KVH Incorporated (KVHI) and The KVH Foundation Incorporated (KVHF) held its Annual General Meeting on Thursday 23 July. All resolutions put forward to the members were approved.
Elicitors on Gold3 potted plants, January to March 2015
Field trials on potted Gold3 plants tested efficacy of a range of elicitors in inducing a plant immune response to Psa. TNL3454 (at higher concentrations) and AB48414 showed a level of Psa control comparable to Actigard™ for up to six weeks post-Psa inoculation. Citrox BioAlexin showed some significant Psa control four weeks post inoculation. This product could offer organic growers an elicitor option. However, further trials to prove consistent efficacy would be advisable. ProAct and Silver combined and Luna Care did not show efficacy.
Psa control products on Bruno potted plants, December 2014 to January 2015
Field trials on potted Bruno plants further tested the efficacy of a range of potential Psa protectants. At the recommended concentration, Nanospada significantly decreased leaf spotting for up to three weeks post Psa inoculation. When diluted, Nanospada had no significant effect, supporting the use of the recommended rate. Another product, TNL3214, significantly reduced leaf spotting throughout the trial. KOF products only provided control when combined with Streptomycin.
KVH and Zespri have established a Kiwifruit Biosecurity Steering Group with a goal of reducing the risk and impact of biosecurity incursions to the kiwifruit industry.
Consisting of members from KVH, Zespri, Plant and Food Research, Scion, Avocados New Zealand and the Ministry for Primary Industries (MPI), the steering group will identify knowledge gaps and prioritise research needs relating to kiwifruit biosecurity threats not yet established in New Zealand.
Associated with the steering group is the newly established Kiwifruit Biosecurity Research Portfolio. The portfolio is funded by the KVH biosecurity levy with matching contributions by Zespri and managed by the Zespri Innovation team.
The Biosecurity Steering Group will prioritise research to meet the following objectives;
More information about the new Biosecurity Steering Group will be provided in the next Kiwifruit Journal article.
Ceratocystis fimbriata is a fungal pathogen causing wilt disease in a number of plant species, including kiwifruit where significant impacts have been reported in Brazil in recent years.
The serious potential impacts of Ceratocystis fimbriata and the lack or kiwifruit specific research being done elsewhere makes this a high priority organism for Kiwifruit Biosecurity Research and is on KVH’s Most Unwanted List.
Ceratocystis fimbriata projects within the Kiwifruit Biosecurity Research Portfolio include:
A Ceratocystis fimbriata fact sheet can be found on the KVH website here.
Last week KVH held its second KiwiNet workshop. The aim of the workshop was to bring together KiwiNet coordinators to discuss industry deployment into the Queensland Fruit Fly response earlier this year, lessons learnt from the response and next steps for developing KiwiNet.
Many attendees were involved in the QFF response in Auckland and overall the deployment of KiwiNet into the QFF response went well and feedback was positive. However, there is always room for improvement so the workshop provided valuable feedback from those involved.
Presentations from the workshop are available below:
Additional research to determine the efficacy of Ambitious for controlling Psa on mature Hayward vines is now available on the R&D section of the KVH website.
Ambitious currently holds a limited label claim for the control of Psa in kiwifruit. An application to ACVM for a full label claim will be made this season. Work is still needed to better understand the mode of action of this product.
The efficacy of Ambitious 10SL on mature Hayward Vines for controlling Pseudomonas syringae actinidiae, by Fruitfed Supplies
Trials testing the efficacy of Ambitious for controlling Psa on mature Hayward vines showed Ambitious was effective in reducing the severity of leaf spotting and performed similarly to Actigard. Ambitious did not appear to show any efficacy on reducing the levels of bud rot and bud loss.
Ambitious 10SL efficacy on Psa disease on Hayward kiwifruit 2014-15, by HortEvaluation
Trials at two high inoculum sites in the Bay of Plenty showed application of Ambitious mid-season (between budbreak and flowering) significantly reduced Psa leaf spot on mature Hayward kiwifruit vines. No significant differences in percentage flowers retained, fruit set or reject fruit type were observed between trial and control plots.
In early July KVH revisited six Waikato orchards (both conventional and organic) to discuss harvest results and also understand how Psa-V had affected growers through the 2014-15 growing season.
Generally growers reported good harvests with excellent pollination and strong autumn growth, lifting fruit numbers, dry matter and fruit size.
On the Psa-V front, it was acknowledged that challenges are still very much front of mind, particularly on colder and less well-drained areas of orchards, or in areas highly exposed to wind. For some growers, river mists and hail events have added further challenges.
There are still a good number of Waikato blocks in recovery mode as Gold3 grafts develop and young plants replacing Chinensis rootstocks mature.
KVH revisited colder sites where organic Hayward males had severe Psa-V exudate symptoms last spring. Where males were cut back hard to remove infection, regrowth has been excellent. Further pruning rounds to encourage spur growth has resulted in great structure with spurs expected to be very floral for spring 2015. Grafting of older variety males to more Psa-V tolerant varieties continues as a strategy to further reduce site Psa-V risk. Infected female canes within the canopy were being removed during winter pruning.
One of the conventional Hayward sites visited similarly showed the impact of extensive spring infection of males. Previous management of the male vines had failed to focus on height and density reduction, resulting in vigorous and high growth becoming badly affected. An intense spring programme including elicitors, streptomycin and coppers had subsequently been followed. However, the impacts were still seen as many of the leaders remained ring-barked due to the severity of infection. Restructuring of the males was taking place.
