Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information


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July 20, 2009



Potato Leafhoppers

High numbers of potato leafhoppers continue to be found in some hay fields.  Be sure to use a sweep net to monitor potato leafhopper numbers and treat if numbers exceed the threshold.  For more information on managing potato leafhopper, see pages 107 - 110 of the June 21, 1999 Iowa State University Integrated Crop Management Newsletter or  Remember, waiting to see hopperburn is waiting too long as substantial losses have already occurred by that time.  Be careful to not confuse leaf diseases with hopperburn.



Leaf Diseases



Text Box: Common Leaf Spot (left) and Leptosphaerulina leaf spot


Many hay fields now have evident leaf diseases, most commonly common leaf spot and “lepto” leaf spot.  Fields in third year alfalfa have greater disease risk than first and second year alfalfa fields because the pathogens build up over time. There are differences in disease tolerance between varieties. Because many of the hay nutrients are in the leaves and because severe leaf disease can cause defoliation, if the disease level is high, early cutting generally is recommended so that defoliation can be avoided. Cutting as early as mid-bud stage may be necessary when the disease is severe.








Rotation Resistant Western Corn Rootworms


As you know, rotation resistant western corn rootworms have been confirmed throughout the counties I cover, and levels above threshold were confirmed in the area from northeastern Muscatine County through Scott County and into Clinton County in 2006.  The Illinois and Indiana experience with this pest is that it starts out very spotty, so a cart blanc use of rootworm management in first year corn is not yet warranted.  Rather, soybean fields that will be planted to corn in 2009 should be monitored for western corn rootworm adult activity beginning in the last week of July and continuing through the first three weeks of August using the Trece Pherocon AM yellow sticky traps.  Follow the protocol developed by the University of Illinois, which can be found at  The traps can be ordered from:


Great Lakes IPM
10220 Church Road NE
Vestaburg, Michigan 48891


100 Countryside Drive
PO Box 270

Belleville, Wisconsin 53508



The time is fast approaching or upon us when final decisions about applying foliar fungicides to corn will be made.  Alison Robertson, ISU Extension Plant Pathologist, wrote an excellent article on the subject, which can be viewed at







X.B. Yang, ISU Extension Plant Pathologist, addresses soybean fungicide application issues at




Japanese Beetles


Japanese Beetles were reported on ornamentals in Scott County some time ago, and reports og them in agronomic fields have come in from areas with a previous history of Japanese Beetles.  The adults have a metallic green head and pronotum (neck region) and reddish bronze wing covers with a row of white hair tufts along the abdomen. There is a single generation in the Midwest, with beetles living for 30 – 45 days. Beetle feeding tends to occur from late June to early September, with the heaviest defoliation in July and August.

Text Box:

In soybean, the economic threshold for the beetles is the general leaf defoliation threshold used for other pests. During the reproductive stages of soybeans, the threshold for considering an insecticide treatment is if greater than 20% of the leaf area is gone due to feeding. However, the high price of soybean may lower the threshold slightly.  But remember that most people tend to overestimate defoliation. If it looks like 20% defoliation, most likely it’s only 10%. The pictures in the following article can help in estimating percent defoliation: 


In corn, Japanese Beetle adults feed on leaves, tassels, silks, and pollen and are capable of interfering with pollination   If silks are being clipped to within 0.5 inch of the end of the ear and pollination has not yet occurred, consider and insecticidal treatment.


For more information and insecticides labeled for Japanese beetles see the July 28, 2003 ICM Newsletter at





Upper Midwest Manure Handling Expo

Boone, IA

July 22, 2009


The Upper Midwest Manure Handling Expo is scheduled for July 22 at the Central Iowa Expo site between Ames and Boone.  The theme of the expo, SET for Fall, will focus on safety, efficiency and technology.  This expo will be a great opportunity to see many different kinds of liquid and dry manure application equipment.  The expo will include educational sessions, exhibitors, and 19 field demonstrations as well as a spill response demonstration. There is no fee to attend the expo, however parking is $5 per vehicle.  A complete list of expo activities and maps can be accessed at:




Illinois Forage Expo

Meier Farms, 205 N Dakota Road, Ridott, IL

Stephenson County

Friday, July 31, 2009 9 AM to 4 PM


Directions From the West: Exit US Rt 20 at RT 75 (Freeport/Dakota) exit. Go south (right) 3/4 mile on Route 75. Go east (left) 2 miles on River Road, turn right on Dakota Road 1/2 mile.


Equipment Field Demonstrations

times subject to change

9:00 AM — 10:00 AM                  Mowing & Tedding

10:00 AM —11:00 AM                 Raking

10:30 AM                                         Baleage

11:00 AM — Noon                        Chopping

1:00 PM                                            Chopping

2:00 PM — 4:00 PM                     Baling


Educational Presentations

10:00 AM     Autosteer in Forage Systems

Jay Solomon, U of I Extension

10:20 AM     Dollars & Cents of Alfalfa Production

Jim Endress, U of I Extension

10:40 AM     Managing Risk with Hay Insurance

Speaker TBA

11:00 AM     Nutrient Management Planning & How EQIP Can Help


11:20 AM     Forages & Today’s Milk Price

Dr. Mike Hutjens, U of I Extension


Industry and Equipment Exhibits



Crop Management and Diagnostic Clinics

August-September – Ames


The Field Extension Education Laboratory is a 43-acre teaching and demonstration facility dedicated to providing a hands-on learning experience for crop production professionals.  The demonstration plots are used to show a wide range of management problems, solutions, and diagnostic challenges. “We make the mistakes on these plots so you won't in the future!”  The clinics and programs are taught by Iowa State University staff and faculty and invited specialists from other institutions and industry.  Modern, air-conditioned classroom facilities complement the in-field sessions, all of which are within walking distance.  Current open programs for this summer include the following:


     Aug 25-27, Iowa Drainage School

     September 2, Alfalfa Production Clinic

     September 3, Corn Disease Diagnostics and Management

     September 15, Soil Management Clinic

For other Agribusiness Education program information, check out the Homepage at:



Advances in Precision Ag Field Day

ISU SE Iowa Research & Demonstration Farm – Crawfordsville

September 17


See the latest in precision agriculture technology, including RTK guidance systems, auto-steer, automatic shut-off planters, and sprayers. As details emerge, they will be posted at



If you have any questions, please feel free to contact the Iowa State University Extension Office.
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Last Update: July 20, 2009
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