V. Cultural Practices
     A. Seedbed Preparation
     B. Seeding Date
     C. Method and Rate of Seeding
     D. Fertility Requirements
     E. Varieties
               Semi-leafless Growth Habit
               Selecting a Variety
     F. Weed Control
               Mechanical Control / Cultural Weed Control
               Chemical Control
               Crop Desiccation
     G. Insects
     H. Disease Prevention
     I.   Common Diseases
     J. Yield Potential
     K. Harvesting

A. Seedbed Preparation
Field pea can be grown in a no-tillage or conventional tillage cropping system. Field pea grows best when planted into a weed-free seedbed in fertile soils. Land preparations for seeding peas is much the same as for wheat. In order to obtain good soil contact with the seed, seedbeds should be firm and well worked. Avoid seedbeds with large clods. Do not work the soil too fine, or subsequent soil crusting following rains could cause emergence problems. Overworked land will be much more difficult to pack level - and having level ground is critical for easy harvesting of peas. Stony fields should be avoided or rolled after seeding to bury loose stones that otherwise might be picked up in swathing and harvesting.

Plant the pea seeds 1 to 3 inches deep in rows 6 inches apart as early in the spring as feasible, provided the temperature of the surface inch of soil is above 40 degrees F. Soil should not be excessively wet. Early seeding advances maturity of the crop, so that the probability of detrimental high temperatures during flowering is reduced. Pea seedlings can withstand considerable frost. Even if the frost is severe enough to kill the main shoot, the pea plant will initiate regrowth from buds at one of the nodes at or below the soil surface but will be delayed in maturity. Early seeding, in general, results in higher yields, but protein content may be slightly lower.

Seeding can be done with an air seeder or grain drill. Care must be taken to adjust the seeder to prevent cracking of the seed, especially of the large-seeded varieties, since cracked seed will not germinate. Do not pack or roll immediately after seeding if soil moisture is high or excess compaction or crusting can occur. Some producers seed barley, oat, mustard, or canola at reduced rates in their peas crop to reduce lodging and facilitate swathing. However, pea plants are poor competitors and yield of the pea component will be reduced.

Planting pea on flax stubble should be avoided because flax crop residue may make swathing peas difficult. Slow degradation of flax stubble limits this rotation.

Pea should be separated by four years from oilseeds and other legumes in the rotation to avoid serious disease problems such as sclerotinia and other similarly shared problems.

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B. Seeding Date
Being a cool season crop, field pea cannot tolerate hot weather or drought stress during flowering, thus seeding early is important. Seeding should be as early in the spring as feasible provided soil temperature in the upper inch is over 40 degrees F. In Minnesota and Wisconsin this ranges from the end of March to
mid-May, so flowering will occur during cooler weather in June and early July rather than during the heat and drier conditions at the end of July or into August. Seeding date studies conducted at Minot and Carrington, North Dakota indicated that field pea yields decreased significantly when seeding is delayed beyond mid May. Seeding peas beyond mid May will result in the crop beginning flowering in mid July, which increases the risk of heat stress and late season disease problems, which will reduce yield.

One should avoid seeding into wet, poorly drained, cold soils because pea seeds will rot, or roots will become subject to disease and rot. Pea growing points remain below ground so seedlings can withstand a mild frost at 23 to 19 degrees F. without damage.

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C. Method and Rate of Seeding
Care must be taken to properly adjust the grain drill to prevent cracking of the seed (cracked seed will not germinate). Rate of seeding depends on the variety to be planted. Field pea varieties will range from 1,600 to 5,000 seeds per pound. Field pea is not a strong competitor; therefore, poor germination or sowing at less than recommended rates may result in severe weed problems. It is important to use the recommended seeding rates to gain optimum yields. Seed rates may vary because seed weights are not the same year to year. Drills should be calibrated for each variety and seed lot to achieve optimum seed rates. The goal is approximately 300,000 to 325,000 plants per acre or 8 plants per square feet. This is about 4 seeds per feet in drill rows 6 inches apart. Germination percentage should be taken into account. Always select high quality, disease-free seed. Drills should be calibrated to allow for seed and inoculant to flow properly without cracking the seed or plugging the opener.

Pea seed requires considerably higher amounts of moisture for germination than cereal grains. Maintaining firm seed to soil moisture contact is critical. Seeding pea well into moisture is essential and seeding pea into dry soil should be avoided. A rule of thumb is that the pea should be seeded at least a half inch into moisture and never seeded onto the interface where soil moisture meets dry soil.

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D. Fertility Requirements
A fertility soil test should be conducted to determine the status of the primary nutrients in the soil. Well nodulated field pea does not require much added nitrogen. However, field pea grown on soils with less than 20-30 available pounds of nitrogen may benefit from the addition of 20 to 40 pounds of nitrogen applied at seeding. Over-application of nitrogen is usually not profitable and may suppress nitrogen fixation. N-fixation by field pea will reach a maximum just before or at flowering and then drops during pod formation. Field pea is among the most highly efficient nitrogen fixing crops. It may fix as much as 80% of the total nitrogen requirement under good growing conditions. Producers should avoid high levels of nitrogen regardless of whether the source is a high testing field or high nitrogen fertilizer rates. Excess nitrogen will promote vegetative development over reproductive seed production. Higher nitrogen levels will also reduce the potential of nitrogen fixation and increase the potential for lodging. An experiment with pea grown using a split -root procedure suggested that at the time of harvest, 22 to 46 percent of the belowground N had been shed into the rhizosphere (root zone).  Because this N "rhizodeposition" has not previously been assessed for annual legumes, nitrogen fixation may be underestimated by about 10 percent.

