Pest & Crop Newsletter, Entomology Extension, Purdue University
- Corn Rootworm's 2005 Impact Lower Than Anticipated
- Perceived Risks to Western Corn Rootworm Damage in First-Year Corn
- Rootworm Soil Insecticides: Choices, Considerations, and Efficacy Results
Corn Rootworm’s 2005 Impact Lower Than Anticipated – (John Obermeyer, Christian Krupke, and Larry Bledsoe)
- It was a relatively quiet year in Indiana for rootworm larval damage.
- Good early-season growing conditions and lack of strong storms kept rootworm damaged plants upright.
- Beetles seemed abundant during corn ollination but later soybean sweets revealed lower statewide numbers.
- Beetles were present in soybean fields treated for aphids before and after application to lay eggs.
In 2004, rootworm beetle numbers were high in many corn and soybean fields. It was reasonable to believe that many eggs were laid and waiting to hatch and feast upon 2005 corn. Environmental conditions seemed perfect this spring and early summer for both corn and rootworm larval development. From this and the early root feeding we observed, we fully anticipated severely lodged cornfields in many areas of the state. It didn’t happen.
For the second year in a row, corn planting was on record pace and growing conditions afterward promoted early plant vigor. As well, rootworm larval hatch and development was on schedule this past spring. During the corn’s critical rapid vegetative growth, just before tasseling, rootworm larvae were at their peak of feeding. Root systems weakened by feeding predispose top-heavy plants to lodging. Weather fronts with gusty winds moving through during this period can potentially push susceptible plants (and sometimes entire fields) over. In 2005, severe storms did not occur during this pre-tassel period of growth. Even during the mild drought conditions before and during pollination this past season, good brace root development and anchoring of plants occurred. It is likely that many fields with marginal rootworm protection dodged the “bullet” this past season by not getting pushed over during early summer storms.
Once rootworm beetle emergence commenced, initial reports of economic silk clipping in areas of the state seemed to support our suspicion of rootworm larval (and emerged adult) numbers. In addition, where pest managers inspected roots in these beetle-infested fields, they found significant root injury. Treatment decisions to protect silks were complicated by spotty pollination because of the dry conditions that had affected many areas of the state. However, by the time we conducted soybean sweeps for western corn rootworm beetles, July 22 through August 19, numbers captured were lower than expected (see accompanying color-coded map). If you desire to see the state map with specific soybean sweep numbers from 2005, refer to the October issue of the Pest&Crop or click HERE. We can only speculate that the beetle’s life span, approximately 6 to 8 weeks, was cut short by hot and dry conditions. Also, lower beetle numbers in the soybean sweeps in northern counties may have reflected mortality effects of insecticides intended to treat soybean aphid. This, by the way, does NOT eliminate next year’s risk because of the pre and post treatment egg laying that occurred.
Bottom line, 2005’s beetle numbers may have been lower but this has not reduced the perceived risk to next year’s first-year corn. See the following article.
Perceived Risks to Western Corn Rootworm Damage in First-Year Corn – (John Obermeyer, Christian Krupke, and Larry Bledsoe)
- Risks of 2006 WCR damage is based on beetle numbers and past trends.
- The following risks are to be used as a general guideline, refinement should be done on a local scale.
- Risk categories defined below.
Weather is, and will always be, the major influence on insect numbers and subsequent crop damage. Numerous other biotic and agronomic variables occurring statewide or in localized areas make predictions of corn rootworm problematic.
Nevertheless, the following risk map has been developed by previous year’s soybean sweeps taken while western corn rootworm (WCR) beetles were actively laying eggs and frequency of reported larval damage. Because we draw these conclusions from a few fields sampled per county there is a large margin of error. We continue to encourage pest managers to monitor soybean fields in their specific area so that more precise risks can be assigned and appropriate management strategies implemented.
Producers in “fringe” areas may consider on-farm strip trials with rootworm products to determine the economic impact of WCR in their first-year corn. The following article, “Rootworm Soil Insecticides: Choices, Considerations, and Efficacy Results,” may give some guidelines in choosing a product.
