Check your Sunflower Stand!

11 Jun Check your Sunflower Stand!

Check your Sunflower Stand!

Achieving the target population in Sunflower production is key to optimum production.

Evaluate your stand

Now that you have planted the crop it is critical that you monitor the plant population while there is still time to replant if needed. There are several factors that can result in uneven and/or less than desirable stands.

• • Sunflower is well adapted to drier climates but still need adequate moisture to germinate.
  • Sunflower seedlings are strong emergers but may struggle to emerge through heavy residue.
  • Seeding depth — emergence is much better from 2” vs. 4 “
  • A heavy soil crust can inhibit emergence.
  • Preplant herbicide applications — burndowns applied too close to planting time.

What is the right population for your crop?

• • End use matters? Plant Confection flowers from 14,000 to 20,000 and oil seeds at up to 25,000 plants/ac.
  • What is your moisture situation? Lower populations are recommended in droughty areas and lighter texture soils.

Determining the need for replant

The decision to replant ultimately rests on the current population and the new planting date but other inputs such as availability of equipment and labor, herbicides already applied, seed cost, etc. must be considered.

• • Accurately determine your current stand – It is critical to evaluate the entire field rather just the poorest looking area. Take at least 5 stand counts from random selections across the field.  At each location mark off a length of row, count the plants in three adjacent rows and average to get one result for that location.   Average the counts across the field for the final stand count.   Determine the % stand vs. the original target.  While Sunflower can compensate for lost population and optimal populations vary by hybrid and location the study below suggests populations below 15K plants per acre can result in significantly lower yield and oil.

*Robinson, R.G. et al.  Minnesota Ag Exp St Report 180 – 1982

Planting dates

While sunflower has a wide planting window timing is always a factor in deciding on replanting. This is especially true in shorter season and higher elevation areas.   Yield, oil, and oleic percentages decease in ND as planting dates move toward the end of June.  The chart below shows flowers planted in late June on the High Plains may only yield 70% of optimal planting time and oil content may drop by 10%.

*Meyer, Pilcher & Piers – Colorado State University Cooperative Extension

• So, the decision ——– Combining the effects of the stand reduction and the later planting date can help you compare the impact of leaving the current sunflower stand or replanting on your bottom line at the end of the year!