Field pea research has also indicated the importance of adequate phosphorus fertility for optimizing seed yield . Phosphorous and potassium are required by field pea in relatively large amounts and they should be added as required on the basis of soil test results (Table 2). Fertilizer may be broadcast in the spring during seedbed preparation or banded with the seed. Care must be taken to prevent direct contact between the seed and fertilizer because germinating field pea is extremely sensitive to high salt concentrations. If P and K are applied as a starter, the recommended placement of the fertilizer is in a band 2 inches to the side and 2 inches below the seed. When fertilizing in a band, the amount of P recommended at very low (VL) and low (L) soil P levels could be decreased by one-third. At medium or high soil P levels, the rates should remain as shown in Table 2. The limit to P fertilizer applied in a band with the seed is about 20 lb/acre P₂O₅ as MAP (mono -ammonium phosphate, also designated as 11-52-0, or 10-50-0. DAP (di-ammonium phosphate, also designated 18-46-0) is often too "hot" for the germinating pea seeds and seedlings.

Sulfur deficiencies on field pea have been observed in North Dakota on sandy, eroded hillsides and hilltops under low organic matter conditions. These areas may respond to sulfur fertilizer if treated with a soluble form of sulfate. Elemental sulfur products are not generally effective in the first year of application due to a slow microbial conversion to sulfate.

No reports of responses of field pea to iron, copper, zinc, chloride, manganese or boron have been reported in North Dakota.

Table 2. Nutrient recommendations for lentil and field pea.

Soil Test Phosphorus, ppm       VL L M H VH Yield goal Bray-I 0-5 6-10 11-15 16-20 21+   Olsen 0-3 4-7 8-11 12-15 16+               lb/a ----lb P205/acre---- 1400 20 15 10 0 0   1800 30 20 10 0 0   2200 35 25 15 0 0   2600 40 30 15 10 0

Soil Test Potassium, ppm       VL L M H VH Yield Goal Bray-I 0-40 41-80 81-120 121-160 161+   Olsen                         lb/a ------lb K20/acre------ 1400 35 25 15 0 0   1800 45 30 20 0 0   2200 55 40 25 10 0   2600 65 45 30 10 0

Bray-I P recommendation  = (0.01710-0.00085 STP)YG
Olsen P recommendation   = (0.01710-0.0011 STP)YG
Potassium recommendation = (0.03000-0.00018 STK)YG

Source:  NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Web site http://www.ext.nodak.edu/extpubs/plantsci/soilfert/sf882w.htm#Table%2021.

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E. Varieties
Many registered dry pea varieties are adapted to the northern states and Canada. Trapper, a small seeded variety, has been the old standard and matures in 95 to 100 days. Trapper has the advantage of smaller seeds (reduced cost of seed purchase) but it has long vines and is low yielding as compared with newer varieties. Pea varieties fall into two main types: yellow cotyledon or green cotyledon. Green cotyledon pea varieties can be more difficult to market than yellow varieties due to their susceptibility to bleaching. Currently available green varieties yield approximately 20 percent less than yellow varieties under similar growing conditions. Dry pea is grown for either the human consumption market (food type) or as animal feed.

Food Peas - A good yellow or green food pea has a large, round, and smooth seed. It also has a uniform color seed coat.

Feed Peas - Low grade food pea types are acceptable in the feed market. Varieties designated as feed are unacceptable as food types. Feed pea costs of production are often lower because cleaning is not as important, damaged seed does not have to be removed, and bagging is not necessary. Feed pea varieties may vary in seed shape, cotyledon color, and seed coat pattern and color.

Do not choose a feed pea variety on the basis of protein content. Variation in protein content is due more to environmental factors such as effective nitrogen fixation, soil fertility, temperature, or moisture availability, than to varietal differences.

Specialty Pea - Pea types such as marrowfat, Alaskan, maple, and Austrian winter peas are grown for specialty confection, birdseed, and forage markets. They are usually lower yielding and involve more production and price risk. These types should only be grown under contract, and should receive a premium price to yellow food types.

Semi-leafless Growth Habit
Some peas varieties have a semi-leafless growth habit. The tendrils of adjacent plants intertwine to provide better support (resistance to lodging) for the entire canopy. This characteristic can ease harvest under good growing conditions. The semi-leafless varieties, however may be less competitive to weeds. It is important to establish a uniform heavy stand for semi-leafless types. The semi-leafless varieties are often better suited to areas of high moisture in part due to their shorter vine length and in part to their more open canopy.

Selecting a Variety
Selecting the appropriate field pea variety should be based on review of the many differences that exist among varieties. Factors to consider should include market class, yield potential, harvest ease, vine length, maturity, seed size, and disease tolerance.

The first criteria for selecting a variety should be market class. The green and yellow cotyledon types will be the primary classes. All field pea varieties may be considered feed peas, but only selected varieties are acceptable for either the green or yellow human edible market.

After market type is determined, growers should review the field pea performance test information from trials conducted across the northern states with particular attention paid to those trials reflective of their farming area.

Crop harvestability is a very important factor in variety selection and is often noted by harvest ease scores in trial results. Most growers prefer a variety that will stand upright at harvest since it allows a faster harvest, minimal equipment modification, and higher quality seed. The newer varieties that have shorter vines and are semi-leafless will be easier to harvest.

Another factor to consider in variety selection is the producer's location. The indeterminate nature of the long -vined normal leaf type varieties may make them a preferred type in western North Dakota where moisture stress is more prevalent. Indeterminate varieties tend to express more stable seed yields when moisture and heat stress impact crop development. This type of variety, however, due to its long vines can be heavily lodged at harvest and require special harvest procedures.

