Evaluation of BAS-750-07F (Revysol), DMI and SDHI fungicides with LI 700 for control of apple scab in 2018

摘要

An apple scab management trial was conducted in Highland, NY, to evaluate efficacy of a new DMI triazole fungicide Revysol SC (34.93% W/W mefentrifluconazole; proposed FRAC 3) and compare it to the SDHI fungicides alone or in mixture with the surfactant LI 700. We used 23-yr-old apple trees on M.9 rootstock planted in discrete three-cultivar replicated plots at 25 ft between rows, 10 ft between trees within rows, and 20 feet between plots within rows. Treatments were replicated four times using a complete randomized design (CRD). Each replicate plot consisted of all three cultivars listed above. Treatments were sprayed dilute to drip (300 gal/A) using a tractor-carried handgun sprayer (Rear's Pak-Tank 100-gal sprayer, 250 PSI) at 2-20 day intervalsdepending on apple bud growth development and weather conditions as shown in Tables 1 - 3 (24 Apr - HIG, half-inch green; 1 May - TC, tight cluster; 5 May - PK, pink; 7 May - EB, early bloom; 9 May - BL, bloom; 14 May - PF, petal fall; 25 May - 1C, firstcover; 6 Jun - 2C, second cover; 26 Jun - 3C, third cover; 16 Jul - 4C, fourth cover; 23 Jul - 5C, fifth cover; 4 Aug - 6C, sixth cover). Insecticides during the trial were applied with an air-blast sprayer to all plots including control trees. The Unigreen Turboteuton Mistblower air-blast sprayer (Uni-green Crop Protection, S.p.A., Reggio Emilia, Italy) delivered 45 gal of spray solution per acre. Trees in the untreated two rows on the east side of the experiment block never protected with fungicidesin the past, were rated and labeled as Untreated control (Tables 1-3). Control trees not treated until first cover and then treated with Captan 80 WDG from 1C - 6C, were randomized among the fungicide treatment trees throughout the research block and arelabeled as treatment no. 2 (Tables 1-3). Eight major infection events were determined by using RIMpro apple scab prediction model (RIMpro B.V., Zoelmond, Netherlands) connected to weather data collection feed from an on-site NEWA-RainWise weather station in Highland, NY. These infection events were reported, i.e. recorded on 25 and 27 Apr and 6, 11, 12, 15, 17, and 19 May. The first major scab infection on 25 Apr at HIG required an early protective application of mancozeb at 1.5 lb/A and was not anticipated in planning of the fungicide programs (the first spay application in each treatment program was planned to start at TC). The last, but weak infection event, occurred on 22 May. The first apple scab symptoms were detected in untreated control 'Redcort' leaves on 11 May. The apple scab incidence on spur leaves was rated from 5 - 12 Jul and on fruit from 7 - 10 Aug. The percent incidence on spur leaves was calculated from the number of leaves with scab lesions versus the leaves without lesions on 20randomly selected leaf clusters per tree. The percent incidence on fruit was calculated from the number of fruit with scab lesions versus the fruit without lesions on 20 randomly selected fruit clusters per tree, for a total of up to 100 fruits per treereplicate. Disease incidences in Tables 1-3 were subjected to Tukey's tests (a=0.05), for a completely randomized design using PROC MIXED procedure in SAS Studio software (SAS Institute Inc. 2017, Cary, NC). Where needed data were transformed prior to analysis.