General Information
This publication was prepared to help producers manage insect populations with the best available methods proven practical under Kansas conditions. The information in this publication is thought to be correct at the time of writing; however, labels frequently change without warning. Plus, it is impractical to include all of the usage, safety and precautionary statements for any given product in this publication. Users should check labels carefully before making any application to ensure the product(s) under consideration can and will be legally applied.
The insecticides listed, except where indicated, are intended for use as foliar sprays. The first name listed refers to the common chemical name of the active ingredient, followed by the most commonly used trade name(s) in parentheses. Occasionally, specific formulations are listed for a particular use. The economics associated with achieving control should be considered as a factor in any pest management decision. However, product and application costs vary greatly over time and geography and are influenced by factors beyond the scope of this publication. We recommend that producers always compare price, safety and availability of products. The mention of commercial products in this publication does not imply approval to the exclusion of other similar products.
Rates are usually given as pounds of active ingredient per acre (a.i./acre). Rates of product to be applied per acre will depend on the formulation used. For example, if a recommendation calls for 2 pounds of carbaryl, then 2.5 pounds of Sevin 80 S or 4 pounds of Sevin 50 WP would be required to achieve the correct dosage.
Remember that illegal contamination of the treated crop or commodity can occur if pesticides are misused. K-State entomologists assume no responsibility for product performance, personal injury, property damage or other types of loss resulting from the purchase, handling, or use of the pesticides listed. As with all pesticides, the user bears responsibility for correct use. If there is any question about the intended use, contact the manufacturer of the product, K-State Research and Extension, or the Kansas Department of Agriculture before making any application. Always read and follow label directions carefully. Never use a pesticide when the validity of the label or the intended use is in doubt.
Insect Damage
Historically, soybeans in Kansas have usually escaped serious insect injury. But occasionally economic damage may occur. Most insects attacking soybeans may be grouped into three general types: foliage feeders, which are the most common, stem borers and pod feeders. Another group, sap feeders, may rise in importance if the soybean aphid reaches economically important densities.
Examples of foliage feeders include bean leaf beetles, blister beetles, grasshoppers, green cloverworms and webworms. Control decisions often are based on the amount of foliage that is being destroyed. Research has shown that soybean plants can withstand as much as 35 percent foliage loss during the blooming period. But when pods are forming and beginning to fill, a foliage loss of 20 percent or more may decrease yields. Defoliation rarely causes yield reductions after the beans are nearly filled.
An example of stem-boring damage is caused by the Dectes stem borer (or soybean stem borer), a small longhorned beetle whose larvae tunnel within soybean stems and often girdle the plants as they become mature. Serious infestations have been most common in south central Kansas, but are becoming more prevalent in north central and western Kansas.
In certain circumstances, pod-feeding insects such as stinkbugs or corn earworms can cause serious yield reductions. Growers in extreme southeastern Kansas are more likely to encounter problems from these two insects.
Terms
The preharvest interval (PHI) refers to the time that must elapse between application and harvest. The interval usually is different for forage use than it is for grain harvest, but when not specified, the interval usually is the same regardless of use of the treated product. The waiting interval does not signify how long an insecticide will provide control following application.
The restricted entry interval (REI) specifies the time that must elapse before people can safely return to work in treated fields without the use of protective clothing and/or equipment.
A number of insecticides are classified as restricted use pesticides. All individuals must be certified by the Kansas Department of Agriculture before they can purchase or use restricted products. Some pesticide uses may be permitted by means of State of Kansas Special Local Needs (SLN) label. The law requires applicators to possess this label before making an SLN application.
Sampling Techniques
Surveying for soybean insects attacking aboveground plant parts is not difficult if beans are planted in rows. On plants less than a foot high, insect densities can be established by kneeling along the row, turning over leaves and looking for insects. On larger plants a shake cloth technique is generally recommended. Place a 3-foot square cloth between the soybean rows. Bend about 1.5 row feet of plants from adjacent rows over the cloth, and shake vigorously for a few seconds. Count the insects that fall on the cloth. Repeat this operation in at least 10 locations per field, and average the results. Use of a slick-sided material will help keep the insects from crawling away before they are counted.
To survey narrow-row or drilled soybeans for insects use the “Texas Vertical Beat Sheet.” This device is made of a piece of galvanized metal flashing or similarly stiff material, 36 inches wide, 32 inches tall and crimped on the bottom to form a collecting trough 4 inches wide. Place it next to the row and shake plants against the vertical surface. Dislodged arthropods slide into the trough where they can be counted or poured into a container to be counted elsewhere.
Detecting Soybean Aphids
If heavy populations of aphids are observed on soybeans in Kansas, please contact a local K-State Research and Extension office or e-mail Brian McCornack at mccornac@ksu.edu so the infestation can be tracked and studied. To learn more about ongoing research in the North Central Region, visit the Plant Health Initiative website at http://www.planthealth.info/aphids_basics.htm.
Endangered Species
The Environmental Protection Agency has established voluntary interim measures for protecting endangered species in seven Kansas counties: Barton, Clark, Comanche, Meade, Reno, Rice and Stafford. The program is aimed at protecting the interior least tern and the piping plover. More information can be obtained from K-State Research and Extension offices in the counties mentioned or from the Kansas Department of Agriculture.
More Information
For help identifying insects found on soybeans, see K-State Research and Extension publications Identifying Caterpillars in Soybeans, S-116, and Insects in Kansas, S-131. For more information about insect problems in Kansas, visit the Entomology home page at: www.entomology.k-state.edu and select “Extension” from the menu on the left side of the page.
The Worker Protection Standard
The Worker Protection Standard (WPS) is a series of federal regulations pertaining to pesticides used in agricultural plant production on farms, forests, nurseries and greenhouses. You must comply with these regulations if you are an agricultural pesticide user and/or an employer of agricultural workers or pesticide handlers. For more complete information, consult the U.S. Environmental Protection Agency publication The Worker Protection Standard for Agricultural Pesticides —How to Comply, What Employers Need to Know. This publication is available at your local K-State Research and Extension office.
Stored Grain Management
This publication deals with insects during the growing season. For information on insects that attack grain during storage see publication number: MF-917, Management of Stored Grain Insects, Part III: Structural Sprays, Pest Strips, Grain Protectants, and Surface Dressings or go to the K-State Entomology Website at www.entomology.k-state.edu and click on “Extension,” then “Insect Information,” then “Stored Grain Management.”
This publication was prepared to help producers manage insect populations with the best available methods proven practical under Kansas conditions. Pesticide label directions and restrictions are subject to change, and some may have changed since this publication was written. Kansas State University entomologists assume no responsibility for product performance, personal injury, property damage, or other types of loss resulting from the handling or use of the pesticides listed. Remember, it is illegal to use a pesticide in a manner that is inconsistent with the label. The user bears responsibility for correct use. Always read and follow label directions carefully.