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Northwest Iowa Crop Update Newsletter |
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Please view pictures and give me your comments, suggestions
Field 1, Pocahontas County
2nd Yr Alfalfa
Farmer reported that alfalfa was "shrinking"
After walking through the field, he found 20 to 30 aphids per stem.
Treated with insecticide the same day
I visited the field about 8 hours after treatment. I did not find many live aphids, but I did find symptoms of Spring Black stem and possibly other (disease) problems.
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Field #2, Sac County
3rd or 4th year Alfalfa
Farmer reported very similar problems as field #1, said alfalfa appeared to be
"shrinking" and dying. He did not report any insect or root problems.
I visited the field on Monday, May 20th. I found very similar symptoms
compared to field #1. The alfalfa showed symptomology of spring black
stem, but most stems were dead. New shoots were growing from the crown.
The leaves on the dead stems appeared to be frozen or bleached. The
affected area was about 20 acres on a south facing slope. The top of the
hill (about 5 acres) looked Good but was also starting to show black stem
symptomology. We also noticed a few stems with a very reddish color ( I
noticed this was symptomology for verticillium wilt)
We dug crowns and roots the best we could (the soil was hard) and found no problems with the root system to our digging depth.
I recommended to plow the field and go to another crop.
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Todd Vagts
Iowa State University Extension
Field Crops Specialist
1240 D. Heires Avenue
Carroll, IA 51401
Office: 712-792-2364; Cell: 712-249-6025; Fax: 712-792-2366
Email: vagts@iastate.edu
For questions or comments please respond to vagts@iastate.edu
This page last updated on 05/21/02
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