Forage management: Production and maintenance

Table of contents

• Foreword
• Introduction
• Harvesting
  • GRAZING MANAGEMENT
  • The Forage Plant
  • The Grazing Animal
  • Grazing Systems
  • Fencing
  • Water Systems
  • HAY AND SILAGE
  • Harvest Scheduling
  • Harvesting and Storage Systems
  • Equipment
• Bloat Management
• Fertilization
• Pest Management
  • Weed control
  • Disease control
  • Insect and rodent control
• Fall management of Alfalfa
• Rejuvenation
• Wildlife considerations

The authors thank the Saskatchewan Forage Council, the Saskatchewan Advisory Council on Forage Crops and the following for their helpful suggestions while drafting this publication: g. Bowes, G. Chu, D. Clark, P. Grilz, N. Frazer, R. Horton, P. Jefferson, C. Nykoluk, J. Romo, and J. Moen for his efforts in coordinating this project.

This publication is sponsored by Saskatchewan Wheat Pool, Ducks Unlimited Canada, Saskatchewan Soil Conservation Association, SeCan Association, Saskatchewan Wetland Conservation Corporation, and PFRA through the Canada-Saskatchewan Agreement on Soil Conservation

PHOTO CREDITS:
Agriculture Canada, PFRA and Research Branch, Ducks Unlimited Canada, Saskatchewan Agriculture and Food, Saskatchewan Agriculture and Food, Saskatchewan Rural Development, Saskatchewan Soil Conservation Association, Saskatchewan Wheat Pool, SeCan Association, H. Bjorge and D. McCartney

Foreword

About half of the organic matter in Prairie soils has been lost due to intensive tillage practices. In addition, much of our fertile topsoil has been lost through soil erosion. If agriculture is to remain viable, we must reverse these trends. Forage crops will play an important role.

Perennial forages are key agents in soil conservation and soil improvement. They add more organic matter to the soil than most annual crops. Because they reduce cultivation and provide a permanent ground cover, they also reduce erosion. For these reasons, perennial forages are particularly well suited to marginal lands, sloped lands, waterways and erosion prone soils. They can also be used in areas subject to flooding and to control salinity.

But soil conservation and soil improvement are only part of the story. Forages can also help farmers diversify their production. And they provide a habitat for wildlife.

Introduction

In both pasture and hay fields, four key elements determine the productivity of a forage stand: land, climate, species and varieties, and management.

The land and climate are givens for any geographic area, and the advantages of various forage species for pasture and hay have been covered in a related publication, Forage Selection.

This publication focuses on the variables that can be managed in existing stands. Subjects covered include: the grazing of pastures; the management of hay and silage crops; the management of weeds, insects, diseases and other forage crop pests; mechanical harvest; and brief overviews of stand rejuvenation techniques and wildlife considerations.

Harvesting

GRAZING MANAGEMENT

Grazing management is goal directed, planned livestock grazing. It involves planning, and then controlling the timing, intensity and frequency of grazing. Good grazing management allows sustained livestock production while maintaining healthy and vigorous forages and good soil cover.

Successful grazing management considers both the forage plant and the grazing animal.

The Forage Plant

Forage plants need water, space, nutrients, and sunlight. A shortage of any of these four basic elements will restrict plant growth. Shortages sometimes occur naturally, caused by longterm climatic changes, shallow soils that restrict rooting depth, or poor soil fertility. More frequently, they are caused by poor grazing management.

Long-term overgrazing creates its own drought conditions by baring the soil surface, increasing soil surface temperature and weakening plant root systems. When the ground is bare from overgrazing, weeds invade. Some weeds compete strongly for the basic nutritional elements in the soil, taking them from desirable plants that have been weakened by improper grazing.

By removing too many green leaves, overgrazing destroys a plant's ability to nourish itself. Leaves are the plant's solar collectors. They convert the sun's energy to a form the plant can use for growth and maintenance. Roots anchor the plant, gather water and nutrients, and store food reserves. Grazing that removes more than 50% of the plant's leaf area will slow and sometimes stop plant growth, both above and below the ground. Severe and frequent grazing will produce a shallow, weak root system, leaving the plant prone to drought, and unable to compete with its neighbours or produce leaves.

