DOI: 10.5061/dryad.h18931zjc
title: Montana codling moth trap-based biofix compared to two fixed biofix models, 2018-2020

description: Codling moth (Cydia pomonella) is the primary insect pest of apple and
 pear trees in Montana and can destroy an entire crop if uncontrolled.
 Understanding the moth's life cycle is important for determining
 management methods and timing of treatments. The purpose of this
 study was to compare trap-based biofix (first consistent moth capture in
 the spring) to two temperature based trap-free models for fixed biofix
 developed in other apple producing regions. Trap-free models determine a
 date for fixed biofix using temperature accumulation data (growing degree
 days) from nearby weather stations. Trap-free models compared in
 the present study were developed and are used in Washington state and Utah
 state; compared to Montana, Washington is similar latitude but lower
 elevation, and Utah is similar to higher elevation, but lower
 latitude. Results presented here suggest that the Washington
 state model for fixed biofix more closely aligns with Montana trap-based
 biofix in the 3 years of the study. Generally, trap-based biofix
 in Montana occured after the Washington state model fixed biofix growing
 degree date; we surmise that low evening temperatures and frequent high
 winds in some parts of the state and certain years could influence trap
 catch.
description: Data were collected in 2018, 2019, 2020 by a combination of
 Montana State University (MSU) staff, fruit growers, or volunteers. Data
 collected by paid staff are indicated in the dataset. We would like to
 thank all staff, fruit growers, and volunteers who assisted with this
 study. Trap-based biofix dates were established by
 hanging Trece Pherocon III Orange Delta traps equipped with a 1-month
 Trece codling moth lure in apple trees in participating orchards around
 100 growing degree days (GDD) after January 1 (50 degrees Fahrenheit base
 threshold, 88 degrees Fahrenheit maximum, single sine calculation method,
 horizontal cutoff); GDD for the orchard were determined using the nearest
 weather station with GDD data available through USPest.org. Personnel
 collecting data were instructed to check traps daily for adult male
 codling moth until biofix was established. Fixed biofix
 dates were determined using a USPest.org GDD accumulation (as described
 above) from the weatherstation nearest to the orchard combined with fixed
 biofix GDD per the Washington state method (175 GDD) and the elevation and
 latitude specific Utah state fixed biofix GDD calculated per this
 equation: GDD in Fahrenheit =
 (1755.559-(66.777*latitude)+(0.676*(latitude^2))-(0.0347*elevation in
 m))*1.8 Differences between trap-based biofix and fixed
 biofix dates for the two models are compared in the dataset.
 References for the fixed-biofix models are:
 Washington state method (Model 1):  Jones, VP, Doerr, M, Brunner,
 JF. 2008. Is Biofix Necessary for Predicting Codling Moth (Lepidoptera:
 Tortricidae) Emergence in Washington State Apple Orchards? J. Econ.
 Entomol. 101 (5):1651-1657. Utah TRAPs method (Model
 2): Jones, VP et al 2013.  Predicting the emergence of the codling moth,
 Cydia pomonella (Lepidoptera: Tortricidae), on a degree-day scale in North
 America. Pest Management Sci., 69:1393-1398.
description: This dataset will be a reference for a MSU Extension Bulletin
 titled "Managing codling moth (<em>Cydia pomonella</em>)
 in Montana" (currently in draft, 10/9/2020) where we will make
 recommendations for codling moth management in Montana, including which
 trap-free model to use.
 <strong>Definitions</strong>
 Growing degree days (GDD) are units of daily
 heat accumulation calculated using daily or hourly temperature
 data.  Biofix is the date when two
 adult codling moths are trapped two nights in a row in the
 spring. Trap-based biofix is
 synonymous with biofix and refers to the date when two adult codling moths
 are trapped two nights in a row in the spring.
 Fixed biofix is the date, per calculations
 based on GDD, when adult codling moths emerge from pupae and begin flying
 and mating.  Fixed biofix GDD vary between the two models compared in this
 dataset.