Alvin J. Bussan, MSU Extension Crop Weed Specialist
Greg Carlson, Agronomist, Northern Ag Research Center (NARC), Havre
Joyce Eckhoff, Agronomist, Eastern Ag Research Center (EARC), Sidney
Ken Kepheart, Agronomist, Southern Ag Research Center (SARC), Huntley
Dave Wichman, Agronomist, Central Ag Research Center (CARC), Mocassin.
Phil Bruckner, Winter Wheat Breeder, Plant Sciences Dept., Bozeman
Jeff Jacobsen, Soil Fertility Specialist, LRES Dept.,
Bozeman
This article was originally written in
the fall of 2000, but with the persistent dry conditions around the state, the
information is still applicable. Even
though it’s now looking better, the information is still pertinent and some
producers might still be in the decision mode. Besides, the best time to deal
with these issues is when they are the topic of discussion at the coffee shop.
The following is a compilation of input from several research agronomists and
Extension specialists concerning the best approach to growing winter wheat
under drought conditions. Here is what
they had to say.
Based on the
current status of the soil moisture profile, should winter wheat planting be
considered this fall?
A must have bulletin for all farmers of
MT trying to determine which crop is best suited for their environment and
plant available moisture is entitled ‘Grain Yields Related to Stored Water and
Growing Season Rainfall’ by Paul Brown and Greg Carlson (AES special bulletin
SR35, Nov. 1990). This bulletin
predicts yield of various crops based on stored water and probability of in
season rainfall. This bulletin is
exceptional and provides statewide information on average growing season
precipitation. The following grain
yield prediction was calculated with the bulletin.
For example, the current soil moisture is estimated at 2 foot. Heavy clay soil holds 2” of plant available water/ft (sandy loam holds 1”/ft and silty soils hold 1.5”/ft). Based on 70% probability (7 out of 10 years), a minimum of 4 to 4.5” of precipitation in season. Very little winter precipitation benefits crops during the season so it is not included in these calculations. Therefore, total plant available water for crops is predicted to be 7.5”. It takes 3.8” of water to grow the first bu. of winter wheat and each inch of water after that results in 5.8 bu of winter wheat (this varies by crop). Projected winter wheat yield is: (7.5” plant available water – 3.8” needed to maturity)*5.8 bu of winter wheat per inch of water = 21 bu/A.
Greg Carlson (NARC). Depends on if it will rain between now and October 1 and when will it freeze (some areas of the Hi-Line have received no precipitation the past 2 months of 2001). Winter wheat is amazingly resilient. Cut way back on acreage, but still grow some to take advantage of small windows of opportunity that may open up. Base decision to grow winter wheat on market, weeds, wheat stem sawfly as well as soil moisture status.
If growing winter wheat is essential within the cropping system, what are some specific recommendations for growing a successful crop this year?
For making decisions on winter wheat variety please refer to the MSU 2000 winter wheat variety performance evaluation and recommendations (Bulletin 1098). The bulletin contains information on winter hardiness, wheat stem sawfly tolerance, disease tolerance, yield and much more. Wait until soil temperatures are below 55 degrees (mid afternoon, at 2” soil depth, 3 days in a row) before seeding to minimize insect and disease problems. Tillage equipment pulled in front of seeding equipment can be used to pull up deep soil moisture to help place seed in moist soil and improve stand establishment. Do not conduct tillage of any kind except seeding to conserve as much soil moisture as possible.
Greg Carlson (NARC). If winter wheat can be sown into moisture, than seeding should be done by October 1 in the NE triangle. Winter wheat varieties with winter hardiness ratings of at least 4 (Norstar, Morgan, Erhardt, Agazzi, Rough Rider) should be seeded in NE triangle if sawfly is not a concern. Winter wheat needs fall growth in order to reach full winter hardiness potential. If a super winter hardy variety such as Norstar is seeded, but fails to establish before winter, than all winter hardiness benefits are lost.
Dormant seeding winter wheat may be the only option due to lack of moisture in the soil surface. If dormant seeding, then use varieties with a winter hardiness rating of 3. Winter wheat varieties with high winter hardiness ratings (4 or 5) also have more stringent vernalization requirements (colder for longer durations). Germination has to start to allow vernalization of winter wheat. If germination prior to winter is uncertain, varieties won’t reach winter hardiness potential, but intermediate varieties (winter hardiness of 3-includes sawfly tolerant varieties) are more likely to vernalize if germination was delayed until March.
Joyce Eckhoff (EARC). If winter wheat can be sown into moisture, than seeding should be done from September 15 to 30. Grow winter hardy varieties. Without fall moisture, frost seeding winter wheat may be an option.
Ken Kepheart (SARC). Have to rely on in season moisture for successful winter wheat crop in 2001. As such, use minimal inputs and minimize exposure to risk if seeding winter wheat in fall of 2000. Don’t seed after October 15th. At the same time, winter wheat yields will not benefit from early seeding due to lack of moisture to get it growing so wait as long as possible in the hopes of receiving some fall precipitation.
Dave Wichman, (CARC). Dormant seed re-crop winter wheat, after mid October up until January (do not dormant seed winter wheat after mid February. If dormant seeding winter wheat, absolutely do not incorporate Fargo. Germinated, but non-emerged wheat seedlings will not survive through the winter in Fargo treated soil. Early seeding winter wheat in September requires at least 15” of soil moisture to ensure the crop gets established prior to winter and is robust enough to survive.