Good grazing management leaves adequate leaf area for continued above and below ground growth and allows adequate rest periods for plants to regain vigour. Grazing management should achieve even utilization so that plants will have equal opportunities for growth and regrowth.

The Grazing Animal

Cattle perform best when they quickly fill their stomachs with high quality forage. If forage is of poor quality (low in energy, protein or digestibility) or in short supply, production will suffer.

Ruminants pass food slowly through their digestive systems, and can consume only limited amounts of forage. They cannot compensate for low quality forage by simply eating more.

If cattle are turned onto pasture too early in the growing season, or remain too long, forage is often in limited supply. Animals must graze longer and use more energy to satisfy appetites. Shortages also occur when a pasture unit is overstocked (too many cattle for too many days).

Cattle are at peak harvesting efficiency when forage is 15 to 22 cm tall and of good quality. They prefer green material over dry, and leafy material over stems and seed heads. Therefore, plants that remain leafy over a long growing season will be subject to repeated grazing if grazing is not controlled.

Cattle prefer some grazing areas over others. When given a choice, they spend a majority of their time near water sources and on level terrain rather than steep slopes. They choose warm, south facing slopes during spring, and shaded areas such as north facing slopes during summer. Cattle seek shelter and cover to avoid strong winds or hot, direct sun.

You can improve livestock production by following a few simple rules:

1. Provide the best quality of seasonal forage.
2. Reduce grazing times by providing sufficient forage.
3. Reduce distance travelled by strategic placement of range improvements (see sections on fencing and watering).
4. Reduce stress on animals by providing shelter, shade and water in each grazing unit.
5. Remain flexible in your management and leave a forage buffer in case of unforeseen shortages.

Grazing Systems

Grazing systems fall under two broad categories: extensive and intensive.

Extensive systems have minimal crossfencing and other developments. The land area may be large or small. Livestock densities (number of animals per unit area) are low and animals are allowed to graze selectively for relatively long periods.

Extensive grazing systems are characterized by low overall livestock performance, poor grazing distribution, spot overgrazing, wasted forage in large areas, and poor health of the forage stand. Uncontrolled grazing leads to a steady and inevitable decline in long-term productivity.

Intensive systems require high levels of management. The manager determines where, when and what livestock will graze, and controls livestock distribution. Stock density and capital investment are nominally higher. More grazing units or paddocks are required. Livestock movements are based on plant growth rates and forage availability.

The increased capital and managerial investment demands results. Intensive management systems that pay proper attention to plant growth and long-term stocking rates allow the range or pasture to improve while being used. However, production will have an upper limit imposed by site potential and condition or health of the forage base.

Site potential is determined by soil, topography and climate. Porous, saline or shallow soils do not have production potentials equal to deep, well drained, medium textured soils. Managers must experiment to determine correct long-term stocking rates for their land. References listed at the end of this publication give guidelines for initial stocking rates.

Table 1 summarizes the approximate number of acres of tame pasture required by a 1000 pound cow and her calf for one month. Use these numbers as guidelines when determining how many cattle you can safely pasture.

Complementary grazing systems can be extensive or intensive, depending on the management level. A planned combination of forages complement each other in order to lengthen the grazing season and provide high quality feed.

For example, a complementary system for the brown or dark brown soil zone may be crested wheatgrass for May-June, native needlegrass-wheatgrass range for July-September, and Russian or Altai wild ryegrass for October-November. Do not regraze crested wheatgrass in the fall. Fall grazing causes a delay in the next spring's growth, reduces total forage production and may increase winterkill. Russian wild ryegrass or Altai wild ryegrass are best used as late fall or early winter pasture. They maintain good forage quality late in the season, and their erect growth forms make them easy to graze even with snow cover.

Smooth bromegrass/alfalfa or intermediate wheatgrass/alfalfa provide good mid-season pasture throughout the black and grey wooded soil zones. Meadow bromegrass appears to have the longest growth period in these areas. It begins to grow earlier in the spring, continues to grow in summer and has better fall regrowth than either smooth bromegrass or intermediate wheatgrass.

For a complete description of forage species, see Forage Selection.

Fencing

Proper fence placement is key to good pasture management. Fencing should be designed with the following in mind:

1. Ease of livestock handling and movement.
2. Improving livestock distribution.
3. Controlling livestock access to pasture units.
4. Intensifying management on pasture units.
5. Providing protection and deferral on pasture units.

