ISSUE 15   September 18, 2008

SOYBEAN VARIETY SELECTION

At this time of the year, the soybeans are turning yellow and will soon be harvested. Many of the seed companies already are starting to market soybean varieties for the 2009 season. Soybean variety selection should be based on maturity, yield, seed quality, lodging, iron deficiency chlorosis tolerance, and disease reaction.

Later maturing varieties tend to yield more than early maturing varieties when evaluated at the same location. After determining a suitable maturity for the farm it would be important to compare yields of varieties that are of similar maturity. Although later maturity increases yield potential, later maturing cultivars are more risky to grow than earlier maturing cultivars because an early fall frost may kill a late maturing cultivar before the beans have filled the pods, which will greatly reduce yield.

Varieties of maturity groups 00 (double zero), 0 (zero), and 1 are suitable to eastern North Dakota and northwestern Minnesota. Maturity group 00 is very early and primarily grown in the northern Red River Valley. Maturity group 0 is adapted to Traill, Cass, Richland, Barnes, Sargent and Richland counties. Maturity group 1 is primarily suitable for southern areas. These maturity groups are further subdivided. For example, a 0.1 maturity group is an early group 0 variety and a 0.9 is a late maturity group 0 variety.

The best way to select a high yielding variety is to use data averaged across several locations and years. Because weather conditions are unknown in advance, averaging across several years’ data will identify a variety that will likely yield well across different weather conditions. Selecting a variety that has performed well in dry and moist conditions is the best way to identify a cultivar that does relatively well, regardless of weather fluctuations. An extensive excel spread sheet was prepared with the 2007 variety information. This tool (www.ag.ndsu.edu/pubs/plantsci/rowcrops/a843.pdf) provides multiyear and multi location information about the performance of tested soybean varieties.

Phytophthora root rot is the number one disease problem of soybeans in North Dakota. Phytophthora root rot tends to be more of a problem in the Red River Valley and on poorly drained, heavy soils, but the disease can cause significant stand reduction and yield loss in other areas when conditions are favorable. Most varieties have Phytophthora root rot resistance genes. Each gene for resistance confers resistance to a different race (or races) of Phytophthora. For example, a gene that may confer resistance to Race 3 may not confer resistance to Race 4, and vice versa. According to a recent survey of Phytophthora races done by NDSU’s soybean pathologist Dr. Berlin Nelson, races 3 and 4 are most common in North Dakota. However, numerous other races are found in the state. Based on his findings, resistance genes RPS 6 and RPS 1K (commonly called the ‘k gene’) are the most likely genes to provide resistance against the races common in North Dakota. Although selection of RPS6 or RPS 1K does not guarantee control, selection of one of these two resistance genes will maximize the likelihood you will have some protection against Phytophthora root rot next year.

There are genetic differences among varieties for tolerance to white mold. Varieties that are less susceptible to white mold should be grown on fields where white mold has a past history of causing problems. The same pathogen causing white mold in soybeans causes white mold in other crops (dry bean, sunflower, pea, canola, etc.), therefore recent white mold problems in any crop in that field should be noted.

Iron deficiency chlorosis (IDC) is a major problem in the eastern part of ND. Iron chlorosis symptoms are present during the two to seven trifoliate leaf stages. Plants tend to recover and start to turn green again during the flowering and pod filling stages. However, IDC during the early vegetative stages can severely reduce yield. Some varieties are more tolerant to IDC than others. For high pH soils with known IDC problems, select an iron chlorosis tolerant variety of suitable maturity that is high yielding.

The soybean cyst nematode (SCN), Heterodera glycines, is a small plant-parasitic roundworm that attacks the roots of soybeans. Soybean cyst nematodes are now found in Cass and Richland Counties of North Dakota and are causing yield losses in infested fields. Crop rotation is one of the most important management practice growers must use to control the nematode disease. Growers may want to consider testing their soils for SCN. See Berlin Nelson’s article in the plant pathology section for more information. If there is a nematode problem in the field only tolerant soybean varieties should be planted.

Variety trials

Hans Kandel, Extension Agronomist
Sam Markell, Extension Plant Pathologist
Ted Helms, Soybean Breeder/Agronomist

 

NCR-SARE ANNOUNCES 2008 FARMER RANCHER GRANT CALL FOR PROPOSALS

Many farmers and ranchers have great ideas for innovation. Sometimes there is a little risk in trying out new farming methods. Farmers and ranchers have the opportunity to reduce their risk by applying for a sustainable agricultural grant and be part of a research project.

The 2008 North Central Region Sustainable Agriculture Research and Education Program (NCR-SARE) Farmer Rancher Grant Call for Proposals is now available online at www.sare.org/NCRSARE/prod.htm.

Farmers and ranchers in North Dakota can submit proposals for grants to support sustainable agriculture project ideas initiated by them. Projects should emphasize research or education/demonstration. Grants can range from $6,000 for individual farmers and up to $18,000 for groups of 3 or more farmers.

NCR-SARE expects to fund about 50 projects in the twelve-state North Central Region for the 2009 growing season.

