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Two-Year Summary Of Corn Rootworm Insecticides And Yieldgard® Rootworm, Marlin E. Rice, James Oleson Nov 2004

Two-Year Summary Of Corn Rootworm Insecticides And Yieldgard® Rootworm, Marlin E. Rice, James Oleson

Integrated Crop Management News

Two integrated pest management strategies are commonly used to protect corn roots from corn rootworm injury: crop rotation and insecticides. If corn is not rotated, or if extended diapause northern corn rootworms occur in a field, a soil insecticide might be necessary to protect the roots in 2005. The reason we say it might be necessary is because many fields do not have a rootworm population of a sufficient size to cause economic damage. There are thousands of continuous cornfields across Iowa in which a rootworm insecticide is not used and is not necessary.


Continuing Instructional Courses, Fall 2004, Elizabeth Minner Sep 2004

Continuing Instructional Courses, Fall 2004, Elizabeth Minner

Integrated Crop Management News

Pesticide use in Iowa is regulated under the Pesticide Act of Iowa. Iowa State University Extension provides raining and certification programs for commercial pesticide applicators in Iowa. Several fall courses are scheduled.


Long-Legged Flies In Crops, Marlin E. Rice Aug 2004

Long-Legged Flies In Crops, Marlin E. Rice

Integrated Crop Management News

It is not unusual to find something in corn or soybeans that normally does not occur there. This year, a species of long-legged fly is abundant, especially in soybeans, but it is not a pest of either this crop or corn. The adult fly is a metallic green and copper with clear or patterned wings, and of course, long legs. Adults are common in damp woods and fields, and along streams, where they can be found running in circles on leaves.


Soybean Aphids: No Widespread Problems, Marlin E. Rice Aug 2004

Soybean Aphids: No Widespread Problems, Marlin E. Rice

Integrated Crop Management News

The soybean aphid has been a pleasant disappointment this year. While many of us were anticipating a repeat performance of widespread, economically damaging populations in 2004, the soybean aphid, for whatever reason, has fizzled. The aphid can be found throughout much of Iowa, but nearly all field reports are that populations are way below the economic threshold of 250 aphids per plant. The one reported exception is in Marion County. Steve Crozier, Smith Fertilizer and Grain, reported he was finding more than 50 percent of the plants with more than 250 aphids, and 500 aphids per plant was not uncommon.


Speed Sampling For Soybean Aphids, Marlin E. Rice Jul 2004

Speed Sampling For Soybean Aphids, Marlin E. Rice

Integrated Crop Management News

The soybean aphid is not making much of an impression in Iowa this July. Reports from across the state indicate that aphids can be found in soybeans but populations are mostly small and very scattered. Recently I had several participants at a field training school ask about the Minnesota speed sampling procedure for soybean aphids. This method was developed by Erin Hodgson, Department of Entomology, University of Minnesota. It is still being refined with additional research being collected this year.


Predicting First-Generation Bean Leaf Beetles, Marlin E. Rice, Richard O. Pope Jul 2004

Predicting First-Generation Bean Leaf Beetles, Marlin E. Rice, Richard O. Pope

Integrated Crop Management News

Bean leaf beetle feeding on soybean pods can lead to significant reductions in seed quality and yield. Management during the pod setting and filling stages can be frustrating because beetles may feed on pods for a couple of weeks before the population reaches the economic threshold. In this situation, some loss in seed quality and quantity occurs before an insecticide application can be economically justified. Several years ago, Larry Pedigo, a lecturer in the Department of Entomology, and his students developed research-based information to help make a management decision for second-generation bean leaf beetles based upon the population size of ...


Don't Confuse Thrips With Aphids, Marlin E. Rice Jul 2004

Don't Confuse Thrips With Aphids, Marlin E. Rice

Integrated Crop Management News

I have received reputable reports from around the state that some field scouts and farmers are confusing soybean thrips with soybean aphids, and maybe some of these fields also are being sprayed. Soybean thrips almost never injure soybeans in Iowa and then probably only during dry weather. Correct identification of each insect is critical if the field is going to be sprayed with an insecticide because fields should not be sprayed for soybean thrips.


