Ceratocystis fimbriata - Actinidia spp. pathosystem: mechanical dispersal, disease control and pathogenicity of isolates from different hosts

Ceratocystis wilt, caused by Ceratocystis fimbriata, is a vascular disease that causes wilt, root rot and canker in various agricultural and forestry crops worldwide. It is currently one of the main limiting factors for kiwifruit cultivation and expansion of the crop in Brazil and constitutes a serious threat to the world's largest kiwifruit producers, where the disease has not yet been reported. Studies developed since the occurrence of Ceratocystis wilt in kiwifruit have provided important information about the pathosystem, however, there are some questions to be answered for the development of disease management strategies. There are few studies on the control of C. fimbriata in kiwifruit and there is no information on the effectiveness of fungicides against the pathogen, one of the objectives of this Dissertation. Thus, in Chapter 1, among four fungicides tested (metalaxyl + mancozeb, boscalide + cresoxim-methyl, pyraclostrobin, copper hydroxide) against the in vitro mycelial growth and spore germination of the fungus, metalaxyl + mancozeb and pyraclostrobin were the most effective, but they were not effective as protectors of pruning wounds against C. fimbriata infection, evaluated in two kiwifruit cultivars. In Chapter 2, we found that C. fimbriata can spread from diseased to healthy kiwifruit vines by pruning tools and that its immersion in hot water at 80 °C for 15 seconds is an effective method for eradication of the pathogen. In chapter 3, we determined that isolates of the fungus from different hosts can infect kiwifruit vines, with different levels of aggressiveness, including C. lukuohia from ohia. The results of these studies contribute to increase knowledge about the C. fimbriata-kiwi pathosystem and provide useful information for the disease management. Keywords: Ceratocystis wilt. Chemical control. Host range. Kiwifruit. Pruning tools.