Citricola Scale Insecticide Trial, 2018

摘要

Citricola scale causes loss of tree vigor, yield reduction, anddowngrading of fruit in the packing house due to sooty mold growthon honeydew deposited by the insect. A field trial was conductedin a 36-yr-old ‘Washington’ navel orange orchard at the LindcoveResearch and Extension Center, Exeter, California, to comparevarious rates of insecticides for efficacy against citricola scale.Insecticides were applied using 200 PSI and 500 gpa to 10 treesper treatment using a 100 gal high-pressure D30 diaphragm pumpsprayer with mechanical agitation. Treatments were assigned to treeson 15 May 2018 in an RCB design based on pretreatment counts ofmature female citricola found on five twigs (~40 cm in length) randomlyselected from the northeast corner of the tree. All insecticidetreatments were applied with 0.5% Summer IAP oil on 31 Jul or 1Aug, when the population consisted of first-instar nymphs infestingleaves. Posttreatment sampling consisted of counts of first-instarcitricola nymphs infesting five leaves collected from the NE cornerof each sample tree during Sep and Oct 2018. An additional sampleof mature female citricola on five twigs per tree was collected inspring on 22 Apr 2019. Data were analyzed using one-way ANOVAafter testing for NS block effect. Differences in the mean numbersof nymphs per leaf or adult female scale per twig were determinedusing Fisher’s protected least significant difference test (P ≤ 0.05)after log10(x + 1) transformation of numbers.