Dose Responses of Field Populations of Alfalfa Weevil from Various Western States to Lambda-Cyhalothrin® Using a Feeding and Contacting Assay

Insects, including alfalfa weevil (AW), are known for their genetic ability to develop resistance to insecticides. In a population of an insect species, there may be a few individuals that carry the genes for resistance to a chemical. Upon exposure to insecticides, insects that do not carry the resistance genes die, thus allowing the individuals with the resistance genes to survive and reproduce, creating more resistant insects. With every subsequent generation and continued selection, the number of resistant insects increases; therefore, the insecticide becomes less effective in controlling the pest population. Ayman Mostafa and Kyle Harrington of the University of Arizona Cooperative Extension Field Crops IPM Program investigated lambda-cyhalothrin (Warrior II™) against AW to test for any resistance by comparing the dose response of field populations of AW from seven states using feeding and contacting assay. The results of these experiments will be helpful to growers and the agriculture industry in the western region and around the nation as they decide which insecticides to use on their crops and which ones are most effective.

Improving Alfalfa Yield with Applications of Balanced Fertilizers

Among the potentials for enhancing production, profitability, and nutrition efficiencies of alfalfa crops is through effective use of fertilizers. For many soils in the low desert of Arizona, phosphorus (P) as a phosphate fertilizer is very commonly applied prior to planting alfalfa. Potassium (K) is assumed to be abundantly available in desert soils; therefore, not typically applied to crops. Nitrogen (N) fertilizer is generally not applied for alfalfa production since alfalfa can obtain its own N from N-fixing nodules. Specific information about the interactions and effects of P and K on alfalfa yield and quality for Arizona has not been developed. This publication by Ayman Mostafa and Worku Burayu of the University of Arizona Cooperative Extension Field Crops Program investigated and demonstrated the importance of balanced fertilizer applications to maximize alfalfa yield.

Cotton Insecticide Use Guide, Knowing and Balancing Risks

This is another IPM short, and is the result of many seasons of critical work on non-targets and efficacy of cotton insecticides. It’s that time of the season where many insecticide applications will be made in cotton, making this the perfect opportunity to share this important information on making insecticide spray decisions based on what we know about the risks associated with certain chemistries. Each insecticide decision carries with it a variable combination of risks. Isadora Bordini, Al Fournier, Steve Naranjo, Naomi Pier, and Peter Ellsworth have developed this guide in the hopes of aiding field managers in this, sometimes difficult, decision making process. This two page guide includes a table of cotton insecticides commonly used and information on their selectivity, efficacy, and associated risks along with a page that explains how the table is to be used and an explanation of how to interpret the information in order to identify, balance and prioritize all insecticide risks, by considering each spray decision on a case-by-case basis to fit the unique requirements of a situation.