“Very High” indicates that consistently high numbers of WCR beetles have been found in soybean fields. First-year WCR damage is likely and may be severe in parts of or whole fields.
“High” risk indicates that most soybean fields sampled or observed in that area contained high numbers of WCR beetles coupled with the fact that first-year corn rootworm damage frequently occurs.
“Moderate” risk means that WCR beetle numbers vary from field to field and that significant first-year rootworm damage is expected to be spotty.
“Low” risk areas have consistently low WCR beetle numbers in soybean with very few, if any, damaged first-year corn fields expected.
Rootworm Soil Insecticides: Choices, Considerations, and Efficacy Results - (John Obermeyer, Christian Krupke, and Larry Bledsoe)
- Four delivery methods for rootworm insecticide exist, none provide 100% control.
- Brief discussion of each delievery method and product rootworm efficacy compared.
When one uses a rootworm control product it is important to remember that protection of the primary portion of the root system from economic rootworm attack is the goal. Also, one needs to understand that products do not provide 100% control (60-80% control more likely) and occasionally some economic damage may occur depending on the larval population, weather, planting date, plant development, and time of larval hatch. All of these factors can ultimately impact product performance and must be considered when using a soil insecticide. The important things for producers to understand are the positive and negative aspects of each product and determine which fit best within their farming system. Also, one needs to understand what the warranty for each product really means. Finally, it makes sense to have untreated check strips in fields to gauge the performance and economics of the products used.
Listed below, by application method, are the current registered soil products and their efficacy in protecting roots in 2005 Indiana and Illinois university rootworm trials. Products were grouped by application technology for easier comparison. There is no consideration of other insect pests (e.g., wireworms, white grubs, cutworms) in these evaluations.
| Insecticide Coated Seed Root-Rating Peformance1, 2005 | ||||
| Location | Best2 Rating |
Cruiser 1.25 |
Poncho 1250 |
Check |
| Lafayette, IN | 0.05 |
0.93 |
0.19 |
1.83 |
| Wanatah, IN | 0.02 |
0.10 |
0.08 |
0.79 |
| Columbia City, IN | 0.05 |
0.06 |
0.08 |
0.09 |
| DeKalb, IL | 0.18 |
0.78 |
2.37 |
|
| Monmouth, IL | 0.13 |
0.55 |
2.25 |
|
| Urbana, IL | 0.14 |
1.21 |
2.32 |
|
1 Node Injury Scale 0-3. 0=no damage, 3=severe root pruning, 0.25 or greater- plants likely predisposed to a significant yield loss |
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Insecticide-coated seed: The benefits and convenience of having a soil insecticide “wrapped” directly on the seed is clear. Cruiser (1.25mg rate) and Poncho 1250 (1.25 mg rate) are both from the neo-nicotinoid class of insecticides. These products must be custom applied to seed with specialized equipment, therefore producers must order them at the time of seed purchase. Using seed-applied insecticides for corn rootworm control in high-risk areas (see previous article) may be a gamble. This is because of the inconsistencies that have been seen in university trials throughout the Midwest. The labels literally state “protect” or “protection” from rootworm...not control. For producers in areas with low to moderate rootworm pressure, these seed treatments may be beneficial and may also offer protection from other soil insect pests, e.g., wireworms, seedcorn maggots, etc.
