Sunflower

Sunflower

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Crop Rotation - Crop Development

  • As a Rule, Crop Rotation practices improve the performances of crops.
  • By varying crops in the same season, farmers can spread equipment demand throughout the season, reducing costs while increasing utilization.
  • Exploitation of soil fertility is improved, as different crops roots explore different layers of soil and use different nutrients.
  • Structure of soils improves, because residues from crop roots stay at different depths and residues are also different; sunflower roots may achieve 2-3 meters of depth, which is not common with other crops.
  • Risks of sunflower disease will be greatly magnified by short sequencing of sunflower in a crop rotation.
  • Sclerotinia or white mold (wilt, stem rot and head rot) is the primary disease concern with a poor sunflower rotation. Improper rotations can also result in Verticillium wilt, Phoma and premature ripening.
  • Rotations of at least three- or four-year spacing between sunflower or other Sclerotinia susceptible crops (e.g., canola, soybean) are recommended to help reduce disease risk.
  • For sunflower, good prior crops are corn, wheat and similar cereals and sugarbeet. It is not suggested replanting sunflower on sunflower, due to building up of diseases. A period of minimum 3 or 4 years is suggested before the crop returns on the same field. Avoid short rotation with soybeans and canola, because these crops have a common fungi disease with sunflower (Sclerotinia sclerotiorum). A period of two years is suggested before planting such crops on the same field.


Tillage - Primary and secondary

  • Primary Tillage for sunflower is better carried out at fall. Primary tillage should begin right behind the combine.
  • A wide choice of tools are available for Primary Tillage
    - Moldboard plow
    - Chisel plows
    - Disk rippers
    - Offset disk
  • Pre-emergence herbicides may be incorporated with a tandem disk, chisel or sweep plows, disk harrow, long-tine harrow, rolling harrow, or air seeders with sweeps in different sequences or combinations.
  • Disk Rippers are a good option for fall Primary Tillage, as equipment was reinvented with more aggressive residue handling up front, higher clearance, and an array of seedbed attachments on the back.
  • Secondary tillage is carried out before planting, ideally one or two days before. The goal is to achieve a proper seedbed ideal soil particles for good contact between seeds and soil. Soil with a rough surface hinders proper seed germination and plant growth, ultimately leading to lost potential yield.
  • Large soil clods can cause planter row units to bounce. This makes it challenging to control planter depth and maintain seed placement accuracy for uniform plant spacing.
  • A consistent seed bed is important better germination of seedlings
    - A smooth surface improves application and nutrient consistency
    - Plant roots require a balance of water and oxygen from the soil pore space
    - Uniformity of seed bed creates uniform crops reducing plant competition
  • The right soil-air-water balance helps plants to establish strong root structure which:
    - Limits plant stress during drought periods
    - Improves plant water and soil utilization
    - Improves crop anchorage


Planting

Hybrids available for planting differ in maturity earliness and kernels’ oil content and composition. On the base of maturity, hybrids are divided in 5 groups: early, middle-early, middle late and late. Sunflower seeds begin to germinate at a temperature of 8°C. Seeds are sold in package of 70.000- 75.000 seeds, which is the rate for one hectare with a weight of 4 to 6 kilograms. Seeds are dressed with insecticide and fungicide to be protected in the very early stage of growth. We suggest a rate of 8 seeds per square meter in order to have 6-7 plants at harvesting time: This rate is ideal for fertile soils with a good moisture content during the season. In worst soils the rate would be 5 plants per square meter at harvesting.
• Sunflower yield components are:
1. The number of heads per hectare.
2. The number of kernels per head.
3. Average weight of kernel.

• Because cropped sunflower produces only a head per plant, the number of plants per hectare is the most important factor for production.
• Commonly sunflower is planted with ann interrow spacing of 70 or 75 centimetres. reducing spacing down to 40-45 centimetres can increase yield of 10-20%, specially when planting hybrids of low size (not tall).


Spraying

  • Crop protection is of paramount importance, whatever the crop pattern are. The less tillage is applied, the more chemical control of weeds becomes crucial.
  • Weed control is carried out both with pre-sowing, pre-emergence and post-emergence (on-top spraying). Weeds can damage the yield up to the 100%, if not controlled or controlled to late.
  • When spraying is needed, timeliness is more crucial than in other operations. Weeds and pests are to be hit in right time and with precise doses of chemicals.
  • Productivity and reliability are important factors that affect the result of spraying operations, as well as accuracy in application rates of expensive chemicals.
  • Uniform droplet size helps to produce consistent canopy coverage and the desired pest prevention.
  • Adjustments of pressure and volume are required depending on what our target is (weeds, fungi, insects).
  • Drift control is another important factor


Hoeing

  • Conventional tillage plans may include the option of row cultivation once or twice during the early growing season before the sunflower reaches a height too tall for cultivation. This can be used with or without pre-emergence or post-emergence herbicide.
  • A rotary hoe or harrow can be used just before sunflower emergence and/or at the V-4 to V-6 development stage. Harrowing or rotary hoeing between emergence and the V-4 stage can result in injury or death of the sunflower plant. Depending on planting depth and stage of crop development, stand losses are generally less than 5 percent if the sunflower crop has at least two fully expanded leaves.
  • Proper adjustment of the harrow or rotary hoe will maximize damage to the weeds and minimize injury to the sunflower crop.


Harvesting

  • Harvesting traditionally begins between September and October when moisture content reaches an ideal 9-10%.
  • It is possible to begin harvesting from a 25% moisture content level if drying facilities are available. This practice is not recommended as Sunflower burns easily and there is significant risk for crop damage.
  • A dedicated header with catch pans is essential to avoid heavy losses of heads.
  • Desiccants can be applied to the crop after it reaches the physiological maturity to speed the dry-down process. The chemical compounds act much like a frost to kill the green tissue on the plant and accelerate the drying process.


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