Fences should follow natural vegetation, topographic and soil boundaries when possible. These boundaries normally coincide, as soil and topography determine the plant community. Design grazing units to provide adequate forage, water and shelter.

Always separate tame pastures from native pastures. This allows control of livestock grazing and reduces selective grazing behaviour. Forage mixtures should be chosen to include species having similar palatability, growing seasons, growth rates and tolerance to grazing.

Fence pasture units according to intended season of use, for example:

1. Pasture with a south exposure and good drainage may make an excellent spring calving field.
2. A unit with wet meadows is best grazed in late summer after the soil has dried out.
3. An area having flowing springs may be designated as a late fall and early winter grazing field.

Water Systems

Water supply often limits livestock production and distribution. Livestock must have enough good water to perform well. Consumption of poor quality water will reduce forage intake and may prevent absorption and use of key minerals.

Grazing systems should be designed to make best use of existing water sources.

Consider doing the following to protect water sources:

1. Fence out water sources to prevent livestock from tramp ing the banks.
2. Pump water into troughs.
3. Discourage livestock from loitering around water sources by keeping the lioness areas small.
4. Landscape the spoil piles from dug-out excavation, and seed sodfomming grasses. This will stabilize the area and prolong dugout life.
5. Plant trees or shrubs, or place fences to trap snow and maxi- mize runoff into dug-outs.

HAY AND SILAGE

Hay or silage crops can provide economical feed with adequate nutrition for ruminants when pasture is unavailable. The objective is to manage a perennial forage stand to maximize yield while maintaining vigorous growth.

Photo left: High dump silage wagon.

Three factors emerge as management trade-offs: yield, forage quality and sustainability of a vigorous forage stand. Figure 3 shows some inter-relationships in the system. Land and climate are the main factors that determine yield, quality and longevity. But field and harvest management also contribute.

Harvest Scheduling

arvest timing is dictated by plant maturity. The stage of maturity affects the yield, feed quality and health of the stand.

Generally, the yield curve for a crop is depicted by the following graph.

Yield increases with maturity until the crop starts to dry off and sheds its lower leaves. After this, quantity declines. But feed quality (protein content) declines steadily, even as the plant grows, because the plant becomes woody and hardens with age.

So, aim to schedule your harvest at the intersection of the quantity and quality lines on this graph. You might harvest earlier if you want high protein dairy feed, or delay cutting if you want a greater yield of lower quality beef-cow maintenance fodder. Likewise, you may adjust cutting to affect the timing of subsequent cuts during the year or to fit around other farm enterprises, or to provide wildlife habitat.

The number of harvests per year is determined by moisture, heat and the growth habit of the forage species selected. One harvest is normally practical on dryland in the brown and dark brown soil zones, two in the black soil zone. Generally, take the first cut when legumes are at 10% blossom and grasses are heading.

Harvesting and Storage Systems

The forage harvesting system you choose depends on a number of things:

1. Available capital and labour.
2. Amount of crop to be harvested and expected time available to harvest it.
3. Acceptable feed quality.
4. Kind of livestock to be fed or market to be served.
5. Distance from field to place of storage, feeding or market, if sold off the farm.
6. Storage, feed processing and feeding facilities available.

No matter how good the harvesting system, success depends on good management. Failure to cut the crop at the right stage of maturity, putting it up at the wrong moisture content, or leaving the harvested hay exposed to the weather can cause substantial losses.

Equipment

Self-propelled windrowers are often used to cut tame hay. This eliminates raking and reduces time and labour. Conditioners on self-propelled windrowers crush the hay stems for fast drying and fluff up the windrow to allow better air movement and uniform drying.

Mowers are sometimes used for harvesting short native hay on rough, stony land. This operation is slow, and exposes the hay to severe weathering.

Raking losses increase rapidly as the hay dries. To reduce losses, the hay should be raked in the same direction as it was cut, at 40 per cent moisture content or higher. If raked below 40 per cent moisture content, tame hay losses can be as high as 25 per cent.

LARGE BALER SYSTEMS

Large Round Balers pick up the hay and roll it into a bale. Typical bales weigh 400 and 800 kg (880 and 1760 lb) depending on the size of baler.

Hay should be baled at 20 per cent moisture content to ensure top quality and minimum loss.

