ISSUE 5    June 2, 2005

SUNFLOWER - HOW LATE CAN WE PLANT?

Most years in North Dakota, a number of sunflower fields are planted late or replanted. The many reasons for this include: extremely cold or dry conditions, wind erosion, insects (cutworm), diseases, hail and frost. The wet May in 2005 will go down as one of the later planting of sunflower and several other crops.

Research on late planted sunflower has been conducted at various North Dakota NDSU Research Center sites. Results of these studies are shown below:

Table 1. Sunflower yields* (lb/A) as influenced by planting dates at Prosper and Carrington, ND.

Approximate planting date

Hybrid

 

% oil

SW101**

894

June 1

2046

2087

43.9

June 15

2323

1891

44.1

June 30

1692

1076

40.5

July 15

312

123

33.9

* Average 3 years, 2 locations ** Sunwheat 101 - early semi-dwarf sunflower

Table 2. Sunflower oilseed yields* - Early vs. late planting

Planting time

Langdon

Minot

Mid May

1828

1632

Early June

1179

1368

difference

649

264

• 5 year ave. Yields - lbs/A

• When planting sunflower late (after June 10) it’s suggested to plant early maturing hybrids. Selection of short season sunflowers will increase the chance of reaching maturity in the northern areas of North Dakota and Minnesota.

• Planting of non-oilseed or confectionary sunflowers is discouraged in June.

Duane Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.edu

 

FORAGE OPTIONS - WARM SEASON GRASSES

Hay and certain forage supplies may be short in 2005 with the early frosted alfalfa plus dry conditions early in the southwestern region of the state. This first cutting of alfalfa and alfalfa-grass harvest is expected to be below average yield potential because of early dry and cold conditions. Emergency hay crops to consider include sudangrass, sorghum, sorghum x sudan hybrids and millets. Planting dates for crops such as hay millets, sundangrass, sorghum, sorghum x sudan is mid to late June. These crops are warm season grasses and develop rapidly under warm, moist conditions.

Foxtail Hay millets

Foxtail millets are grown primarily for shortseason emergency hay crops. Several landraces have been developed over time and are grown in North Dakota. Foxtail millet would be the best choices for emergency hay. Proso millets are slightly inferior to foxtail hay millets for hay. Planting foxtail millets can be delayed until mid-June into the first week of July. When used for emergency hay production, late planting is usually encountered.

Plant into moist soil about 1 inch deep. Shallower seeding may be desirable on heavy textured soils with good moisture. Germination is fairly rapid but early seedling vigor is lacking. Foxtail millets have low seedling vigor and in general are poor competitors with weeds. A seeding rate of 15 to 30 pounds per acre is recommended. The higher rates are recommended in eastern North Dakota with the higher rainfall potential. In western North Dakota, 15 pounds is adequate on weed free fields.

Harvest millets for hay in the late boot to early bloom growth stage. Any delay after full head emergence will reduce quality. Bristles become hard as maturity approaches and may cause sore mouth, lump jaw and eye infections when fed to livestock. Hay protein content is highest when the ratio of leaves to stems is high. Curing foxtail millet requires attention as light stands tend to sun dry rapidly after cutting, while heavy stands, especially of the German type, cure at a slower rate. If expected yield levels are greater than 1 ˝ tons per acre, crimping will help the curing process. Potential yield of foxtail millet has is influenced by moisture relationships. Research trial yields from North Dakota Research Centers ranged from 2.1 to 3.2 tons/acre, with German millets having the most consistent yields for the hay millets.

Sudangrass and Sorghum - sudan crosses

The best time to plant sudangrass or sorghum - sudan crosses is late May or early June. If emergency forage is required, planting can be delayed until late June. Forage yields will be reduced with late planting.

The seeding rate varies considerably depending on the sorghum type. Sudangrass and sorghum-sudan crosses in 6 to 7 inch row spacings should be seeded at 25 to 30 pounds per acre. Forage sorghum varieties, hybrids and crosses in 30 inch or wider row spacings should be seeded at 5 to 8 pounds per acre. There has been some information from commercial sources suggesting much lower seeding rates. This may be true for some specific hybrids, but low seeding rates may result in thin stands and lower forage yields. A well prepared, firm, moist seedbed is best, although acceptable stands may be established with stubble-planting equipment. Plant 1 to 1.5 inches deep on medium and heavy textured soils and 1.5 to 2 inches deep on sandy soils.

Both Piper and Trudan are older traditional varieties of sudangrass. New sudangrass varieties with "BMR" (Brown Mid Rib leaf characteristic) are now available and have shown to be of better feeding value than the older traditional varieties. Seed may be difficult to locate but can be found with some searching.

