Fazed by Zinnia Spots? This May Be Why

摘要

Zinnia leaf and flower blight causedby Xanthomonas campestris pv. zinniae (X. c. zinniae) is so familiar today that it's rarely studied. Luckily, it causes only localized spotting and none of the systemic effects found with the bacterial diseases of geraniums and begonias caused by other (different) Xanthomonas strains. All too often, though, this bacterial disease of zinnia steals the profitability of one of the most popular bedding plants by causing ugly spots on leaves, stems and flowers.This bacterial disease was first noted in Italy in 1929 and the pathogen was identified in Southern Rhodesia in 1949. It was first found in North America in Ohio and North Carolina in 1972. Over time, it has been found in many countries around the world,including Australia, Brazil, India, Malawi and Sierra Leone. Recently, it reappeared in Europe and first reports were also published from China and Korea, where the disease caused conspicuous symptoms on garden plantings of zinnia. In the United States, this disease is seen often in gardens and occasionally in greenhouses, particularly towards the end of the production season when temperatures are warmer.