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No. 03/May 15, 2003

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First Issue for 2003
Starting with the April 4 issue, the Bulletin will be published weekly through mid-August, with a team of Extension specialists and educators keeping readers informed of pest situations and crop development throughout Illinois. Several new members have joined the team since last year. Don't hesitate to contact us with reports from anywhere in Illinois or elsewhere.

Transgenic Corn Rootworm Hybrids: A Promising IPM Tool, Yet Important Concerns Linger
Despite their promise as an IPM tool, transgenic corn rootworm hybrids pose lingering concerns about marketability. A Scientific Advisory Panel has outlined benefits and suggested recommendations for resistance management.

Control of Soil-Inhabiting Insect Pests of Corn
This overview surveys the options currently available to Illinois producers for controlling rootworms, cutworms, white grubs, and wireworms with insecticides and insecticidal seed treatments.

Baiting for Wireworms
The procedure for placing solar bait stations for wireworms remains essentially unchanged, with the exception of two additional product options.

First Black Cutworm Moth Capture of the Season
One black cutworm moth has been found in each of two upland traps in Massac and Pope Counties. Predictions of cutting dates won't begin until nine or more moths are captured within two days.

Little Activity Expected from Corn Flea Beetles
Because the average temperature of December, January, and February was low enough, little flea beetle activity is expected throughout much of Illinois.

Keep an Eye Out for Alfalfa Weevils
Alfalfa weevils generally become active when temperatures exceed 48 degrees Fahrenheit, usually in late March and April in southern Illinois. We suggest scouting begin when 250 to 300 degree-days accumulate. As temperatures increase, accumulations will occur quickly; people in areas near Belleville, Dixon Springs, and Carbondale should begin to spot-check for alfalfa weevils soon.

New Products for Insect Control
Empower, Herculex I Insect Protection, and Mustang Max have been labeled for insect control in recent months. Brief discussions and abridged label information are presented for these new products.

Corrections for the 2003 Illinois Agronomy Handbook and Illinois Agricultural Pest Management Handbook
A correction for use rates for Lumax needs to be made to the 23rd edition of the Illinois Agronomy Handbook and the 2003 Illinois Agricultural Pest Management Handbook.

New Herbicides and Label Changes for 2003
An overview is presented of label changes and recently registered weed control products for use in field crops:
  • BASF: Distinct 70WDG (diflufenzopyr + dicamba); Extreme 2.17L (imazethapyr + glyphosate); G-Max Lite 5L (dimethenamid-P + atrazine); Prowl 3.3EC (pendimethalin); Raptor IS (imazamox); Scepter 70DG (imazaquin)
  • Bayer CropScience: Option 35WDG (foramsulfuron)
  • Dow Agrosciences: Warrant 5.4L (glyphosate); Keystone 5.25SE (acetochlor + atrazine); Keystone LA 5.5SE (acetochlor + atrazine)
  • DuPont: Cinch 7.64EC (S-metolachlor); Cimarron 60DF (metsulfuron); Steadfast 75WDG (nicosulfuron + rimsulfuron)
  • FMC: Aim EW 1.9EW (cargentrazone); Spartan 75DWG (sulfentrazone)
  • Monsanto: Roundup WeatherMax 5.5L (glyphosate); Yukon 67.5WDG (halosulfuron + dicamba)
    Syngenta Crop Protection: Callisto 4SC (mesotrione); Lumax 3.95L (S-metolachlor + mesotrione + atrazine)
  • Valent: Gangster (flumioxazin + cloransulam-methyl); Phoenix 2EC (lactofen)

Too Early to Plant Corn?
Other States' Newsletters
Every state in the U.S. north-central region produces a newsletter on pest management and crop development and conditions. They are viewable on the Internet at

Field Crop Scouting Manual on Sale
The CD-ROM version of the Field Crop Scouting Manual, a recommended resource for all scouts, is on sale for $10, or free with a purchase of the printed manual ($40). Call (800)345-6087 or see to order.

