Cultivar Assessment for Bacteria Spot of Pepper Resistance in South Florida

Bacterial spot (BS) of pepper, caused by the plant pathogen Xanthomonas euvesicatoria, is the most common and problematic foliar disease Florida pepper growers contend with. Therefore commercially available bell pepper (Capsicum annuum L.) cultivars with varying degrees of BS resistance were evaluated using a randomized complete block design and 4 replications during the fall of 2015 in Ft. Pierce. Investigators measured disease incidence, yield by fruit grade, and the following postharvest fruit characteristics; number of lobes, length, width, thickness, cracking, and bruising susceptibility. This trial was conducted on a commercial pepper farm using standard grower production practices for the region including seepage irrigation, fumigated plastic mulched beds, two rows of plants with nine-inch spacing between plants, and 18-inch spacing between rows resulting in a plant population equivalent to 19,360 plants/acre. Each plot consisted of 26 plants/replicate (13 plants/row). The above average temperatures and rainfall experienced during trial were conducive to disease development leading to widespread losses from bacterial soft rot caused by Erwinia carotovora and plant death from Phytophthora capsici. Consequently only one harvest was conducted instead of the standard two. Of the cultivars evaluated, only ‘Rampart’ from Syngenta-Rogers and ‘3255’ from Seminis yielded super-jumbo fruit. Their average number of super-jumbo peppers per replicate was 66 and 48 respectively. Along with ‘SW001’ from Seedway, ‘3255’ was also an overall yield leading cultivar. The latter averaged 1,125 marketable fruit per plot and was found to be statistically equivalent to the 1,105 produced by the former. The cultivar with the lowest marketable yield was ‘Bastille’ from Syngenta-Rogers with an average of 622 marketable peppers per replicate. With a disease severity rating of 3.5, ‘Bastille’ was also the most susceptible cultivar to BS. Frequent rains and high humidity led to BS symptoms on 17% of the ‘Bastille’ plant canopy whereas the characteristic water-soaked necrotic lesions on all other cultivars ranged from 1.75 – 0.0% incidence. Cultivars in this low range were statistically equivalent and received a disease severity rating ranging from 0.63 - 0. The data generated by this trial provides useful information to aid in the selection of varieties for commercial pepper production in south Florida. However, these findings represent the results of one season’s growing conditions. UF/IFAS Extension recommends repeating the trial annually and encourages growers to take into account data collected from previous years due to weather and pest pressure variability.