Soybean Aphids Found In Southwestern Iowa, Marlin E. Rice Jul 2004

Soybean Aphids Found In Southwestern Iowa, Marlin E. Rice

Integrated Crop Management News

New reports of soybean aphids have diminished during the last week, but one new location is worthy of mention. Tracy Cameron, DeBruce regional agronomist, reports that Kevin Rugaard, DeBruce manager at Corning, found soybean aphids in Taylor County (southwestern Iowa) on July 1. Tracy noted that the population was not anywhere near the economic threshold, but one plant had "about a 100 around the apical bud and stem area." Tracy has scouted many other fields in southwestern Iowa and has not found aphids at any other location.


Soybean Aphid Reproduction At Summer Temperatures, Marlin E. Rice Jul 2004

Soybean Aphid Reproduction At Summer Temperatures, Marlin E. Rice

Integrated Crop Management News

One of the more frequently asked questions about soybean aphids is how fast do they reproduce and how long do they live? Now we have an answer based on research from the University of Minnesota. Temperature effects on soybean aphid reproduction and survival have not been well understood until now. Minnesota entomologists determined the optimal temperature for soybean aphid growth and reproduction on soybean under controlled conditions. They conducted their experiments at constant temperatures of 68, 77, 86, and 95°F with a photoperiod of 16:8 (light:dark) hours.


New Soybean Aphid Publication Available, Marlin E. Rice Jul 2004

New Soybean Aphid Publication Available, Marlin E. Rice

Integrated Crop Management News

A new publication Soybean aphids in Iowa 2004 (SP 247) is now available from Iowa State University Extension. The publication contains 14 color images and covers numerous issues related to soybean aphids including biology, natural enemies, management options and insecticides. It also has the latest information on economic thresholds based on research from the University of Minnesota.


Soldier Beetles Are Not Crop Pests, Marlin E. Rice Jul 2004

Soldier Beetles Are Not Crop Pests, Marlin E. Rice

Integrated Crop Management News

Soldier beetles can be common in Iowa crops, especially corn and alfalfa, but they do not feed on either of these crops or soybeans. These beetles are known as leather wings in some regions of the U.S. and they somewhat resemble lightning bugs or fireflies, but they lack the light-producing organ on the abdomen and the head is not tucked under the pronotum.


Soybean Aphids Mostly Quiet In Late June, Marlin E. Rice Jul 2004

Soybean Aphids Mostly Quiet In Late June, Marlin E. Rice

Integrated Crop Management News

Reports from Extension field crop specialists on June 28 revealed that the soybean aphid populations are consistently small, or nonexistent, in many fields and the insect is not a significant problem anywhere in Iowa. Paul Kassel, Extension field crop specialist, reported that a crop consultant had found soybean aphids in Buena Vista County, but again this was a small population. Matt O'Neal, assistant professor of Entomology, noted that the soybean aphids in his research plots in Ames were slowly increasing and had spread to about a half dozen plants in two rows.


Soybean Aphid Insecticide And Herbicide Tank Mixing, Marlin E. Rice Jul 2004

Soybean Aphid Insecticide And Herbicide Tank Mixing, Marlin E. Rice

Integrated Crop Management News

There are questions regarding the value of tank mixing an insecticide for soybean aphids with the application of glyphosate for weed control in glyphosate-resistant soybeans. This seems like a logical approach to reduce cost, however it is probably impractical because of timing and application issues. The optimum timing for soybean aphids has historically been between mid- or late July and early August; the optimum timing for glyphosate in soybean is when the weeds are less than 4-inches tall which is most likely to be in June.


Grape Colaspis Found In Central Iowa, Benjamin Kaeb, Jon J. Tollefson Jun 2004

Grape Colaspis Found In Central Iowa, Benjamin Kaeb, Jon J. Tollefson

Integrated Crop Management News

The grape colaspis is a root-feeding pest of crops, occasionally injuring corn. Historically in Iowa, it was a pest in crop rotations where corn followed red clover. As Iowa agriculture placed a greater emphasis on row crops (primarily corn and soybean), the incidence of grape colaspis infestations declined. However, in recent years (since 1999) the grape colaspis has reemerged in modern crop rotations causing damage to corn following soybeans. Significant populations in seed corn and commercial corn following seed corn have been observed in central Iowa.


Soybean Aphids, Natural Enemies And The Economic Threshold, Marlin E. Rice Jun 2004

Soybean Aphids, Natural Enemies And The Economic Threshold, Marlin E. Rice

Integrated Crop Management News

Small colonies of soybean aphids were found in eastern Iowa on June 8. Natural enemies of soybean aphids, such as lady beetles (especially the multicolored Asian lady beetle), green lacewings, insidious flower bugs and other beneficial insects occur in Iowa soybean fields and will eat aphids. These predators probably will be most helpful in June and early July when fields are most likely to have small aphid populations.