An Information Network for Corn Earworm and European Corn Borer Counts
Anyone who will be operating a corn earworm pheromone trap or a light trap or a pheromone trap for European corn borer is asked to contribute regular trap counts to an information database. Contact Kelly Cook at (217)333-6651 or

"New Products for Insect Control" in issue no. 1 of the Bulletin contained several errors. Correct information is provided here.

White Grubs in Corn
White grubs--most likely Japanese beetle grubs--have caused damage in some areas of Illinois in recent years. This article outlines life cycles of Japanese beetle and other white grubs, the injury caused, anticipating white grub problems, related research upcoming in 2003, and insecticides for control of white grubs.

Bean Leaf Beetles: Will They Pose a Threat in 2003?
Researchers are working to shed more light on bean leaf beetles and their ability to transmit bean pod mottle virus. A recommended article on the relationship between winter temperatures and survival of the pest is available at

Scouting for Alfalfa Weevils
Maps showing actual (Jan 1-Mar 30)and projected (Jan 1-Apr 13) degree-day accumulations across the state offer guidance regarding timely scouting for alfalfa weevils. Scouting tips are also provided.

Soybean Rust and Illinois Field Crop Diseases in 2003
Predicting which plant diseases will take their toll on field crop yields in any given year is a guessing game. Soybean rust is a new and unknown plant disease, as yet undiscovered in the continental U.S. Its development and the injury it causes are described, along with expected management responses should the disease come to Illinois. Photographs and more details are available at several Web sites.

Weather Concerns That Could Affect Weed Management Decisions in 2003
Reflecting on the challenges posed by weather in 2002 can give some insight into the problems that may arise in 2003. Weather conditions for last year's growing season are reviewed, and accompanying tables list the rotational restrictions for most corn and soybean herbicides.

Herbicide Premixes for Corn and Soybean
Tables list many of the corn-herbicide and soybean-herbicide premixes used in Illinois, including trade names and their formulations as well as common names of the herbicide components. Knowing common names is beneficial because trade names can disappear, then reappear on products with completely different formulations.

Too Early to Plant Corn?
Soil conditions in much of eastern Illinois make planting corn early a tempting proposition. Should producers succumb? A number of observations regarding relevant factors provide guidance.

Regional Reports
The regions from which periodic reports appear in the Bulletin are defined, and the first report is presented for northern Illinois.

They're on Their Way: Black Cutworms Arrive in Southern Illinois Traps
Two southern Illinois monitors have reported intense captures of black cutworm males in April. Legwork is required to determine whether black cutworms pose a threat in any given field. We continue to encourage reliance on timely field scouting and application of an insecticide only if damage exceeds published thresholds. Please keep us posted regarding black cutworm activity in your area.

Legs Are the Giveaway: Black Cutworm and Crane Fly Larvae
Larvae of the black cutworm and crane fly are often confused. Photos and text here identify the differences.

A Note Regarding Soybean Aphids
Although soybean aphids caused little concern among Illinois soybean producers in 2002, monitoring will continue in case the potential for dramatic increases in their numbers occurs.

Development of Alfalfa Weevils Proceeds, Despite Colder Temperatures
We have received no confirmed reports of alfalfa weevil activity; we expect larval hatch when about 200 degree-days accumulate. Check alfalfa fields on south-facing slopes or lighter soils first. If temperatures warm up and stay warm, alfalfa weevil activity could be in full swing in a couple of weeks in the southern half of the state.

Mistaken Identity: Alfalfa Weevil or Clover Leaf Weevil?
Clover leaf weevils, which may be lurking in alfalfa fields, are commonly confused with alfalfa weevils at this time of year. Photos and text here identify the differences.

Winter Wheat Disease Situation
Reports indicate that winter-wheat viruses are mild and scattered this season. Symptoms are described for the three most common early-spring virus diseases, along with life cycle, management, and diagnosis.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

University of Illinois Plant Clinic to Open Its Doors
The clinic provides impartial plant-problem diagnosis across a range of disciplines. Diagnoses are also available electronically; see

On the Move: Black Cutworm Moths Are Here
As reported last week, black cutworm moths are beginning to make themselves known in the southern counties; recap of the "intense" captures. Watch emerging seedlings for early signs of cutworm feeding. Looking for cooperators to send weekly counts traps.

