Newsletter No. 10 June 2026

Posted on June 27, 2026

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Cracker of a frost this morning here in the Manawatu, no wind but not quite cloudless blue skies. The autumn colours have pretty much faded as we hunker down for winter.

Poplar and willows have or are in the process of loosing their leaves and the nurseries are gearing up to harvest poles. Rain has softened most of the country to make planting easy but sometimes can cause havoc for access.

Planting your pole correctly is important. Check out video.

Growing a network of advocates

In May, it was great to host our Ambassadors both new and old in Palmerston North. Seven ambassadors attended in person, with a further two joining online, for two half-days of discussion, learning and planning alongside Trustees - Susan Kilsby, Jacquie Harper and Peter Kemp, and researcher Trevor Jones.

Ambassadors have been an important way of connecting practical farming experience with the Trust’s research and extension activities. As part of implementing the Trust’s new strategy, the programme has been reinvigorated, welcoming a mix of returning ambassadors and new faces from across New Zealand.

Representing predominantly sheep and beef farming businesses, with many also involved in deer, dairying and viticulture, the ambassadors bring a wealth of practical experience using poplar and willows in real farming systems. Their role is to share that knowledge with fellow farmers, act as trusted local contacts, and help strengthen the connection between research, regional councils and on-farm practice.

During the workshop, ambassadors were introduced to the Trust's strategic direction and discussed the important role they can play in supporting sustainable hill country farming. A visit to the Trust's nursery provided an opportunity to see the breeding, propagation and trial work underway, reinforcing the long-term commitment behind developing the next generation of poplar and willow genetics.

One of the greatest strengths of the Ambassador Programme is its farmer-to-farmer approach. Farmers often place the greatest value on advice from people who understand the realities of farming because they face the same challenges themselves. By sharing practical experiences and encouraging conversations within their own regions, ambassadors help ensure the Trust's research reaches the people who can put it into practice, while also providing valuable feedback that helps shape future research and extension priorities.

The Trust thanks both our returning and newly appointed ambassadors for their ongoing commitment and generosity in volunteering their time and expertise. Together they form an important link between research, regional knowledge and the farming communities they serve.

Ambassadors above (left to right): Alex Campbell (Tiniroto), Susan Kilsby (Trustee), Guy Williams (Wairarapa), Tom Mandeno (Waikaretu), Brook Wyllie (Toko), Shane Carroll (Pohangina), Peter Gaulter (Marlborough), Jacquie Harper (Trustee) and Hamish Pain (Cheviot). Online: Alistair Wilson (Southland) and James Hunter (Central Hawke’s Bay)

National trials of P. maximowiczii x nigra hybrids

Monitoring trees 20 years after establishment, gives NZPWRT key insight into their performance, and matching the right tree to the right environment. It has been found that P. maximowiczii x nigra hybrids performs best where it is cooler and wetter and less suited to exposed coastal or salt-laden conditions.

There is no single “best” poplar clone and performance can vary markedly between regions. The results at the trial sites (Parakai, Mapiu, Ashhurst, Rissington, Windwhistle) clearly demonstrated this. The best sites for survival were Rissington, Windwhistle and Mapiu (78, 86 and 91%). This is shown in the figure 28 below.

Below is a summary of how the trees performed in the different sites (5 performed well, 3 average and 2 low). This reiterates that matching the right clone to the right site remains the key to success.

Taihape Demonstration

Utiku

This demonstrations looks at the growth and resilience of 16 poplar clones that were planted in 2017 as a collaboration between NZPWRT, Beef + Lamb NZ and Horizons Regional Council with support from Ravensdown.

It is planted into deep sandy loam soils with an average rainfall of 900-1000 mm. A number of dead trees were replaced in 2019 and all trees have been pruned to a single leader.

The results from 2026 monitoring is shown in Table 11 below.

Note that one Kawa tree has been removed and Rima poles were light at planting which could account for their lower survival. Wind damage was observed following the windstorm event in February 2026, predominantly P. maximowiczii x trichocarpa NZ 07-006-007 clone, and one P. deltoides x nigra Veronese.

