Samantha Pettus
Dr. John Settimi
Agronomy
February 10, 2016
Wheat
Wheat is grown in many countries across the world, according to the USDA the top three
producers are China, Europe, and the United States. In the U.S. the top producing states are
Kansas, Oklahoma, Montana, North Dakota, and Washington. Of the many wheat varieties
Washington predominantly grows Soft White wheat; Kansas, Montana, and Oklahoma
predominantly grow Hard Red Winter wheat, and North Dakota predominantly grows Hard Red
Spring wheat. Although Kentucky is not a large wheat producer a small amount of Soft Red
Spring wheat is grown in north western Kentucky. Western states tend to be large wheat
producers due to their mild climates. “Extreme heat causes wheat crops to mature faster,
reducing yield potential. The stress of high temperatures and/or lack of moisture results in
smaller wheat kernels with a higher protein content than would occur with more favorable
weather.” (USDA). Wheat is typically grown on rotation. A common wheat rotation is a three
year rotation where wheat is grown year one, sorghum is grown year two, and the land is left
fallow year three. This rotation or a rotation very similar are used in most western wheat
growing states.
Wheat is best known for its role in products such as breads, pastas, breakfast cereals, and
ice cream cones. However wheat has many other uses such as livestock feed, livestock bedding,
and in some cases wheat is used in pastures. Other products made from wheat and wheat
byproducts are alcohol, gluten, and paper products which are made from the stalk of the wheat
plant. The different wheat varieties are used for different products due to their protein content.
Hard red winter wheat and hard red spring wheat are used mostly for bread; soft white wheat and
soft red winter wheat are used for crackers, cookies, and cakes, and durum wheat is used to make
pasta.
While Kentucky is not one of the large wheat producing states it still produces a
reasonable amount of wheat. The following statistics are from the USDA’s 2014 Crop
Summary.
Location
Kentucky
Kansas
U.S. Total
Wheat Acres Harvested
2012
2013
440,000 acres
610,000 acres
9,100,000 acres
8,450,000 acres
48,758,000 acres
45,332,000 acres
2014
510,000 acres
8,800,000 acres
46,381,000 acres
Table 1
Wheat prices vary depending on which variety is being sold, price trends for the year, and
the quality of the wheat. The average price per bushel of wheat in 2009-2010 was $4.87
(USDA). Average wheat prices within the last years have seen a low of $3.27, and a high of
$6.78. Wheat is sold by the bushel, each bushel of wheat weighs 60 lbs. According to the
USDA in 2009 hard red winter cost $4.84 a bushel, hard red spring cost $5.26 a bushel, soft red
winter cost $4.35 a bushel, soft white cost $4.52 a bushel, and durum cost $5.47 a bushel.
Wheat crops require nitrogen fertilizer. “During the growth season, microorganisms
convert organic sources of nitrogen to inorganic nitrogen that can be utilized by the wheat
plant.”(USDA). Optimal pH for wheat crops is between 6.0 and 7.0. According to M.L. Vitosh
at Michigan State University, “growing wheat at a pH below 6.0 often results magnesium (Mg)
deficiency, slower mineralization of organic nitrogen (N), reduced availability of phosphorus (P),
and increases the possibility of aluminum (Al) and manganese (Mn) toxicity.” The fertilizer
needs for growing wheat depend upon the type of wheat being planted. Wheat with a higher
protein content requires more nitrogen fertilizer in order to reach the adequate protein level. This
means that hard red winter, hard spring winter, and durum require more nitrogen fertilizer than
soft red winter and soft white require.
Many farmers are confronted with the choice of how to till their fields for the next crop.
Wheat fields can be tilled in the conventional manner where residues from the prior crop are
buried under the turned soil. Conventional tillage methods using a disk plow leave little to no
soil unturned. Another method of tilling a wheat field is by minimum tillage. Minimum tillage
is defined by the Food and Agriculture Organization as, “a one-pass tillage operation at sowing
synchronous with seed placement […]”. The third method by which wheat fields can be tilled is
by no-tillage. No-tillage disturbs only enough of the soil for the seed to be dropped. Minimum
till is a happy medium between conventional tillage and no-tillage. Conventional tillage disturbs
all of the soil and leads to a loss of soil structure; no-tillage fields may run into weed control
issues unless herbicides are applied to the field.
