Last year, agronomy firm H L Hutchinson began its Enhanced Light Interception Orchard System (HELIOS), a 10-year project looking at how orchard design can be improved to capture more sunlight and so increase yield, while also factoring in establishment costs and likely technological developments such as robotic picking and mechanical pruning, building on work in New Zealand by Dr Stuart Tustin of the government-owned Plant & Food Research institute and putting it in a UK context.
Last month (July 2019), Hutchinson invited growers to visit the programme’s two orchards in Herefordshire and east Kent. During an open evening at the Herefordshire orchard, horticultural project manager and chair of AHDB tree fruit panel Rob Saunders and agronomist Nigel Kitney explained the trials, starting with the "photovoltaic" configuration of Gala Galaxy on M9 rootstock at 70cm spacings, but sloping northward at 50 degrees.
"This imitates the orientation of an array of solar panels, in an east-west rather than north-south orientation, and you can capture about twice the amount of light energy," says Kitney. "But it’s a bit blue-sky and we’re not sure where we’re going with it. Perhaps a white membrane underneath would reflect light onto the lower parts."
Saunders adds: "We may be wrong about this altogether. The peak light intensity could be too much."
In trials on more conventional fruit wall-type formats, shoots at 30cm intervals from T-shaped tree frames are being trained up individual bamboo canes, while another features shoots at the same intervals from a single angled stem. "We may soon see robotic picking, for which you will want a planar canopy no more than a foot [30cm] wide," says Saunders. "But in the early days there will be a lot of faffing about to train them."
"Robotics won’t work if you haven’t got a growing system ready," adds Kitney. "But this is a productive system anyway for which the robotics will be a bonus." He explains: "Closer spacing gives better light interception. This system is in year five in New Zealand and is already producing the same yield as a commercial orchard, but it can achieve double that, with easier ongoing management."
Saunders says: "They are looking to get 180 tonnes a hectare but they have great light exposure. In our light levels that would be 80-100t/ha, and Helios East [the Kent trial site] is already getting that on Gala. But here we should have done it on M9 or M26 rather than M116 rootstock."
The trees are supplied by Worcestershire nursery Frank P Matthews in a "kinked" shape with a bare vertical trunk rather than as a traditional cordon angled from the ground, which makes sense given the orchard’s problems with rabbits, he adds.
Saunders says of a V-shaped trial system made up of angled spindle trees planted on M9 at 46cm spacings: "They pay their way in the early years, developing a crop very rapidly, though they are expensive to set up and it’s less clear what the best management is long-term."
On the subject of pollinator partners in the format, Kitney says: "Jester doesn’t produce as much pollen as a Malus (crab apple) but will pollinate even in bad conditions." Saunders adds: "Apples with more pips taste better, store better, have better colour and work better with thinners."
"A chemical thinner will pull off the fruit with the fewest pips," says Kitney. "We have tended to go away from pollinators, but one Italian grower put in one pollinator for every nine Gala trees, yet is getting 110-120% of the typical crop."
On thinning, Saunders says: "A one-size-fits-all approach will mostly underdo or overdo individual trees. We are trialling taking Lidar scans of the orchard then mapping the blossom to it via a drone, so you can tailor dosing to the individual tree."
In another trial, 13 rootstocks in 14 replicates are being compared for susceptibility to canker. "M26 is getting less canker and less aggressive canker than M9, while the continental M9 has more than the English M9," says Kitney.
The orchard is also trialling tree formats from the Carolus tree nursery in Belgium, including the Magnum, which spends an extra year on the nursery. Put in this spring at 1m spacings, "they haven’t transplanted very well, with some branches snapped", Saunders admits. Kitney adds: "We hope next year they will catch up and overtake the younger trees. If we take the fruit off in year one, we should get a bumper crop in year two." Carolus’s Fortis format, meanwhile, "has potential for fruit walls", he says.
Lastly, a low-cost, low-intensity approach is also being trialled, with Gala Galaxy on M116 planted at 1.22m spacings with minimal support. "We see less canker and more resistance to drought," says Kitney. "Yield per hectare isn’t looking any different, at a fraction of the cost. If you lose control of them in 10 years’ time that’s not a problem because you have already made your money back."
Building up a picture
Mounted on a quad bike or buggy, H L Hutchinson's newly introduced TerraMap soil mapping system logs 800 data points per hectare, yielding a comprehensive picture of a site’s soil composition.
Adapted from its original use in mineral prospecting, "it’s a good thing to do before you plant an orchard", says precision technology specialist Nick Strelczuk. "It gives you a percentage of the sand, silt and clay as well as key minerals and pH, highlighting any issues to avoid, and can cover 50 hectares a day."
Hutchinson horticultural technical manager Jonathan Blackman adds: "This can take the place of a soil surveyor and can inform how you plant — for example, the spacing between trees."