Most growers will select among the semi-leafless varieties that are more determinate in development. Selection within these semi-leafless types should consider the impact of vine length. In areas with higher rainfall and cool summers, the shortest-vined varieties may be best, while in the drier regions a grower should choose a semi -leafless type with longer vines.

Table 3 shows research results from the 1997 -1999 seasons for Red Lake Falls, Oklee, Fosston, Kennedy, and Baudette.  Among the varieties tested Majoret and Astuce have a green seed coat.

Table 3. Minnesota peas variety trial results 1997-1999 data.

	RLF*	Fosston	Oklee	Kennedy	LOW	RLF	Fosston	Kennedy	Mean
Peas variety	1997	1997	1997	1997	1998	1998	1998	1999	97-99
	Yields bushels per acre
Spitfire	54.6	68.2	57.2	51.3	73.2	74.5	66.4	56.0	62.7
Carneval	39.7	69.8	41.8	56.9	64.6	62.5	71.7	53.7	57.6
Carrera	40	57.4	41	51.6	73.1	60.7	60.6	65.5	56.2
Grande	46.5	59.8	63.1	53.8	58.2	49.1	67.7	49.7	56.0
Highlight	50.3	50	49.2	63.4	62.4	62.7	49.9	49.6	54.7
Majoret	42.6	56.4	39.1	43.6	67	54.6	61	52.8	52.1
Mustang	39.4	56.9	50.5	58	55.7	56.8	48	48.3	51.7
Profi	39	52.1	33.6	47.2	72.7	53.5	48.2	51.9	49.8
Astuce						67.6	46.3	63.5
Trapper	30.5	25.7	19.5	39.1	42.2
Integra								68.2
Mean	42.5	55.1	43.9	51.7	63.2	60.2	57.8	55.9
LSD (0.10)								7	5.6

RLF = Red Lake Falls, MN, LOW = Baudette, MN (Lake of the Woods County)

Research data from Dr. Hans Kandel.

Peas Variety	Powdery Mildew	Mycosphaerella (Ascochyta)	Fusarium Wilt	Leaf type2	Maturity Rating 3	Vine Length4	Seed Size5	Seed Color6
	Resistance To 1
Spitfire	P	P	?	T	M	M	M	Y
Carneval	F	F	P	SL	E	M	M	Y
Carrera	P	P	P	SL	E	S	M	Y
Grande	P	F	P	N	M	M	M	Y
Highlight	VG	F	P	SL	E	S	S	Y
Majoret	P	F	P	SL	M	S	L	G
Mustang	P	P	P	SL	VE	S	S	Y
Profi	P	P	P	SL	VE/M	M	M	Y
Trapper	P	F	P	N	M/L	T	S	Y
Integra	P	P	F	SL	M	M	L	Y

1) Disease ratings provided by Dr. Allan Zue, Agriculture and Agri-food Canada, Morden.
   VG = Very Good; F = Fair; P = Poor.
2) N = Normal; SL = Semi-leafless; T = Tare (reduced leaves).
3) VE= Very Early; E = Early; M = Medium; L = Late. M = about 95 days, varies with growing conditions.
4) S = Short; M = Medium; T = Tall. M = approximately 33 inches, varies with growing season conditions.
5) S = Small; M = Medium; L = Large. M = 220 g/ 1000 seeds, varies with growing season conditions
6) Y = Yellow; G = Green.

Langdon

Field Pea  - Langdon
									Yield			Avg.Yield
Variety	Days to 1st Flower	Days to End Flower	Days to Mature	Harvest Ease	Vine Lgt	1000 KWT	Protein	Test Wt.	1999	2000	2001	2 year	3 year
Yellow				0-9	in	gms	%	lbs/bu	-----------------bu/a---------------
Ceb. 4119	57	75	92	8.0	50	197	25.8	61.1	--	--	46.8	--	--
CDC Handel	55	81	92	9.0	46	150	28.1	60.4	--	63.7	29.5	46.6	--
CDC Minuet	59	84	94	8.3	44	150	25.2	61.5	--	--	38.2	--	--
CDC Mozart	54	79	91	9.0	41	196	21.6	61.3	--	82.6	41.8	62.2	--
Carneval	56	80	93	7.0	46	161	24.9	61.1	70.0	68.5	39.8	54.2	59.4
Integra	55	74	91	6.5	47	264	22.7	61.4	78.3	73.5	51.4	62.5	67.7
Ceb. 1475	54	81	94	8.3	39	225	23.9	62.5	80.4	82.6	46.0	64.3	69.7
NSA 468	57	80	95	8.5	38	226	25.4	62.1	--	--	35.3	--	--
Marble	54	71	90	9.0	34	260	23.0	61.5	--	--	47.3	--	--
Trapper	61	89	107	9.0	61	98	29.0	61.5	20.2	28.6	7.0	17.8	18.6
Green
Bluebird	55	74	92	9.0	35	219	23.8	60.5	--	--	33.3	--	--
Ceb. 1170	54	77	94	7.0	50	284	22.3	61.8	--	--	47.7	--	--
CDC Montero	57	84	94	8.5	47	175	26.4	61.3	--	--	28.4	--	--
CDC Verdi	58	85	96	8.8	39	158	29.8	61.8	--	66.4	21.7	44.1	--
Ceb. 1171	55	74	93	9.0	40	233	25.4	61.5	--	81.7	40.4	61.1	--
Majoret	56	74	94	8.0	43	212	26.8	62.3	65.6	66.6	35.9	51.3	56.0
Toledo	55	74	93	7.3	43	264	23.9	61.4	78.8	65.0	48.8	56.9	64.2
Atomic	56	75	94	8.8	42	268	23.6	61.5	68.7	63.8	40.4	52.1	57.6
Scuba	52	73	88	8.3	42	209	21.0	60.3	--	--	47.1	--	--
Mean	55.7	77.9	93.5	8.3	43.5	--	24.9	61.4	64.4	67.5	38.2	--	--
C.V. %	1.6	1.3	1.4	7.3	6.6	--	4.2	0.7	10.4	8.3	11.4	--	--
LSD .05	1.3	1.5	1.9	0.9	4.1	--	2.2	0.6	9.5	7.9	6.2	--	--

