KVH and Zespri have initiated a large research programme looking to better understand Kiwifruit Trunk Diseases (KTDs) in New Zealand kiwifruit.

While relatively early on in our research programme, it is becoming clear that no single pathogen is responsible for KTDs but rather it is a complex of fungal pathogens that are associated with these vine decline symptoms in kiwifruit. One of the groups of organisms that appears to be involved are a fungal group called the Ilyonectria species group.

Species of Ilyonectria cause root rots of a wide range of plants including kiwifruit. In other countries infection of kiwifruit by these pathogens causes leaf wilting, black and necrotic lesions on woody tissues of both the rootstock and roots, and death of the trees.

Prior to this research, we did not know much about Ilyonectria and its presence in kiwifruit. This project aimed to clarify the species of Ilyonectria associated with kiwifruit in New Zealand and establish whether they were pathogenic (disease causing).

We discovered four species within the Ilyonectria group in New Zealand but we did not understand if they were causing disease, or simply secondary invaders. As such, we set out to understand the pathogenicity of these four species that make up this complex. From this report, we now understand that these species are capable of causing disease in inoculated roots which suggests that they are pathogenic to kiwifruit.

Further work on these species in whole plants would aid in confirming their association with the disease symptoms we are seeing from diseased vines.

Read the report here.