Phage hunt blog: Phage Treatment for Kiwifruit

Pseudomonas syringae pv. actinidiae or PSA is a bacteria which infects kiwifruit that was first discovered in Bay of Plenty  New Zealand late in 2010. Since then it has devastated the kiwifruit industry in New Zealand with more than 1600 orchards being infected. The losses associated with this are huge with an estimated loss to the industry of $885 million. You may ask what this has to do with phage, well there is a possibility that a phage could be used to help combat this bacterial infection.

In July 2011 the kiwifruit marketing company Zespri partnered up with the US bacteriophage producer OmniLytics Incorporated in an attempt to find a phage that will infect the PSA bacteria. The discovery of a phage that could be used on kiwifruit to combat PSA and still be safe for consumption could be a savior for the New Zealand kiwifruit industry.

The strain of bacteria we are working with, pseudomonas phosphorescence (SBW25), is from the same genus as the PSA bacteria. This means they are very similar both geneticly and in physical appearance. It is possible that a phage that effectively infects and kills the bacterial strain we are working with could be used to infect the PSA bacteria as well, because of their similarities but it means we are not working with and possibly transporting the PSA bacteria. In this way we have been investigating possible solutions to a very real problem in New Zealand while still learning.

Although we still do not know everything about phage and their relationship with bacteria and probably never will they are proving to be hugely in the primary industries of New Zealand.



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2 Responses to Phage hunt blog: Phage Treatment for Kiwifruit

  1. charlotterobertson007 says:

    I had a read of the sources you have used and I note that PSA grows both in and on kiwifruit vines (leaves, stem, roots, fruit). It would be fantastic if a phage was isolated to treat PSA disease and stop its spread through NZ orchards. As you have said, using phage is a possible solution. I think it is unrealistic to expect we could eradicate PSA only using only phage because of how widespread the disease is. Using phage to control the disease is a great idea though because phage do not leave chemical residues behind like conventional pesticides do. I wonder then, how we would administer phage to infected plants. Kiwifruit orchards are large (usually a bit below 5 hectares) and bacteria are very small. I imagine something could be set up with irrigation equipment – a phage-infected solution for topical application – but this might only be effective for killing bacteria on the surface of the vines as the phage may not diffuse into the plant tissues. I expect that we would also require very, very large quantities of phage for this kind of treatment. Nevertheless, that is why we are carrying out this research – to find the answers to important questions!

  2. sarahlomas19 says:

    When I was reading through your sources I decided to look up the company that is contracted to produce the phages: OmniLytics. According to their website,, it says that they believe that “phage therapy will be part of a fast growing revolution in determining how patients and crops will be safely and reliably treated in the future.” They have also previously done work on eliminting Samonella in poultry uses phages. It’s exciting to see how phage therapy is actually catching on, and becoming an interesting research field! After a quick google to see whether there are any NZ companies involved with phage therapy, ironically the first result up with the google search “phage companies NZ” was Phage Hunt NZ at Massey! It seems like we are leading NZ in phage therapy research :O

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