How to Use This Publication
General Comments on Alfalfa Insect Management
This publication was prepared to help producers manage insect populations with the best available methods that have proven practical under Kansas conditions. It is revised annually and intended for use only during the year listed in the title. The mention of commercial products in this publication does not imply approval to the exclusion of other similar products. This publication summarizes the most common insect problems associated with this crop and lists chemical control options along with a discussion of other pest management strategies where reliable information exists. Additional information on many of these pest problems is available through the local K-State Research and Extension office.
Except where indicated, the insecticides listed 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. Price is influenced by factors beyond the scope of this publication, hence product cost in general was not considered as a reason for either including or omitting specific insecticides from these recommendations. We recommend that producers always compare price, safety and availability of products. Rates are usually given as pounds of active ingredient (a.i.) per acre. If a recommendation calls for 2 pounds of carbaryl, then 2.5 pounds of Sevin 80S or 4 pounds of Sevin 50WP would be required to achieve the correct dosage.
The waiting or preharvest interval (PHI) refers to the time that must elapse between application and harvest. 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 treated fields without the use of protective clothing and/ or equipment.
A number of insecticides are classified as restricted use pesticides. Private or commercial applicators must be certified by the Kansas Department of Agriculture to purchase or use restricted products.
Some pesticide uses may be permitted by means of State of Kansas Special Local Needs (SLN) labels. The law requires possession of this label when using an SLN product.
Caution
This document is intended to help consultants and producers make preliminary decisions on insect management options. The information in this publication is thought to be correct at the time of writing; however, labels frequently change without much warning. Plus, it is impossible to include all usage, safety and precautionary statements for a given product in this type of publication. Users are reminded to check labels carefully before use to ensure the product(s) under consideration can and will be legally applied.
Remember that illegal contamination of the treated crop or commodity can occur through pesticide misuse. 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 question about the intended use, contact the product manufacturer, K-State Research and Extension, or the Kansas Department of Agriculture before applying. Always read and follow label directions carefully. Never use a pesticide when the validity of the label or the intended use is in doubt.
Managing Insects in Alfalfa
Some pest problems can be avoided or reduced by selecting varieties resistant to insect and disease attack. Growers should check with seed dealers for information
on pest resistance when choosing varieties. The National Alfalfa Alliance (100 N. Fruitland, Suite B, Kennewick, WA 99336) produces a publication, Winter Survival, Fall Dormancy and Pest Resistance Ratings for Alfalfa Varieties, which is available on the Web site: www.alfalfa.org .
The site lists more than 250 public and private alfalfa cultivars offered through more than 60 marketing outlets. Resistance ratings for spotted alfalfa aphids, pea aphids, blue alfalfa aphids, potato leafhopper and a number of diseases are provided. Some of this information is reprinted in the annual Kansas Performance Tests with Alfalfa Varieties, on the Internet at http://kscroptests.agron.ksu.edu/.
Cultivars with high resistance (greater than 50 percent resistant plants) to spotted alfalfa aphids and pea aphids may have an advantage where these pests are frequently encountered. Blue alfalfa aphid resistance is harder to find, and cultivars possessing moderate resistance (31 to 50 percent resistant plants) may be acceptable choices.
Do not select cultivars on insect resistance alone. Remember that variety choice should be based on a combination of factors including yield, dormancy rating and hardiness, disease resistance, insect resistance, and a number of interrelated factors.
Alfalfa grown in Kansas often is used miles from the production area in the form of hay or dehydrated products. Because it is necessary to avoid using pesticides capable of leaving illegal residues in milk or meat products, these recommendations consist of relatively nonpersistent insecticides labeled for forage alfalfa production. Longer residual insecticides are sometimes used in seed production fields if they have been labeled specifically for that purpose. As always, verify use patterns by reading the product label.
Economic insect infestations often occur early in the growing season when weather conditions are variable. Insecticidal control usually will be more effective when daytime temperatures are above 60°F.
Most of the insecticide treatments recommended in this guide are designed for use with conventional ground or aerial equipment. The applicator should read labels carefully to determine specifically how a product should be applied and what type of safety equipment is required. If the producer is considering using chemigation, check the label to be sure chemigation is allowed, and review the Kansas Chemigation Safety Law and published regulations to determine legal requirements for chemigators.
Endangered Species
The U.S. Environmental Protection Agency (EPA) has established interim measures for protecting endangered species in seven Kansas counties: Barton, Clark, Comanche, Meade, Reno, Rice and Stafford. Currently, the program is aimed at protecting the interior least tern and the piping plover. While this program is now voluntary, it could become mandatory in the future. More information can be obtained from K-State Research and Extension offices in the counties mentioned, the Kansas Department of Agriculture or visit the Web site www.epa.gov/espp/kansas/kansas.htm.
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 EPA 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.
Biological Control
Biological control is an important part of any insect management system. For more information on how biological control fits into alfalfa insect management programs read the K-State Research and Extension publications Alfalfa Weevil Management in Kansas: II. Non-chemical Controls, MF-918, and Biological Control of Insect Pests on Field Crops in Kansas, MF-2222.
More Information
For help identifying insects found on alfalfa, see K-State Research and Extension publications Identifying Caterpillars in Alfalfa, S-120, and Insects in Kansas, S-131. S-131 is a book containing more than 900 color photos that can be used to identify many common insects found throughout the state.
For more information about insect problems in Kansas, visit the K-State Research and Extension Entomology home page at: www.entomology.k-state.edu and select “Extension” from the menu on the left side of the page.
From: MF-809, Phillip E. Sloderbeck, and Robert J. Whitworth. Alfalfa Insect Management, Kansas State University.
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.