Integrated Crop Management News

Links to these articles are strongly encouraged. Articles may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If articles are used in any other manner, permission from the author is required.

Adapting to Alfalfa Winterkill and Winter Injury

April 29, 2008

By Stephen K. Barnhart, professor, Department of Agronomy

Significant areas of alfalfa winterkill are now evident in Iowa.  The worst areas are along the Highway 20 corridor in eastern and northeast Iowa, with notable losses to the Minnesota border in Iowa and also in random fields in other parts of the state. Frozen alfalfa crown and upper taproot tissue is not able to recover. Evidence of the injury was delayed because some plants began to green-up and then died. Plants that still exhibit good taproot and crown tissue are likely unaffected. Read more about Adapting to Alfalfa Winterkill and Winter Injury

Delayed Burndown Applications in No-Till

April 22, 2008

By Bob Hartzler, Department of Agronomy

As the end of April nears with little field work accomplished, getting the crop in the ground becomes the priority for many farmers. No-till farmers may plant fields prior to killing weeds with a burndown herbicide, with the intent of returning later to control the weeds with an early postemergence application. While this strategy can be effective, it is important to realize that planting into established weeds greatly shortens the time required for weeds to impact crop yields (critical period). Read more about Delayed Burndown Applications in No-Till

Alfalfa Weevil Predictions for 2008

April 22, 2008
Image of an alfalfa weevil larva

By Marlin E. Rice and Rich Pope, Department of Entomology

Cold! That is the best way to describe the first three and a half months of 2008. A cool spring has delayed alfalfa weevil hatch this year, however Iowa fields should have accumulated sufficient temperatures for larvae to hatch starting April 23-25 in southern Iowa. Naturally, weevils with hatch at slightly later dates in the central and northern counties of the state. Read more about Alfalfa Weevil Predictions for 2008

Surface Waters: Ammonium is Not Ammonia – Part 1

April 21, 2008

By John Sawyer, Department of Agronomy

A recent article in The Des Moines Register newspaper has caused considerable controversy regarding nitrogen in Iowa streams and rivers. The article (High ammonia levels threaten D.M.’s water, April 6, 2008) featured information about “ammonia” levels in certain Iowa surface water systems during the recent winter time period. Read more about Surface Waters: Ammonium is Not Ammonia – Part 1