It has been hot and dry most of the summer in extreme SE Kansas. The lack of rainfall has effected nut size (smaller nuts than normal) and has delayed the emergence of pecan weevil.
During most years pecan weevil adults emerge from the soil starting in early August (male and female weevils pictured above). However, during periods of drought, soil hardness prevents adult weevils from tunneling out of their subterranean pupal cases.
We finally received 3/4 inch of rain last Saturday which should have been just enough moisture to soften the ground and allow weevil emergence. I was all ready to start up the sprayer on Sunday, but then I looked at the weather forecast. More significant showers were predicted for my area on Monday, Tuesday, and Wednesday. To avoid wasting insecticide by spraying one day and getting it washed off the next, I decided to wait until the danger of heavy rain was past.
Turns out, we never did get any heavy rainfall earlier this week, just plenty of cloud cover and fog. So I decided to make an application of Sevin insecticide today. My orchard does not have a history of heavy weevil infestation but I have a neighbor that has un-managed native trees. When and if I get weevil damage, it is usually a result of weevils migrating into my grove from the adjacent property. Hopefully, today's spraying will keep visiting weevils from getting established in my grove.