds to monitor the progress and safety of the flock. Herding on steep slopes is difficult, can lead to injuries, and there is the potential for causing soil erosion. Access to water is an important consideration. Sheep trampling around sensitive watercourses may cause erosion of the banks and siltation and may contaminate the water with fecal coliform bacteria. If there is potential for damage to watercourses or if there isn't enough water on the site, water must be hauled in. Road access to the project blocks is also important. If blocks are not accessible by vehicle, herding sheep over long distances may stress the animals and attract predators.
• Conflicts with Wildlife: BC Environment does not approve the use of domestic sheep in the vicinity of wild sheep or mountain goats, or in areas where there are known to be high concentrations of predators.
  

Managing the Grazing Flock

If a site is suitable for sheep, the key to successful vegetation management is careful supervision by experienced shepherds to ensure that sheep move uniformly through the area. This must be combined with constant attention to the health of the animals. Careful shepherding is required to ensure that competing vegetation is reduced evenly, to prevent overgrazing, trampling or browsing of crop trees and to protect sheep from predators. Well trained herd dogs are very useful to assist shepherds and, under certain conditions, night corrals, fences and guardian dogs have prevented the loss of sheep and minimized losses to predators. Currently, the average grazing flock numbers 1,000 to 1,200 animals, which requires two or more full-time shepherds as well as several herd dogs and guardian dogs to handle.

A health survey of flocks grazing on provincial forest plantations conducted by Dr. Lange in 1991, confirmed the need for a certification program to ensure compliance with the provincial Health Protocol. According to this protocol, all sheep must be inspected by the contractor or a veterinarian 2-8 weeks before they leave the farm to go to the forest plantation. Official ear tags are required for most flocks. An entry inspection is also required within two weeks of arrival on the project area and sheep that do not meet the Health Protocol must be removed. Inspections in 1992 found that the general level of health improved for all flocks using the Health Protocol, but that there are continuing problems with animal welfare and deaths that must be addressed.

Using sheep on forest plantations requires changes in some sheep husbandry techniques. For example, lambing on forest plantations is not acceptable and any lambs born on site must be removed immediately. This is because lambing would attract predators and newborn lambs could not cope with the rough terrain. Some diseases are also transmitted at lambing, which could contribute to the spread of disease to other sheep and wildlife. Large, healthy lambs born on the farm during the previous winter can be used in the grazing flock, but they may need additional feed supplements at the grazing site to enable them to gain weight.

There are many unanswered questions regarding the successful application of sheep to vegetation management. Experience so far clearly shows the need for careful management and for caution when choosing to use sheep in forests. A continued high level of cooperation is needed between the sheep industry, foresters, agrologists, veterinarians and wildlife managers to define the most appropriate niche for domestic sheep in vegetation management in the province.

Note: For further information or to obtain copies of the "Interim Guidelines for the Use of Domestic Sheep for Vegetation Management in British Columbia" write to:

Dr. Helen Schwantje (Chair) Sheep Vegetation Management Committee C/O Integrated Management Branch Ministry of Environment, Lands and Parks 780 Blanshard Street Victoria, B.C. V8V 1X4

Note: The use of domestic sheep for forest work in B.C. increased dramatically from low experimental levels in the 80's to over 10,000 animals in 1990. In 1991, 21,502 sheep grazed 4,562 hectares1 and in 1992 over 26,700 were expected to work 6573 hectares2. Because B.C. sheep producers are unable to supply enough sheep to fill the increased demand, approximately half of the sheep used on provincial forest sites since 1990 have been brought from Alberta for the field season.

According to B.C. Ministry of Forests fact sheets (see PUBLICATIONS, this issue): the overall value of sheep grazing contracts planned in 1992 was worth $2,108,935. In 1992, the cost of domestic sheep grazing varied from $225/ha to $740/ha. In comparison, costs for using manual methods, such as hand pulling, machetes, chainsaws, and girdling tools to control competing vegetation range $380 to $880/ha; the cost of mechanical controls, including raking, chopping or shredding vegetation with heavy duty equipment varied from $260 to $800/ha.

1 Michael B. Green. 1992. Impacts of sheep grazing for vegetation management on large carnivores. Feb. 1992 (Draft); pg. 6.

