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.

Twisted Whorls

July 13, 2008
Image of plants exhibiting twisted whorls

By Roger Elmore, Department of Agronomy and Alison Robertson, Department of Plant Pathology

Corn is seemingly racing toward tassel and silking thanks to a spell of relatively good weather.  Field appearances improve daily. As we scan the tops of canopies a few plants stand out, not because of height but because of color; yellow, bright yellow leaves seem to wave to us in the breeze.  These trapped, sun-starved leaves emerge as splotches of bright yellow in a dark green sea of plants.

Yellow corn, Wet soils, and Nitrogen loss (Part 3)

July 13, 2008
Image of experimental plot for wet soil and nitrogen loss experiments

by John Sawyer, Department of Agronomy

Earlier I provided observations in two articles (June 19 and June 26, 2008) on corn growth and response to nitrogen (N) applied in an anhydrous ammonia study being conducted at the ISU research farm between Ames and Boone. Following are some final observations (July 7, 2008).

Reseeding Flood and Weather-Damaged Forage Crops in Late Summer

July 13, 2008

By Stephen K. Barnhart, Department of Agronomy
New forage seedings are susceptible to a wide array of problems and stresses -flood, hail, drought, weed competition, insects, etc. Late summer can be a good time to ‘patch in’ bare or thin spots in forage stands or reseed entire fields. However there are some risks. The following steps will improve the chances for successful forage stand establishment in late summer.

Renovating Pastures or Hay Meadows Damaged by Flooding

July 13, 2008

By Stephen K. Barnhart, Department of Agronomy
Flooding has damaged pasture and hay meadows across the state of Iowa. While most forage will likely recover, other areas that were eroded or silt- or sand-covered will require some reseeding. The following considerations may guide you in your planning and management.

Estimated Corn Silk Dates and Yield Potential, Iowa 2008

July 10, 2008
Map of estimated corn silk date ranges based on Hybrid-Maize simulations

By Roger Elmore, Department of Agronomy

Silk dates mark a milestone in growth and development of corn. This year in particular estimates of silk date are of interest since they provide an idea on timing of fungicide application as well as providing a look forward for conditions that might occur during this time critical for corn development. Crop simulation models are useful tools to project silk dates based on season-to-date weather conditions. Models also provide estimates of yield potential.

Knee High by When?

July 9, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to July 6, 2008

By Rich Pope, Department of Plant Pathology

Independence Day has come and gone, and scant acres of corn in most of Iowa have reached that old, outdated saw of knee high by the fourth of July. On my weekend trip to western Iowa, I saw corn ranging from V2 to VT! Admittedly, very little acreage was at either extreme, but it illustrates the continuing range of crop conditions that we will deal with through and after harvest this year.

Questions and Answers on Soybean Fungicide Applications

July 9, 2008
Image of soybean leaves infected with brown spot

XB Yang, Department of Plant Pathology

 As the difficult planting season passes, we continue to receive not so positive reports on soybean and corn with the development of foliar diseases due to weather conditions.  In Iowa there have been many observations and questions on soybean foliar diseases, especially brown spots, by field crop specialists and producers. Producers have questions about how and when to use fungicides to control foliar diseases. This article addresses some of those questions.