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6/11/2012 - 6/17/2012

Earn CCA Credit at June 21 Southeast Iowa Field Day

By Jim Fawcett, ISU Extension and Outreach Field Agronomist


Certified crop advisers (CCAs) can earn 5 hours of credit (3.5 hours in soil and water management, 1.0 in crop management, and 0.5 in nutrient management) by attending a special CCA morning session, followed by the afternoon 25th anniversary celebration & spring field day tour at the Southeast Iowa Research and Demonstration Farm near Crawfordsville on Thursday, June 21.

The morning session will begin at 9:00 a.m., with a presentation by Dick Fawcett, Fawcett Consulting, on “Reducing atrazine’s impact on water quality in Iowa– how are we doing?” Also in the morning will be a demonstration in the field on “What soils can tell you about how they should be managed” by Tom Fenton, Iowa State Professor Emeritus – Soils, and will conclude with a presentation by Matt Helmers, ISU Extension and Outreach Ag Engineer, on “Strategic placement of buffers to reduce nutrient and sediment export.”

The keynote speaker at the afternoon celebration will be Neil Harl, ISU Professor Emeritus, on “The future of agriculture in Iowa.” Also featured in the afternoon will be a panel of speakers who will review 25 years of research on the farm. The panel of speakers will include: Matt Helmers and Stu Melvin, ISU Extension and Outreach Ag Engineers, on drainage research; Kendall Lamkey, Agronomy Department Chair, and Bernie Havlovic, original superintendent of the farm, on crop productivity; Greg Brenneman and Mark Hanna, ISU Extension and Outreach ag engineers on tillage research; and Antonio Mallarino and John Sawyer, ISU Extension and Outreach Soil Fertility Specialists, on soil fertility studies.

Also helping with the celebration will be Wendy Wintersteen, ISU Dean of Agriculture and Life Sciences, Cathann Kress, Vice-President for ISU Extension and Outreach, and John Lawrence, ISU Associate Dean of Agriculture and Life Sciences. In addition to the presentations, research displays and field plots highlighting most of the crops ever grown on the farm can be viewed.

Registration for CCAs will begin at 8:30 a.m. The registration fee is $50, which includes lunch. Pre-registration is required. Please pre-register by calling the Johnson County Extension Office at (319) 337-2145 or send an e-mail to Jim Fawcett (fawcett@iastate.edu) by June 20.  The registration fee can be paid at the door. To reach the research farm go 1 3/4 miles south of Crawfordsville on Highway 218, then 2 miles east on G-62, then 3/4 mile north.

 

Jim Fawcett is an ISU Extension and Outreach field agronomist. He can be reached at 319-337-2145 or e-mail fawcett@iastate.edu.

Scouting for Japanese Beetle

By Erin Hodgson, Department of Entomology 

 

Adult Japanese beetles first emerged in some areas of Iowa around the end of May. This is very early compared to a normal year. At the same time, many other beetles in this large insect family (Scarabaeidae) are becoming active and causing confusion with identification. In general, scarabs are stout beetles that are boxy in shape, have clubbed antennae and thick legs adapted for digging. Adults can be active during the night or day depending on the species; regardless, they are clumsy fliers. Some species are scavengers that feed on dung, carrion or decomposing organic materials; others can be significant plant pests. In most years, adult scarabs emerge mid-June and can be active until August.

 

Japanese beetle

Adults are just over ½ inch in length. These scarabs have one generation per year. Probably the most diagnostic features are the white tufts of hairs along the sides of the abdomen and metallic green head and bronze forewings (Photo 1). The forewings do not fully cover the tip of the abdomen. Adults have a very wide host range (>300 plants), including roses, fruit and shade trees, grapes, corn and soybean. Japanese beetles are skeletonizers and feed between leaf veins. View this online slideshow for more information on Japanese beetle management.

Photo 1. True Japanese beetle. Photo by Dorothy E. Pugh.

 

False Japanese beetle

Also known as a sandhill chafer, false Japanese beetles closely resemble true Japanese beetles. They are about the same boxy shape and size (½ inch in length). The body is dark brown and shiny (Photo 2), but is not metallic green and bronze. They can have white hair along the side of the abdomen, but the hair is evenly spread out instead of in tufts. These scarabs have one generation per year. False Japanese beetles feed on the flowers, foliage and fruit of many plants, but they are not typically considered field crop pests.

Photo 2. False Japanese beetles. Photo by Marlin E. Rice.

 

Masked chafers

There are several masked chafers in Iowa. These scarabs have one generation per year. Adults are about ½ inch in length and oval in shape. Masked chafers can be dark yellow or tan in color with dark markings on the head (Photo 3). The body, legs and wings can be hairy. Adult masked chafers are not known to significantly feed on plants.