2 Ministry of Forests. 1992. Using sheep for managing forest vegetation in B.C. 2 pp.

The CP Rail System Vegetation Steam Car

In November, 1988, CP Rail System established a task force to evaluate the company's herbicide programs with the objective of developing a vegetation management policy as part of an overall environmental program. The policy addresses CP Rail System's major concerns, which are to protect the integrity of the railway, to develop programs of vegetation management that address both employee and public safety, and to minimize environmental impacts.

The control of vegetation on railway lines is vital to safe train operations. The railway bed carrying the ties that support the tracks is covered with broken rocks or gravel (called ballast). This part of the track must be kept free of vegetation and organic material that would hold water and cause the ties to rot; tangled and slippery vegetation on the tracks is also a safety hazard to railway workers and interferes with the inspection of track components for wear. Along the railbed right-of-way, on either side of the tracks, vegetation must be controlled to maintain good visibility along the tracks, to protect switching equipment and to reduce production of weed seeds that would fall on the ballast. Although herbicides are widely used by all rail companies to control vegetation, for several years CP Rail System has been investigating alternatives. Among them, the most promising has been the use of steam to destroy the cell structure of foliage and germinating seeds.

CP Rail System developed its first prototype vegetation management car in 1989 and a second generation prototype the following year. A third generation prototype, featuring an enhanced steam distribution system, was used in 1992 to treat about 2,250 kilometres of track on the railway's main lines throughout British Columbia. In the summer, the train was also taken to Alberta for testing on prairie weeds.

The vegetation control concept is simple. Steam is generated in an oil-fired boiler housed in a rail car, then fed to the specially designed vegetation management car where it is reheated to more than 200deg.C in a non-pressurized heater. Through an extensive distribution system leading from the second heater, steam is fed underneath the car to adjustable wings running along both sides of the steam car. These wings have thick rubber shrouds to guide the steam downward onto the track. Each wing can be independently lifted or lowered by the operator to adjust to the profile of the ballast or to clear an obstruction. Although the steam is produced at high temperatures, because it is low pressure, it does not present the safety hazard that high pressure steam would. The ground and vegetation is cool to the touch immediately after the steam shroud passes by.

CP Rail System's vegetation management car is operated as part of a small work train consisting of a flat car with the control cab, the vegetation management car, two steam generator cars, tank cars for water and fuel, a locomotive and a caboose. At the front of the train is a three-person control cab. From the cab, technicians and train crews are able to monitor and control the application of steam and the train's movements. In addition to gauges and controls for the vegetation management machine, the cab is also equipped with the safety equipment found on a locomotive as well as railway communications equipment. Although testing has been done at speeds up the 24 kilometres per hour, most steaming is done at about 5 kilometres per hour. Laboratory testing commissioned by CP Rail System indicated that exposing vegetation for a few seconds to high temperature steam kills the above ground portion of the plant and exposed seeds. Subsequent studies have shown that as little as 1 second of steam is required to disrupt cells sufficiently to kill some weeds. This may mean that is possible to design a faster moving, thus more economical, steamer in the future.

The current studies being conducted with the prototype train are establishing the economics of steam treatments, including how frequently steaming must be used on each section of track. Early results indicated that the train must be used three or more times in a season to kill deep rooted weeds because the steam only kills the foliage. Over time, however, it is expected that the number of treatments needed will decline as desirable plant communities are established along the tracks and the seed bank is depleted on the ballast.

CP Rail System is using their steam car within the context of a whole integrated vegetation management program that is tailored to regions and to the species found along the track. It is used in conjunction with brush cutting on the track right-of-ways, seeding disturbed areas with competitive grasses, and using herbicides. The long-term effect of this program is that competitive, low-growing plants would colonize the right-of-ways and prevent the re-establishment of tall, broadleaved weeds. In another, very important area, CP Rail System is also working with a botanist on researching treatment thresholds for weeds on tracks so that treatments can be targeted to sections of track, rather than the entire line. The railway plans to continue to research and test the use of the prototype steam car to determine whether it can control vegetation on the ballast in a manner that is environmentally friendly, safe and cost effective.

