Where do I advise the grower to get this tested?
Last week I was called to a property, in West Auckland, to take a look at tomato plants that were mysteriously suffering from deformities. There were different symptoms presenting, but with all the plants the end result was termination of plant growth. The leaves on some plants had become variegated and very spikey looking (hormone damage type look). On other plants, the flowers on the truss, looked to have gone white at the ends (potential phytotoxic damage from spraying or root drench) and other plants stopped setting and had the appearance of Candidatus Liberibacter solanacearum (CLso) vectored from the TPP (Tomato Potato Psyllid). The root systems looked fairly constant, there was not any indication that Pythium or root issues were the cause of the deformity. The plant was only 8-10 weeks old.
I am still not sure what the deformity has been caused by but I am sure I have seen something similar before. It does appear a bit different than CLso, in that when you see plants infected by psyllids they stop setting fruit and the head goes yellow but it keeps growing vertically. This issue has seen the plants growth rate almost stop, see the pictures below, the leaf stunts and curls up. With hormone damage I’ve witnessed the leaf turning almost thistle like and odd shape fruit occurring, if the ‘hit’ of hormone is not that strong the plants will keep growing and sometimes they will grow through it. This crop had random areas with this mystery deformity and I cannot totally dismiss hormone but I would think you would see more of a pattern.
I always ask lots of questions, to try and eliminate possible grower error. In one irrigation valve there were more plants effected than the valve alongside, so I think it could have potentially been a root treatment, but I can not say that with certainty.
What I recommend is that the grower get the plant tested, sent to a laboratory to be examined by a plant pathologist expert. So where do I recommend to get plants tested? Recently it has become apparent that confidence in plant pathology testing in New Zealand is lacking, and to receive full in depth results companies prefer to send plants to Holland for testing. For years there was a particular plant pathologist here in New Zealand, he was fantastic at plant diagnosis, unfortunately he is no longer with us. For smaller growers the cost to send plants overseas is quite onerous and there is a certain amount of red tape to go through. I do understand there are places you can send plants here but I do ask myself why are growers sending plants overseas?
If there is a laboratory here in New Zealand I’m confident they could help diagnose this problem. I would really like to know about them so I can advise growers, pass on their contact details and even suggest they advertise on the grower2grower site!! It is a frustration of mine to advise growers to send plants half way around the world. It is not practical and can be very expensive and difficult to do so.
I appreciate your comments and help. Please feel free to comment below or on the grower2grower Facebook page:
Article Written by Stefan Vogrincic, Consultant, Grower2Grower