How much fertilizer should be applied? Jeff Jacobsen, Soil Fertility Spec.
Greg Carlson (NARC). Starter fertilizer must be applied to improve crop establishment and fall growth. Starter should include 5 to 15 lb/A of actual N, but cannot exceed 15 lb/A total of actual N and K if applied in the seed row (can be increased in wide seed rows). Starter P fertilizer applications will include appropriate amount of actual N for starter.
Do not band apply anhydrous at seeding in dry soils. Separation between the seed and anhydrous is decreased in dry soils and may affect stands. Moisture is critical for absorbing the anhydrous and preventing it from moving through the soil or escaping from the soil altogether. Nitrogen fertilizer can be applied if deep or side banded (1.5” away from seed row). May want to cut N rate back for this fall than apply 40-50 lb/A of actual N in spring if a good crop has established. If all N fertilizer is applied in the fall and the crop fails, reseeded spring wheat can still utilize the applied N.
Joyce Eckhoff (EARC). Fertilize according to yield goal and soil test recommendations. Yield goal should be easier to estimate in the spring, so top dress nitrogen fertilizer to optimize results. Starter fertilizer should be used to apply P and K.
Ken Kepheart (SARC). Do not apply any N fertilizer in the fall. Wait until spring when yield potential can be accurately determined and top dress. Nitrogen fertilizer needs will be met with starter P fertilizer.
Dave Wichman, (CARC). Anhydrous applications in dry soil can be lost if there is inadequate moisture to tie up the ammonia. Deep incorporation of ammonia into soil moisture can cause water losses and delay or decrease crop emergence. As an alternative, consider top dressing nitrogen fertilizer in the spring. Starter fertilizer is absolutely necessary for seeding into stubble or fallow. Recommend 50 lbs/A 11-56-0 or 20-20-20 as starter fertilizer.
What rate should winter wheat be seeded at considering current soil and weather conditions?
Greg Carlson (NARC). Winter wheat seeding rate is to establish a population and seeding rate should vary with seed size. Don’t recommend lowering seed size for drought conditions.
Joyce Eckhoff (EARC). Winter wheat seeding rate should be one million live seed per acre regardless of climatic conditions.
Ken Kepheart (SARC). Go with lower seeding rates (45 lbs/A) to insure full head and seed develop and better grain protein. Tillering should help compensate for low seeding rate in the event sufficient moisture is received during the growing season.
Dave Wichman, (CARC). Recommend 45 to 60 lb/A under fallow and 55 to 70 lb/A in recrop. Recommend higher seeding rate under recrop to compensate for reduced tillering and lower crop establishment.
Weed management recommendations A.J. Bussan, Crop Weed Specialist
Don’t seed winter wheat if downy brome or jointed goatgrass is anticipated to be a problem (grew winter wheat within the last 2 years or failed to prevent seed set in fallow). New downy brome herbicide, Maverick, requires root activity for effective control. Therefore, precipitation will be required to incorporate the herbicide and achieve the most satisfactory results. In addition, risks associated with growing a successful winter wheat crop in 01 may not justify cost of Maverick applications.
Drought stress can increase susceptibility of winter wheat to injury from soil applied (PRE) Finesse or Amber applied for downy brome control. Crop can be safened with Post emerge applications of 2,4-D or MCPA if Finesse or Amber are used. Do not apply Fargo for wild oat and downy brome control in dormant seeded winter wheat. Germinated wheat that has not emerged can be susceptible to Fargo injury.
Control flushes of volunteer grain and/or weeds immediately if precipitation stimulates fall growth to minimize water use. In the event of precipitation, grain re-growth from hailed fields or new flushes should be managed to prevent survival of the wheat curl mite and potential spread of wheat streak mosaic virus.
Disease management recommendations Jack Riesselman, Plant Path Specialist
Greg Carlson (NARC). Do not plant winter wheat without seed treatment for root rot. Under stress conditions root rot tends to be more of a problem. Shallow seeding can reduce root diseases.
Joyce Eckhoff (EARC). Select varieties with tolerance to stem rust. In direct seeding, may also want to consider seeding varieties with tolerance to Septoria or tan spot as they increase in stubble.
Dave Wichman (CARC). Treat seed to minimize the risk of common/dwarf bunt. The risk from these diseases is too great to not seed treat.
Insect management recommendations
Greg Carlson (NARC). Treat for wireworms if they have been problematic in recent years in your fields. Fallow does not manage wireworms. Delaying planting will avoid grasshoppers.
Dave Wichman (EARC). Russian wheat aphid typically are not a problem if winter wheat is seeded after mid September. Russian wheat aphid can survive mild winters like 99-00. Scout fields in spring if winter is mild to determine if Russian wheat aphid will need to be managed. Grasshoppers could potentially be active into early October. Consider a seed treatment such as Thimet for protection from grasshoppers.
This note is
part of the Agronomy Notes series, a weekly news release and fact sheet series
prepared by Dr. Jim Bauder, Extension Soil and Water Quality Specialist at
Montana State University. Past Agronomy Notes can be viewed at
http://AGNOTES.org/. For additional information on this subject, for subscription (no
charge) to this Agronomy Notes series, or for questions about Agronomy Notes,
Jim Bauder can be contacted by E-mail at
or by calling 406-994-5685 at MSU.
Categories: Drought, Wheat, Wheat Agronomics
Date: 2001