In summary

• P. deltoides x ciliata clones had slow tree growth, and low survival for the Kaimai clone, which suggests they are not well adapted to the field trial site.
• P. deltoides x nigra and P. deltoides x nigra x nigra clones had excellent tree survival, and fast growth on the trial site, and were well adapted to the site. Slower stem diameter growth for Fraser and Crowsnest clones, attributed to light branching and narrow tree crown.
• P. deltoides x nigra x yunnanesis Toa and P. deltoides x yunnanesis Kawa had excellent tree survival, and fast growth, indicating they were well adapted to site.
• P. maximowiczii x nigra clones had lower tree survival and slow growth for Pecam. Surviving trees of Mapiu had fast growth, but lower survival of this and Pecam suggests establishment might be a risk with these clones.
• P. maximowiczii x trichocarpa clones grew fast, but survival was variable, though good for NZ 07-005-103 clone. NZ 07-006-007 was susceptible for wind.
• P. nigra x maximowiczii Shinsei had excellent tree survival and fast growth.
• P. trichocarpa x nigra Rima had lower tree survival, possibly due to light poles, but fast tree growth.

Sustainable pasture production with poplars and willows

Peter Kemp

Research (Douglas et al. 2009) has found that poplars, willows and Eucalypts planted at densities of 30-60 stems per hectare (13 m to 18 m spacing) on hill country slopes of mostly 25-30o, reduced the extent of soil slippage at 65 sites by an average of 95% compared with slippage on nearby pasture control sites. If slips do occur then pasture production will recover very slowly but it is typically still only 80% of what it was before slipping, 20 years after the slip (Lambert et al. 1984). Hardly a sustainable approach.

Poplars and willows shade pasture, especially when leafed up, but the effect of the shade can be managed by pruning lower branches as the trees mature, or by using cultivars with narrow crowns. A major objective of the NZPWRT’s breeding programme is breeding cultivars with narrow crowns. When choosing poles for your farm ask for the most suitable cultivar for your area that has a narrow crown. A good time to prune lower branches is during dry summers when sheep and cattle will feed on the leaves and small branches.

Directly below the middle of the canopy of mature trees is too shady for optimum pasture growth rate. But lower branch pruning minimises the effect of canopy shading by increasing the gap between tree canopies. The canopy photo shows a range of canopy gaps. As a rule of thumb 40 – 50 % canopy closure allows 50 – 60 % of full sunlight while the trees are in leaf which provides reasonable pasture growth rates (Wall et al. 2006). Even when soil moisture and fertility are not limiting pasture growth, rare on hill country, only 70 – 80 % of full sunlight is need for maximum pasture growth.

Poplar and willow trees planted at 13 - 18 metre spacings across slopes provide sustainable soil management and reasonable pasture productivity provided canopy closure does not exceed 50%.

Figure 1: shows the importance of the gap in tree canopies when decreasing the shading of pasture (from AJ Wall)

Figure 2: Poplar canopies with 36,58,77 and 80% canopy closure, clockwise from top right (Wall, 2006)

Forestry Hub - Mystery Creek

A great week was had at the National Fieldays, again sharing a stand within the Forestry Hub with NZ Farm Forestry. There was a buzz of traffic through the tent as a range of discussions took place. There was plenty of strategic discussions and networking with others such as Te Uru Rākau, Biochar Network NZ, Bioeconomy Science Institute, Forest Owners Association, Forest Growers Research, University of Canterbury School of Forestry, Wingspan Birds of Prey Trust, Kaingaroa Tipu, Tane Tree Trust and many others. These events are important to help NZPWRT connect with end users and professionals where poplar and willow are key tools.

Showcasing … Wai-iti (poplar)

‘Wai-iti’ is a Populus deltoides x trichocarpa hybrid. It is a large-crowned poplar with large branching and a straight stem. It is female and bitter leaves that are resistant to possum browsing. It can be prone to suckering it there is no grazing.

‘Wai-iti’ has deltoid (triangular) shaped leaves with a rounded base. They are dark green on top and light green lower surface. The midrib and lateral veins are green but the petiole is red. The leaves are resistant to Melampsora laricipopulina leaf rust fungi

‘Wai-iti’ can be used for soil conservation as a space-planted tree, especially in drier areas. At age 37 years, it had a crown width of 30m, DBH of 64cm and average height of 28 m. To read more see the Factsheet.