PNL Volume 16
Muehlbauer, F. J. Agric. Res. Service, US Dep. of Agric.
Washington State University, Pullman
U.S. dry pea production is concentrated in the Palouse region of
eastern Washington and northern Idaho where an estimated 95% of the U.S.
crop is grown. The major production area is located 46° to 47° N,
117° to 118° W and at elevations of 600 to 800 meters. The crop is
produced in rotation with winter wheat in the rolling hills of this region
that is commonly referred to as the "Palouse". Although dry pea production
is centered in the Palouse region, other areas such as Oregon, Minnesota and
North Dakota have produced the crop. Whether or not these states will
produce dry peas in the future will depend the relative profitability of dry
peas compared with alternative crops.
In the Palouse, dry peas are included in rotations with cereals for a
number of reasons, namely: (a) the benefit of a legume in crop rotations in
terms of soil erosion control (the legume replaces summer fallow, a practice
known to increase the probability of severe soil erosion); (b) less severe
disease infestations in cereals because the legume is not an alternate host
for most cereal pathogens; (c) better control of grassy weeds compared with
cropping systems with only cereals in the rotation; (d) diversification to
exploit the symbiotic association with Rhizobium and so to decrease
applications of expensive inorganic fertilizers, although in many instances
residual soil N is so high that effective symbiosis is inhibited; and (e)
broader market opportunities because of demands in domestic and foreign
The area sown to dry peas (excluding both wrinkled seed peas and
'Austrian' winter peas) has remained relatively constant from 1974 to 1983
at about 65,000 ha, although the area sown was as low as 45,000 ha in 1981.
Average seed yields over the past 10 years have been about 1760 kg ha-1
with a low of 700 kg ha-1 in 1977 to a high of 1900 kg ha-1 in 1980.
The low yields in 1977 were caused by a rare occurrence of severe drought,
whereas the high yields of 1980 were associated with the cool-moist season
that followed the volcanic eruption of Mt. St. Helens in the spring of that
Peas were introduced into the Palouse near the turn of this century.
Commercial production began during the 1920's and it seems probable that the
substantial increase in area sown was due to the introduction of the Alaska
type cultivars that are typically rapid emerging, early flowering, and early
maturing. 'Alaska' originated in New York State prior to 1880 where it was
used primarily as a canning pea.
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About 78 percent of the peas produced in Washington and Idaho are green
(cotyledon) types, while about 22 percent are yellow (cotyledon) types
(Table 1). Green pea cultivars used in the Palouse include 'Alaska',
'Garfield', 'Latah', 'Tracer', and numerous commercial Alaska type strains.
A strain locally known as 'Columbia' is a popular commercial type because of
its high yield and uniform dark green color. Yellow pea cultivars include
'Latah', 'First and Best*, and to a limited extent, 'Paloma'.
Alaska types have large smooth round green seeds and bloom in about the
10th node. The vine type is tall and weakly upright, indeterminate and
usually non-branching. Alaska peas typically reach maturity approximately
95 days after sowing.
Garfield, a green dry pea cultivar released to growers in 1977 is
larger seeded, higher yielding and has a longer vine habit when compared
with Alaska (Muehlbauer et al., 1977). The greater plant height of
Garfield, when compared to Alaska, improves harvesting ease, especially on
ridges where poor vine growth has been a chronic problem. Garfield does not
differ from Alaska in resistance to seed bleaching but, because of its
longer growth period, it often bleaches to a greater extent than Alaska if
cool-wet weather persists after dry seed maturity but prior to harvest.
Garfield flowers at the 14th node, has tolerance to pea root rot (F.
solani), and resistance to common wilt (F. oxysporum race 1). The later
blooming of Garfield and its resistance to root rot are two factors that
contribute to the approximate one week delay in maturity when compared to
Alaska. This maturity delay is a disadvantage and can result in lowered
seed quality due to adverse weather after dry seed maturity.
Tracer, a green dry pea cultivar released in 1977, is a small sieve
Alaska type with good yield potential when compared to other small sieved
Alaska strains (Muehlbauer et al., 1977). Tracer has uniform seed size,
shape and color, greater plant height, lower susceptibility to seed
bleaching when compared to other small sieve Alaska cultivars, and
resistance to common wilt (F. oxysporum race 1). The taller plant height
improves harvestability in areas where poor vine growth has contributed to
harvesting problems. Tracer sets triple pods at one or more reproductive
nodes and is somewhat later maturing when compared to other small-sieve
Alaska strains.