Handling and Storing Large Round Bales. Remove bales from the field to prevent damage to the next hay crop. To reduce hay spoilage, store bales on a well drained site.

Large Square Balers form bales weighing up to 900 kg (2,000 lb) depending on the type of forage harvested. Large square bales are well suited for hauling on flat-bed trucks.

SMALL BALER SYSTEMS

Available systems offer everything from completely manual to completely mechanized handling. A moisture content of 20 per cent is best for baling.

Bale Stooker System. A 6-,10-, or 1 5-bale stocker may be pulled behind a baler. Mechanical 6-bale stockers are available; however, the 10- and 1 5-bale stocks are normally built by a person riding on the stooker.

Bale Thrower System. This system consists of a baler with a bale thrower, several wagons to catch and haul the bales to storage, and a bale conveyor. Random piling of bales in storage is an integral part of the system.

Mechanical Bale Wagon Systems are self-propelled or tractor pulled. When the bale wagon is filled, it is usually unloaded at the storage site.

Bale stacks may collapse unless the bales are solid and straight- sided.

A great deal of experience is often required with mechanical stackers to obtain well-rounded, weatherproof stacks. Moisture contents of up to 25 per cent appear to be safe for stacking hay.

A Sweep and Stacker System consists of a tractor frontend loader and sweep with a hay basket and push-off which piles the hay in a stack cage. The hay basket may be used to sweep the windrow towards the stack. Two persons are usually required. Large windrows are needed for efficient pickup of hay.

Compression-Type Stackers. With the rectangular type, a rotary paddle picks up the hay and blows it into the stack former. The roof of the stack former is lowered hydraulically to compress the hay. The stacks are dropped in the field or hauled to the feeding area and then dropped. If stacks are to be picked up, hauled and dropped, a separate transporting machine is required.

Loose Fill Stackers. One type uses a shredder- harvester, with knives mounted on the fan blades. It picks up the windrow, shreds the hay, and blows it into a stack fommer. Chain conveyors, on the floor of the stack former, unload the stack. The same equipment, with the forming chamber removed, can be used to reload transport and unload stacks at the feeding location.

All three types of loose hay systems can be used to pick up chaff piles, transport them, and unload them at feeding locations.

Stack Mover. The cable type uses a winch and cable to pull the stack onto the mover. The chain type works its way under the stack with a series of chains on the floor of the mover.

SILAGE

Forage crops for silage may be harvested almost independently of weather conditions. If stored properly, silage will retain its feed value with little loss.

In a silage operation, the tractor must be powerful enough to drive the harvester, and to pull it plus a wagon or truck. To allow the harvester to operate continuously, sufficient manpower and equipment must be available to load, haul, unload, and pack the silage.

The cylinder type of forage harvester is most common, due to its high capacity and uniform length of cut. It can be equipped with row crop, cutting or pickup attachments.

Silage storage systems range from horizontal earth-wall types to vertical oxygen-limiting structures (see Table 2). Poly bags are also an effective oxygen-limiting storage system for lower volumes of silage.

Bloat Management

Pasture

Forages are classified as bloat-causing or bloat-safe, with only a few in the intermediate position. Table 3 shows risk levels of different forages.

The bloat-causing potential of crops is related to the ease with which they are digested by rumen microbes. Bloat-causing forages are digested rapidly, whereas bloat-safe forages are digested more slowly. The low-risk group is intermediate.

Forages containing tannin, a substance which inhibits rumen microbe activity, are bloat-safe. Other characteristics of bloat- safe forage include leaves with thicker, stronger cell walls and veins. Bloat-causing forages have leaves with thin, low strength cell walls.

Crop maturity is one of the more important factors in preventing pasture bloat. Bloat potency is highest at the vegetative (pre-bud) stage. It progressively decreases as the plant grows and matures to full flower.

* Bloat is said to occur when one or more animals exhibit bloat on a given day.

Bloat is traditionally associated with lush growth of pasture forage. Reports of grasses that cause bloating are rare, and are restricted to vegetative and lush pastures where initial digestion rates are high.

Alfalfa's potential for causing bloat is highest when there is optimal moisture for vegetative growth. Under such conditions, stems are swollen and fleshy, leaves are soft and easily crushed between the fingers.

