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Alternative Field Crops Manual

Hairy Vetch

D.J. Undersander1, N.J. Ehlke2, A.R. Kaminski1, J.D. Doll1, K.A. Kelling1

1Departments of Agronomy and Soil Science, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
2Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108. September, 1990.

I. History:

The vetches (plants of the genus Vicia) are distributed throughout the temperate zones of both hemispheres. There are about 150 species of vetch, several of which were of agricultural importance centuries ago. Some 25 species are native to the United States. However, the species in commercial use, including hairy vetch (Vicia villosa Roth), are all native to Europe or western Asia.

Hairy vetch, also called sand vetch, is a moderately winter-hardy species. It is the only vetch species that can be fall-seeded and reach maturity the following July.

II. Uses:

Hairy vetch is a legume used primarily for soil improvement along roadsides and for bank stabilization. Well-nodulated hairy vetch can enrich the soil with 60 to 120 lb/acre of nitrogen through nitrogen fixation. Later seeded vetch grown as a cover crop for green manure, will supply a smaller amount of N.

Vetches are also grown for pasture. They withstand trampling, provide grazing during May and June and have a feeding value slightly lower than that of clover and alfalfa. The protein content of vetch hay ranges from 12 to 20%, depending on the stage of development of the crop when cut.

Vetch is often grown with a small grain for forage; rye is generally used for this purpose in the Upper Midwest. The grain supports the weak stems of the vetch and reduces lodging. However, when grown together, vetch and rye make a hay that is fair in quality but tangles badly.

Vetch can be difficult to grow for seed. The pods mature unevenly and tend to shatter easily.

III. Growth Habits:

While most of the cultivated vetches are annuals, hairy vetch is grown as an annual or winter annual. When hairy vetch is sown in late July or August, the seed germinates readily and the plants generally form a crown before the first snow. In spring, the plant produces 3 to 10 long, weak, branching stems or vines 3 to 6 ft long. The leaves have 12 to 20 leaflets and terminate with tendrils. Although hairy vetch is typically pubescent, the most extensively used commercial variety is called smooth vetch because it appears to have no pubescence. The purple and white flowers appear in mid-June and are borne in a cluster, or raceme. Seed pods, bearing 4 to 8 seeds each, mature unevenly from July 10 to July 25. Pods tends to shatter soon after maturity. When hairy vetch is spring sown, it will bloom and produce some seed the same season.

IV. Environment Requirements:

A. Climate:

Hairy vetch is the most winter-hardy of the commercial vetches, though it may not survive a winter without a snow cover. Plants on poorly drained soil will kill more easily than those on well-drained land. Late seeding and unusually cold fall weather also result in more winter injury. Protective covering by a companion crop or crop waste reduces the danger of winter kill. Hairy vetch will not successfully overwinter in many northern areas of the Midwest. Check on the adaptability of hairy vetch to your location before planting.

Although the vetches are not drought resistant, this is rarely a problem. The crop is summer-seeded and harvested the following July before the hot, dry conditions of late summer.

B. Soil:

Vetches grow well on a wide range of soil types, but are best adapted to loamy and sandy soils. Because they are legumes, vetches can be grown on nitrogen-depleted soils without the addition of N fertilizer.

C. Seed Preparation and Germination:

The seed should be inoculated with the proper strain of Rhizobium bacteria within 24 hours of planting, unless well-nodulated peas or vetch have been grown on the field recently. Follow instructions carefully to achieve an even coat of fresh inoculum on the seed. Seed should be sown when the soil is moist, because a hot, dry soil will reduce, if not prevent, effective inoculation. Some fungicide seed treatment compounds can also interfere with the nodulation process.

V. Cultural Practices:

A. Seedbed Preparation:

Vetch can be grown following any crop harvested before mid- August. For crops which leave a relatively uniform seedbed, vetch can be planted without plowing. Similarly, vetch seeded into small grain stubble need not be plowed or disked before sowing. The stubble may provide enough winter protection to overwinter a vetch crop by holding snow on the field.