| Liquid Soil Insecticide Root-Rating Peformance1, 2005 | |||||
| Location | Best2 Rating |
Capture |
Regent |
Lorsban 4E |
Check |
| Lafayette, IN | 0.05 |
0.45 |
0.89 |
0.29 |
1.83 |
| Wanatah, IN | 0.02 |
0.19 |
0.09 |
0.14 |
0.79 |
| Columbia City, IN | 0.05 |
0.06 |
0.08 |
0.14 |
0.09 |
| DeKalb, IL | 0.18 |
1.44 |
1.64 |
0.49 |
2.37 |
| Monmouth, IL | 0.13 |
0.99 |
1.53 |
0.26 |
2.25 |
| Urbana, IL | 0.14 |
1.46 |
2.25 |
0.91 |
2.32 |
1 Node Injury Scale 0-3. 0=no damage, 3=severe root pruning, 0.25 or greater- plants likely predisposed to a significant yield loss |
|||||
Liquid soil insecticides: Producers have had the option of using liquid insecticides such as Capture, Lorsban, and Regent for several years. For some producers, plumbing a planter for liquids better suited their operation. Some soon found that the performance of these products under high rootworm pressure was inconsistent, sometimes with disastrous results. We would encourage producers in the very high-risk areas shown on the map above to carefully evaluate their recent experiences with rootworm before considering liquid insecticides. The efficacy results of these products for 2005 are as expected, namely satisfactory performance where rootworm pressure is light to moderate and mostly unacceptable levels of damage when pressure feeding is high.
| Granular Soil Insecticide Root-Rating Peformance1, 2005 | ||||||
| Location | Best2 Rating |
Aztec 2.1 | Force 3G |
Fortress 2.5 |
Lorsban 15G |
Check |
| Lafayette, IN | 0.05 |
0.29 |
0.38 |
0.20 |
0.19 |
1.83 |
| Wanatah, IN | 0.02 |
0.12 |
0.13 |
0.06 |
0.14 |
0.79 |
| Columbia City, IN | 0.05 |
0.09 |
0.15 |
0.06 |
0.07 |
0.09 |
| DeKalb, IL | 0.18 |
0.29 |
0.47 |
0.20 |
0.29 |
2.37 |
| Monmouth, IL | 0.13 |
0.48 |
0.41 |
0.37 |
0.46 |
2.25 |
| Urbana, IL | 0.14 |
0.32 |
0.48 |
0.20 |
0.66 |
2.32 |
1 Node Injury Scale 0-3. 0=no damage, 3=severe root pruning, 0.25 or greater- plants likely predisposed to a significant yield loss |
||||||
Granular soil insecticides: Granular insecticides have long been considered the standard to which other rootworm control products are compared. Their shortcomings include being bulky, dusty, and time-consuming to use. However, they have also delivered the most consistent level of performance. Though formulations and product names have changed over the last several years, the chemical classes have remained the same…organophosphates and synthetic pyrethroids. Insect resistance or enhanced biodegration has not been an issue with the current registered products. There is a concern of using these products when planting very early, incorporating the granules into the soil to slow UV degradation and/or off-target movement from rainfall is strongly encouraged.
| Insecticide Coated Seed Root-Rating Peformance1, 2005 | ||||
| Location | Best2 Rating |
YieldGard RW |
Force 3G |
Check |
| Lafayette, IN | 0.05 |
0.05 |
0.38 |
1.83 |
| Wanatah, IN | 0.02 |
0.02 |
0.16 |
0.79 |
| Columbia City, IN | 0.05 |
0.05 |
0.06 |
0.09 |
| DeKalb, IL | 0.18 |
0.70 |
0.47 |
2.37 |
| Monmouth, IL | 0.13 |
0.21 |
0.41 |
2.25 |
| Urbana, IL | 0.14 |
0.19 |
0.48 |
2.32 |
1 Node Injury Scale 0-3. 0=no damage, 3=severe root pruning, 0.25 or greater- plants likely predisposed to a significant yield loss |
||||
Bt Corn Rootworm: This technology, although far from perfect, has been the most consistent in protecting roots from significant damage in its short history on the market. Dow/Pioneer’s Herculex event will be commercially available to producers next season. Unfortunately, direct data comparisons with Monsanto’s YieldGard rootworm performance are not available at this time. Both Herculex and YieldGard seed will be packaged with either Cruiser (low rate) or Poncho (low rate) for protection from other soil insect pests, e.g., wireworms, seedcorn maggots, etc. It will be mandatory that producers follow refuge guidelines (20% within or adjoining field). The 20% non-Bt refuge will need chemical protection from rootworm.