Bloat potential is reduced when drought or soil salinity causes insufficient soil moisture. In western Canada, pasture bloat is more frequent in parkland regions, especially gray wooded soil zones. It becomes progressively less frequent in dark brown to brown soil zones.

Fertilization and grazing management may be used to maintain a 50:50 mixture of grass and alfalfa. There are several points to consider in proper field management.

1. Nitrogen fertilizer and heavy or frequent grazing promotes grass growth at the expense of alfalfa.
2. In areas where the incidence of bloat is high, the critical upper limit of alfalfa may be as low as 25-30%.
3. Mixtures grown in sandy areas rather than heavy soils are less likely to produce bloat.

Although alfalfa-grass mixtures may be seeded to produce the desired proportion of alfalfa and grass, selective grazing and variation in field terrain may allow excessive intake of alfalfa. The period following mechanical harvesting or intensive grazing may pose a potential risk of bloat, because alfalfa generally recovers faster than grass (in the short term).

The ideal companion grass should have the same seasonal growth and regrowth characteristics as alfalfa. Smooth bromegrass, though widely grown in alfalfa-grass mixtures, has a much slower regrowth rate than alfalfa. Pasture bloat may occur when alfalfa- bromegrass mixtures are used in rotational grazing systems. A new grass called meadow bromegrass offers a faster regrowth rate than smooth bromegrass.

Stored and Processed Legume Feeds

Alfalfa hay combined with cereal grain is probably the most common mixture of dry feed causing bloat in western Canada. Outbreaks of bloat are often associated with particular lots of hay. While there is no sure way of predicting bloat potential of individual lots, a good indication of risk is leafy, immature hay with soft

1. Hay grown under cool, moist conditions is more likely to cause bloat than hay produced in hot dry areas.
2. Reports of bloat on damp, moldy hay are common.
3. High protein content alone is not a reliable indicator of bloat risk. Bloat potential is more likely related to the nature of fiber constituents of the hay.
4. Chopping hay can increase the incidence of bloat.

Alfalfa silage and haylage are normally bloat-safe. Processed alfalfa, such as dehydrated and sun-cured pellets, do not usually present a hazard when fed as protein supplements or cereal grain replacements.

Treatment

Oils and detergents can be used to prevent and treat pasture bloat. Most vegetable oils are effective in breaking down rumen foam, but of the various detergents available, only certain types work. Products such as Bloat Guard contain an antifoaming detergent called poloxalene. The daily dose is 4-8 g of Bloat Guard (2-4 g poloxalene) per 100 kg of body weight, in two daily feedings.

NITRATE POISONING

Forages containing nitrates can cause death in cattle and sheep by interfering with the transport of oxygen in the blood. Symptoms of nitrate poisoning include:

1. rapid breathing and pulse
2. frothing from the mouth
3. blue color on mucous membranes, muzzle and udder
4. brown colored blood.

Frost, drought and weed sprays may be factors in high nitrate accumulation in plants.

The rule of thumb when feeding is to dilute nitrate-containing roughage. Total feed should contain no more than 0.5% nitrate. For example, if forage has 1% nitrate, dilute half & half with nitrate-free roughage. Do this with each feeding to prevent over consumption by individual animals. This system does not work if high-nitrate feed is fed one day, and nitrate-free feed is fed the next.

DICOUMAROL POISONING

Sweetclover contains varying amounts of coumarin a chemical often converted to dicoumarol in moldy feeds. Dicoumarol interferes with the blood clotting mechanism in animals. When fed to livestock (in moldy feeds), it can result in internal bleeding, anemia and death.

Although most sweetclover forage is safe for feed, improperly cured and moldy forage should be used with caution. Send samples to the nearest Feed Testing Laboratory for an analysis of dicoumarol content. Remove severely spoiled parts of sweetclover forage and dispose away from farm animals.

It is often advisable to limit the amount of sweetclover in the diet, particularly before calving and lambing periods.

The use of low-coumarin varieties of sweetclover, such as Norgold, eliminates the problem of sweetclover disease.

Fertilization

Nitrogen, phosphorous, potassium and sulphur are the primary building blocks of protein and other nutrients required by livestock. Nitrogen can provide a good response in the year of application; phosphate fertilizer, however, does not move quickly through the soil, so larger and less frequent applications are common. (Since inoculated legumes fix their own nitrogen, they do not need nitrogen fertilization.) Potassium deficiencies have been noted on sandy or gray wooded soils, resulting in severely depressed legume yield and reduced winterhardiness. Sulphur deficiencies, too, are most common on sandy or gray wooded soils and on land which was previously cropped to canola or other high protein crops. A deficiency of micronutrients such as boron can also limit forage yield.