Evaluate Insecticide Seed-Treated Cornfields, Marlin E. Rice Jun 2004

Evaluate Insecticide Seed-Treated Cornfields, Marlin E. Rice

Integrated Crop Management News

I have had reports of white grubs causing significant stand loss in a handful of fields, while reports of black cutworm and wireworm damage have been infrequently reported this spring. Now would be a good time to evaluate the performance of cornfields with insecticide seed treatments. The systemic seed treatments (Cruiser, Gaucho, and Poncho) were widely promoted last winter as effective treatments for control of white grubs, wireworms and cutworms.


Armyworm Defoliating Young Corn, Marlin E. Rice Jun 2004

Armyworm Defoliating Young Corn, Marlin E. Rice

Integrated Crop Management News

Armyworms (sometimes called true armyworms) are reported defoliating a few fields in Iowa. Mark Carlton, Extension specialist-field crops, reports damage from Lucas County and Larry Metcalf, a producer, reports damage from Dubuque County.


Stalk Borers Moving Into Corn, Marlin E. Rice Jun 2004

Stalk Borers Moving Into Corn, Marlin E. Rice

Integrated Crop Management News

Stalk borers are notorious for killing or stunting corn rows next to fences, grassed waterways, and conservation terraces. Control measures can be taken to prevent this damage, but fields must first be scouted on a timely basis.


Soybean Aphid Hits Eastern Iowa, Marlin E. Rice Jun 2004

Soybean Aphid Hits Eastern Iowa, Marlin E. Rice

Integrated Crop Management News

On June 8, soybean aphids were being found in several Iowa locations. Brian Lang, Extension specialist-field crops, found one winged aphid on V1-V2 stage soybeans near Decorah. Virgil Schmitt, Extension specialist-field crops, also stated he had received a "report of a couple of fields being sprayed for soybean aphid between Wapello and Burlington." Brian Wischmeier, NK Seeds agronomist, also on June 8, had received information that a field near Mediapolis in southeastern Iowa had large enough populations in V4-V6 stage, 14-inch soybeans that honeydew was collecting on the pant legs of the farmer as he walked the field.


Soybean Aphids In Iowa—2004, Marlin E. Rice, Matthew E. O'Neal, Palle Pedersen Jun 2004

Soybean Aphids In Iowa—2004, Marlin E. Rice, Matthew E. O'Neal, Palle Pedersen

Agriculture and Environment Extension Publications

This publication reviews what is known about the insect and makes management suggestions for 2004. Included is a new economic threshold based on a review of data from field trials and university research. Entomologists from 11 universities used this information to develop a consensus recommendation for the 2004 growing season.


First Cutting Dates Predicted For Black Cutworm, Marlin E. Rice, Richard O. Pope May 2004

First Cutting Dates Predicted For Black Cutworm, Marlin E. Rice, Richard O. Pope

Integrated Crop Management News

The black cutworm is an occasional pest of corn, yet it deserves our attention because of its potential for causing economic damage. Significant flights of black cutworm adults (moths) entered Iowa during April 19-21 and were caught in pheromone traps. From these catches we can predict first cutting of corn. Black cutworms require 300 degree days (base 50°F) for larvae to be large enough to cut corn plants (which is about the length of a dime). So by calculating cutworm hatch and development over time, we can anticipate when to look for damage.


Blacks And Dingys: Confusing Cutworms, Marlin E. Rice May 2004

Blacks And Dingys: Confusing Cutworms, Marlin E. Rice

Integrated Crop Management News

Each spring, seedling corn is attacked by a variety of caterpillars. Insect identification is the first step in determining whether there is a potential problem. Two of the most commonly confused insects are black cutworms and dingy cutworms. Black cutworms are less than 0.5 inch in length and feed on leaves, whereas larger larvae can cut or drill plants. Blacks cause almost all cutworm damage to corn. Cutting can occur below the surface when soil is dry, or above ground, when soil is wet and tight around the plant.