Sponsored by the Purdue Pest Management Program Additional Information |
SCHEDULE (Central Time for Valparaiso, other locations are Eastern Standard Time) |
Topics (for each location)
|
|
| 8:30-9:00 9:00-11:50 11:50-12:35 12:35-4:15 4:10 |
Registration Morning Presentations Lunch Provided Afternoon Presentations CCH/CEU Forms |
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| Brochures soon to be mailed to all Indiana commercial applicators. Online registration, with a credit card, is available after Monday, November 28, 2005. Go to www.conf.purdue.edu and click on the "Programs Catalog" and then click on "Conferences" and choose the Crop Management Workshop you want to attend. | |||
INSECTS, MITES & NEMATODES |
Asian Lady Beetle
Asian Lady Beetle: Beneficial or Nuisance? - 24
Alfalfa Weevil
Don’t Forget the Alfalfa - 4
Armyworm
Armywork Look-Alike in Wheat - 10
Bean Leaf Beetle
Bean Leaf Beetle Waking Up from Winter’s Nap - 6
Chewing Insects and Soybean Yield - 18
Inspect Seed Production Soybean for Bean Leaf Beetle Pod Feeding - 23
Black Cutworm
Black Cutworm Adult Pheromone Trap Report - 2, 3, 4, 5, 6, 7, 8, 9, 10
Watching for the Black Cutworm Moth Arrival - 2
Pheromone Trap Cooperators Have Detected Black Cutworm Arrival - 3
Black Cutworm Moth Flight Has Been Low This Spring - 5
Extremely Low Black Cutworm Moth Catches, Hopefully Good News - 8
Black Light Catch Report
Black Light Catch Report - 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 21, 23, 24, 25
Corn Earworm
Corn Earworm Activity - 14
Corn Flea Beetle
Winter Temperatures, Corn Flea Beetle Survival, and Potential for Stewart’s Wilt - 3
Corn Flea Beetle or Frost Damage - 5
European Corn Borer
Consider Corn Borer - Bt for Replanting of Corn - 8
European Corn Borer Moths Flying - 12
European Corn Borer Damage Showing Up - 15
European Corn Borer Late But Not Out - 22
European Corn Borer Threat Has Changed…So Have We - 26
Hessian Fly
No Reports of Hessian Fly Damage in 2005 - 23
Insecticides
Seed-Applied Insecticide for Soybean - 1
Rootworm Insecticide Classifications and Consistency of Performance - 1
Pre-Applied Insecticide Corn Seed Treatments - 2
Insecticide Restrictions When Replanting Corn - 7
Early Planting and Rootworm Insecticide Efficacy - 9
Insects (Miscellaneous)
Perfect Weather for Seed Damaging Insects - 7
Armyworm Look-Alike in Wheat - 10
Diagnosing a “Short Corn, Tall Corn” Field - 12
Red Mites in Soybean Fields - 15
Japanese and Rootworm Beetles Emerging - 15
Chewing Insects and Soybean Yield - 18
Road Trip Observations of Soybean Aphid and Soybean Cyst Nematode - 20
Asian Lady Beetle: Beneficial or Nuisance? - 24
S.L.A.M. the 2005 Crop - 25
Japanese Beetle
Japanese Beetle Expected Soon - 12
Japanese and Rootworm Beetles Emerging - 15
Chewing Insects and Soybean Yield - 18
Mexican Bean Beetle
Mexican Bean Beetle Appearing in Southern County Soybean Fields - 19
Nematodes
What Should We Expect from Nematodes This Spring - 5
Nematode Updates - 12, 18, 22
Road Trip Observations of Soybean Aphid and Soybean Cyst Nematode - 20
Changes in SCN Soil Testing Policy - 22
Winter Annual Weed and Management of Soybean Cyst Nematode - 26
