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.

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.

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).

Will 2008 be the “Perfect Storm” for Soybean Seedling Disease?

April 21, 2008

By Palle Pedersen, Department of Agronomy and Alison Robertson, Department of Plant Pathology

There have been several reports in the press about poor soybean seed quality for this growing season. Seed quality is a problem for many companies this year but all are doing everything they can do to ensure we have the best quality seed possible. In Iowa, however, seed quality issues are minor compared to the south.

Seed quality

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.

Iowa 2008 Prediction for Stewart’s Disease of Corn

April 17, 2008
Map showing the Stevens-Boewe Index

By Forrest W. Nutter, Jr., Department of Plant Pathology, Lu Liu, Sustainable Agriculture Program, Rich Pope, Department of Entomology, and Marlin E. Rice, Department of Entomology

Following an Iowa winter of ice, snow and cold temperatures, the predicted risk for Stewart’s disease of corn in 2008 is negligible throughout most of Iowa, with only the southeastern-most counties having a low risk.

Calculating Degree Days

April 17, 2008

By Rich Pope, Department of Entomology

Warm-blooded animals including humans generate their own internal heat and have regulatory systems to hold maintain body temperature in an operational range. These systems provide insulation from fluctuations of temperature in the environment and allow growth and development based on the passage of time in minutes, hours, weeks, months and years.

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