| Abstrakt: |
Euwallacea fornicatus (polyphagous shot hole borer, PSHB) is an invasive ambrosia beetle that infests hundreds of tree species worldwide. Damage occurs due to colonization of host sapwood with both the beetle and its fungal symbiont, Fusarium euwallaceae, which leads to Fusarium dieback disease in highly susceptible hosts. Except for almond (Prunus dulcis), and despite the name of the disease, the pathogenicity of F. euwallaceae towards stone fruit tree species have not been demonstrated. Here we set out to determine the pathogenicity of F. euwallaceae towards nectarine (P. persica) and plum (P. domestica) following its detection on various Prunus species in South Africa. Trees were inoculated with multiple isolates of F. euwallaceae, lesion development was characterised, and the causal agents were re-isolated to fulfil Koch's postulates. The influence of factors such as branch diameter, cultivar, host species, inoculum load and isolate identity on lesion development was also assessed. We confirm that F. euwallaceae is a pathogen to nectarine and plum and that the susceptibility of nectarine to F. euwallaceae was higher than for plum. Lesion development did not differ between the two plum cultivars. Branch diameter and an increase in inoculum load did not influence the rate of lesion development. We confirm that PSHB can breed in many Prunus species in gardens, including almond, nectarine, apricot, cherry plum and black plum. [ABSTRACT FROM AUTHOR] |
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