Western flower thrips, Frankliniella occidentalis Pergande (WFT), is a severe pest on many greenhouse crops. Damage caused by WFT feeding decreases the aesthetic quality of ornamental crops. Accurate damage assessment is necessary to provide data to determine action and economic thresholds, and to evaluate the efficacy of different management strategies. Damage caused by WFT feeding on ivy geranium (Pelargonium peltatum L.) was quantified after scanning the adaxial and abaxial leaf surface with Adobe PhotoShop and Scion Image software. Damaged areas were identified by their colors in Adobe PhotoShop, and percentage of damaged leaf area (PDA) was then calculated in Scion Image for three leaf strata – young, youngest fully expanded, and old leaves. Total PDA of individual plants was then correlated with total WFT numbers which had developed for four weeks after inoculation. PDAs were also correlated to the subjective overall plant quality ratings which were assigned to each plant based on a scale of 1 to 10, with 7 to 10 representing ivy geraniums meeting commercial standards. The damage assessment method is presented in a step-by-step fashion.
Species 1: Thysanoptera Thripidae Frankliniella occidentalis (western flower thrips)
Species 2: Geraniales Geraniaceae Pelargonium peltatum (ivy geranium)
Keywords: image analysis
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