ISSUE 4   June 3, 2010

REMINDER ON PESTICIDE APPLICATIONS

The 2010 growing season is upon us once again, and most of you have already been out in the field. Pesticides are an important tool for producers to manage pest problems, and many of you will be making pesticide applications or contracting with a commercial applicator to do so. Unfortunately, the ND Department of Agriculture continues to respond to pesticide drift complaints each year. Therefore, it is important to consider a few things as you go out into the field to make pesticide applications.

First and foremost, remember to read and follow the pesticide label since it is the best resource on how to safely and legally use the product. Many labels contain a maximum wind speed for applications, and failure to comply with such restrictions could not only result in drift, but also a label violation. In addition, North Dakota pesticide rules prohibit making any pesticide application when environmental conditions favor drift. Second, it is important to ensure that your sprayer is calibrated, in good working order, and configured to match the application conditions. The publication, "Spray Equipment and Calibration (AE-73)" from the NDSU Extension Service contains some excellent information in this regard.

Every pesticide user has a responsibility to read and follow the label and to use pesticides safely, legally, and responsibly. Sound product stewardship is the best defense against additional laws and regulations. Donít hesitate to call the ND Department of Agriculture if you have any questions on how to comply with state and federal pesticide requirements, including how to interpret label language. We would be glad to help you.

Jeremiah Lien
Pesticide Outreach Specialist
North Dakota Department of Agriculture

 

ROLLING SOYBEAN GROUND

Rolling soybean ground pushes rocks, large soil clods, or root clumps from the previous crop down into the soil and levels the soil to allow the appropriate combine cutter bar height during harvest. This will reduce harvest loss by allowing soybean stems to be cut below the pods. Cutting above or through low pods would result in non harvested pods and shattered seeds in the field. Harvesting soybean in a field that has been rolled also decreases the risk of rocks going into the combine and damaging the equipment. This helps reduce stress for the combine operator at harvest. Rolling a field may also help with the decomposition of the previous cropsí residue especially corn stalks. The advantage with rolling before the crop has emerged is improved seed-to-soil contact.

Disadvantages of rolling are increased potential for soil surface crusting and soil erosion.

The preferred time to roll fields is just after planting the soybean crop. However, if fields were seeded, but not yet rolled, there are still opportunities to roll the field after plant emergence.

Do not roll when the crop is just emerging. When the soybean seedling is in the crook stage (cotyledons just being pulled out of the soil) the stem may easily break. Plants will die if the stem is broken below the cotyledon leaves, because there are no growing points below the cotyledons. Rolling fields after soybean plants have fully emerged may cause some plant injury such as cracked or broken stems. Injured plants may be more susceptible to lodging and disease.

University research and farmer observations indicate that rolling between the cotyledon and first trifoliate stages of soybean may limit injury potential. Also, rolling during the warmest part of the day with less turgid plants may reduce potential plant injury. The percent damaged plants reported in University trials in 2003 and 2009 was around 20 percent for post-emergence rolling.

Rolling studies indicated a trend of lower remaining plant population as rolling was delayed from pre-emergence to the second trifoliolate soybean growth stage. However, seed yield was similar among the unrolled check and all rolling treatments (see Table).

Table: Soybean yield after rolling at different growth stages, Carrington ND, Wood Lake MN and combination of four locations in MN.

Plant stage

Yield Carrington 2003

Wood Lake MN 2008

Yield 4 locations in Minnesota 2009

 

Yield in Bushel per acre

Untreated

29.2

36.5

44.7

Pre-plant

 

38.6

46.6

Pre-emergence

30.9

39.9

46.6

50% Cotyledons emerged

28.7

-

46.1

Cotyledon

29.1

39.8

-

First trifoliolate (V1)

30.8

40.2

45.2

V3

-

-

45.3

P < 0.05

Not significant

Not significant

Not significant

Source: Carrington 2003, Endres and Henson, www.ag.ndsu.nodak.edu/carringt/agronomy/Research/ProdMgmt/03%20Soybean%20Rolling.pdf
Minnesota 2008, DeJong-Hughes,
www.smallgrains.org/PGConf08/DeJong08.pdf
Minnesota 2009, locations Canby, Wendell, Winger and Wood Lake, Holen et al.
  www.smallgrains.org/2009conf/GroundRollingHolen.pdf

A few observations about rolling:

  • High residue levels may protect the plants from damage during post-emergence rolling.
  • Plant damage in the wheel tracks (with post- emergence rolling) is likely to be more severe than in the rolled area.
  • Soybean plants are able to compensate, and although there may be stand losses or damaged plants, the yields at the end of the season tended to be similar between post-emergence rolling and pre-emergence rolling.
  • In certain soil types there may be a higher risk of sealing or crusting the soil.
  • There is an additional cost to own or rent a roller and go over the field with a tractor pulling the roller.
  • Harvesting of the crop after rolling is easier and one can potentially drive the combine a little faster.
  • Hans Kandel
    Extension Agronomist broadleaf crops
    hans.kandel@ndsu.edu

     

    IMPROVING CORN EMERGENCE IN CRUSTED FIELDS

    Parts of the state received pounding rain this past week followed by warm dry weather. In some soils this resulted in the formation of a nearly impenetrable crust for emerging seedlings. Soil crusting cannot only prevent emergence but can induce variability in timing of emergence. This is of particular concern for recently planted corn.

    What can be done to prevent stand losses and improve uniformity in emergence when crusting is a problem? This question is even more important given that it is probably too late in the season for replanting to be a viable option. The first step in determining what action is needed is to examine the extent of crusting and the stage of the germinating seedling. The coleoptile of the corn is designed to penetrate through the surface of the soil, so if you find leaves that have been force out of the side of the coleoptile before reaching the surface of the soil because of the crust, there is probably a need to help plants establish by breaking up this crust. Timing is critical in making a decision about dealing with crusting, as older seedlings are more easily damaged by crust breaking interventions. A range of implements have been used to break up crusts, with the rotary hoe the most commonly recommended. Since rotary hoes are rare in North Dakota, harrows, culti-packers, coulter-carts, and press drills have also been used with some level of success. Perhaps trash whippers can might also be adjusted to break up crush, though I have not heard of anyone actually using this approach successfully. Whatever implement you decide to use, try it in a small area of the field first. Make sure that the benefit from breaking the crust will be greater than any losses associated with damage caused to emerged or emerging seedlings. Don't worry too much if the operation "roughens"or breaks the tip of the coleoptile, as the emerging leaves will likely be able to establish normally. If the operation leaves seedlings on the surface or excessively damages developed seedlings, then try something less aggressive. Less seedling breakage will occur when operations are done later in the evenings when plants are typically more pliable.

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


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