Plowing or heavy disking is essential on heavy soils and firmly packed soils, or where there is heavy weed infestation. Grassy fields should be plowed or thoroughly cultivated during July before planting vetch.

For best results, the seedbed should be firm and have adequate moisture for good seed germination.

B. Seeding Date:

In central Wisconsin or Minnesota, the best time to plant vetch is from July 25 to August 30. Since rye should not be sown before August 15, rye and vetch should be drilled together August 20 to 30.

C. Method and Rate of Seeding:

Inoculated hairy vetch seed can be drilled at a rate of 25 to 35 lb/acre. When seeding a mixture of vetch and rye, the quantity of vetch seed should be reduced by about 25% and the grain should be reduced by about 50% of the monoculture rate. Some separation of seed will occur if the two seeds are mixed together in the same seed box. Good stands are obtained from planting the vetch at a depth of 1/4 to 1/2 in. Shallower plantings will give good stands if there is sufficient moisture.

D. Fertility and Lime Requirements:

Vetch does not require nitrogen fertilization. This legume grows best in soils high in available potassium. Requirements for phosphorus, calcium and other minerals are less pronounced. For most soils, applications of about 40 lb/acre of P2O5 and 120 lb/acre of K2O should be adequate. However, where soil tests are very high (greater than 25 to 30 ppm P and 110 to 130 ppm K) applications can be eliminated. Small amounts of nutrients can be applied with the drill (less than 40 lb of N + K2O/acre), or topdressed.

Vetches are more tolerant to acid soil conditions than most legumes. Soils should be limed to a pH of about 6.0.

E. Variety Selection:

Hairy vetch is the most winter-hardy of the vetches. It is the only vetch that can be grown in the Upper Midwest.

F. Weed Control:

Weeds are rarely a serious problem in vetch fields, especially when seeded in late summer or early fall. Repeated production of rye and vetch on the same land, however, favors growth of winter annual and perennial weeds.

The crop should be planted in a relatively weed-free seedbed, and the land should be plowed and planted to a row crop every three to five years to control weeds.

G. Diseases and Their Control:

Vetches are susceptible to several fungal diseases, some of which are restricted by temperature and moisture conditions to certain parts of the country. Black stem occurs wherever vetches are grown in the United States and is caused by several closely related fungi. Stem discoloration is the most distinctive symptom, although the fungi also produce large, dark, irregular lesions on the leaves. The disease can cause serious damage to hairy vetch seedlings.

Root rot also occurs wherever vetches are grown. It may be caused by one or several unrelated fungi that can attack plants at all stages of growth. Symptoms are most conspicuous in seedlings, which wilt and die. Older plants become stunted or discolored red or yellow when infected. Roots of diseased plants are badly discolored.

Gray mold, or botrytis leaf spot, sometimes causes considerable defoliation of vetch. The spots are small and dark red when young, later fading to light gray or brown with a maroon border.

A disease that resembles anthracnose, but is caused by a different fungus, is prevalent on hairy vetch in the South. This "false anthracnose" produces a brown discoloration and girdling of stems. Spots on leaves are small and circular but tend to form elongated streaks. When pods are heavily spotted, the fungus penetrates the seed. Seed development may be hindered by this disease.

Downy mildew has caused considerable damage to common vetch in the Pacific Northwest. The underside of infected leaves is covered with fine grayish fungal threads. Infected leaves turn yellow and drop off prematurely.

Stem rot of vetch is caused by a fungus that is destructive during cool, wet weather. This disease sometimes causes considerable damage in the Pacific Northwest.

Root-knot nematode can cause considerable damage in vetch. Nematodes are most active in warm weather, and damage may be reduced by moderately late planting.

Resistant varieties may offer the best means of control of vetch diseases. In addition, it is advisable to avoid growing vetch continuously on the same land, use disease-free seed, and destroy volunteer plants that may harbor or spread diseases to new seedlings.

