Alabama Phenology Garden Project: Using Degree-days and Phenology to Predict Pest Activity

Abstract

Accurate prediction of pest activity is crucial crucial for maintaining a successful urban integrated pest management program. Plant phenology and growing degree days can be useful tools in tracking important pest stages thus signaling the most critical treatment time. Because plant and insect development is mostly dependent upon temperature, biological calendars can be developed to help monitor key stages. The main objectives of this research were to (1) establish phenology gardens containing common taxa throughout Alabama, (2) compare the emergence, flight, or appearance of insect pests with the progression of ornamental plant bloom stages in each garden, and (3) produce a website with key phenological indicators and pest correlates. Phenological data collected from two sentinel insect species, dogwood borer and crape myrtle aphid on five sites and eight additional landscape pests in Auburn from 2010 to 2011 were used to establish phenological bloom sequence-based prediction models for 12 plant species for landscaper management personnel, growers, and laypersons. Growing degree-days models were implemented and compared to test accuracy of each. A total of 32 phenological events were studied in correlation with key insect life stage events such as first appearance and peak stages. The rank order of phenological events showed that there was significant correlation of bloom stages from year to year and site to site based on results of the Spearman’s bivariate correlation and regression analysis. A common phenophase was not found to be consistent with activity statewide of the two sentinel pests. Variations in cumulative growing degree day and Julian date proved no reliable statewide indicator for pest prediction. However, In future studies, recommendations could possibly be on a broader latitudinal area such as region or USDA hardiness zone.