Yes, it is spring in Sevier Valley, but sometimes it makes you wonder. Some days it feels like summer and other days it feels like winter and then there is the wind. We have had a relatively mild winter and a lot of precipitation, which has been a great turn around to last year’s drought. Erratic temperatures make it a real challenge to grow gardens, orchards and field crops.
As of Friday our office has received the latest prediction report from Dr. Marion Murry, Utah State University Extension integrated pest management specialist. Murry uses a system of orchard based pheromone monitoring traps, weather stations that record duration of temperatures, and a computer based prediction model that very accurately predict when it is time to treat for the codling moth.
This year that day for Sevier Valley is Wednesday, May 29. The greatest egg hatch is expected to occur beginning June 8. If you apply an insecticide by May 29, you should prevent an infestation of codling moth larvae or worms in your fruit. This gray adult female moth lays the eggs that hatch into the worms that bore into the fruit of apples, pears and other fruit. This occurs every year in Sevier Valley in late May or very early June a few weeks after full bloom. Some years when it’s warmer we have needed to spray insecticides as early as May 15. Cooler years it has been as late as June 4. It all depends on warm temperature and duration.
A couple weeks ago the temperature in Sevier Valley dipped to about 26 degrees and many, but not all, of the fruit blossoms were frozen. The blossoms that survived are just now starting to develop into fruit. Before you apply your first preventative insecticide application, it would be a good idea to check and make sure you have enough surviving blossoms and developing fruit on the tree to justify protecting it. Just because you had or still have blossoms with petals doesn’t mean it will produce viable fruit. You can check the status of your fruit crop by picking several blossoms and careful cutting them lengthwise with a good sharp knife to expose the center of the blossom. The bottom center part of the blossom is female reproductive part that has the potential to produce fruit and is called the “pistil.” If it is still green the blossom has survived.
If it is brown the blossom may look alive and have beautiful petals, but the female part of the blossom has been killed by the frost and could not develop into fruit.
After several days of warm enough and long enough daytime temperatures the codling moths mate and the females begin to lay eggs on leaves or fruits. The eggs hatch into worms called larvae that usually bore into the fruit through the blossom end of the developing fruit. They feed on the inside of the fruit until the larvae mature when they leave the fruit, making an unappetizing exit hole.
They become the next generation of moths to lay more eggs and continue the cycle. In Sevier Valley we typically have at least two generations per year and sometimes part of a third generation.
For more information visit the Utah State University Extension office located at the Sevier County Administration Building, 250 North Main in Richfield, or call (435) 893-0470.