Other
Christian Krupke, New Field Crops Entomologist - 1
Prepare Grain Bins for Wheat Harvest - 11
Diagnosing a “Short Corn, Tall Corn” Field - 12
Potato Leafhopper
Potato Leafhopper Have Arrived - 10
Leafhopper Populations Booming - 15
Rootworms
Early Planting and Rootworm Insecticide Efficacy - 9
Rootworm Hatch Detected in West Central Indiana - 11
Rootworm Sampling in High Risk Fields - 13
Rootworm Larval Damage Being Reported, Could Get Worse - 14
Japanese and Rootworm Beetles Emerging - 15
Corn Lodging Being Reported - 16
Stressed Corn, Pollination, and Rootworm Beetles - 16
Sticky Traps for Monitoring Western Corn Rootworm Beetles in Soybean - 17
Root Damage Ratings Can Now Be Conducted - 17
Rootworm Beetles Very Active in Soybean, Even Treated Fields - 21
2005 Western Corn Rootworm Soybean Sweep Net Survey - 26
Corn Rootworm’s 2005 Impact Lower Than Anticipated - 27
Perceived Risks to Western Corn Rootworm Damage in First-Year Corn - 27
Rootworm Soil Insecticides: Choices, Considerations, and Efficacy Results - 27
Sawfly
Armyworm Look-Alike in Wheat - 10
Seedcorn Maggots
Perfect Weather for Seed Damaging Insects - 7
Slugs
Slug Damage and Rescue Controls - 9
Southwestern Corn Borer
SWCB Spring Survey Update - 3
Soybean Aphid
Soybean Aphid Waking from Winter’s Nap - 4
Planning for the 2005 Soybean Aphid Population - 9
Soybean Aphid Found in Soybean - 11
Soybean Aphid Causing a Stir - 13
Soybean Aphid Update - 14, 15, 17
What’s Happening With Soybean Aphid - 16
Soybean Aphid Numbers Continue to Rise - 18
Soybean Aphid Threshold Clarification - 19
Soybean Aphid: The Spraying and Learning Continues - 20
Harvest Restrictions for Soybean Aphid Insecticides - 20
Road Trip Observations of Soybean Aphid and Soybean Cyst Nematode - 20
Soybean Aphid, Recent Treatment Quandaries Becoming Clear - 21
Spider Mites
Spider Mites Responding to Dry Conditions - 14
Spider Mites, Rain, and Control - 16
Stored Grain
Prepare Grain Bins for Wheat Harvest - 11
S.L.A.M. the 2005 Crop - 25
White Grubs
Grub Problems: Wait and See - 5
Perfect Weather for Seed Damaging Insects - 7
Wireworm
Perfect Weather for Seed Damaging Insects - 7
Some Wireworm Damage Being Reported - 10
WEEDS |
Control
Burcucumber Control - 2
Spring Weed Control in Winter Wheat - 3
Star-Of-Bethlehem - 4
Poison Hemlock - The Toxic Parsnip - 5
Glyphosate Resistant Horseweed (Marestail) Found in 9 More Indiana Counties - 8
Pokeweed Control - 12
Musk Thistle and Its Control - 13
Weeds to Look Out For - 23
Herbicides
Spring Weed Control in Winter Wheat - 3
Cold Weather and Postemergence, Spike Stage Herbicide Applications in Corn - 6
Weed and Volunteer Corn Management in Replaced Corn Fields - 9
Sugar Maple in No-Till Fields - 9
Postemergence Control of Grass Weeds in Field Corn - 11
Harvest Aid Herbicides for Winter Wheat - 11
A Little Something About Harvest Aids - 24
Fall Applied Herbicides for Soybean, Corn, and Wheat - 25
Other
Indiana’s Top Ten Most Problematic Weeds - 14
A Little Something About Harvest Aids - 24
PLANT DISEASES |
Corn
Winter Temperatures, Corn Flea Beetle Survival, and Potential for Stewart’s Wilt - 3
