April 22, 2004
Much of the following is quoted from Jim Fawcett, my counterpart to the west.
Oats Yield Best if Seeded By April 15
past the best time to seed oats, so any left to do should be done ASAP. Oats are a
cool season crop and yield best when planted in late March to April 15 so that flowering
occurs before the hot part of the summer. Grain yields drop about 10-15% per week after
April 15 in the central part of the state. Seeding rate should be about 30 seeds per
square foot, which is about 2-3 bu/A. Best results are obtained with a drill. See Small
Grain Production for Iowa-Spring (Pm-1497) at http://www.extension.iastate.edu/Publications/PM1497.pdf.
Much of the oats seeding will be done as a companion crop for alfalfa and other small seeded forages. The seeding rate should be cut some to reduce competition with the forage. One to 2 bu/A of oats is commonly seeded with alfalfa.
may also be seeded by April 15, but mid-April to late-April is a better seeding time for
forages since they require soil temperatures similar to corn and soybean for germination.
Soil temperature information around the state can be found at: http://mesonet.agron.iastate.edu/agclimate/display.php?src=/agclimate/daily_pics/4in-temp-out.png.
It is best to have forages seeded by late-April because as we get later into the spring, the soil surface tends to dry out more rapidly with the warmer temperatures, making successful establishment of forages more difficult. Seeding depth and seed-soil contact are critical for the establishment of alfalfa, smooth bromegrass, and other small-seeded forages. They should be seeded no deeper than 0.25-0.5 inches deep. Seed-soil contact can be improved by following the seeding with a cultipacker or harrow.
also time to start scouting hay fields for alfalfa weevils in areas along and south
Highway 30 and very soon north of Highway 30. Alfalfa weevils begin to hatch at 300
Growing Degree days (GDD) Base 48 and quit feeding at 900 GDD Base 48. Because south
facing slopes are somewhat warmer than average, they should be scouted beginning at 200
(south of I-80) - 250 (north of I-80) GDD Base 48.
Following are GDD Base 48 accumulations as of the end of the respective day.
DATE BURLINGTON CEDAR RAPIDS DAVENPORT DUBUQUE April 15 240.5 202.5 210.5 149 April 16 261.5 221.5 232.5 166.5 April 17 285 241 252 181 April 18 310 265.5 276 199.5 April 19 323.5 276 287.5 209.5 April 20 335.5 282.5 297 214.5 April 21 343 288 302 219
For details on managing this insect, see pages 22-23 of the April 19, 2004 Integrated Crop Management Newsletter http://www.ipm.iastate.edu/ipm/icm/2004/4-19-2004/. Also, watch http://www.extension.iastate.edu/Pages/eccrops/insect.html for updated information on the development of this and other insects during 2004.
Stalk Borers Begin to Hatch
Stalk borers are beginning to hatch
along Highway 34 (Burlington - Mount Pleasant area), and the hatch will move north.
In areas of fields with high grassy weed or giant ragweed pressure in 2003, spraying an
insecticide just prior to egg hatch is one strategy to consider if corn will be planted
this year. Stalk borers begin to hatch at 575 Growing degree days base 41 and hatch
is complete at 750 GDD Base 41.
Following are GDD Base 41 accumulations as of the end of the respective day.
DATE BURLINGTON CEDAR RAPIDS DAVENPORT DUBUQUE April 15 438 349.5 374.5 282 April 16 466 374 403.5 306 April 17 496.5 400.5 430 327.5 April 18 528.5 432 461 353 April 19 549 447 477.5 366.5 April 20 568 457 491.5 375 April 21 582 466 500 383
For more details on managing this pest, see http://www.extension.iastate.edu/Pages/eccrops/insect.html.
If you have any questions, please feel free to contact the Iowa State University Extension Office.
Last Update: April 22, 2004
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