Pollen tests put heat on Psa

Pollen producers are feeling more confident they can resume normal sales to the kiwifruit industry after a breakthrough in controlling the Psa bacterial disease.
The producers, in conjunction with Te Puke-based Plant and Food Research, have found a high-temperature treatment process kills the Psa without affecting the pollen's performance/viability.
Steps are being taken to commercialise the process and introduce an independent standard or test to verify the pollen is free of Psa - before the next round of artificial pollination begins in October.
"It's all very promising and there's more hope now than there was a few weeks ago," said Steven Saunders, managing director of PlusGroup which includes PollenPlus, the world's largest supplier of pure chieftain male pollen.
"The early indications show there are a lot of growers wishing to use supplementary pollen because they understand its value and potential.
"The heat treatment will give them surety that the pollen is safe to use - though there's still a little bit of work to do in applying the process commercially," he said.
The supplementary pollen helps increase the yield and quality of kiwifruit, particularly in areas where the bee population is low.
Since Psa was first detected west of Te Puke last November, the pollen producers - up to 10 of them from the Bay, South Auckland and Kerikeri - have met regularly to find a way of dealing with the problem. The group looked at chemical and UV treatment, cooling and even physical cleaning.
"It's been heartening seeing the producers working together for the good of the industry over and above their own commercial aspirations," said Mr Saunders.
PollenPlus employed a university student over summer to run heat trials, and the region's other big pollen producer, Kiwi Pollen NZ, provided information and worked closely with Zespri, Kiwifruit Vine Health (KVH) and Plant and Food.
Kiwi Pollen director Graeme Crawshaw successfully trialled the new methodology in Italy as an integral part of the milling process used to prepare pollen.
In early March, Plant and Food suggested that heat treatment was a viable solution, and it confirmed that last week.
Plant and Food will now be providing the group with final details about the temperatures and heating durations required to ensure the pollen is Psa-clean.
The cleansing heat treatment process involves two steps. After milling, the first move is to ensure that the physical state of the pollen is consistent so that all parts will be heated sufficiently. The heat, at least 45C, is then applied and could last up to half an hour.
"We don't want only 10 per cent of the pollen being heated at that temperature. It has to be all; that's the trick," said Allister Holmes, operations manager of PlusGroup.
After the heating treatment, the pollen is packed in jars and frozen. PollenPlus will test every two kilograms of pollen as normal before packing.
Mr Saunders said they wouldn't be using any flowers from the Te Puke priority zone, where the more serious Psa-V strand has been detected.
Te Puna-based PollenPlus, which picks up to 100 tonnes of chieftain flowers each season and produces one tonne of pollen, is investing in specialised heating equipment and will introduce a new clean room for packing and storing the pollen.
Mr Saunders said "we just need to be more vigilant with a more specialised room that has a good, clean environment".
Producers such as PollenPlus shut down their operation as soon as the Psa was detected during the pollination period last November.
PollenPlus harvested only 40 per cent of its normal supply and sold 8 per cent to local growers. Its stock was re-tested in February and most of it was exported to Japan, Korea and Italy between March and May.
"We kept a small amount of stock for existing local clients and that's already committed," said Mr Holmes. "But when the freezers were full of pollen, there was no guarantee we could do anything with it."
Mr Saunders said the heat treatment was the breakthrough "we were looking for because supplementary pollination is a valuable tool".
He said the kiwifruit industry was resilient and he was confident solutions would be found to contain Psa.
"But you can never relax with Psa; it's a major threat and normal isn't normal any more."