Southern States developed three new varieties of soft red winter wheat for 2016. Two of
these varieties are SS 8513 and SS 8530. According to Southern States the SS 8513 matures
early allowing for an early planting of the next crop, this variety has a very good resistance to
stripe rust and the plants grow to be medium tall. For SS 8530 Southern States describes this
variety as high yielding with large kernels at maturity. Southern States seeding guide states “The
objective is to achieve 22 to 25 vigorous seedlings per square foot, which typically requires
planting 30 to 35 seeds per square foot.”
Planting Time
Recommended
Planting Rate
Table 2
Timely
Row Width
4”
6”
7”
8”
12
18
20
22
2 weeks late
1 month late
Seedlings Per Linear Foot
13
14
20
22
22
24
24
26
The picture below shows a seeding drill being pulled behind a tractor. The drill places
each seed at a specific depth within the soil and at a set distance from other seeds. This ensures
uniformity of the crop rows.
Photo 1
Wheat fields are susceptible to many different types of weeds some of which are
dandelions, chickweed, deadnettle, cheat grass, and downy brome. Having a large quantity of
weeds in any crop field is an issue because the weeds suck nutrients out of the soil that otherwise
could have gone to the crop plant. Broad leaf weeds such as dandelions, chickweed, and
deadnettle can be killed using 2,4-D, however 2,4-D must be applied at the correct time to
minimize crop injury. According to Bill Johnson and Glenn Nice at Purdue University “The
occurrence of stem elongation can be easily detected by the appearance of the first node or
“joint” above the soil surface, commonly referred to as the “joint stage.”[…] If jointing has
occurred, applications of 2,4-D, MCPA and Banvel should be avoided because crop injury and
yield loss are likely.” For grass type weeds such as cheat grass and downy brome other herbicide
chemicals may be applied. The two most common herbicide chemicals that are effective in
killing grass type weeds are Mesosulfuron-methyl, and Pinoxaden. Mesosilfuron-methyl should
be applied before jointing and Pinoxaden should be applied between the 2-leaf stage and the
preboot stage.
Three possible insect pests that may be a problem in wheat are Bird Cherry- Oat Aphids,
Greenbugs, and Brown Wheat Mites. The bird cherry-oat aphid is dark green with a red patch on
its abdomen. According to Kansas State Research and Extension bird cherry-oat aphids are one
of the largest aphid varieties found on wheat; these aphids thrive in cool temperatures allowing
them to live longer into the wheat growing season than many other insects. Bird cherry-oat
aphids can be killed using any pesticide labeled for aphid use. The next insect pest is the
Greenbug, which is a light green aphid that feeds on the underside of the wheat plant’s lower
leaves. The table below shows the damage levels of greenbugs in wheat crops.
Table 3
Approximate Damaging Levels of Greenbugs
Stage and Development of Plant
Number of Greenbugs per linear foot
Seedlings, thin stands less than 3 tillers
50
3-to-6 inch wheat, 3 tillers or more
100 to 300
6-to-10 inch wheat
300 to 500
The information in this table was found in the article, Wheat Insect Management 2015, written
by Kansas State Research and Extension.
Greenbugs can be killed using a number of different insecticide chemicals such as
Chlorpyrifos, Malathion, Dimethoate, and Endosulfan. The final pest listed is the brown wheat
mite, this brown insect is a problem for wheat grown in dryland areas such as Kansas.
According to Kansas State Research and Extension “Activity is highest in the late fall and early
spring, with populations usually peaking around mid-April.” Brown wheat mites can be killed
using Chlorpyrifos and Dimethoate. There are some insect control practices that can be
performed before planting crops that may reduce the need for insecticides down the road. One of
these is making sure that all volunteer wheat in the field is destroyed prior to the planting of the
wheat crop. This ensures that any insects feeding on the volunteer wheat will not spread to the
planted crop. In the photos below, photo 2 depicts a brown wheat mite, photo 3 depicts a pair of
greenbugs, and photo 4 depicts a pair of bird cherry-oat aphids.
