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20
Sep
2012
Wheat Planting Dates, Variety Selection, and Seeding Rates
Author: Jason Kelley, Wheat & Feed Grains Extension Agronomist

A new wheat season is rapidly approaching, and many producers are starting to get ready.  The last few mornings have sure felt like fall with lows near 50 degrees!  Grain prices are good and have increased interest in wheat in many areas of the state.  This is a good time to discuss wheat planting dates, variety selection, and seeding rates, which I consider to be some of the most important decisions that will be made all season long.

Planting Date

Proper planting date for wheat is very important for optimal yields.  Rainfall (lack of or too much) often dictates when we plant wheat.  If soil conditions are ideal for planting, it may be hard to resist the temptation to plant earlier than recommended.   With recent rains, most areas have good soil moisture or may even be too wet to get in the field.  The current weather forecast is calling for high temperatures in the 80’s and no rain for the next several days, so we are in a drying period and will likely be able to get in the field in the next few days.  However, planting wheat too early can be a costly mistake.  Recommended planting dates for Arkansas are listed below:

Region Planting Date
North Arkansas October 1-November 1
Central Arkansas October 10-November 10
South Arkansas October 15-November 20

 

 

 

 

 

These dates represent the ideal planting dates for Arkansas, planting earlier or later can still produce good yields, but there are some risks that should be considered.

There are several reasons to avoid planting wheat earlier than recommended.  This year, fall armyworm numbers are extremely high across much of Arkansas.  I have gotten several calls about wheat in pastures and wildlife food plots that came up to good stands and then suddenly disappeared.  Planting wheat in September appears to be very risky this year from a fall armyworm standpoint.  Early planted wheat also is more at risk for damage caused by hessian fly.  We have not seen large numbers of hessian fly the last few years, but when we do it can be devastating.  The fields with the worst damage always seem to be ones that were planted earlier than recommend.    Early planted wheat is also more prone to barley yellow dwarf virus, which is transmitted by aphid feeding during the fall.

Last year with the extremely warm fall/winter/spring, many fields of early planted wheat often had too much fall growth which makes the plant more susceptible to freeze damage during the winter and early spring.   With increased corn acreage in the state this year, wheat planted following corn should not be planted earlier than recommended because of potential for residual nitrogen which may encourage excessive fall growth.

Late planting can also have risks.  A wet fall may delay or prevent planting.  This is the number one risk that I hear from producers.  Fall tiller development is very important for yield.  Fall tillers represent a majority of the yield potential of wheat.  When wheat is planted late, fall tiller development may be reduced, hence reducing yields.  With later plantings, seeding rates should be increased to compensate for reduced tillering.

Variety Selection

There are lots of varieties out on the market that will yield well, but choosing more than one variety with different genetics and having varieties with varying maturity is critical to spread your risks out.   Varieties should have resistance to stripe and leaf rust as well as good resistance to lodging and have good test weight and of course yield well.

Please refer to the 2012 Wheat Update publication, which contains a summary of current variety disease ratings, agronomic data including test weight, lodging, and relative maturity, and multi-year yield data from the University of Arkansas Wheat Variety Testing program.

One key production practice to consider is to plant late maturing varieties early and early maturing varieties should be planted later in the planting season.  Early maturing varieties tend to have less vernilization requirement and can begin to joint very early which greatly increases risk of freeze damage.

Seeding Rates

Seeding rates can vary considerably, depending on planting date, quality of the seedbed, and whether the wheat is drilled or broadcast seeded.  Using a grain drill allows for more precise seed placement and generally allows for a lower seeding rate.  Broadcasting wheat allows you to cover many acres quickly.

Recommended seeding rates for drilled wheat planted within recommended planting dates is 26 seeds/ft2.  The lbs/acre of seed can vary considerably with seed size, but with a normal seed size, this would be approximately 90 lbs of seed/acre (assuming you had good quality seed).   The figure below shows a summary of approximately 12 trials conducted in Arkansas over the last few years evaluating seeding rate response of drilled wheat when planted in October.  Planting more than 26 seeds/ft2 on sands or silt loams in these trials did not increase yields, while on clay soils, a higher seeding rate was needed to achieve maximum yield. A higher seeding rate on the clay soil was likely needed because of a rougher seedbed.

Figure 1.  Impact of Seeding Rate of Drilled Wheat on Yield in Arkansas

Figure 1. Impact of Seeding Rate of Drilled Wheat on Yield in Arkansas

If we are planting later in the planting window or into a rough seedbed or both, increasing seeding rates 10-20% or more would be justified.  Broadcast seeding generally takes higher rates of seed to obtain stands, since the seed is placed at varying depths with incorporation (some too deep, some on top of the soil).  Having a good firm seedbed prior to spreading seed is important.  Many producers are having good results broadcasting seed and then shallowly incorporating using a harrow, roller, or field cultivator with rolling baskets.  Using a disk to incorporate often buries much of the seed too deep and can result in poor stands.

I get asked whether broadcast planting or drill planting is better.  I prefer drilled wheat because I have better control on seed placement and I can usually use less seed.   In past research, yields between broadcast vs. drilled were variable depending on seedbed preparation and how soon rainfall occurred after planting.  In instances where broadcast wheat received a rain soon after planting, had a good seedbed initially, and wheat emerged nearly the same time as drilled wheat, little to no differences in yield were seen between drilled or broadcast at the same seeding rate.  However when dry conditions persisted after broadcasting and seed did not germinate timely or uniformly, and drilled wheat came up shortly after planning, drilled wheat tended to produce greater yields at the same seeding rate.

 


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