Stewart's Disease Risk For 2004, Alison E. Robertson, Marlin E. Rice May 2004

Stewart's Disease Risk For 2004, Alison E. Robertson, Marlin E. Rice

Integrated Crop Management News

There have been reports of corn flea beetles in southern Iowa from May 4 to 10. Overwintering flea beetles may be infested with the bacterium Pantoea (Erwinia) stewartii, which causes Stewart's disease. Field corn inbreds and sweet corn are particularly susceptible to this disease. Seed producers should pay attention to early season flea beetle populations because, if left unchecked, you could have substantial Stewart's disease during grain fill, resulting in yield loss.


Bean Leaf Beetle Mortality In Winter: 2003 Vs. 2004, Marlin E. Rice, Richard O. Pope May 2004

Bean Leaf Beetle Mortality In Winter: 2003 Vs. 2004, Marlin E. Rice, Richard O. Pope

Integrated Crop Management News

Bean leaf beetle populations have shot upward during the last several years and reached an historical high during 2002, but declined during the summer of 2003. These large populations have been partially due to favorable winter conditions, such as mild temperatures or snow cover in previous winters.


New Soybean Aphid Information Online, Marlin E. Rice May 2004

New Soybean Aphid Information Online, Marlin E. Rice

Integrated Crop Management News

A series of scientific papers on the soybean aphid were recently published on the World Wide Web, as free PDF documents. You must enter your name and a password before you access the publications. At the site, click on Annals of the Entomological Society of America, and then the "bullet" Online Edition (1999-Current). Then click on Current issue under the Annals journal title. Below are the titles and edited summaries for each paper.


New Seed Treatments: The Neonicotinoids, Marlin E. Rice May 2004

New Seed Treatments: The Neonicotinoids, Marlin E. Rice

Integrated Crop Management News

Three systemic insecticides applied as seed treatments will be used in Iowa this year: clothianidin, imidacloprid, and thiamethoxam. All three insecticides are in the neonicotinoid chemical family and closely resemble nicotine in mode of action. Neonicotinoids have high activity against sucking insects such as aphids and against chewing pests such as beetles and some Lepidoptera (cutworms, for instance). These chemicals are highly systemic in the plant roots and new leaf tissues, and can be used for several purposes, especially as seed treatment.


Soybean Aphids Hatching On Buckthorn, Marlin E. Rice May 2004

Soybean Aphids Hatching On Buckthorn, Marlin E. Rice

Integrated Crop Management News

Reports from my colleagues around the Midwest indicate that soybean aphids are hatching on buckthorn. Bob O'Neil, Purdue University, is working with aphids in Illinois and noted the first hatch occurred on March 27. Chris DiFonzo, Michigan State University, found newly-hatched aphids in central Michigan on April 17. To the west of us, Tom Hunt, University of Nebraska, found soybean aphids on buckthorn in Lincoln on April 23.


Western Bean Cutworms: Status And Scouting, Marlin E. Rice Apr 2004

Western Bean Cutworms: Status And Scouting, Marlin E. Rice

Integrated Crop Management News

Western bean cutworms have caused significant damage to some cornfields in Iowa since 2000. In the last couple of years, this insect seems to be moving eastward in Iowa. As it expands its range, it will cause damage to those fields not protected against this insect. A network of pheromone traps have been placed throughout the state to assist in scouting efforts for this pest. Iowa State University Extension is cooperating with Pioneer Hi-Bred agronomists in eastern Iowa to survey counties where the insect has not yet been reported.


Scout Alfalfa Weevils During April, Marlin E. Rice, Richard O. Pope Apr 2004

Scout Alfalfa Weevils During April, Marlin E. Rice, Richard O. Pope

Integrated Crop Management News

Degree-day information indicates that alfalfa weevil larvae are hatching throughout southern Iowa (see map). Proper management of this insect requires timely scouting, correct identification, determination of population levels, and if necessary, cultural or chemical control.


Section 18 Specific Exemption For Gaucho 480f, Marlin E. Rice Feb 2004

Section 18 Specific Exemption For Gaucho 480f, Marlin E. Rice

Integrated Crop Management News

On February 6, the Environmental Protection Agency granted a specific exemption under the provisions of Section 18 of the Federal Insecticide, Fungicide and Rodenticide Act, as amended, to the Iowa Department of Agriculture and Land Stewardship (IDALS) for the use of imidacloprid, formulated as Gaucho 480 Flowable, on soybean seed to control bean leaf beetles and soybean aphids in Iowa. The exemption is for 455,000 seed units and will allow seed for seed production, food production, and commercial "field" beans to be treated with Gaucho.