Captures of Insects Other Than Black Cutworms Also Noted
Observers also monitor flights of other important Lepidoptera adults, such as corn earworm, European corn borer, fall armyworm, and southwestern corn borer. Keep in mind, however, that reports of captured insects do not necessarily translate into projections of crop damage.

DuPont and Monsanto and Rootworm-Protected Corn
On April 15, 2003, DuPont and Monsanto agreed to a worldwide licensing agreement to Monsanto’s recently approved YieldGard Rootworm insect-protected corn technology; therefore even more hybrids than had been anticipated will be available.

Pollen Drift and Refuge-Management Considerations for Transgenic Hybrids
Unseasonably warm weather has hastened the pace of planting, or at least the preparations for planting. Despite the lingering concerns among many, YieldGard Rootworm hybrids are being planted. Summarizes facts about the physical characteristics and longevity of corn pollen, questions of how far the pollen will drift, likelihood of cross pollination, strategies to minimize pollen drift.

Remain on the Watch for Alfalfa Weevil
Although confirmed reports of alfalfa weevil larvae have been almost absent, the warm weather is sure to have accelerated weevil development. Discusses feeding patterns, what to look for.Although confirmed reports of alfalfa weevil larvae have been almost absent, the warm weather is sure to have accelerated weevil development. Discusses feeding patterns, what to look for.

Spring Alfalfa Diseases
Basic information on three diseases of alfalfa that are often seen in the spring: Sclerotinia crown and stem rot, Aphanomyces root rot, and spring black stem and leaf spot. Also see

Insect-Weed Interactions in 2002
In various fields, weeds such as giant ragweed, Pennsylvania smartweed, horseweed (marestail), common lambsquarters, and common waterhemp were not effectively controlled by glyphosate. The culprit in many of these fields with “poor control” was not herbicide resistance or poor herbicide performance but insects feeding within the stems of these plants. Implications.

PPO-Resistant Waterhemp in Illinois
At least one (and most likely several more) waterhemp population in western Illinois is now confirmed to be resistant to PPO inhibitors. We are concerned that resistance may be more widespread than initially perceived; but poor waterhemp control is not necessarily attributable to herbicide resistance. Discusses field experiments.

Notes on the Wheat Crop
Travels in southern and northern Illinois over the past 2 weeks have shown the 2003 wheat crop to be in mostly good condition, after a rather slow start last fall. One problem been noted in several fields, mostly in northern Illinois, is that of injury from nitrogen application. As the crop enters the jointing stage and moves toward heading, yield potential will start to become clearer.

Corn Planting Under Way
Soil moisture conditions are generally good for planting, with more worry in some places about lack of rainfall over the past months than about its being too wet. Discusses risks of early planting, compares to last year.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

Cutworms Continue Their Move Across Illinois
Black cutworm moths are being found in pheromone traps more frequently across the state. First dates of larval cutting activity are predicted in this article based on the dates of intense captures. These dates suggest when cutting may begin to occur and should be used as a guideline for scouting cornfields. Instructions are provided for scouting for cutworms and for estimating how much longer larvae will feed if they are found.

Few Reports of Alfalfa Weevils
Though most reports indicate very few alfalfa weevils in fields, the watch for them should continue. Southern Illinois has already reached the degree-day benchmark.

Corn Flea Beetle Spotting
Though corn flea beetle activity is expected to be low in Illinois, one report of 8 to 10 flea beetles per seedling corn plant on 2-leaf-stage corn has been received from Franklin County. Guidelines for scouting and treatment recommendations are provided.

Influence of Agricultural Practices on Earthworm Populations
Facts presented by Purdue's Dr. Eileen Kladivko during the 2003 Crop Protection Technology Conference are summarized on how agricultural practices, including chemicals, influence earthworm populations.

Identifying Early-Season Weed Species
A pocket-size guide with color photographs of hard-to-identify early-season weed species common in Illinois is now available for purchase. Those species are described and shown here.

Burndown Considerations for 2003
Existing vegetation to be dealt with before planting is often denser than 10 years ago, and likely includes unfamiliar species. Guidelines are provided for using burndown herbicides prior to corn or soybean planting.

