Introduction
Above normal temperatures forecasted for this week should help advance area crops (particularly corn) towards maturity.  Some harvest has occurred on early maturing soybeans.  Degree-day totals are still running much below normal, but with the recent surge in temperatures and dry conditions, maturity in most fields should be reached by the end of September and before a killing frost.  Use the next few days to make that last field scouting operation.  Refer to the University of MN fact sheet for those common grain drying questions.  This is also a good time for pasture weed, fertility and quality management.

Row-Crop and Forage Information
Growing Degree-day Last week proved to be an exactly normal week (110 degree-days), given the large fluctuations in temperatures from warm to cool to warm again.  A warmer week is forecasted with 121 degree-days over the next seven days, which is 26% greater than the average of 96 degree-days.  The above normal temperatures are very welcome at this time of year to help progress the crop towards maturity.  Seasonal total degree day accumulations for April and early May planting dates continue to improve slightly when compared to the 13-year average (90 to 94% of normal).  This equals about 200 degree-days (about 10 calendar days) behind normal.  Degree-days (average for NW Iowa) can be accessed at this web site:  http://www.extension.iastate.edu/carroll/crops/degree-days-2004.htm

Corn development  Most corn in the area should be fully dented with the milk line advancing down the kernel, near ½ milk line in most fields.  Corn taken for silage is occurring now.  Information from a MN Extension newsletter (http://www.extension.umn.edu/cropenews/Regnews/SEAugust272004.pdf) suggests that corn requires 194 degree-days to advance from full dent to ½ milk line and 176 degree-days to advance from ½ milk line to black layer (physiological maturity).  Therefore if area corn fields are near ½ milk line, full maturity should be reached within 10 to 12 days.

Soybean Development:  Many soybean fields are reaching physiological maturity across the region, noted by the changing leaf color and dropping of leaves.   Scattered harvesting has begun on early maturity soybeans.

Grain drying and storage fact sheet (University of MN):  An excellent two page fact sheet on grain drying and storage can be found at this University of MN website:  http://www.extension.umn.edu/distribution/cropsystems/M1080-FS.pdf

Winter Rye Cover Crop  My colleague in N.E. Iowa noted in his newsletter that winter rye can be planted now through late October. As a cover crop for soil erosion, 0.75 bushel per acre should be plenty. Using winter rye as a forage for harvest in spring, 1.5 bushel usually provides for a "full" stand (about 90 lbs of seed per acre). If seeding technique is a little questionable, then increase the seeding rate a little.  Using a cover crop on corn acres harvested for silage can be very beneficial for soil protection.

Plant Pest and Disease
Scout and evaluate corn and soybean fields now while you have time.   This year soybean fields are full of diseases (brown stem rot, white mold, downy mildew, sudden death syndrome and powdery mildew) and western bean cutworm is showing up in more locations (check your fields now for damage from this pest).  The next few days may be the last opportunity to scout for these many diseases, insect and weed pest problems as well as to evaluate the effectiveness of current pest management strategies.  Obtaining a positive ID on the disease, weed or insect will be very important when making crop rotation, hybrid and variety selection decisions for next year.  If you cannot absolutely identify what the problem is, contact your local extension office and send plant or insect samples to ISU for help.  Sample submission forms from the ISU plant disease clinic can be found at (http://www.extension.iastate.edu/Pages/plantpath/pdcintro.html).  Also weed, insect and soil fertility specialists are available to help you identify problems and develop remedial actions.

Fall Pasture Management
In the case of pastures, fall is a good time to eliminate perennial weeds, fertilize and prepare for improving tired pastures. Depending on the desired plant species in the field and the species of weeds, products that may be considered are 2,4-D, 2,4-DB (Butyrac), Ally, Banvel, Crossbow, Roundup, Spike, Stinger, and Tordon. Be sure to check the label for grazing restrictions.  Fall is also a good time to take soils tests to determine phosphorus, potassium, and pH levels. For phosphorus and potassium, the timing of application is not critical, but early spring and August are preferred for pastures. If the soil test calls for liming, generally it is suggested to apply only 1/3 to 1/2 the recommended amount in any year as there is relatively little stirring of the soil and applying the total amount at once can result in a very high pH at the surface and a low pH just below.

Producers wishing to enhance an existing pasture by frost seeding or interseeding next year should start preparing the field this fall.  The existing mix of plants should be weakened to make the new seedlings more competitive in the following spring.  The area should be over grazed this fall and then do the frost seeding in February or early March or the interseeding later in the Spring. To further reduce competition from existing plants, spring grazing or an application of Gramoxone is suggested.  For more information, contact the county ISU Extension office and ask for NCR-547 "Alfalfa Management Guide" ($4.00), Pm-1713 "Pasture Management Guide for Livestock Producers" ($10.00), Pm-1688 "A General Guide for Crop Nutrient and Limestone Recommendations in Iowa" ($1.00 or free), Pm-1097 "Interseeding and No-till Pasture Renovation," Pm-856 "Improving Pasture by Frost Seeding," and/or Pm-869 "Fertilizing Pastures."

For questions or comments please respond to vagts@iastate.edu

The information given in this publication is for educational purposes only.
Reference to commercial products is made with the understanding that no
discrimination is intended and no endorsement by Iowa State University with
any specific product(s) used in this is implied

This page last updated on 09/13/04