With this call, the Farmer Rancher Grant Program will now accept project proposals by email. NCR-SARE is asking applicants to complete a brief budget narrative in their project proposal. Also, beginning farmers and/or youth may apply. The deadline for proposals is Monday, December 1, 2008 at 4:30 p.m.

Potential applicants with questions can contact Joan Benjamin, NCR-SARE Farmer Rancher Grant Program Coordinator, at jbenjamin2@unl.edu or 402-472-0809.

The NCR has funded more than 650 farmer rancher grants worth more than $4,300,000 since the inception of this program.

Each state in SARE's North Central Region has one Professional Development Program State Sustainable Agriculture Coordinators. In ND, Frank Kutka is the State Sustainable Agriculture Coordinator and he is responsible for administering sustainable agriculture activities and educational events, and providing educational opportunities for potential grant applicants.

Farmers and ranchers are encouraged to involve their local extension staff in developing a project and grant proposal.

Hans Kandel
Extension Agronomist
hans.kandel@ndsu.edu

 

ASSESSING CORN MATURITY AND MOISTURE

Corn in North Dakota is still 150 (or more) corn growing degree days (GDDs) behind normal. With typical GDD accumulations of only 8-9 per day this time of the year, there is continuing concern that corn will not mature and that the moisture content of the grain will be excessive at harvest. The good news is that there is no frost forecast for the near term and temperatures will be in the mid-to high- 70s for the remainder of this week and into next. This will help the crop progress, but given the significant temperature deficit for the season, the crop will still likely be behind normal by the first killing frost. The most recent USDA Crop Report indicates that 55% of the corn crop is in the dent stage. Based on extrapolations of data from other states, assuming that an 85 relative maturity hybrid is grown and that our growing degree day accumulations will be normal for the rest of the period, dented corn will need between 12 and 19 days to reach physiological maturity (Table 1). A killing frost before maturity, of course, does not mean that the crop will be lost, but means that yield will be reduced and that the harvested grain will have a lighter test weight ( Table 1). Additionally, it means that dry-down in the field will starts at a much higher moisture level than normal (e.g. 47% for a crop in the late dent stage, verse 30% for a mature crop). Excessively wet grain, not yield and test weight losses, will in fact, be our biggest challenge this fall.

Table 1. Characteristics of corn grain at differing growth stages1.

Stage

Grain moisture content

GDD to reach PM2

Frost-free days needed to reach PM3

Test weight4

Blister

85

800

88

-

Late Milk/
early dough

70

600

66

-

Early dent

59

400

44

47

Full dent

51

200

19

50

Late dent

47

110

12

53

Physiological maturity

30

-

-

58

1Adapted from Coulter, 2008 and Thomison and Geyer, 2008.
2Assuming 85 day relative maturity hybrids are grown. PM= Physiological maturity.
3Assuming 9 GDDs are accumulated each day. Nine GDDs per day is normal for late September.
4Test weight values assume that the plant is killed by frost at this growth stage and no additional increase in grain weight occurs.

 

FIELD DRY-DOWN OF CORN

Given the above scenario, how dry will corn get before harvest in 2008? Unfortunately, the answer to that question, like so many in agricultural is, that it depends. It depends on the moisture content of the grain at the time when grain dry-down starts (wetter grain dries at a faster rate than drier grain), the temperature (warmer air can hold more moisture and will dry grain at a faster rate), the relative humidity, and the hybrid grown. Figure 1 shows the rate of dry-down of hybrids with differing maturities at Carrington in 2007. Using these data, starting from September 7th, the average rate of moisture loss ranged from 0.42% to 0.58% per day. However, starting from September 21st (closer to where we are today) it averaged 0.23% to 0.33% per day. It is interesting to note from this figure that most of the drying occurred in September, when temperatures were warmer. In fact, we actually observed an increase in the moisture content in late October as we had rain and unusually cool temperatures at that time. Unfortunately, we did not follow the drying process into November. Though normally we do not expect much drying to occur in November because temperatures are too cold. In 2007, November was warmer than average and there was measurable drying if corn was still in the field. Nevertheless, combining corn in December, I am told, is not a preferred task.

Figure 1
Figure 1

By applying the rates of drying we measured in 2007 (0.33% per day and 0.58% per day), moisture losses will range from 15-25% between now and November 1st. For mature corn, that is good news, as it means that no artificial drying will be needed if harvest occurs in late October. For the corn that is in the dent stage (more than half the state), it looks like the corn crop will indeed still be wet at the beginning of November. This analysis suggests that significant artificial drying will be needed, so plan accordingly. Options for corn that will be too wet to be harvested for grain include earlage and silage especially if they can be used on-farm.

References

Coulter, J. 2008. Maturity, frost, and harvest moisture considerations. Available at http://www.extension.umn.edu/cropEnews/2008/08MNCN26.html (verified 17 September 2008). Univ. of Minnesota Extension Service.

Thomison, P. and Geyer, A. 2008. Assessing the risk of frost injury to late maturing corn. Available at http://corn.osu.edu/story.php?issueID=255&layout=0&storyID=1584 (verified 17 September 2008). The Ohio State University Extension Service.

Joel Ransom
Extension Agronomist for Cereal Crops
Joel.ransom@ndsu.edu


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