Temperature Effects on Burndown Herbicide Activity
When is the air temperature too cold to apply a burndown herbicide? A 2002 experiment was initiated to address this question. Overall, increases in temperature significantly enhanced weed control and reduced week biomass.

Watching Corn Emerge
At few times during the season is the question about the future potential of the corn crop as clearly drawn as it is at emergence: Low stands do not yield up to potential, and even complete stands that have uneven plant size early in the season will not produce maximum yields. Ideally, corn plants in a field will all emerge within about 48 to 72 hours. If something delays emergence, it’s much better if the whole field or large parts of the field are delayed uniformly.

Scouting for Soybean Cyst Nematode
Over 80% of the soybean fields in Illinois are infested with SCN. It can reduce yields up to 30% without causing visible symptoms. How to sample.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

Be on the Lookout for Black Cutworm Larvae
Western and southern parts of Illinois continue to be the hot spots for black cutworm moths. Projected cutting dates are provided for locations reporting intense captures, along with insecticides labeled for use as rescue treatments.

More Corn Flea Beetles
Reports of corn flea beetle activity continue to filter in. Keep scouting fields.

Bean Leaf Beetles Are Numerous
Early-planted soybeans are very attractive to bean leaf beetles that already have emerged from their winter dormancy. The insect's life cycle, ability to cause injury to soybeans, and potential to transmit bean pod mottle virus are reviewed.

Aphids in Wheat
Aphid numbers seem to be increasing in some wheat fields. Economically important outbreaks of aphids are uncommon in wheat in Illinois, but noting their presence and potential buildup is important. But it's also important to diagnose the problem in wheat before making a decision to control aphids.

Alfalfa Weevil Update
Mixed reports continue regarding alfalfa weevil activity. Actual and projected degree-day accumulations are provided, along with tables showing economic thresholds and recommended insecticides.

Planting Season Is Topdressing Time
Despite the busyness of planting season, attention to managing stored grain insects in corn that will be stored into early summer is critical. Management techniques are detailed here.

Corn Seed and Seedling Diseases and Fungicide Seed Treatments
This review includes the effects of seed and seedling diseases on corn, symptoms to look for, the pathogens that affect corn seeds and seedlings and the conditions that favor them, and what treatments are available.

Weeds to Watch for in 2003
Survey results reveal changes in the weeds reported by growers and others to be most prevalent in corn and soybeans in Illinois.

Soybean Planting Considerations
Multiple considerations relevant to soybean planting are detailed, including planting dates, planting depths, row spacing, and seeding rates.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

2003 Agronomy Field Days
Dates and locations of field days for 2003 are provided.

In issue 6, Baythroid 2 was omitted as a rescue treatment for black cutworm.

Time for Alfalfa Watch
Alfalfa Watch uses the PEAQ estimation method to help producers monitor quality and plant growth. At the project's Web site you can view reports twice weekly as well as learn to calculate PEAQ, view PEAQ values statewide, and enter and track personal PEAQ values.

Reports of Damage Caused by White Grubs and Wireworms
Symptoms of injury caused by subterranean insects are beginning to appear. Wireworm problems seem to be more numerous than white grub problems at present. There are no rescue treatments for either pest after damage is discovered; we are testing the efficacy of several products that we applied for Japanese beetle grub control this spring.

Southern Corn Leaf Beetles Are Active in Western Illinois
Reports of injury by the southern corn leaf beetle in portions of Illinois are growing. This article reviews pest identification, injury to corn seedlings, life cycle, and control.

More on Black Cutworms
As corn begins to emerge in your fields, remember to scout for cutworms! Dingy, variegated, and claybacked cutworms can be mistaken for black cutworm. This article tells how to distinguish them.

Reports of Flea Beetles Continue
More reports of corn flea beetle feeding on seedling corn have come in; anecdotal evidence on the effectiveness of seed treatments varies.

Update on Heat Unit Accumulations for Corn Rootworm Larval Hatch
Though there is considerable variation from year to year regarding the onset of corn rootworm larval hatch, soil heat unit accumulations at the 4-inch level suggest that this year's hatch may be very similar to last year's (late May).