Table 6 provides general guidelines which may be used to plan annual fertilizer programs in the absence of a soil test. Larger and less frequent applications of phosphorus, potassium and sulphur have been used successfully. Accurate fertilizer requirements can only be obtained with a soil test.

Suggested rates for nitrogen are defined for average soil moisture conditions. Rates for potash and sulphur are for coarse textured, well drained soils in the more humid regions of the province. On other soils these nutrients should only be applied on the basis of a valid soil test. It is advisable to use some sulphur on Grey soils particularly when seeded to oilseeds or legumes.

* Potash and sulphur in soils are quite variable and soil testing is recommended before applying these nutrients.

SOURCE:General recommendations for fertilizer in Saskatchewan.

*If properly inoculated, legumes such as alfalfa and clover much of their nitrogen from the air.

The following photographs show that sulphur affects the plant's yield and its ability to compete with weeds.

When nutrient deficiencies cause forage to become unhealthy and uncompetitive, weeds invade.

Sulphur deficiency in red clover on prey soil

Narrow-leafed hawks-beard infestation in sulphur deficient alfalfa.

SOURCE: SOIL IMPROVEMENT WITH LEGUMES (Saskatchewan Agriculture and Food).

Pest Management

WEED CONTROL

Weeds simply plants that grow where they are not wanted fall into two categories Noxious and Nuisance.

Noxious weeds are defined as those listed in schedules of either a Provincial Noxious Weeds Act or the Federal Seed Act. The Noxious Weed Act lists the weed species which Rural Municipalities may control and prescribes the procedures for control. The Seeds Act outlines tolerances of Prohibited Primary and Secondary Noxious Weed Seeds in field crop seed.

Nuisance weeds are those which are not addressed through legislation but which are undesirable for a variety of reasons.

Weeds in forage cause a number of possible concerns:

1. They compete with the crop.
2. They may be unpalatable or toxic or cause milk flavour problems for livestock consuming the forage.
3. They may make a crop unsuitable for export; regulations limit weeds in export forage, to avoid introducing them to the importing country.
4. They may harbour insect and disease organisms.

Weed tolerance limits vary widely from one situation to another. Limits for seed fields and for dairy or export hay are very low; acceptable weed content in beef maintenance hay or pasture can be considerably higher.

Weeds can be controlled either before the crop is planted or after it emerges. Over a number of years a combination of cultural and chemical control methods is generally used on any given field. Cultivation, herbicide application, timely mowing and grazing management are all effective tools for weed control.

Although weeds are generally a problem, they sometimes have value. For example, they reduce soil erosion on abandoned land, provide food and cover for wildlife, and add organic matter to the soil.

The best way to avoid a weed problem is to have a healthy growing crop. This can be achieved only by proper fertility and management of harvesting, insect and disease control so as to avoid prolonged or severe crop stress.

The following suggestions will help you deal with weed problems in forage stands.

1. Cut hay or silage crops before weeds go to seed
2. Do not overgraze pastures
3. Fertilize older forage stands to keep them productive
4. Control weeds adjoining fence-lines, roadways and rights-of- way to minimize spread.
5. Break up old, depleted or winter-killed stands where there is no longer a vigorous forage stand to compete with weeds.

DISEASE CONTROL

Disease are often introduced into fields on infected seed and plant material. They can also be introduced by infected machinery. Good planning and management - e.g., using clean seed and crop rotation- reduced potential for subsequent disease problems.

Here are some of the significant diseases of forage crops in Saskatchewan, with suggestions for control:

• Leaf spot diseases.Harvest early to minimize leaf loss if disease is severe. Burn fields in early spring if outbreaks were severe the previous year.
• Verticilium wilt of irrigated alfalfa. Use wilt-free seed. Resistant varieties are available.
• Ergot. Spreads when grasses are in flower. Mow headlands to reduce inoculum. Cut early to prevent maturation of ergot bodies.
• Snow molds. Winter hardy varieties are generally resistant to snow molds. Important in areas of high snowfall.
• Head smut of grasses. Use smut-free seed or resistant.

