NDSU Crop and Pest Report

Plant Science

ISSUE 1   May 6, 2004


Field peas that have been emerged for 2 to 3 weeks should have nodules forming on root hairs of both the primary root and lateral roots. Nodulation, the symbiotic relationship of bacteria on the pea roots, can be seen and should be checked for healthiness of nodules. Healthy nodules actively fixing nitrogen for the plant are pink or red inside. White, brown or green nodules indicate that nitrogen-fixation is not occurring. If the pea plants appear yellow and the roots appear not to be nodulated, then its suggested to get the field top-dressed with nitrogen. Nitrogen fertilization after planting is not generally recommended as too high levels of nitrogen fertilizer applied can and will inhibit nodule formation and ability to fix N for the legume plant for later grain development and protein content of the seed. One really should let nature take its course and let the nodules fix the N for the growing legume plant.

When checking the health of your pea nodules also check root proliferation, look for any root rot diseases or insect damage. Diseased roots will have low nodule formation and donít physically pull the plants since root hairs will slough off along with the nodules you are checking. Itís best to dig plants up with small spade or trowel. The roots should be shaken gently to remove the soil or can be soaked and washed in a pail of water or taken back to the farm and sprayed carefully with a hose to get a better observation of the roots and nodules forming. Its suggested to check and sample 5 different locations of the field for nodule development. Also one should go back and check again just before the flowering stage to insure that the N fertility for the legume will be adequate. Nitrogen fixation ceases with the onset of pod formation in peas and lentils. Good nodulation and N fixation not only benefits the growing crop but also is most beneficial to the crop that will follow in next years rotation. These principles and methods of checking for nodules are also suggested for lentils, chick peas and soybeans.



Since the 2004 planting season is off to a good start, being 10-14 days ahead of the past five years, readers may wish to note the approximate crop maturity differences. Below is a listing of the average days to physiological maturity of many crops grown in North Dakota. Early killing frosts, plus extreme high temperatures at flowering time are the most limiting factors of high yields.





Field Peas


Dry beans
Proso Millet


Time required for maturity varies with variety or hybrid, seeding date, geographic region and available growing degree days. A shortage of growing degree days can increase days required for maturity. Corn, soybean, sunflower and millet are especially sensitive. Relative maturities for major crop hybrids and varieties are listed in the respective NDSU variety performance circulars.



As we get later into the planting season, its suggested that canola (a heat sensitive crop) be seeded first and then complete small grains, sunflower and beans planting later. Research has shown that canola yields drop quickly if planted late. For canola planted acreage south of U.S. Highway 2, its suggested canola always be planted before small grains and, if possible, before May 15. For the NE and growing areas north of Highway 2, canola should be planted no later than May 25. The optimum planting date for canola is mid-April to May 10th. Canola yields have decreased sharply across most of the state (except the northeast) when canola is planted beyond mid-May. Canola is more sensitive to heat stress than all small grains, flax, and other cool season broadleaf crops, thus the importance to seed canola early. Canola is also quite tolerant to spring frosts. Once weather conditions are favorable, seed canola first prior to small grains to avoid the potential of decreased yields due to late seeding.

Duane R. Berglund
Extension Agronomist



The weather this spring in most regions of the state has not hindered field operations and excellent progress has been made in planting small grains and corn. At the time of writing more than half of the small grains and corn area have been planted. Nevertheless, since planting is still on everyone's mind, I thought it would be useful to review the recommendations and recent research findings on planting corn in North Dakota.

Planting date:

Planting corn early consistently produces the highest grain yields with the lowest moisture. What is meant by early? Even though there are several distinct environments in North Dakota, research indicates that the optimum period for planting corn for the state in general is the last week of April to the middle of May. Planting early reduces the risk of frost damaging the crop before physiological maturity in the fall and in most seasons enables the development of more yield potential. During the 2003 growing season, several studies that included planting date as one of the factors were carried out by NDSU researchers. Table 1 summarizes the planting date data from these studies. In Fargo and Lisbon, the highest yields were obtained from the May 16 planting date while the earliest planting dates at Carrington and Devil's Lake were the most productive. Yields dropped drastically when the planting was delayed until early June. The latter half of the 2003 growing season was extremely dry so the differences in grain moisture levels between planting dates was less pronounced than would have been expected in a normal season. These data support the recommendation of planting corn by the middle of May.

Table 1.  Effect of planting date on yield and moisture content at harvest in three locations in ND, 2003.
Location Planting Date Yield Moisture
    (bu/acre) (%)
Fargo 5/1 104 14.4
  5/16 117 14.8
  6/3 87 19.3
Lisbon 5/1 121 18.9
  5/16 143 17.0
  6/3 107 22.1
Carrington1 5/1 179 12.4
  5/16 168 13.7
  6/9 146 19.9
Devils Lake2 5/13 110 22.7
  5/27 107 27.8

1 Irrigated. Data courtesy of P. Hendrickson, CREC.
2 Collaborative trial with T. Gregoire

Hybrids for delayed plantings

Invariably even with the best of plans, some fields will be planted late or will have to be replanted. For the northern regions of the state, corn should not be planted beyond May 20th as the risk of late planted corn not reaching physiological maturity and having very high moisture content at harvest is very high. Furthermore, in this region of the state crop insurance may not cover corn planted later than this date. Recent data from Langdon (representing the most northern corn growing region of the state) indicate that the earliest maturing hybrids are the most profitable, even when planted early. In the central and southern regions of the state, it is recommended that you stay with a hybrid that is considered to be full season for your region until May 20th, plant an adapted hybrids after May 20th and for the southeastern part of the state an early hybrid (hybrids that are 5 to 7 RM earlier than hybrids that are considered adapted) after 1 June.

Hybrids that varied in maturity from 69-99 RM were included in the planting date trials at Fargo and Lisbon described above. The most profitable hybrids were in the 90-99 range for both locations at the May 16th date and 85-96 RM and 85-90 RM hybrids at the Fargo and Lisbon sites, respectively, at the June 3 planting date. A more detailed write up of this study can be found at


Planting Depth

Normally, corn should be planted between 1.5 and 2 inches deep. The warmer soil temperatures nearer the surface may hasten germination, but the risk of "stranding" seeds in soil too dry to enable germination in a season like this season, should far outweigh the benefits of the soil being warmer near the surface. Given the lack of rain this year and the rapid drying of the soil surface, seeding down to a reliable moisture zone is suggested, even if it means seeding deeper than 2 inches. Uneven emergence of stands can result in significant yield losses, in most cases more than from a reduced stand with uniform emergence. Late "emergers" are often barren and yet compete with early emerged plants for light, nutrients and water (and can't be controlled by herbicides!). So use, extra care in adjusting your planting depth this year! Additional information on reducing uneven emergence can be found in the following articles:




Joel Ransom
NDSU Extension Agronomist - Cereal Crops

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