Planting Date: May 10, 2001
Harvest Date: August 27, 2001
Source: Langdon Research Extension Center Box 310, Hwy 5 E.
Langdon, ND 58249 (701) 256-2582 Fax: (701) 256-2580 North Dakota Agricultural Experiment Station Link http://www.ag.ndsu.nodak.edu/langdon/01data/fieldpea.htm

NDSU Pea Variety Langdon Results 2004: http://www.ag.ndsu.nodak.edu/langdon/04data/fieldpea.htm

2006 Field Pea Variety Trials From All NDSU Research Extention Centers: http://www.ag.ndsu.nodak.edu/aginfo/variety/fieldpea.htm

Carrington Field Pea

---Seed Yield--- Variety Days to Bloom Bloom Duration Days to PM Harvest Ease Seed Protein Seeds per Pound 1000 KWT Test Weight 2001 3-yr Ave.         0-9 %   gram lb bu ------bu/ac------ Green Cotyledon Type                 Atomic 50.0 12.0 81.0 7.0 20.7 1588 286 64.2 57.0 59.0 Bluebird 49.0 14.0 80.5 8.0 21.2 2001 228 62.7 52.4 -- CDC Montero 52.0 1425 83.3 8.3 21.9 2746 166 64.5 50.2 -- CDC Verdi 51.3 16.8 85.8 7.5 29.2 2869 159 62.6 39.8 -- Ceb.1170 46.0 15.5 80.3 5.8 20.7 1588 286 63.2 75.5 -- Ceb.1171 47.3 14.0 80.0 7.8 23.2 1985 229 62.8 62.8 -- Crusier 48.0 16.3 81.3 6.3 21.8 2507 182 63.0 62.9 -- DS-49500 46.8 14.5 81.8 5.0 23.0 1886 245 64.1 55.3 -- DS-49543 46.5 15.5 80.3 6.0 23.3 1911 238 63.8 67.0 -- DS-49548 44.0 15.3 79.0 6.3 22.3 1540 296 62.8 53.2 -- Majoret 50.3 12.5 81.3 5.8 22.8 2045 222 64.6 59.4 60.3 Nitouche 49.0 14.8 83.0 5.8 23.4 1846 246 63.2 59.6 -- Scuba 46.3 14.5 77.3 7.0 21.5 2190 208 62.5 64.0 -- Sothis 48.5 17.8 83.0 6.8 22.5 2510 181 64.7 49.0 -- Toledo 46.3 14.3 80.3 5.8 22.3 1824 249 62.7 56.6 60.2 Venture 49.0 14.5 82.5 6.0 21.8 2436 187 64.3 41.9 --

Yellow Cotyledon Type                 Athos 44.0 15.3 80.5 8.0 24.6 1826 249 63.5 62.3 65.0 Avatar 46.5 15.5 80.0 7.8 23.8 2690 169 63.3 41.8 -- CDC Handel 49.8 16.8 83.3 7.3 26.3 2890 157 63.5 45.4 -- CDC Minuet 52.5 14.3 82.3 6.5 23.0 2803 162 64.7 61.6 -- CDC Mozart 47.8 18.0 81.5 7.5 20.8 2279 199 64.6 67.4 -- Carneval 49.8 15.3 81.8 5.0 21.1 2551 178 63.4 59.1 62.3 Ceb. 1475 47.8 17.3 82.8 5.3 23.2 2158 210 64.1 69.6 -- Ceb. 4119 51.8 11.3 82.5 5.5 22.3 1864 244 63.5 57.9 -- DS-Admiral 47.5 14.3 80.3 5.3 21.7 1954 233 64.8 65.7 -- Delta 48.5 13.3 78.5 7.0 22.9 2189 209 62.6 59.9 -- Integra 46.5 14.8 79.3 5.0 23.0 1773 256 63.0 62.2 61.8 Marbsle 47.3 14.3 78.5 7.0 23.3 1908 238 62.7 66.9 -- NSA468 51.8 13.5 83.3 7.5 23.2 2255 202 64.7 56.2 -- SW995877 45.5 16.0 79.3 8.0 23.5 2128 214 63.3 63.9 -- SW995966 49.0 13.8 80.5 5.5 23.6 2424 188 63.8 62.4 -- SW995985 46.5 16.5 79.8 7.3 23.4 2196 207 62.7 59.4 -- SW995990 45.0 17.0 79.5 6.5 24.5 2259 201 63.3 59.0 -- Salute 49.8 14.5 81.0 7.3 22.9 2334 195 63.7 61.0 -- Trapper 53.3 28.5 87.5 9.0 33.1 5016 91 63.7 12.2 23.3                       Misc.Type                   Austrian Winter 55.0 15.8 84.3 7.0 28.6 5817 79 6..5 8.7 10.9 Whero 54.5 14.8 85.3 7.3 27.0 2689 171 63.7 27.0 37.8 Supra 48.3 14.0 82.5 7.5 20.8 1397 325 62.6 43.6 45.1 Mean 48.6 15.3 81.2 6.7 23.2 2319 212 63.6 55.3 -- CV% 1.1 7.3 1.3 10.6 2.9 7.9 6.0 0.8 9.1 -- LSD.05 0.8 1.6 1.5 1.0 0.9 258 18 0.7 7.1 --

