Weather station for determining degree days for coddling moth control

Asked January 6, 2015, 4:28 PM EST

We have 70 fruit trees, mostly apples,in Talent Oregon. I understand that determining degree days can help you decide when to spray for coddling moth. Would it be advisable for us to place a weather station on our property for that purpose? If so, what type of weather station and what functions would be needed? If using a weather station is not needed, how many pheremone traps and lures would you recommend for our ~acre of trees? thank-you! Cindy Harper

Jackson County Oregon

1 Response

Hi There,

Unless you live on a site that has a very different climate than the surrounding area, I would use the data from the closest government weather station to your site. SOU has fully functional weather station with easy to access data (

OSU also maintains an online calculator of degree days for many different crops and pests around the state. It is a bit cumbersome, but you can access it here: Look for the link that says 'online phenology and degree day calculator'. Use the google map pins to choose the location nearest you. You can also read the supporting documentation if you're interested in the OSU model (intended primarily for commercial growers and scouts ~ so they have more information than you probably need).

If you are on a site with very different climatic conditions, you only need to know temperature to do a simple degree day calculation. Thus, you don't really need a fully-stocked weather station. You only need a thermometer.

If you choose to use pheromone traps, just 2-4 traps (total . . . not per tree) are all that are needed to monitor for adults and decide on the timing of your pesticide sprays (if needed). That's one benefit of using pheromone traps over degree days to determine if/when to spray ~ you can usually keep your spray costs lower if using pheromone traps, because you won't need to spray unless you start catching moths in traps.

If you want to use pheromone traps to help MANAGE and CONTROL codling moth, folks recommend you use ~ 4 traps per tree.

I hope this helps. Make sure to check out EC-631E (managing pests in home orchards) from the OSU Extension catalog ( for more information on home orchard IPM.