Riversun Nursery

July 2014

The nursery that helped the kiwifruit industry bounce back from the effects of Psa

With over 30 years of experience as a secure nursery for plant importation and quarantine, and using certified production methods for plant propagation, Riversun in Gisborne quickly responded to the Psa-V threat to the NZ kiwifruit industry with the semi-tolerant Bounty 71 rootstock and the production of grafted G3 Gold. The programme was threatened by the discovery of Psa-V on two Gisborne orchards in November 2012, but over the following nine months no further discoveries were made and Riversun’s entire production continued to test negative, enabling Riversun to go ahead with commercial sales of G3/Bounty 71 and G3/Bruno pot-grown vines.

Geoff Thorpe, principal of Riversun, founded a backyard nursery in Gisborne in 1982, where he was born and brought up on one of the first two kiwifruit orchards in the region. He attended Lincoln for a Hort Comm degree between 1977 and 1980 and had an OE before returning to the family business, which had expanded to 20ha of kiwifruit, 15ha of vineyard and 12ha of citrus. On his own account he planted some kiwifruit vines and grafted avocado trees. Over the following decade, Riversun produced kiwifruit, avocado, nashi, persimmon, citrus seedlings and grafted grape vines commercially for the Gisborne-East Coast horticulture industry. The Thorpes also had a retail garden centre and managed two kiwifruit orchards.

In 1989 Riversun sold its first grafted grapevines into Marlborough and during the next decade, volumes increased from 100,000 per year to two million, and peaked at five million in 2006, while staff numbers grew from half a dozen full timers to 60,with up to 200 seasonal staff at peak season. To manage that growth, Riversun exited all other crops and activities in 1998 and focused 100% on grafted grapevine production. It launched its own independently audited grapevine certification programme in 2000, opened a virus testing lab in 1999, a Level 3 quarantine facility in 2003, and signed up several licensee agreements with key breeders around the world.

In 2005 a licensing agreement with the Avocado Industry Council (AIC) resulted in 11 new varieties and rootstocks being imported between 2005 and 2008.

The Global Financial Crisis coincided with a big increase in NZ wine production and the demand for grafted vines disappeared almost overnight. Of the 30 nurseries producing grafted vines in NZ, 25 disappeared. Riversun hung in and took on relatively low-volume orders for persimmon trees and Bruno kiwifruit seedlings.

Following the discovery of Psa in Te Puke in November 2010, Zespri bought up all the nursery stock in the Bay of Plenty and buried it. The following spring (2011) the first semi-commercial trial plantings of a new rootstock variety Bounty 71 were showing promising tolerance to PSA. Riversun was approached by two large Bay of Plenty growers to commercialise the rapid propagation of grafted Bounty 71, which had never been done before anywhere in the world. The clients wanted 25,000 grafted vines ASAP.

Given that Gisborne was PSA virus free and Riversun did not want to bring any kiwifruit material into the region, even from other PSA-free regions, it had only 40 mother vines to work with, in two local orchards. The first 1000 cuttings were set out in December 2011 with a wide range of treatments and a month later another 3000 with two treatments. In February, having settled on the best propagation technique, a further 7000 were set and in March 20,000. Additional polyhouse space was leased and brought up to specifications.

By the end of April Riversun had 28,000 cuttings potted up and growing in heated polyhouses.

At the same time, Riversun worked very closely with Kiwifruit Vine Health (the body charged with managing the PSA situation in NZ by the government and the industry) on the development of an industry certification programme, drawing on its decade of experience in developing high health plant certification programmes for both the NZ grape vine industry and the AIC. Between 1992 and 2007 Geoff had travelled overseas almost annually to research international certification programmes, nursery production techniques for vines, and would visit the main research universities and grapevine variety/clone breeders. This scheme was launched in July 2012 and Riversun was one of the first nurseries to earn accreditation in September 2012.

In June 2012, Riversun conducted the first out-of-season grafting trials onto Bounty 71 to prepare for the spring, when 25,000 rootstocks had to be grafted. It needed to see what techniques, temperature and timings worked best. The average diameter of rootstock shoots to be grafted into was 3-4mm and fruiting vines rarely grow wood less than 1cm in diameter, so there were big technical challenges. Riversun had also signed up 80,000 grafted or chip-budded orders for delivery winter 2013 on Bounty 71, plus another 80,000 on Bruno, all to be grafted with G3 Gold, which was showing considerable promise for its moderate tolerance of PSA.

All the seedlings were potted and growing well by October 2012 and Riversun had developed a 7ha remote field nursery site, with planting out planned for mid-November when the frost risk had passed. But Psa-V was found in two orchards in Gisborne.

Both orchards had also taken delivery that winter of a couple of hundred of Riversun’s previous year’s field grown Bruno rootstock production – all of which had been grown in a remote and secure inland site, sprayed regularly with copper, inspected weekly by Riversun, inspected by the local KVH chairman prior to lifting; as well as being intensively Psa-V tested in Te Puke prior to lifting. Unfortunately the finger now pointed at Riversun as being the source of Psa’s arrival in Gisborne, despite the fact it had never introduced any plant material into the district and had followed industry best practice or higher.

Riversun’s brand was built over 30 years on providing plant quality second to none, so this was an untenable situation and the decision was made to dump all the cuttings and seedlings due for planting out in the new field nursery and to refund all deposits. However, over the next 10 days, Riversun was convinced by clients to continue with the grafting programme on the already potted up Bounty vines. Two local clients pulled together the resources to take all Bounty 71 cuttings and grow them on themselves in a glasshouse in Gisborne. The Bruno seedlings were sold to a number of Bay of Plenty growers for growing on by them.

Over six months, orders were filled with vines grown indoors and with no overhead watering, to minimize the risk of PSA getting established. One year later there had been no new finds of Psa in Gisborne and all Riversun production continued to test negative. To date it has never had a single symptomatic vine in the whole nursery operation.

The first deliveries of pot-grown, grafted G3/B71 vines were well-received by Bay of Plenty clients but as grape vine grafting was back to full swing, Riversun limited the kiwifruit vine production to 25,000, which could be handled in the existing polyhouse infrastructure. The first round has been delivered and a second round established and is well-advanced.