Source: North Dakota Agricultural Experiment Station "web site"
Carrington Research Extension Center
Web site http://www.ag.ndsu.nodak.edu/carringt/01data/field%20pea.htm

NDSU Pea Variety Carrington Results 2004: http://www.ag.ndsu.nodak.edu/carringt/04data/field%20pea.htm

2006 Field Pea Variety Trials From All NDSU Research Extention Centers: http://www.ag.ndsu.nodak.edu/aginfo/variety/fieldpea.htm

1999 Field Pea Varity Trial Prosper, ND

Prosper 1999 Trial
Variety	Days to Flowering	Plant Height	Lodging	Test Weight	Yield
		inches	0-9†	(lb/bushel)	(lb/acre)
Athos	39	22	7	65	3807
Atomic	45	27	5	65	3114
Carneval	46	27	8	62	3383
Grande	48	38	8	61	1617
Majoret	46.8	26	3	65	2949
Profi	44	26	4	65	3056
SW93605	46.8	24	8	62	3225
SW955180	46.3	25	8	63	3248
Trapper	50	39	8	61	850
CV %	1	8	11	1	15
LSD (0.05)	0.4	3	1	1	596

Planting Date: May 31, 1999
Harvest Date: August 26, September 8, and October 14, 1999
Source: North Dakota Agricultural Experiment Station Prosper Experiment Station Prosper North Dakota http://www .ag.ndsu.nodak.edu/fargo/99data/fieldpea99.htm

2006 Field Pea Variety Trials From All NDSU Research Extension Centers: http://www.ag.ndsu.nodak.edu/aginfo/variety/fieldpea.htm

2000 Field Pea Variety Trial Erie, ND

Erie 2000 Trial
Variety	Plant Height	Lodging	1000 Seed Weight	Test Weight	Yield
	inches	0-9†	g	lb/bu	lb/acre
Athos	22.8	7	238	63	3404
Atomic	29.5	4	233	63	2740
CDC Handel	30.8	8	171	64	2950
CDC Mozart	29.5	7	201	64	3503
CDC Verdi	27	8	159	63	2269
Carneval	27.8	3	174	64	2733
Grande	35.5	3	159	64	2348
Highlight	29.3	7	165	64	3197
Jasmine	27.3	5	233	64	2862
Majoret	28.8	3	194	64	2921
Profi	29.5	4	195	63	3177
Trapper	47.3	9	104	64	993
Mean	30.4	6	185	64	2758
CV%	12.7	16.2	5.5	0.6	8.1
LSD (0.05)	5.5	1	15	1	322

^† 0 indicates perfectly upright plants; 9 indicates perfectly flat plants
Planted: May 24, 2000
Harvested: August 23, 2000
Source: North Dakota Agricultural Experiment Station, Erie Experiment Station Erie North Dakota.
 Website http://www.ag.ndsu.nodak.edu/fargo/00data/fieldpea.htm

2006 Field Pea Variety Trials From All NDSU Research Extention Centers: http://www.ag.ndsu.nodak.edu/aginfo/variety/fieldpea.htm

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F. Weed Control
Relatively slow early-season growth and lack of complete ground cover by the crop canopy allow weeds to be competitive. A well-established stand of seven to eight plants per square foot is critical for field pea to be competitive with weeds.

Weeds compete severely with field pea, particularly at the time of crop emergence, resulting in sharply reduced seed yield and lower quality. Costs associated with cleaning and transporting dockage decrease prices paid to the producer. Therefore, an effective weed control program is essential and often the most important consideration for profitable field pea production. An integrated approach to weed control combines preventative and cultural measures (such as clean seed and appropriate tillage) with effective use of selective chemicals.

Weed control during summer fallow years (particularly for perennials), fall spraying for winter annuals, and selection of a field where anticipated weed problems can be controlled by products registered for use in field peas are important points to note when planning field pea production. No new weeds should be introduced with the seed, and effective weed control must be obtained during the cropping season so that the pea fields will remain suitable for subsequent cropping. Avoid areas where perennial weeds may be a problem. Perennial weeds and annual weeds that emerge early in the season including common lambsquarters, kochia, volunteer grain, wild mustard, and wild oat are very competitive with peas. For example, a Canadian trial indicated that two wild mustard plants per square foot reduce peas yield as much as 35 percent. Good weed control is also very important in raising high quality human edible peas. Weeds such as kochia, Russian thistle, and wild buckwheat can cause harvest problems within fields that are intended to be straight combined. Nightshade berries can stain the pea seed, causing a reduction in quality and when harvested with certain types of combines can easily clog the combine.

Heavy weed infestations should be controlled by cultural or chemical measures prior to rotating into field pea, and prior to planting.

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Mechanical Control / Cultural Weed Control                                            
Cultural methods that should be used as part of an integrated weed management system include crop rotation, field selection, rapid crop establishment at an adequate density, and use of clean seed.  

Harrowing land between the time of seeding and emergence of the pea crop can control newly emerged weed seedlings and aid in the removal of weeds that may have escaped previous tillage operations. Harrowing should be avoided as the crop plants emerge and for several days after emergence to permit effective rooting and stand establishment. Post-emergence harrowing must be viewed as a drastic measure. Harrowing at slow speeds can reduce the amount of damage to pea plants. However, once the peas plants have reached the 4- to 6-leaf stage an additional operation, preferably using a finger weeder or flexible harrow, may provide a limited degree of control of germinating annual broadleaf weeds. Weed control from post-emergence harrowing is often erratic, and crop damage may cause variable maturity in field pea. The best weed control will be obtained by harrowing on a dry, warm, sunny day. Harrowing should be avoided during damp, cool weather, or during a heavy dew to prevent the spread of diseases. Harrowing may also be required to break crusted surfaces in clay soils. Post-emergence tillage with a rotary hoe or light spring-tooth harrow needs to be timed to control emerging weeds on small (0.5 to 2-inch tall) field pea. Some pea stand reduction probably will occur with post-emergence tillage, but must be compared with the economics of leaving weed control to post-emergence herbicides or hand hoeing.