Common Rust of Corn - 17
Aflatoxins in Indiana Corn? - 24
Soybeans
Spraying for Soybean Rust: Fact vs. Fiction - 2
Asian Soybean Rust is Off the Selected Agent List - 2
Soybean Rust Update - 11, 17, 20
Soybean Rust - 13
What’s Wrong with my Soybean Leaves? - 14
Phytophthora Root Rot of Soybean - 15
Root Rot Problems in Soybeans - 17
Soybean Sudden Death Syndrome - 18
Downy Mildew on Soybean - 19
Frogeye Leaf Spot - 19
Soybean Rust Update for Indiana - 22
Frogeye Leaf Spot on Soybean - 22
White Mold of Soybean - 22
Soybean Sudden Death Syndrome - 22
Wheat
Identifying Wheat Growth Stage - 2
Yellowing of Wheat - 3
A Risk Model for Fusarium Head Blight of Wheat is Up and Running - 5
Leaf and Head Blight of Wheat - 5
Wheat Stripe Rust - 11
Leaf Blotch and Leaf Rust of Wheat - 13
AGRONOMY TIPS |
Corn
Planter Maintenance: Less Down Time, More Yield - 1
Did We Dodge a Frozen Corn Bullet? - 6
I’ve Got the Corny Stand Establishment Blues… - 7
Stress Continues for Corn Growing Under Refrigerated Conditions - 7
Some Mid-April Planted Corn in Trouble - 8
Tips for Staging Damaged Corn - 9
Singin’ From the Same Sheet of Replant Music - 10
Ear Size Determination in Corn - 10
No Tillage: The Best Tillage Choice for Replanting - 10
A Tale of Two Plants - 11
Yellow Tops and Twisted Whorls - 12
Jumping on to the Drought Bandwagon - 15
Suggestive Behavior in the Corn Field: A Fast & Accurate Pregnancy Test for Corn - 16
Tassel Emergence & Pollen Shed - 15
Silk Emergence - 15
Yield Loss Potential During Grain Fill - 18
Behind the Proverbial Eight Ball - 18
Grain Fill Stages in Corn - 19
Kernel Set Scuttlebutt - 20
Estimating Corn Grain Yield Prior to Harvest - 20
Impact of Warm Night Temperatures on Corn Grain Yields - 20
Assessing Potential for Nitrate Problems in Corn - 20
Corn Yield Trends for Indiana: 1930-2005 - 21
Field Drydown of Mature Corn Grain - 22
Fear Monger Alert: Monitor Corn Fields for Weakened or Diseased Stalks - 22
Take Time Now to Evaluate Hybrid Plots - 23
Top Leaf Death in Corn - 23
Grain Drydown, Stalk Lodging, and Harvest - 24
Corny Oddities: Popped Kernels and Silk Cut - 24
Corn Yield Trends for Indiana: 1930-2005 - 25
Fall Soils Sampling for Next Year’s Crop - 25
Miscellaneous
Planter Maintenance: Less Down Time, More Yield - 1
Soybeans
Frosted Beans: Should I Replant? - 8
Wheat
Wheat Tiller Number and Spring Nitrogen Recommendations - 1
Identifying Wheat Growth Stage - 2
Spring Wheat Injury and Shallow Planting - 3
Wheat Yield Response to Cold Stress - 7
Anthesis: Critical Stage for Soft Red Winter Wheat - 9
FROM UNDER THE MAGNIFIER |
Purdue’s Plant and Pest Diagnostic Lab Plans for Timely
ID of Soybean-Rust Sample Submissions - 2
BITS & PIECES |
Miscellaneous
2005 Popcorn Agri-Chemical Handbook Now Available - 2
Purdue Forage Day - 7
Purdue Booklet Speaks Volumes About Soybean Rust - 12
Donald H. Scott - 14
Exercise Caution When Using Fungicides Near Water - 17
Indiana and Ohio CCA Program at the Farm Science Review - 22
Organic Farm Tour in Indiana - 25
2006 Crop Management Workshop Announcement - 27
WEATHER UPDATE |
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