Small sieve Alaska types are used less extensively and are
characterized by slightly smaller seed size and earlier maturity (90 days
from sowing) when compared to regular Alaska types, and they tend to be
slightly dimpled and more susceptible to seed bleaching. It is impossible
to distinguish between small sieve Alaska strains and regular Alaska strains
based on seed appearance or plant stature (Muehlbauer, 1982). An improved
regular Alaska cultivar (designated as 'Alaska 81') that is immune to pea
seedborne mosaic virus and resists seed bleaching will soon be available to
growers. Alaska 81 has also been significantly higher yielding when
compared to other Alaska cultivars.
PNL Volume 16 1984
Latah a large yellow dry pea cultivar selected from the old 'First and
Best' cultivar was released in 1972 (Wilson, 1977). Latah has a long vine
habit, blooms in the 14th node, and is relatively high yielding. Maturity
is comparable to Garfield (Muehlbauer, 1982).
The Palouse dry pea crop is normally sown in mid to late April after
danger of severe frost and matures within 95 to 120 days. Nearly all of the
current production area is rain-fed (although the potential for irrigated
pea crops in this area and nearby drier areas, is not precluded) and
includes crop land that has slopes that range from 8 to 30 percent
(Papendick and Miller, 1977).
Dry pea crops in the Palouse produce highest economic yields when grown
on well drained soils on south and east facing slopes. Crops grown in draws
and on flats can yield well, but those areas often remain wet until late
spring, and sowing is delayed, crop duration is restricted, and for current
cultivars yields are reduced. Crops seeded in low lying areas often produce
excessive vegetative growth and are prone to various foliar diseases such as
downy mildew, sclerotinia white mold, and powdery mildew.
The common practice used for seedbed preparation is to plow or disk
fields intended for peas in the fall or early spring to incorporate previous
crop residues (Reisenauer et al., 1965). In spring, when soils are
sufficiently dry, fields are cultivated and firmed with a harrow although
some growers prefer to use a rod weeder. Deep tillage is avoided to prevent
excessive moisture loss.
Growers use the same grain drills to plant dry peas that are used for
wheat and barley. The drills have either 15 or 18 cm row spacings. For
optimal yields, peas should be planted as early as possible in the spring
and when soil temperatures are above 4°C (Murray, 1982). Plant
populations of about 740,000 plants per hectare have been optimal for Alaska
peas in the Palouse region (Muehlbauer and Dudley, 1974).
Molybdenum is known to be deficient in the soils of the Palouse and as
a result dry pea crops can be severely affected. Symptoms of affected crops
include yellowing, reduced growth rate, earlier flowering, poor pod and seed
development, and reduced yields. The deficiency is routinely corrected by
applying sodium molybdate to the seeds at the rate of 35 g ha 1. It is
important to distribute sodium molybdate uniformly over the seed and to
insure adherence to the seeds with a "sticker". Ammonium molybdate
(NH4)6Mo7O4) at the rate of 1.1 kg ha-1 applied broadcast to the
soil in combination with gypsum has also been used successfully to correct
molybdenum deficiencies. Also, fertilization with molybdenum as NaMoO4 at
the rate of 0.5 kg ha-1 has generally been sufficient to prevent
The common practices for broadleaf weed control in dry peas include
preemergence applications of Dinoseb amine or metribuzin after all tillage
and seeding operations are completed, or to apply dinoseb amine post
emergence when the weeds are small and when wax is present on the pea
PNL Volume 16 1984
foliage. Grass type weeds (wild oats, downy brome, etc.) are usually
controlled with shallow incorporation of trillate during the final tillage
operations or by shallow incorporation of the chemical after seeding.
Pea crops in the Palouse are severely affected by pea root rot. Other
diseases are important and include Fusarium wilt races 1 and 2, powdery
mildew, Sclerotinia white mold, and various viruses transmitted by aphids.
Pea root rot caused by Fusarium solani (Mart.) Sacc. f. sp. pisi (Jones)
Snyd. & Hans, can severely damage most Alaska strains, particularly when the
seedbed is heavily compacted. Because Alaska peas are early maturing, they
usually escape powdery mildew (Erysiphe polygoni DC.). Most Alaska strains
are resistant to wilt caused by Fusarium oxysporum Race 1, but some small
sieve strains are susceptible. Yields of Alaska peas are variable due to
weather, diseases, and other stress factors and somewhat lower than the
released cultivars, Garfield and Tracer.