Codling Moths: Sterile Release Project Update

Early this summer Dr. Ken Bloem was hired as the Program Coordinator for the Sterile Insect Release (SIR) program to control codling moths in the Okanagan Valley of B.C. He has included the following update:

Twelve SIR trap monitors checked a total of 3620 codling moth pheromone traps in 1280 commercial orchards in Zone 1 of the SIR project area (this covers Summerland southward to the U.S. border). Traps were also deployed in urban areas during the period of second brood flight activity and the monitors continued to check these traps as well until the end of the trapping season in mid-September.

Two additional monitors surveyed backyard trees in the urban and rural areas of Summerland and Penticton and applied cardboard bands to codling moth host trees in both locations. The SIR project is hoping to identify the location of all backyard and wild apple, pear and crabapple trees in Zone 1 during the 1992 and 1993 clean-up years. This year, SIR monitors are urging backyard tree owners to remove infested fruit as it appears and dispose of it properly. Tree owners are being told that next year we would ideally like to see them strip all fruit from their trees early in the growing season. This would completely eliminate a major reservoir source of codling moths for 1994 when releases of sterile moths are to begin.

Once all monitoring work has been completed for this year, the moth population census data will be analyzed to determine where "hot spots" exist that will need special attention in 1993. In addition, the orchard population census data will be used to calculate the probable release numbers of sterile moths that will be necessary to give control in each orchard once releases begin. To date, grower and public cooperation has been encouraging, with a relatively small number of problem areas to deal with.

The mass-rearing facility is currently at the 60-65% completion stage. The modular steel building, mezzanine structure, underground mechanical and electrical work, concrete floor slabs and sawdust bunker have been completed. In addition, the 32 air handling units have been installed in the building and the main duct work in the containment area is in place. Current activities are concentrating on the placement of insulated panels in the rearing and emergence rooms and the installation of the bulk handling equipment. Over all, construction of the facility is on budget and on schedule, with moth production to begin in January 1993.

Cost and Efficacy Variation of Forest Vegetation Management Treatments in British Columbia, 1992

A report was recently completed for B.C. Environment, Pesticide Management Program, which summarizes "... the efficacy and costs of a variety of forest vegetation management techniques currently in use in British Columbia." Included in the report are discussions of treatment efficacies related to various combinations of methods and species, the costs of different treatment methods under a variety of conditions, and an analysis of costs relative to treatment efficacy. A common set of efficacy and cost criteria are used for all treatments so that comparisons can readily be made. The summaries as presented in tabular and graphical format list a range of options that may be considered in a broad range of situations, and provide a method of ranking the various options in terms of cost and effectiveness.

A comprehensive efficacy table listing common competitive species and a variety of treatments is presented. The table not only describes treatment impacts, but also includes duration of control and an indication of the reliability of the estimated. Costs are also presented in tabular form, and are broken down by forest region. Costs are presented for general categories of treatment such as "Chemical - Injection" or "Manual Cut - Herbaceous". Cost ranges and averages presented in the table are derived from a phone survey and reflect current (1991) prices.

Finally, cost and efficacy are combined in a graphical format. The graphs illustrated both the relative efficacies and costs of two or more treatment regimes (some of which may require more than one treatment) with respect to achieving a desired objective (in this case a free growing crop of conifers). This allows comparison of the cost effectiveness of various options.

Available from:

Dick Heath, BC Environment, Pesticide Management Program 2569 Kenworth Road, Nanaimo, BC V9T 4P7.

Ph: 604-751-3100 Fx: 604-755-2473 (Reprinted with permission from: The Northern Forest Vegetation Manager, Sept. 1992).

Publications

Controlling Vegetable Pests. 1991.

Edited by C. Putnam.

This seems to be the first in a series called Environmentally Friendly Gardening from Ortho Books and it is excellent. Containing up-to-date information for gardeners on least-toxic and biological controls, it also has numerous colour photographs of pests and diseases, beneficial species and control methods. Most, though not all, of the information, is applicable in B.C. There are other good books on the market (see below), but this one is a bargain and widely available.

Available at local garden centres and bookstores. Soft cover $17.95.

The Organic Gardener's Handbook of Natural Insect and Disease Control. 1992.

Edited by B. W. Ellis and F. M. Bradley.

This is another excellent book with the latest on organic pest control methods. It goes into greater detail than in the above text and is well illustrated, with numerous colour photographs of pests, diseases and beneficial insects. For most gardeners, this may be the most useful of the recent new titles from Rodale Press on the subject. Distributions of insect species are described for North America; Canadian pests and beneficial species are well represented.