Photo 2
Photo 3
Photo 4
Two common diseases that can become a problem in wheat crops are powdery mildew
and leaf rust. Powdery mildew can be diagnosed by the appearance of white lesions on the
leaves of the wheat plant. Leaf rust can be diagnosed by the appearance of orange or brown
lesions on the leaves of the wheat plant. Powdery mildew and leaf rust can both be managed by
applying foliar fungicides. Another management practice for disease is genetic resistance.
There are certain varieties of wheat seeds that are more resistant to specific diseases. For
example Southern States carries a soft red winter variety called SS 8500 which has excellent
tolerance against leaf rust, and very good tolerance against powdery mildew.
Harvesting time for both spring and winter wheat crops may depend on many variables
such as the number of acres planted, the weather conditions, yields, and location. The
information in the table below was found in the USDA Agriculture Handbook Number 628, the
title of the article is Usual Planting and Harvesting Dates for U.S. Field Crops December 1997.
Winter Wheat Harvesting Dates
Beginning
Ending
May 1st – July 28th
July 1st – September 8th
Spring Wheat Harvesting Dates
Beginning
Ending
July 15th – August 7th
August 30th – October 5th
Table 4
Wheat crops should be harvested when the plant becomes straw colored and the kernels
harden. The crops must be dry enough to safely harvest, the dryness can be tested with a
moisture meter. If a moisture meter is not available weigh a ½ lb sample, dry the sample in an
oven over night, and reweigh the dried sample. To determine the moisture percentage of the
sample use the equation (wet weight-dry weight)/wet weight X 100 = Seed moisture (%).
(McNeill, Overhults, Montross). A combine is used to harvest wheat crops, the combine will be
equipped with a rotor stripper header or conventional cutter bars based upon what variety of
wheat is being harvested and farmer preference. In the photo below a combine is harvesting
wheat using conventional cutting bars.
Photo 5
Before entering the field in the combine, adjustments should be made to the cylinder
speed, concave clearance, screen opening, and fan speed. These adjustments should be made to
fit the variety of wheat you are harvesting. Once in the field slight adjustments can be made to
perfect the process. According to the article Harvesting, Drying, and Storage Wheat by Sam
McNeill, Doug Overhults and Mike Montross, “Lower cylinder speeds will reduce kernel
damage. Increased fan speed will clean wet chaff more easily, but more grain may be blown out
with chaff.” After wheat has been harvested from the field it needs to be dried in order to prevent
the wheat from spoiling while it is in storage.
References
United States Department of Agriculture. Crop Production 2014 Summary. National Agriculture Statistics Service.
2015.
Gibson, Lance and Garren Benson. Origin, History, and Uses of Oat (Avena sativa) and Wheat (Triticum aestivum).
Iowa State University, Department of Agronomy. 2012. Web.
Vocke, Gary and Mir Ali. U.S. Wheat Production Practices, Costs, and Yields: Variations Across Regions. USDA.
Economic Information Bulletin Number 116. 2013
Vitosh, M.L. Wheat Fertility and Fertilization. Department of Crop and Soil Sciences Michigan State University.
Extension Bulletin E-2526. 1998.
Bligh, K.J., H. Gomez Macpheron and T. Friedrich. Suitable methods of tillage for the farm. FAO Corporate
Document Repository. Agriculture and Consumer Protection. Web.
Clark, Andy. Managing Cover Crop Profitability. Sustainable Agriculture Network, Bettsville, MD. 3 rd ed. 2007.
Michaud, J.P., R. Jeff Whitworth and Holly N. Schwarting. Wheat Insect Management 2015. Kansas State
Research and Extension. January 2015.
Johnson, Bill and Glenn Nice. Weed Control in Wheat. Purdue Extension Weed Science. 2006.
North Dakota State University Extension Service. Wheat Disease Identification. Plant Disease Diagnostic Lab.
2011.
United States Department of Agriculture. Usual Planting and Harvesting Dates for U.S. Field Crops December
1997. National Agriculture Statistics Service.
Herbek, James and Chad Lee. Growth and Development. Section 2. Pages6-12. Untitled Online Book.
McNeill, Sam, Doug Overhults and Mike Montross. Harvesting, Drying and Storage Wheat. Section 10. Pages 6669. Untitled Online Book.
Southern States. 2015/2016 Soft Red Winter Wheat Seed Varieties with the Best Seed Size, Standability, Disease
Resistance and Yield Potential.