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Chemical Control  
Chemical weed control usually provides effective and consistent results. Products are available for pre-plant incorporated, pre-emergence, and post-emergence applications. The advantages from fall application of soil -incorporated herbicides include more uniform distribution of the active materials for improved weed control and crop tolerance, conservation of soil moisture by reduction of spring tillage operations, the potential for earlier seeding, and more efficient timing of labor inputs for herbicide application and incorporation. The primary disadvantage of fall application of soil- incorporated herbicides is the increased susceptibility of the treated fields to soil erosion due to reduction of crop residues and loosening of the soil surface.

2007 North Dakota Weed Control Guide

Post-emergence products herbicides should be applied to small weeds and peas (2- to 4-inch height) to maximize weed control and minimize crop injury. Field spraying should be conducted before the pea vines reach the 5-node stage to minimize mechanical damage. In addition, weeds are generally more susceptible and field pea plants more tolerant to herbicides when applied early. Careful planning of rotations will permit a balanced attack on the weeds. The different products available for use in pea and cereal crops can complement each other, thereby controlling a wide spectrum of weeds and ensuring that no weed species goes unchecked for more than a single season. Carryover of chemicals may necessitate seeding an indicator area with pea 1 year prior to intended commercial cropping as a test for residual activity. Symptoms of chemical injury include an upward cupping of the leaves, reduced growth, and failure of the plants to pod and set seed.

Follow label re-cropping restrictions when growing dry pea after use of any chemical products. Areas of dense perennial weed growth should be avoided or controlled with spot treatments of non-selective herbicides such as glyphosate (Round-Up) where the crop is sacrificed to control patches of thistle or quackgrass. Roundup can also be used as a pre-harvest treatment to control these perennial weeds. A height differential between pea seedlings and taller weeds permits selective application of herbicides through a rope wick applicator. Fall application of a phenoxy will control winter annual weeds.

Several herbicides, which effectively control most of the common weed species, are registered for use in field pea crops. Frequently, a combination of herbicides will be required to provide the desired control of both grass and broadleaf weeds during the cropping season. Precautions should always be taken to carefully read and exactly follow the label recommendations for each herbicide, as these may differ from the more familiar applications in cereals and oilseeds.

Use of non-registered compounds is not advised. Field pea producers may obtain information on the current status of herbicide recommendations and weed control procedures by contacting the University of Minnesota Extension Service or the North Dakota State University Extension Service.

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Crop Desiccation
Desiccation may be used on dry green pea to reduce bleaching of the desirable green color. Desiccation of yellow or green peas also reduces the period of time from maturity to harvest and eliminates an extended harvest period or shattering in early maturing plants.

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G. Insects
Pea aphid (Acyrthosiphon pisum) - The adult is small - about 4 mm (3/16 inch) long is light green with banded antennae and long legs. The insect may be wingless or have prominent, nearly transparent wings. Although pea aphids rarely survive winter in the northern areas, they may over winter as an egg attached to the stems or leaves of alfalfa or clover hatching in early spring. The young aphids feed on the newly emerged alfalfa or clover plants. During May and June, depending on weather and host plant conditions, the insects develop wings and fly, with the aid of wind currents, into pea fields.

The majority of aphids in pea fields are blown in on warm southerly winds from the southern United States in June or early July. Aphid populations usually don't reach economic importance in field pea. The pea aphid weakens the plant directly by sucking its sap, especially under drought stress and can transmit virus diseases from one pea plant to another in the process.

Pea seed-borne mosaic (also called pea leaf roll, pea fizzle top mosaic, pea leafrolling virus), pea enation mosaic and a few other viruses can be transmitted. In some years black sooty mold on honeydew excreted by the aphids may be observed. Infestation by pea aphid can actually stimulate pea production on nodes.

It is difficult to determine whether the crop should be sprayed for aphids. There are no threshold populations developed for aphids in field pea. A heavy shower or strong wind will often cause the insects to disappear. Aphid populations are also kept low by beneficial insects such as lace wings or the ladybird beetle.

An insecticide application may be needed if there are more than 10 aphids on a plant during the period between formation of the 10th node and appearance of the first flower. Population estimates should be calculated by averaging the counts taken from at least five separate areas of the field. To avoid reoccurrence of the problem after spraying, delay application of insecticide until late flowering. One application per season should give satisfactory control. Pea aphid populations usually decrease drastically in mid to late August due to natural mortality factors, including parasitic wasps and disease.

The lygus bug or "tarnished plant bug" has been documented as a serious pest of many fruit and vegetable crops, but has not yet been documented in field pea. Lygus bugs feed preferentially on meristematic tissue or developing reproductive tissue. One effect of Lygus feeding is shriveled seed. This is called "Chalk spot" and is a damage consideration in field pea. It has been documented in Idaho that the Lygus bug caused chalk spot in lentil. Chalk spot is a chalky white spot, which may appear on the cotyledons of some legumes. It severely affects the appearance of the seed, lowering the grade and marketability. In 1996, chalk spot was a major concern in the North Dakota pea crops. Chalk spot damage to some pea samples was as high as 27 percent; however, a connection to Lygus bug was not documented.  Another possible cause of the 1996 damage was high moisture at harvest. Peas harvested at high moisture are susceptible to bruising as they are harvested or handled roughly, causing damage similar to chalk spot.