KVH also revisited some young organic Gold3 blocks which had significant Psa-V cut-out last spring, sometimes with up to sixty percent of canopy removed. Stringing had returned these blocks to almost full canopy. To protect this growth, autumn frost-fighting continued through May and early June 2015 as a strategy to reduce risk of frost damage to the young canes. It was thought that autumn frosts in the previous year had provided entry points for Psa-V, leading to spring infection. Observations next spring may help determine the value of this effort.
For the older Gold blocks, new canes continue to be tied in to replace trunks and leaders ring-barked by Psa-V infection (see photo); and where possible, cankered leaders and canes are being pruned out of the canopy as standard practice.
Overall, there appears to be increased use of copper for Psa-V management on organic orchards, with post-harvest and leaf-fall applications recognised as important to reduce the spread of Psa-V through the colder months. Applying copper as soon as possible after pruning is also being emphasised.
Citrox-BioAlexin is being applied across some organic blocks, again to determine whether Psa-V symptoms can be reduced through use of this product. Organic growers trialling pre-flower girdles on Psa-V affected blocks reported that this practice had definitely reduced flower bud loss, with girdles applied a month out from flowering giving best results. This technique would be used again in 2015.
Psa-like symptoms that are persistent but don’t return a positive result, particularly those from exclusion or containment regions, may be forwarded by KVH to MPI to identify pathogens causing the symptoms. These samples are also screened against other Psa strains and cherry leaf roll virus.
A number of endophytic or environmental bacterial have been reported from previous investigations and also fungal species which are likely to have entered the plants through wounds.
This highlights the value of orchard hygiene, particularly sanitising tools and protecting wounds to minimise plant exposure to pathogens.
A set of sample results are available on the KVH website – click here.
Use conditions for KeyStrepto™ and Kasumin™ have been updated and are available on the Zespri Canopy here.
The number of permitted applications of KeyStrepto and/or Kasumin has been reduced to a maximum of two for both producing and non-producing vines. These may only be applied in the pre-flowering period (after dormancy and before the start of flowering).
The User Guides will be made available to industry once they have been confirmed.
Winter is a key time to reduce orchard vulnerability to Psa-V by moving away from less tolerant varieties such as Hort16A. Grafting onto clean stumps greatly improves chances of establishment of new varieties and rapid return to a productive canopy. The Hawkes Bay orchard in the photo illustrates the value of planning ahead with Gold3 notch-grafts already well-established as the Hort16A canopy is removed.
For Hayward orchards Matua and M-Series males are known to be less tolerant to Psa-V and are generally the worst affected in high Psa-V infection years. They should be progressively removed, and stump-grafted or notch-grafted to the generally more Psa-V tolerant and highly beneficial chieftain males during winter. This change reduces Psa-V infection risk within the orchard with the flow on effect of also reducing risk of flower-bud infection through lower in-orchard inoculum levels.
Growers with Hayward on Kaimai rootstock have identified these plants as more vulnerable to leaf-spot through spring. Plants may have been introduced as replacements and can be scattered through orchards or established in rows where shelters have been removed. They add risk, as high incidence of leaf-spot provides an ongoing inoculum source for the orchard throughout the year and a strategy of replacing these is recommended.
Hort16A rootstocks, or Hort16A interstocks accidentally maintained in cut-over blocks, also add risk as they can be a source of exudate through the spring period. Growers in the Te Puke area are generally looking to reestablish these plants to remove risk. Growers grafting blocks to Gold3 are similarly recommended to ensure interstocks are removed as the influence of these on Psa risk and also future cropping effects are unknown.
When grafting, make every effort to secure budwood from the cleanest source and maximise hygiene through the grafting process to provide the best opportunity of graft success.
Also in winter take the opportunity to replant alongside unthrifty plants. A good source of healthy plants are now available through the Kiwifruit Plant Certification Scheme (KPCS) and replacing weak plants is a future investment into the overall health and cropping potential of the orchard.
Other strategies to reduce Psa-V risk before spring are found on the Psa-V Risk Compass.
Last week a new Psa-V positive result was reported on a Hort16A orchard in Gisborne – the first positive result since March. Red exudate was detected on vines following a recent pruning round.
Winter pruning is a good opportunity to monitor orchards for suspicious symptoms as every vine is visited.
Growers on not-detected orchards who suspect Psa-V or other unusual symptoms are required to report these to KVH on 0800 665 825 or email email@example.com so lab testing can be carried out (or in recovery regions Psa-V can be verified by suitably trained packhouse personnel.)
Southern Cross Horticulture in Tauranga is now producing plants certified under the Kiwifruit Plant Certification Scheme (KPCS). Southern Cross is the first nursery in a Recovery Region to achieve this Standard, demonstrating that with good hygiene and biosecurity practices, a nursery can produce good clean plants undercover even in close proximity to orchards with Psa-V.
KPCS certification demonstrates that Southern Cross Horticulture is managing its biosecurity risks, has been independently audited, visually inspected for target organisms, and returned a non-detected result for a comprehensive test for Psa-V. This involves 600 leaves being sampled from across the operation.
While KPCS plants are permitted greater freedom of movement, movement controls still apply and no plants (KPCS or otherwise) are permitted to move from a Recovery Region to a Containment or Exclusion Region. KVH movement controls are detailed in KVH Protocol: Nursery Stock. Please contact KVH on 0800 665 825 for clarification if you are unsure about any movement.
Nurseries continue to tell us that many growers are not placing orders for plants far enough in advance. To ensure nurseries have plants available to meet demand, orders should be placed before Christmas of the year prior to dispatch (preferably in October).