AgAlerts From Griggs County
By John Swenson, Griggs County Extension Agent

Issue # 11, August 29, 2000

Sclerotinia Stalk Rot in Sunflower and When to Desiccate

    Sclerotinia stalk rot (white mold) is showing up in sunflower fields.  This has caused the question to arise concerning desiccants to try and speed up harvest.  Desiccants have had mixed results depending on weather conditions that occur after application.  When applied during hot dry weather, dry down can be greatly reduced.  Problems occur if wet conditions occur after application.  

    When to apply?  Timing is critical when applying a desiccant.  We first must determine when the sunflower is physiological mature.  The following are the growth stages as a sunflower plant matures.
                R-6
                Flowering is complete and the ray flowers are wilting. 
                R-7
                The back of the head has started to turn a pale yellow color. 
                R-8
                The back of the head is yellow but the bracts remain green. 
                R-9
                The bracts become yellow and brown. This stage is regarded as physiological maturity.

   The R-9 growth stage (which is about 117 days after planting) is when a desiccant should be applied.  At this stage the seeds should be about 35% moisture.  If desiccants are applied earlier, yield, test weight and oil content will be reduced.

    Desiccants that are cleared on sunflower include Gramoxone Extra (paraquat) and Drexel Defol (sodium chlorate).  Gramoxone Extra can be applied at a rate of 1 to 1.5 pt/a (approx. $2.00 to $3.90/a) and applied with a NIS.  There is a 7 day pre-harvest interval.  Drexel Defol is applied at a rate of 1 to 2 gal./a (approx. $6.50 to $13.00/a). 

    For more information on sclerotinia diseases in sunflower click on the following site, NDSU Extension  Publication PP-840 "Sclerotinia Diseases of Sunflower". Or the NDSU Extension Publication EB-25 "Sunflower Production".

Roundup As A Flax Harvest Aid

    A section 18 label has been approved for the use of Roundup Ultra or Roundup Ultra RT for pre-harvest application in flax.  The label was granted to control weeds including Canada thistle, perennial sowthistle, and kochia.  A single ground or aerial application of Roundup may be used at one quart/acre.  Application must be made at least seven days before harvest and when the crop is physiologically mature.  A rule of thumb to determine when flax is physiologically mature is when at least 75% of the bolls have turned brown.  Applicators must read and follow label directions, and have the crisis label in their possession during Roundup application.

Decatur Beef Alliance Feedlot Project 

    Pre-registration for groups of 10 or more spring-born steer calves are due Sept. 15. Calves must be delivered to the Sand Creek Feedlot near Williston Oct. 16 - 18 where they will be backgrounded to about 700 pounds. From there, they'll be shipped to Decatur County Feed Yard at Oberlin, Kan., for finishing to slaughter weights.
    Individual animal performance and carcass data will be collected on feed weight, frame score, live sale weight, days on feed, average daily gain, feed efficiency, quality grade, yield grade, ribeye area and carcass weight. Processing cost, treatment cost, cattle cost, carcass price, live price and net return per head will also be reported. Producers will receive summaries on cattle receipt, end of backgrounding, during finishing and at the end of the project.

    For more information on this project contact by E-mail or by phone, John Dhuyvetter at NDSU's North Central Research Extension Center in Minot,(701) 857-7882.  Or contact the Griggs County Extension Office.

Soil Sampling Season

    NDSU recommendations for soil sampling for N are that soil sampling may begin after August 1 following small grain harvest.  A previous crop credit of 0.5 lb N per day prior to September 15 is either added onto the soil test N number, or subtracted from the N recommendation (either ending number is the same).
    Early soil testing makes the most sense in small grain fields.  Small grains, with a large carbon to nitrogen ratio in their residue tend to buffer changes in soil nitrate levels and tend to tie up N rather than released it into a free nitrate state during decomposition, which can take a very long time.  Broadleaf crops, such as canola or field peas will tend to mineralize more quickly, so a late fall soil test will be more representative of spring soil test values.  Although the uncertainty is small if soil sampling is conducted immediately following small grain harvest, the uncertainty may increase later in the fall, as fields are tilled and small grain seed germinates and results in significant regrowth is some years.  When fields are tilled, it is more difficult to reach consistent depths with soil probes.  It is also more difficult to sample for P, soil PH, K and other nutrients important in the 0-6 inch depth because of inconsistencies of surface soil samples.  A much better 0-6 inch soil core is obtained in unworked fields, so early soil testing is better in this regard.

For Help Call

    The last few years have been difficult for farm and ranch families and many are experiencing financial and emotional stress as a result.   

North Dakota Helpline:  1-800-472-2911

Agriculture Mediation Service:  1-800-642-4752

Hot Line:  701-235-7335

Please Contact Our Office For Additional Information
E-mail: griggs@ndsuext.nodak.edu
Go to the 2000 AgAlert Index Page