First Captures of European Corn Borer Adults in Southern Illinois
Although it's too early to start scouting for European corn borers in Illinois, it's worth noting the presence of adults to prepare for scouting in the near future.

Stalk Borers Could Attack Corn in Southern Illinois Soon
Cornfields in southern Illinois could soon be at risk for stalk borers; farmers in central and northern Illinois probably won't see them for a couple of weeks.

Alfalfa Weevil Update
Nearly all of Illinois has accumulated enough degree-days that scouting for alfalfa weevil is warranted. Several natural control agents may help keep populations in check and should be looked for as well.

What's in a Name?
Trade names may be memorable but misleading. Chemical names are unique but often hard to remember. Knowing common names, which pinpoint active ingredients, can be key to evaluating herbicide premixes, identifying generic products, and accurately rotating herbicides.

Why Has Horseweed (Marestail) Become a Concern?
Horseweed has earned a spot on the list of the six broadleaf weeds most commonly found in Illinois soybean fields. This article details the plant's biology, challenges with management, and concerns about herbicide resistance.

Missed the Preemergence Application Window in Corn?
Growers who have planted corn but couldn't apply preemergence herbicide before the corn emerged have two choices: use a delayed application, or switch to a postemergence strategy. This article outlines considerations for the two approaches.

Crop Recovery from Weather Events
The influences of storms, standing water, and hail on planting dates, seedling development, and decisions about replanting are described.

Regional Reports
Reports are provided this issue for northern and west-central Illinois.

2003 Agronomy Field Days
Dates and locations of field days for 2003 are provided.

Bean Leaf Beetles: To Spray or Not to Spray?
If you haven't done it already, schedule scouting trips to fields where soybean seedlings have emerged and are growing. Apparently growers are anxious about bean pod mottle virus, but we have little verification of its prevalence in Illinois soybeans last year. We urge careful assessment this year before you decide an insecticide is warranted.

Update on Heat Unit Accumulations for Corn Rootworm Larval Hatch
Though it's too early to accurately predict severity of corn rootworm problems this season, several factors could contribute to management challenges. We'll let you know when the larval hatch has been confirmed.

Update on Stalk Borer Development and Management Tips
Stalk borer larvae begin to hatch usually in late April and early May; corn growers in the southern tip of Illinois should begin scouting in the next week. Good management begins with sound weed management practices. Suggested insecticides and economic thresholds are presented here.

Quick Tidbits on Insects
Cornfields should be scouted for early black cutworm injury. For alfalfa weevils, little more than pinhole feeding has been reported, but control may be warranted in particular circumstances. Potato leafhopper activity is beginning, though the pest is not currently a threat.

What's the Scoop on Soybean Seed and Seedling Diseases in Illinois?
This topic produces more questions than any other single disease issue on any crop in Illinois. Described here are soybean seed and seedling diseases, their characteristics and conditions that favor them, and approaches to managing them.

Corn Nematodes in Illinois
Nematodes are often the last cause considered for problems with corn development. The only way to diagnose nematode problems in corn is through analysis of soil samples by a qualified lab. Because control depends on the species involved, a reliable diagnosis is critical.

Rainbows in the Fields
Winter annuals are flowering in many fields because of delays in both planting and weed control measures. Recommendations are offered for several scenarios: no herbicide applied, crop not planted; no herbicide applied, corn has been planted; herbicide applied, crop not planted; herbicide applied, crop has been planted; a change in the hybrid to be planted.

Plant Spacing Uniformity
It's a good time to look at corn stands in many parts of Illinois. The results of recent research on plant spacing uniformity might be summarized this way: Within reason, if a planter is dropping the desired number of seeds per acre with good depth control and adequate seed covering, plant spacing variability is costing little or no yield loss in corn.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

More Details on Corn Nematodes
It is time to reassess the impact of corn nematodes on production and determine whether R&D efforts are what they should be, given the current value of yield losses and expected increases. Corn breeders should be in the vanguard of this reassessment, because resistance or tolerance will be the best weapon for fighting losses. Nematode species are detailed, with images provided.

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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For comments or questions regarding this web site contact: Michael Greifenkamp