Important insect pests of the dry pea crop include the pea leaf weevil
(Sitona lineatus) , pea weevil (Bruchus pisorum L.) and aphids. The pea leaf
weevil feeds on the foliage of the pea plants soon after emergence and has
caused serious economic losses when not controlled. The insect was
inadvertently introduced from Europe to the Pacific Northwest via Vancouver
Island, British Columbia. Control is through use of insecticides; however,
various types of biological control have had some success. Host plant
resistance has revealed levels of tolerance, but good resistance has not
been found.
One of the most important of the insect pests, the pea weevil enters
pea fields at about bloom and feeds on nectar and pollen. After a feeding
period, the females begin to lay eggs on the surface of developing pods.
Upon hatching, the larva eats its way directly from the egg through the pod
and into the developing pea ovule. A small dark spot or "sting" marks the
point of entry on the seed coat. The larvae then feed inside the seeds
until pupae form and later, usually in storage, the pupae transform to
adults. The pea weevil completes one cycle per season and they do not
damage sound seeds in storage. After leaving infested seeds, adult pea
weevils overwinter in debris, fence rows, and the bark of pine trees, among
other places. Host plant resistance is being studied and progress has been
made, however, the level of resistance found does not appear sufficient to
preclude the use of insecticides for control.
Dry pea crops are harvested as soon as possible after dry seed
maturity. Growers in the Palouse use pick up attachments on the combines
(otherwise known as a pea bar) to lift the pea vines from the soil surface
and into the cutter bar. The lifters help avoid a great deal of shattering
that would otherwise take place.
Palouse dry pea crops are inspected and graded according to U.S.
standards as established by the U.S. Department of Agriculture, Federal
Grain Inspection Service. The standards consider the prevalence of damaged
and defective seeds and contamination by foreign materials in determining
PNL Volume 16 1984 FEATURE 8l
Improve standing ability. Progress has been made in developing populations
and germplasm with combined resistance to Fusarium wilt, Fusarium root rot,
powdery mildew and pea seedborne mosaic virus.
Dry peas produced in the Palouse are used in numerous ways that include
whole peas, split peas, reconstituted peas, pea powder, noodles and various
snack, items. Splitting is accomplished by first steaming the peas to loosen
the seedcoats, followed by the use of centrifugal force to split the peas.
A more comprehensive treatment of the dry pea crop in the Palouse and
elsewhere is contained in a recent review by F. J. Muehlbauer, R. W. Short,
and J. M. Kraft entitled "Description and Culture of Dry Peas", 1984.
Copies are available on request.
1. Murray, G. A. 1982. Seeding practices for dry peas, lentils, and
chickpeas, p. 223-228. In Proceedings, Palouse symposium on dry peas,
lentils, and chickpeas, Moscow, Idaho, February 23 24, 1982. College
of Agriculture Research Center, Washington State University, Pullman,
2. Muehlbauer, F. J. 1982. Dry pea and lentil cultivars, p. 101-108 In
Proceedings, Palouse symposium on dry peas, lentils, and chickpeas,
Moscow, Idaho, February 23-24, 1982. College of Agriculture Research
Center, Washington State University, Pullman, Washington.
3. Muehlbauer, F. J. and R. F. Dudley. 1974. Seeding rates and
phosphorus placement for 'Alaska' peas in the Palouse. Washington
Agric. Exp. Sta. Bull. No. 794. p. 1-4.
4. Muehlbauer, F. J., V. E. Wilson, J. M. Kraft, and R. E. Witters.
1977. Registration of Garfield and Tracer dry peas. Crop Sci. 17:485
5. Muehlbauer, F. J., R. W. Short, and J. M. Kraft. 1983. Description
and culture of dry peas. U. S. Department of Agriculture, Agricultural
Research Service. ARM-W-37.
6. Papendick, R. I. 1982. Cropping systems that include grain legumes,
p. 229-235. In Proceedings, Palouse symposium on dry peas, lentils,
and chickpeas, Moscow, Idaho, February 23 24, 1982. College of
Agriculture Research Center, Washington State University, Pullman,
7. Papendick, R. L. and D. E. Miller. 1977. Conservation tillage in the
Pacific Northwest. J. Soil Water Conserv. 32:49 56.
8. Reisenauer, H. M., T. J. Muzik, D. H. Brannon, et al. 1965. Dry pea
production. Washington State University Cooperative Extension Sn vice
Bull. No. 582. p. 1-10.
9. Smith, A. 1980. Future role of cooperative in marketing beans, peas
and lentils. U.S. Dept. of Agric., Economics, Statistics, and
Cooperative Svc, Farmer Cooperative Res. Report No. 16. 46 p.
10. Wilson, V. E. 1977. Registration of Latah dry pea. Crop Sci.
82 PNL Volume 16 1984