A harvestable hay crop 50 to 72 inches tall can be anticipated in about 60 to 75 days after emergence depending on environmental conditions. Under good moisture conditions, sudangrass can grow to 6 to 8 feet tall, but forage quality decreases with advancing maturity. An early harvest (end of July or very early August) will normally permit a second harvest and maintain a higher forage quality.

Be careful when harvesting sudangrass for hay to make sure the forage is dry. The coarse stem will often retain enough moisture to cause the hay to mold even though it appears adequately dried. Always use a hay conditioner to crimp the sudangrass stem to enhance drying. When tall material is harvested, reduce the swather width by half to reduce the quantity of material in the windrow.

Sudangrass is also used as a warm-season pasture. When used as pasture, however, there is potential for HCN or prussic acid poisoning. Only graze once the crop is 20-24 inches or taller as a minimum for safety to livestock. Don’t graze if sudangrass is under any moisture stress. HCN is not a problem in properly cured sudangrass hay.

 

HARROWING AND ROTARY HOEING CROPS

Populations of shallow emerging weed seedlings such as foxtail, kochia, Russian thistle, wild mustard, pigweed, nightshade and below ground white weed sprouts can be severely reduced by timely harrowing or by use of rotary hoe. Use of these mechanical tools will not reduce wild oat, cocklebur and volunteer sunflower populations due to their deeper emergence, and strong root system. However control will be higher if they have not yet emerged and happen to be near the soil surface.

Light spring tooth harrows should be set shallow (1/2 inch deep) and angled back to reduce the potential of crop injury. Rotary hoes should be operated at fairly high speeds.

A general recommendation with mechanical weed control is to till one to five days after planting followed by a second tillage pass 7 to 10 days later. A dry level soil surface is necessary to allow effective operation of the tillage tool and to minimize reestablishment of the displaced weed seedlings. Warm, windy and bright sunshine conditions, as well as dry weather during and following tillage will result in the best weed control as weed roots will dry out before they can reroot. Timing of operations in mid day to early afternoon will allow for better weed seedling desiccation.

It’s best to harrow or hoe wheat and barley at the two leaf stage and not later than the three leaf stage to minimize injury potential. Wheat can be harrowed twice while barley should be harrowed only once. Corn can be rotary hoed or harrowed between the one and four leaf stage, and sunflower, 2 to 6 leaf stage. Soybean and dry beans can be harrowed between the 1 to 2 trifoliolate stage. It’s advised not to harrow or hoe canola, mustard, crambe or flax seedlings. Refer to NDSU Extension Cir. W-1134 for additional information on mechanical weed control with the harrow or rotary hoe. Also see NDSU Extension web site: http://www.ext.nodak.edu/extpubs/plantsci/weeds/w1134w.htm

 

COOL & WET WEATHER FAVORS HIGH YIELD POTENTIAL IN SMALL GRAINS

The cool wet weather of the past month has made field work difficult and slowed emergence and growth of the warm season crops. For early planted small grains, however, environmental conditions have been ideal for high yield potential development.

Small grains are cool season grasses and when other factors such as moisture and plant nutrients are not limiting, develop their highest yield potential when temperatures are cool during their early developmental stages. Wheat that was planted before May 1st is now somewhere between the three and six leaf stages depending on planting date and location in the state. At the three leaf stage tiller production begins in earnest and shortly thereafter the growing point on the main stem switches from forming new leaves to forming the spike.

It is during the very short period between the three leaf and six leaf stages that the number of spikelets per spike are fixed. Most physiologists agree that the short period of active spike development is probably the single most critical phase in determining grain yield potential. Cool weather favors the development of large spikes with daytime temperatures less than 65 degrees being optimum. Similar to last year, temperatures during the early growth of early planted small grain crops during this critical spike development stage have been or are ideal. Soil moisture throughout most of the state have also been favorable; environmental conditions have enabled the development of a good foundation for high yields. Much is to be done on the management side, however, before this potential yield can be realized. The following are key management practices to consider in order to realize the yield potential that has been established thus far:

  • Eliminate nitrogen stress. Most if not all supplemental N should be available to plants’ roots by the 6th leaf stage in order to have an impact on yield (see article by Dave Franzen in last week’s Crop and Pest Report). Now (before the 6th leaf stage) is the time to apply extra N if you think your crop will exceed your initial yield goal. N applied after the 6th leaf stage may increase grain protein levels but will have only marginal impact on yield.
  • Control weeds in a timely manner and carefully evaluate the need for applying a fungicide with your herbicide to control foliar diseases that are common early in the season.
  • Consider applying a fungicide later in the season for scab and foliar disease control. Photosynthesis during the grain filling stage largely determines the kernel weight at harvest.
  • Joel Ransom
    Extension Agronomist – Cereal Crops
    joel.ransom@ndsu.edu


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