FUNGICIDE EFFICACY AGAINST BOTRYOSPHAERIA CANKER ON LEYLAND CYPRESS

Williams, T. J.1; Williams-Woodward, J.L.2
1County Extension Coordinator, University of Georgia, Appling, GA, 30802
2Extension Plant Pathologist, University of Georgia, Athens, GA, 30602

Abstract:

Leyland cypress (Cupressocyparis × leylandii Dallim.) has been the green industries’ standard and the most popular screening evergreen used on the market. Leyland cypress is not native to North America, and has a USDA hardiness zone rating from 6 through 10A (Dirr, 1998). Botryosphaeria canker is a major disease of Leyland cypress especially in Southeastern landscapes, and it is found extensively throughout Georgia. An isolate of Lasiodiplodia theobromae originally recovered from Leyland cypress was used in this study. The protocol for the fungicide product evaluation consisted of five treatments with six single-plant replications per treatment per plant species. The trial protocol was conducted separately on both Leyland cypress and Japanese privet. The trial protocol consisted of five treatments including a non-fungicide (water) treatment, three rates (6, 8, and 10 fl. oz/100 gal) of the experimental fungicide BAS 75007F (BASF Corp., Research Triangle Park, NC), and one rate (8 fl. oz/100 gal) of Banner Maxx (propiconazole; Syngenta Crop Protection LLC, Greensboro, NC). Treatments were placed in a randomized complete block design on the greenhouse bench covering an area of approximately 4’ X 5’ of bench space. Fungicide treatments were applied to the foliage and stems using hand-held pump sprayers until run-off. Plants were treated twice at 14-day intervals prior to inoculation to assure uptake of the fungicide within plant tissues. After inoculation, two additional fungicide applications were made at 14-day intervals. Plants were treated for a total of four applications over a 56-day period. Greenhouse temperatures ranged from 24-30°C during the day to 21-24°C at night for the duration of the trial. Plants were monitored throughout the experiment for indications of canker development such as stem discoloration, sunken tissue, resin flow and callus formation. Botryosphaeria canker development was measured 6-weeks after inoculation by measuring canker length and width (mm).

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