Photo 3. Northern masked chafer. Photo by Mike Reding and Betsy Anderson, USDA-ARS (www.ipmimages.org).

 

May/June beetles

There are several scarabs with the common names of May or June beetles in Iowa. Most have a two to four year life cycle, but some have one generation per year. Adults are 1 inch in length and oval in shape. Body color can range from chestnut brown to red (Photo 4). Adult May/June beetles feed on a wide variety of tree foliage and are not considered field crop pests.

Photo 4. June beetle. Photo by Steven Katovich, USDA Forest Service (www.ipmimages.org).

 

Erin Hodgson is an assistant professor of entomology with extension and research responsibilities; contact at ewh@iastate.edu or phone 515-294-2847.

Should you be scouting for Goss's wilt?

By Alison Robertson, Department of Plant Pathology and Microbiology

 

This weekend, Dr Tamra Jackson-Ziems at University of Nebraska-Lincoln reported that Goss’s wilt had been spotted in multiple cornfields in three counties in south central and eastern Nebraska.  She suspects that infection may have occurred as a result of plant wounding due to severe storms earlier in the growing season. The infected corn plants were at the V6 growth stage and had characteristic lesions of Goss’s wilt. A few plants were systemically infected.

Goss’s wilt was found on a few plants in a field Calhoun County on Monday, June 11 (Figure 1).  The field had been planted to a very susceptible hybrid in 2011, had severe Goss’s wilt and surface residue waspresent.  Strong winds that have occurred in the area likely caused damage to the leaves and enabled infection.

Figure 1. Typical Goss’s leaf blight symptoms on corn in Calhoun County on June 11, 2012. Photo courtesy of E. Lerdal, District Sales Manager, Asgrow/DEKALB.

 

The Goss’s wilt bacterium, Clavibacter michiganensis subsp nebraskensis (CMN), survives well in infested surface residue. Infection is usually associated with severe weather events that injure the corn leaves and thereby enable entry of the bacterium into leaf tissues. In the greenhouse, we typically see symptoms on corn seedlings 10 to 21 days after inoculation with CMN.

 

Scouting tips

If you are scouting for Goss’s wilt, focus your attention on fields that are:

  • planted to a Goss’s susceptible hybrid,
  • have a history of Goss’s wilt,
  • have surface corn residue, and
  • may have recently been injured by severe weather. 

The most characteristic symptoms of Goss’s wilt are “freckles” (Figure 2) within large reddish-brown lesions that usually occur along the edge of the leaves. Bacterial ooze may also occur on the lesion, giving it a wet or greasy appearance. When the ooze dries, it leaves a shiny residue on the surface of the lesion.

Figure 2. Freckles, which are small, dark green to black spots that usually occur in the edge of Goss’s leaf blight lesions, are distinct to this disease. Bacterial ooze may also be seen.

 

Management

Planting a tolerant hybrid is the most effective way to manage Goss’s wilt. 

There are several foliar products being marketed for Goss’s wilt management. Unfortunately there are no field data available on their efficacy. Preliminary trials in the greenhouse on V3 corn seedlings indicated some products might slow disease development. Because greenhouse conditions are very different from field conditions, further evaluations in field situations are needed.

This growing season, we have field trials to evaluate foliar products at three locations in Iowa. On-farm trials in collaboration with ISU-FARM also are being done in northwest Iowa. Furthermore, participants at the Crop Management Clinic and Corn Disease workshops, which will be held in July and August, respectively, at the ISU Extension and Outreach Field and Education Laboratory (FEEL) near Boone, will evaluate foliar products in CMN-inoculated trials.

 

Holcus leaf spot

ISU Extension and Outreach  field agronomist Joel De Jong from northwest Iowa reported seeing Holcus leaf spot in corn.  Characteristic symptoms of this disease are round (~1/4 inch diameter), pale yellow to white spots with a water-soaked halo.  On some hybrids, the spot may have a purple or brown margin. 

Carl Bradley from University of Illinois and Kiersten Wise form Purdue University also reported Holcus leaf spot in their recent newsletters (The Bulletin and Pest and Crop, respectively).

Holcus is another disease of corn caused by a bacterium, Pseudomonas syringae pv. syringae. Infection of leaves occurs through wounds or stomates. Holcus rarely gets
severe enough to impact yield. 

 

Alison Robertson is an associate professor and an extension field crops pathologist in the Department of Plant Pathology and Microbiology. She can be reached at 515-294-6708 or e-mail alisonr@iastate.edu.



This article was published originally on 6/18/2012 The information contained within the article may or may not be up to date depending on when you are accessing the information.


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