Disease do not generally cause major yield reductions in forage crops on the prairies, because of the cold winters and dry climate. Significant losses are most prevalent under irrigation, where conditions for growth and spread of microorganisms are best.

Photo left:Verticilium wilt on alfalfa.

Insect and Rodent control

Several insects can damage forage stands.

Grasshoppers feed on all forages, but newly seeded forages are especially subject to grasshopper damage. Severe crop damage may occur when foliage is short and sparse. Grasshoppers do not usually invade a lush, established alfalfa stand because of the higher humidity and lower temperatures within the canopy. They will feed around field edges, where weeds and grasses occur. Alfalfa is most often attacked in late summer after grain crops have matured.

Usually, infestations of less than 10 grasshoppers per square metre will not cause losses to forage fields. A small, heat- or drought-stressed plant will suffer greater injury from grasshopper feeding than a large, vigorous plant.

Eliminate annual weeds with herbicides or by spring cultivation during seedbed preparation to reduce crop damage. Applying insecticide to field edges may be all that is necessary to control grasshoppers.

Another option may be harvest early and leave a trap-strip which will attract and concentrate grasshoppers in the absence of other food. You can then spray the trap-strip with reduced amounts of insecticide, for both economic and environmental benefits. Applying insecticide as bran bait, rather than foliar spray, will lessen the hazard to pollinators and many other non-target species.

Pea aphids are occasionally a pest of dryland alfalfa. Alfalfa under drought stress, especially second-cut alfalfa, is most susceptible to injury. Because moist, warm weather favours aphid growth, populations of this insect are often greater in irrigated than in dryland alfalfa. But the lush growth of irrigated alfalfa can support more aphids without apparent injury.

Predators, parasites, and diseases generally hold infestations of pea aphids in alfalfa at low levels. In dryland production, populations of aphids greater than 100 to 200 per 180 net sweep cause significant alfalfa injury. Vigorous, thick, healthy stands rage alfalfa are the best safeguard against damage by pea aphids. Early cutting of alfalfa for forage curtails aphid population growth and usually avoids the use of insecticides.

Sweetclover weevil is a problem for sweetclover in the establishment year. In areas where sweetclover acreage is high, population of these weevils builds up. They can destroy new stands by chewing off the first shoot as it emerges. Crop damage is most severe in dry springs when seedling growth is slow, and in summer when the new generation of weevils migrates into the new stands.

Several management practices are useful for weevil control. Sow new clover stands as far as possible from second-year stands; cultivate clover fields as soon as the forage crop is rived; inspect fields in late summer for marginal damage from weevils invading the stand. Use insecticide if damage to new seedlings or to field margins is severe.

Leaves notched by sweetclover weevil and an adult sweetclover weevil (right)

Blister beetles are common in the parkland. They can cause minor damage to forage stands, and if there are many of them in the hay, they can cause mouth irritation in livestock. Diluted feeding with non-infected hay is recommended.

RODENTS. The three main rodent pests in Saskatchewan are ground squirrels, pocket gophers, and meadow voles.Ground squirrels are social, nest in ground burrows, and feed on low growing plants. Pocket gophers are mainly solitary animals which dig extensive tunnels 10-30 cm underground where most of their feeding occurs. Meadow voles are mouse-like rodents which cause localized damage to grasses, making tunnels and eating crowns, stolons, and rhizomes.

Rodent mounds and tunnels can smother forages and pasture grasses, foul haying equipment, initiate soil erosion, provide seedbeds for unwanted plants, and prove a hazard to grazing cattle. Rodents can be controlled by several means, such as trapping with special traps set in burrows, burrow builders and poison baits. On rangelands, natural predators such as hawks and coyotes should be encouraged.

Pocket gopher mounds (left).Tunnel builder (right)

The largest populations of pocket gophers seem to occur in irrigated alfalfa fields and in forage stands on sandy-loam soils in the Parkland, where conditions are ideal for their existence. The soil is usually deep, light and well drained. Periodic flooding does not affect them much, and in fact creates a soil moisture that aids burrowing; and there is an abundance of one of their preferred foods. A symptom of a pocket gopher infestation in alfalfa is "wilt", which is caused by the tap root of the plant being eaten through about 3 or 4 inches below the surface.