Available from local bookstores: Hard cover $36.99.

Pamphlets, Guides, Fact Sheets

Fact Sheets on Forest Vegetation Management. 1992.

Ministry of Forests

This recent series of fact sheets on the various vegetation management methods used in forestry in B.C. is informative and designed to answer the most commonly asked questions on each subject.

New titles:

The Use of Physical or Manual Methods in Forest Vegetation Management

The Use of Mechanical Methods in Forest Vegetation Management

The Use of Livestock in Forest Vegetation Management

The Use of 2,4-D in Forest Vegetation Management

The Use of Releasereg in Forest Vegetation Management

These and other titles are available Attn: Tania Chouinard, Ministry of Forests, Silviculture Branch, 990 Fort St., Victoria, B.C. V8W 3E7

Fx: 604-356-6052. No Charge.

Safe and Sensible Pest Control Brochures (see Brochures section of this website for on-line versions).

By L. Gilkeson

Just off the press are two new titles in the series of guides developed by B.C. Environment to encourage the use of safe, practical alternatives to the overuse of pesticides to control common pests of home and garden.

New titles: Carpenter Ants, Household Insects.

Other titles still available: Fleas, Yellowjackets, Aphids, Turf Weeds, Beneficial Insects.

Insect Pests of Legume and Grass Crops in Western Canada. 1992.

Agriculture Canada Publication # 1435

A pocket-sized field guide to the pests of these crops, contains descriptions and colour photographs as well as information on life cycle, damage and integrated methods of control.

Available from:

Communications Branch

Agriculture Canada

Ottawa, Ont. K1A 0C7. Ph: 613-995-8963. No charge.

Journal

Pest Management Progress

An informative and substantial newsletter from the Silviculture Branch of the Ministry of Forests, reporting on pest management projects and proposals underway in B.C. Two issues per year.

Available from:

Ministry of Forests, Silviculture Branch

31 Bastion Square

Victoria, B.C. V8W 3E7 Attn: Pat Humphreys. No charge.

Catalogue

Least-Toxic Publications Catalogue

From The Bio-Integral Resource Center, North American leaders in providing IPM information for the public and for professional pest managers. The catalogue lists a variety of books, manuals, feature articles, audio-visual materials and services dealing with IPM.

Available from:

The Bio-Integral Resource Center

P.O. Box 7414

Berkeley, CA 94707. Ph: 510-524-2567 Fx: 510-524-1728. No charge.

New Products

Creeping Perennial Ryegrass

Richardson Seeds sells the `Barclay' cultivar of creeping ryegrass for use in turf seed mixtures and for overseeding heavily used turf, playing fields and golf courses. Horizontal growth of `Barclay' is reported to spread quickly, smother weeds, and recover quickly from wear damage, making it a useful component of herbicide-free turf management programs.

For more information:

Richardson Seed Company Ltd.

4055 McConnell Dr.

Burnaby, B.C. V5A 3A7 Ph: (604) 420-3437; Fx: (604) 420-2314

Insect Parasitic Nematodes

Westgro Sales is distributing 3 biological insecticide products from BioSys containing insect parasitic nematodes (Steinernema species). BioVectorreg. is listed for use against white grubs, root weevils, including black vine weevil and strawberry root weevil, craneflies and for fungus gnats in greenhouses and nurseries. BioSafe-Nreg. is for control of cranberry weevils and girdlers. Small packages of BioSafereg., are available in local garden centres for homeowners. For commercial amounts contact Westgro.

For more information:

Westgro Sales Inc.

7333 Progress Way

Delta, B.C. V4G 1e7 Ph: (604) 940-0380; Fx: (604) 940-0258

Cockroach Bait

Gardex Chemical carries a boric acid bait for cockroaches from Blue-Diamond Manufacturing Co., called Magnetic Roach Food 2000 PasteTM. It is a white paste, applicable with a putty knife or paste applicator; it contains boric acid and a feeding attractant to lure roaches to feed. The manufacturer states that the bait is good up to a year. It is only available to commercial applicators at this time.

For more information:

Gardex Chemicals, 950 12th St., New Westminster, B.C. Phone: 525-3634.