OCCURRENCE OF PERSIAN (ENGLISH) WALNUT BLIGHT AND ITS CONTROL IN THE NURSERY

Observations carried out over several years in walnut nurseries in Ita ly revealed bacterial walnut blight, induced by Xanthomonas campestris pv. juglandis, to be the most harmful disease; 4 years of field vials were performed. Infection level was shown to be related to the inter- row distances. The inter-row distances 0.6, 0.8, 1.0, and 1.4 m were t ested. The 1.4-m distance resulted in the best control of bacterial sp read, even under high inoculum pressure due to artificial inoculations . Foliage flush was the stage most vulnerable to bacterial infection. Chemical control with Bordeaux mixture and mancozeb was tested, but on ly Bordeaux mixture showed some effect. Two copper treatments, at the beginning and at the end of the vegetative period, can be recommended for those areas that are heavily infested with X. c. pv. juglandis.