Fall Management of Alfalfa

Damage from Fall Harvesting.For several years, we have heard that alfalfa should not be cut during a "critical fall period", loosely defined as 4 to 6 weeks before the first killing frost. The theory is that perennial forages require large carbohydrate reserves in the roots to maintain strength during the winter and to initiate spring growth. Some sources suggest that root carbohydrate reserves reach a plateau when a foot of top growth has developed. Therefore, the safest fall management program for alfalfa would be to take the last cut early enough that 10"-12" of regrowth occurs before the first killing frost. After a killing frost, topgrowth can be harvested with no effect on the roots or crowns, other than the effect on snow trapping and insulation.

How Extensive is Fall Management Damage? Recent research at Swift Current suggests that significant damage related to fall management occurs only one year in eight, so some farmers may be prepared to accept that level of risk on a portion of their alfalfa hay fields. If a third cut is harvested in September the risk of winterkill will be increased. Less winterhardy varieties suffer the most winter injury. Winterhardiness ratings of alfalfa are listed in provincial variety recommendation publications and should be considered where problems have occurred.

Snow trapping is recommended, since it provides insulation to minimize winter injury and also provides moisture for spring growth in drier areas or on light textured soils.

The following photo illustrates what leaving 20 per cent of the last regrowth in strips can accomplish. This practice also provides a wildlife habitat for game birds.

Rejuvenation

As forage stands become older, productivity often declines due to a number of factors, such as:

1. Reduced fertility (particularly nitrogen).
2. Reduced plant population due to plant die-off, weed encroachment, flooding, winterkill, selective grazing, etc.
3. Excessive plant population due to crowding of creeping rooted forages.
4. Rough field surface due to rodent damage or harvesting when the ground is soft, etc.

These situations can be improved by applying fertilizer or herbicide changing grazing or harvesting schedules, and scarification (light harrowing, disking or cultivation) of stands. The alternative is to break the stand and re-establish it from scratch. The choice between rejuvenating and re-establishing old fields will depend on soil type (i.e., rocky or sandy conditions) and economics.

Scarification has proven effective on forage seed fields. It thins and opens up the stand, enabling individual plants to grow larger and set more seed. Scarification also speeds up the recycling of nitrogen. It is unlikely that scarification will reduce plant populations through excessive mechanical damage, unless the stand is also stressed by drought or winter injury.

Wildlife Considerations

Wildlife requires food, cover (thermal and hiding) and water to survive. It may also require special protection during mating, nesting, calving, staging or migration. Disturbance, loss of cover, and destruction of food or water sources will cause wildlife species to die, abandon a home area, or fail to reproduce successfully.

Wildlife prefer native habitats; however, introduced forages n provide suitable hiding cover and food. They definitely prefer xtures over monocultures (single forage species plantings). Forage mixtures provide better cover, diversity, structure and light than monocultures. Mixtures also provide forage over a longer period, and habitat for a more diverse insect population and other food sources.

Photo left: Sharp-tailed grouse

If managed with wildlife in mind, grazing systems and associated improvements can create good habitat for wildlife. Stock dams have the potential to provide drinking water and brood water for waterfowl, when managed and constructed for wilddlife. Delaying grazing in traditional nesting or calving areas can improve reproduction success.

Hay fields can provide good cover; however, haying in late June destroys the nests of ground nesting birds and may actually kill adults who are incubating eggs. If some reduction in hay quality can be tolerated, consider delaying haycut until about July 7 in the south and July 15 in the aspen parkland. This allows a majority of ducks and upland gamebirds to hatch their eggs successfully.

Forage harvesting should be timed and carried out to allow 6-8 inches of residual cover going into winter. This insures adequate food reserves for the forage plant, provides snowcatch and insulations for plant growing points and provides early spring nesting cover for gamebirds.

Avoid fall grazing of hay fields. Grazing may stimulate new growth at a time when forage plants should be hardening in preparation for winter. Late fall grazing also reduces insulation and snow catching ability, which are critical for winter survival of plants.

Consider the following options when harvesting forages:

1. Mow after July 7 in south, July 15 in north.
2. Use slower speeds to allow wildlife to escape.
3. Work from the centre of the field outward to allow wildlife an avenue of escape.
4. Raise the cutting bar when a nest is encountered.
5. Leave 6"-8" of residual forage cover in autumn.

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