Grasshoppers are usually not a major problem in peas. Pea is not typically a preferred host, but grasshoppers can cause damage to field pea, especially to peas that is in the flower to pod-filling stages.

Wireworms can be partly controlled by broadcasting an insecticide on the field that is later worked before the field pea is planted. Pea moth and root-knot nematode can also attack field pea.

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H. Disease Prevention
Controlling diseases in field pea begins with crop rotation. A four-year rotation between broadleaf crops such as sunflower, flax, canola, crambe, dry bean, lentil, and field pea is recommended. Long-term crop rotational research in Canada indicates that a rotation of small grain/canola, or flax, or lentil/small grain/field pea has been successful without any major buildup of important diseases.

Dry pea crops are subject to a number of plant diseases that can reduce yield and quality. Infection can arise from a variety of sources. Seed-borne, soil-borne, and residue-borne diseases can be minimized through preventative management. For these diseases, the following precautions can prove useful:

   1. Choose a well-drained field.

   2. Practice effective crop rotation.

   3. Seed early.                   

   4. Use the best quality seed available.

   5. Use a registered seed treatment fungicide.

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I. Common Diseases
Mycosphaerella blight - There are three distinct species of Ascochyta that infect dry pea. In Saskatchewan Ascochyta pinodes is the most common –This species has a known sexual stage, given the name Mycosphaerella. Fungi with a sexual stage can spread farther from infected crop residue. Infection can even be caused by inoculum that originates in adjacent or neighboring fields. Thus crop rotation is not a guarantee against infection, but it does help.

Mycosphaerella blight is characterized by purplish-black, irregularly shaped spots on leaves, stems and pods. Severely infected leaves will prematurely die, resulting in premature ripening of the plant. Lesions on pods can develop, resulting in the seed becoming infected. Infected seed will be shrunken and discolored. Its impact on yield depends primarily on the timing of initial infection. If the source of the infection originates within the same field, the disease can develop early and the likelihood of loss is greater. It is unwise to grow dry pea in a field more than once in four years. Disease is most severe with continuous wet weather. Disease spreads by rain, splashing spores to uninfected tissue.

Seed infection is an important source in introducing Mycosphaerella to an area. However, seed transmission of Mycosphaerella blight is of less significance than transmission from infected pea stubble.

Direct infection of stems is also possible. This results in development of Ascochyta foot rot. Blackish-purple lesions will form on the stem at the base of the plant. Severe infections will result in premature ripening, lodging, shriveled seed and reduced yields.

Fungi may survive on plant debris, and spores can survive for years on field pea stubble. Spores of fungi can also be carried on the seed, and planting disease free seed is very important.

Sclerotinia stem rot - This disease attacks many broadleaf crops, but is most severe on sunflower, dry bean and canola. Sclerotinia stem rot can infect field pea. It over winters as sclerotia, small black resting bodies, which stay in the soil. Sclerotia may remain viable for more than three years.

Infection can take place in two ways. First, when in close contact with the pea root, sclerotia may germinate directly and cause infection at the base of the plant. Second sclerotia will germinate and develop tiny mushroom-like structures that produce spores. These spores can only cause infection by first colonizing dead plant material such as fallen flower petals or hail-damaged leaves. Spores can be windblown, so planting dry pea next to previously infected fields of crops damaged by Sclerotinia can assist in spreading the disease. Once infection has occurred, it can spread very quickly by plant-to-plant contact, especially when there is free moisture and lodged plants.

Symptoms of the disease include a white, visible, fungal growth found on dead or decaying tissue. The fungal growth can cause premature ripening of the plant. Hard black bodies (sclerotia) can be found inside the stem. Typically, long vine varieties, having normal leaf arrangement are more susceptible to Sclerotinia. These varieties tend to lodge after flowering, forming a dense canopy close to the soil surface and increase the risk of infection. Production of short-vined and semi-leafless varieties reduces lodging. This delays the onset of infection of the pea plant and reduces yield loss due to Sclerotinia infection. If infection occurs late in the growing season, there may be little effect on yield; however, the build up of sclerotia in a field may jeopardize subsequent crops.

Root Rot - Root rotting fungi can attack any part of the root system, sometimes even including the stem a short distance above the soil surface. When young seedlings are infected with root rot they usually die. Infected plants may appear yellowed and stunted. Seed treatment offers some protection to the developing seedling, especially under cool, wet conditions when emergence may be delayed. Crop rotation is also useful in preventing the build up of root rot organisms in the soil. Low-lying areas favor the development of root rot so a well-drained field is advantageous.

Bacterial blight - This disease is primarily seed-borne so obtaining seed free of bacterial blight is important. The bacteria can also over winter on crop residues, so crop rotation is an important method of disease control. Symptoms start as small water-soaked spots on leaves, stems and pods. During wet weather, creamy white exudates may appear on the spots. When this material dries, the spots take on an olive-brown color and occasionally a shiny appearance. If an infected leaf is held up to the light these leaf spots appear translucent. The bacteria are spread by rain splash. Hail or other physical injury to the plant may favor the spread of infection.

Powdery mildew - This fungal disease is favored by periods of warm, dry, daytime conditions when nights are cool enough to cause dew formation. Rain showers are actually disruptive to the spread of powdery mildew. Powdery mildew is an economic disease with late-planted field pea. The disease over winters on plant residue. Powdery mildew infection usually does not occur until mid summer. Yield loss typically does not occur unless the infection occurs prior to or during early pod set. Research indicates that planting field pea beyond mid May will result in plants more susceptible to powdery mildew.