H. Insects and Other Predators and Their Control:

Vetch is attacked by many of the insect pests of alfalfa, clover and other forage legumes, including the pea aphid, cutworm, corn earworm, fall armyworm, vetch bruchid, grasshopper, lygus bug and leafhopper.

The pea aphid may become abundant on vetch in the spring. It sucks sap from the plant, causing the leaves to turn yellow. A heavy infestation will kill the plants. If the vetch is to be used for hay and is near harvesting, it is advisable to cut the crop promptly. Pea aphid infestation may require chemical control to reduce crop damage.

The vetch bruchid is a small, blackish, chunky seed weevil about 1/8 in. long. The eggs are laid on the green vetch pods in the spring. The larvae enter the pod and feed on the seed, destroying its viability. They do not infest dry seed.

Lygus bugs can cause considerable damage to vetch. Both adults and nymphs suck sap from the plant. These bugs tend to feed on the reproductive parts, often causing the buds and flowers to drop. After the pods are formed, lygus bugs will feed on the immature seeds and cause them to shrivel and turn brown. Control of lygus bugs may be necessary in seed production fields.

I. Harvesting:

1. For soil improvement: When sown in August, a considerable growth of rye and vetch can be plowed down the following spring, prior to June 10, so that a crop of silage corn, late-planted potatoes, or another late-planted crop can be planted on the land. When this is done, the amount of nitrogen credited to the succeeding crop should be about 60 lb/acre. Vetch allowed to grow for a full season can credit 120 lb/acre of N.

2. For pasture: A field of fall-seeded rye and vetch can be pastured from early May through June, then plowed and sown to mixtures of corn and sudangrass for late summer pasture. In this case, the N credit should be determined by the amount of material incorporated and may range from 40 to 80 lb/acre.

Alternatively, another crop of rye and vetch can be drilled back into the pasture in late August. To get the most out of this plan, pasturing should be timed with regard to the weather and other available pasturage.

If the vetch is not grazed too closely and not cut in July, a fair seed crop may be secured later in the summer. Light, early- spring pasturing reduces excessive vine growth, delays bloom and may improve the seed yield.

3. For hay: Rye and vetch produce a tangled hay that is quite difficult to handle. Because rye is well past the stage for best quality hay by the time vetch is ready for mowing, the quality of the hay is low. Earlier cutting will reduce the total yield, but result in better quality hay. Increasing the proportion of vetch also improves the quality, but adds to mowing difficulties. Vetch is generally cut for hay when the first pods are well developed and the grain is in the early soft-dough stage.

When the crop is thin, it can be cut with a mower and windrowed. Heavy, green vetch should be windrowed with a side-delivery rake. The hay can be cured in the windrow or bunched and allowed to cure in shocks.

4. For seed: Harvesting for seed is difficult because the pods do not mature uniformly. Vetch seed can be harvested with a combine when the lower pods are fully ripe. This will provide the maximum ripe seed yield. Harvesting losses due to shattering may be large. Shattered seed can be disked in as soon as possible after harvest to start a new crop.

Vetch, alone or with rye, is threshed with a grain thresher. To reduce losses, it may be necessary to remove a number of the concave and cylinder bars of the combine and to reduce the cylinder speed to 800 rpm or less.

The seed crop must be cleaned at once to remove green pods, immature seeds, insects and other debris. If seed is not cleaned, a white mold will grow on the black vetch seed, lowering the quality. Rye and vetch seed can be separated with a spiral seed separator.

VI. Yield Potential and Performance Results:

Vetch produces a hay yield of 1.5 to 3.5 ton/acre dry weight. Vetch seed remains viable for 5 years or longer.

VII. Economics of Production and Markets:

Growers are advised to identify a seed market before harvesting seed.

VIII. Information Sources:

References to pesticide products in this publication are for your convenience and are not an endorsement of one product over other similar products. You are responsible for using pesticides according to the manufacturer's current label directions. Follow directions exactly to protect people and the environment from pesticide exposure. Failure to do so violates the law.