Orchard trials developing novel solutions for a sustainable future 

Four main projects were discussed at recent breakfast meetings in Kent, Herefordshire and Norfolk, where attendees learned how new options were being developed to help improve productivity and tackle the challenges of scab, canker and codling moth amidst a diminishing armoury of conventional chemistry. 

One major initiative is the 10-year HELIOS project (Hutchinsons Enhanced Light Interception Orchard System), which is investigating whether orchard canopies and tree architecture can be redesigned to intercept more light and improve yields in a cost-effective, sustainable, and ‘future-proof’ way. 

Two orchards of Gala Galaxy clones on different rootstocks were established in 2018, in Kent and the West Midlands, featuring a range of planting systems (see www.hutchinsons.co.uk/resources/helios). 

Analysis of cumulative yield and quality data from the 2019 to 2024 seasons showed some interesting results, with the ‘alternate leaning V’ tree planting configuration producing the highest total yield over the six seasons. 

But, as Hutchinsons agronomist, Ivan Velasco, explained, it was the minimal support system on M116 rootstock that was forecast to deliver the highest rate of return. The largely self-supporting trees attached to just a single wire, yielded well and showed less seasonal variation in fruit size at both sites, plus there would be lower removal costs at the end of the orchard’s life than for other systems with more trellis work. 

“It was a surprisingly good performance, but it’s not necessarily a system that will suit all situations,” he said. 

Trials at the western HELIOS site also showed strong performance from the Geneva 11 (G11) rootstock, Mr Velasco continued. It was used in three planting situations to see how trees fared when established through a weed membrane rather than into a conventional herbicide strip. One treatment included G11 with roots pruned prior to planting to stimulate root development and stronger establishment. 

Cumulative production from G11 rootstocks after just three seasons was already close to that of other rootstocks after six years, so early results looked very promising, suggesting it could be another potential successor to traditional M9 rootstocks.  

Mr Velasco  added: “We know G11 can be really vigorous in the first three or four years, then usually slows down. It may be that we need to plant trees further apart to accommodate early vigour, but the return per hectare should still be higher.” 

Again, G11 would not suit all situations, especially more fertile soils, where it would be harder to control the extra vigour, he noted – the Herefordshire site is on a very sandy loam. 

Improving resilience in scab control 

Hutchinsons colleague Nigel Kitney updated growers on the IRIS project, which aims to improve the resilience of scab protection in the face of a diminishing fungicide armoury. 

Twenty products were being trialled, including four biostimulants, five biofungicides, eight nutritional feeds, a growth regulator, and two traditional fungicides, to see how they could be used to fill gaps in spray programmes left by the loss of important actives and restrictions on the allowable dose of others. 

Early findings showed some excellent reductions in leaf and fruit scab, with the best results from the combination of a conventional fungicide with a biostimulant that enhanced the plant’s natural defences, he said.  

“This defence can take time to build, so we believe the fungicide provides some protection during this period, then as that protection starts to diminish, the effect of the biostimulant kicks in.” 

Detecting scab spores 

In a separate project, Hutchinsons is working with partners to develop a novel system for detecting scab spores in the orchard to assess the correlation with RIMpro predictions. A cyclone air sampler collects spores, the DNA from which is analysed to identify those present. 

The aim is to develop a fully automated system to provide growers with real-time disease warnings. Two scab detection devices will be trialled in orchards this season, and another will be placed in a vineyard to detect Downy mildew. 

Codling moth control 

Hutchinsons agronomist Gloria Endredi introduced growers to a new three-year project looking at codling and tortrix moth control, set up to find new solutions to mitigate the loss of traditional chemistry. 

“Codling moth remains one of the main pests in apple production, but it is becoming harder to control,” she said. “Not only are fewer products available, but the adult flight starts earlier and goes on longer than formerly, so there are more generations each year. It used to be one generation, but now the average is nearer 1.5 or 2.” 

Ms Endredi added that control programmes had to change, with more emphasis on targeting codling moth throughout its lifecycle, using both conventional chemistry and biological options, such as granulovirus. 

Such an approach was being trialled at three commercial farm sites in Kent, where camera traps were being used to help optimise in-season treatment timings. This was being supported with the autumn use of entomopathogenic nematodes to target the overwinter and pupating stages of codling moth in the soil.

“Results from the first year in 2024 showed the biological approach was just as effective as conventional chemistry at controlling codling and tortrix moth at all three sites. The work is ongoing, though, so we’re looking to refine the approach this season.” 

Canker reduction in apple fruit trees 

Finally, Kent-based agronomist Rob Saunders shared some early findings from the CRAFT project, now in its second year, investigating whether elicitor products, growth regulators, foliar feeds or biological fungicides can bolster natural defences of apple trees to canker. 

“Many of the materials being screened are similar to those in the IRIS trial, as we’re looking at similar mechanisms.” 

Several treatments were associated with useful reductions in canker, and one biological fungicide proved surprisingly effective in the first year of trials, coming top in terms of overall control, he said. Currently, the product was only approved for soil application in orchards, but Mr Saunders suggested there could be a case for the industry to apply for an Extension of Authorisation for minor use (EAMU) for use on the branches of the tree. 

In the meantime, five other products that also gave useful canker control were already approved for use, so could be options to consider this season, he said. 

Mr Saunders also highlighted research by Avalon in 2024 that showed up to a 50% reduction in canker expression in the aerial parts of the tree from introducing biological agents into the rooting zone. Two products were tested, one based on mycorrhizal fungi, the other on the beneficial Trichoderma fungus, introduced either into the hole at planting, or added to the soil within established orchards. 

“This work shows that canker is a more biologically mediated issue than we probably thought it was, and there are things we can do either to the rooting zone or aerial parts of the tree to help reduce disease pressure.”

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