The disease first appears as white, powdery growth on the lower leaves and stem that may quickly cover the entire plant. In severe infestations brown, pitted spots may occur on pods and the seed may be visibly affected as well. Wet or heavy dew conditions help in spreading the disease to upper leaves, flowers, and pods. Severely infected plants will not mature normally. In most instances, infected plants stay green while healthy plants mature and ripen normally. This will result in harvest moisture problems and decreased seed yield. Premature ripening may also result in shrunken seed. A foliar fungicide with sulfur will control powdery mildew. It should only be necessary to use fungicide when the disease appears early in the growing season.

Other Diseases - Other fungal disease of minor importance to dry peas include downy mildew, anthracnose, Septoria blight and rust. A few virus diseases also occur in dry peas. Feeding aphids spreads many of these viruses. The exception of this is pea seed-borne mosaic virus, which is seed transmitted.

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J. Yield Potential
For estimating pea yield before harvest, the following procedure may be used:

Step 1. Hand thresh and count the number of seeds contained in a square foot area. Sample
           several square foot areas of the field and average the number of seeds to increase the
           confidence in the estimate.

Step 2. Estimate the number of seeds per pound for the variety grown.

Step 3. Use the numbers from steps 1 and 2 in the formula: (seeds per square foot x 43,560)
           /(60 x seeds per pound) = estimated yield in bushels per acre.

Example:
A pea field was sampled at several locations and the average seeds per square foot was 125. Assume the number of seeds per pound is 1800 (seed count data may be obtained from annual university reports or seed dealers) (125 x 43,560) / (60 x 1800) = estimated yield of 50 bushels per acre.

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K. Harvesting
Harvest management is especially important if field pea is to be marketed as human food or as seed. High-quality peas will receive a premium price when sold for human food or seed markets. If quality problems exist, including bleached, split, cracked, or earth-tagged (dirt attached to seed that cannot be removed) seed, the livestock feed market will likely be the only option. 

Extreme care should be taken in harvesting the crop. Pea samples that have been harvested in a careless manner and contain excessive amounts of foreign material, cracked seed coats, and broken and damaged seeds will have heavy losses in the cleaning process. Field pea may be swathed before combining or straight (direct) combined. Field pea is normally swathed to preserve quality if there is uneven crop maturity or heavy weed pressure present.

When swathing peas, the seed needs to be at physiological maturity. At this stage of growth, the majority of pods should have turned from green to a yellow color. The crop matures from the bottom pods upward. Swathing will normally result in increased harvest losses, but swather modifications make the procedure easier and will reduce harvest loss. Peas should be swathed in the early morning or late afternoon when the pods are tough to reduce shattering losses.

The swather can also be used if cutting is delayed until the crop has reached full maturity. The combine should follow immediately behind the swather; danger of swath damage by strong winds in a mature crop will thereby be avoided. The swather should be equipped with vine lifters (pick-up guards) and possibly a pick-up reel.

If green-cotyledon pea harvest is delayed, bleaching may occur. Bleaching is caused by rainfall at maturity, high humidity, bright sunshine, and warm temperatures. If green peas are swathed, timely harvest is essential, for green pea will be more susceptible to bleaching in the swath than if left standing.

When the pea crop is straight-combined, the following method is used. The vines are permitted to ripen; after reaching full maturity they can be successfully harvested, provided the combine is equipped with a floating cutter bar, a pick-up reel, and vine lifters are attached to the sickle guards.

Many short-to medium-vine and semi-leafless pea cultivars have characteristics that allow straight harvesting compared to cultivars with indeterminate and prostrate-vine growth. For example, semi-leafless peas have a more open canopy, remain erect longer, and dry down more rapidly after rain or heavy dew than indeterminate long-vine types.

The first choice for direct harvest of short-to medium-vine and semi-leafless pea varieties is a combine header with a floating cutter bar or flex head. Also, attachments such as lifter guards and pickup reels reduce losses and improve efficiency. Direct harvesting of weak-and prostrate-vine cultivars is most efficient with an aggressive pickup attachment and a lead coulter on a standard combine.

Since the pea seeds shell very easily when dry, they should be harvested during the humid part of the day, and action of the reels against the crop should be kept to a minimum. Very low cylinder speeds are required in conventional, transverse-cylinder combines to reduce seed splitting. Cylinder speeds of 350 to 600 rpm are normally used, depending on cylinder diameter and the moisture content of the peas. An initial concave setting of 0.6-inch clearance at the front and 0.2 inch at the rear is recommended. Adjust combine settings as crop and weather conditions change. Combine augers and grain loaders should be operated at full capacity and at low speeds to reduce cracked, split, and broken seeds. Alternative seed handling equipment such as belt conveyors should be considered for handling seed intended for seed or the human food market.  Minimize the number of times seed is handled.  Also, don't handle peas during cold temperatures as potential for seed damage dramatically increases.

Peas containing green weed seeds or other foreign materials high in moisture content should be cleaned as soon as possible to prevent heating.

The pea crop can be combined at 16 to 20 percent moisture (wet basis) to keep splitting and shattering losses low and then air-dried for storage. Seed that is too dry will be susceptible to seed coat breakage or peeling.

Peas that will be sold for human consumption must be stored at less than 14 percent moisture, but storage moisture levels up to 16 percent are considered safe for the field pea. Peas at 18 percent moisture can be stored for 20 weeks at 68 degrees F. If drying is necessary, a maximum air temperature of 110 degrees F should be used for peas harvested for seed purposes and 160 degrees F for peas harvested for commercial use. Peas can be dried in storage with unheated air if an airflow of one to two cubic feet of air per bushel per minute is used. An aeration system should be present in the storage facility. Warm seed should be immediately cooled after binning, even if seed moisture is low.

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