One of these days Spring will be over and it will be time to spray codling moth once (or five times) again. Here is a review of the materials available and a few thoughts about their proper use. The standard material for codling moth control since the 1960’s has been Guthion. In most cases it remains the most effective and least expensive material available. For a number of reasons the future for organophosphate insecticides is not bright. Worker Protection Standards, increased label restrictions and potential moth resistance are but a few. The use of Guthion will certainly become more restricted as time moves on. It’s makes sense to learn about and gain experience with the new materials. During the season codling moth is present in an orchard in three distinct stages that can be targeted with insecticides. They are the egg, larva, and adult moth. The “new materials” are very specific as to their targeted stage and timing. Spray coverage is more important with these new products that must be ingested or cover the egg. The table below covers most of your choices for codling moth control this year. The column titled “Effectiveness” is a relative comparison of a materials ability to control codling moth compared to an untreated check. Residual is the approximate days one can expect control to be maintained. The “Stage” column is the life stage the material is targeted for. The cost per acre is figured on the most commonly used rate. Don’t take this as gospel, use it to compare one choice with another for cost, effectiveness and timing.
One of the keys to keeping these materials effective in your orchard is to not build resistance to them. The quickest way to encourage resistance is to use the same material or class of material over and over again against successive generations. By doing this you “select” out those individuals that survive the insecticide to reproduce and build a population that is resistant to that material. Using the same material on the next generation causes further selection and increased resistance. Of the materials listed above only Guthion and Imidan are in the same class of insecticide. If you’ve been having a problem keeping your fruit free of worms, give me a call and lets discuss strategy.
In the last newsletter I mentioned the organic status of NuFilm 17 & P. We recently received a notice from Miller Chemical Co. that they had voluntarily pulled the organic certification. There apparently is a question about one of the ingredients. It will stay off the list until the issue is resolved.