Work smarter, not harder. By Anna Mouton.
“We have to improve the colour of our fruit,” says Hendrik Pohl, production manager at Bokveldskloof in Ceres. “And we have to increase our percentage class 1 fruit on the tree. We’re not going to achieve that with conventional apple farming. We need a mind shift to new rootstocks, new cultivars, new training methods, higher densities, and nets.”
The Orchard of the Future at Bokveldskloof aimed to compare the productivity of two rootstocks — the semi-vigorous M.7 and the dwarfing M.9 Nic29 — at high and ultra-high densities. “We wanted to address the questions around the viability of M.9 under South African conditions,” recalls Pohl. “We definitely settled many of those arguments.”
Adding up the numbers
The orchard was planted in 2013 with Fuji as the main cultivar. The first fruit were harvested in 2015 when M.9 Nic29 demonstrated its precocity by producing more than double the crop that M.7 yielded. This advantage was short-lived — the trees on M.7 overtook those on M.9 Nic29 in the following year. Competition has been fierce ever since.
None of the plantings achieved the aim of a total cumulative production of 300 tonnes per hectare in the sixth leaf. Ultra-high-density M.7 came the closest with 291 tons. Pohl points out that there was one year during the trial when Fuji harvests were poor across the board. “The whole industry saw reductions of 30%–40% with Fuji. We saw the same. In spite of that we came very close to our goal.”
M.7 at ultra-high density had the highest cumulative yield — 372 tonnes per hectare — at the end of 2020. But high-density M.9 Nic29 looks set to surpass it in the near future. M.9 Nic29 has borne more than 100 tonnes per hectare for two consecutive years. Pohl reckons it will do so again in 2021. “Fuji definitely alternates less on M.9 than on M.7. We’re going to hit 100 tonnes for the third consecutive year — that’s not normal for Fuji.”
Pohl has analysed past production data for Bokveldskloof. “I once managed to produce 300 tonnes, cumulative, by the sixth leaf, with a block of Goldens. But that was the only time. If you look at the numbers, then high density is the route to getting into production fast.”
Growing first-class Fuji
All the plantings in the Orchard of the Future at Bokveldskloof produced good-quality fruit. The average percentage of fruit sent from the orchard to the packhouse in 2018–2020 was 94%. In the two years that Fuji Red was packed — 2016 and 2019 — the high-density M.7 treatment produced the highest percentage as well as the highest tonnage of Fuji Red.
Pohl believes that these figures don’t tell the whole story. “If you compare a box of Fuji Red from the M.9 trees to a box from the M.7 trees, the M.9 box looks like a box of Chilean fruit, whereas the M.7 box looks like the fruit we all know from South Africa. The intensity of colour on the M.7 fruit can’t be compared to the colour of the M.9 fruit.” He is convinced that M.9 can contribute to raising the bar for South African fruit colour.
Fruit size was good in all the treatments. The ultra-high-density M.9 Nic29 trees produced the largest fruit, followed by the high-density M.9 Nic29 trees. Pohl observed that the fruitlets on the M.9 Nic29 trees in October 2020 were already a couple of millimetres larger than on the M.7 trees, even though the M.9 carried a heavier crop load.
Sunburn was the main cause of defects. However, sunburn was no worse in the trial orchard than in other young orchards, asserts Pohl. “I looked at the data, at what percentage we usually send to juice directly from the farm. It was even higher than we saw on the M.9 trees. So it’s not true that sunburn is worse with dwarfing rootstocks.”
The Orchard of the Future at Bokveldskloof is not protected by shade-nets. “In future, we’ll put up nets,” says Pohl. “In general, in our industry, if we want to improve our pack-outs, we’ll need nets.” He adds that the success of nets depends on using a precocious and productive rootstock such as M.9
“The risk with nets, if you are using a vigorous or semi-vigorous rootstock, is that you lose productivity over time. The first three years are magic, and then your production drops and your fruit are smaller.”
Work smarter with M.9
“We initially decided to treat the M.9 and M.7 trees the same, because we wanted to see whether we could achieve higher yields and better quality without intensive manipulation and pruning,” says Pohl. “By the second year, we realised that we can’t treat the M.7 trees the same. We had to either change our strategy or pull them out.”
The problem was that the M.7 trees were too vigorous. Pohl set about controlling the growth, but he highlights that it takes a lot of work — which costs money. Besides pruning multiple times per season, the M.7 trees are also sprayed twice with a growth inhibitor. “We get good fruit colour on the M.7 trees, but that’s because we prune them hard just before harvest, to open them up to light.”
Pohl has had a similar experience with other M.7 orchards at Bokveldskloof. “We planted M.7 at 3.5 by 1.25 because we couldn’t get hold of M.9 plant material. Those orchards are three to five years old, and they perform very well, but they take the same amount of effort as a conventional orchard.” The M.7 trees have produced more and better-quality fruit, but they require the same interventions as a 4.5 by 1.5 orchard, only on a greater number of trees. In Pohl’s view, this is taking a step back.
What is the situation with the M.9 Nic29 trees? “I prune them, I thin them, and I harvest them,” says Pohl. “Three simple actions. There’s no detailed pruning — a branch is either on or off — and we prune in winter. I thin once, and I probably don’t need to go back. I only harvest once, then it’s done.”
To date, the highest tonnages in the trial have been harvested from the ultra-high-density M.7 trees. But the M.9 Nic29 trees have produced similar crops with less effort. Pohl reckons it’s a no-brainer. “If you want to work hard, plant M.7. If you want to work smarter, not harder, plant M.9.”
“I would definitely not have wanted to use Fuji for a trial,” says Pohl. Fuji is a difficult cultivar with a strong tendency to alternate. But Fuji was all that was available on M.7 and M.9 Nic29 rootstocks when it was decided to plant the orchard. Fortunately, Pohl could obtain good-quality nursery trees of comparable sizes.
In retrospect, Pohl doesn’t regret planting Fuji. “One of our questions was, will M.9 give us the same productivity per hectare in terms of volume that we’re used to seeing with other rootstocks. The answer is yes. We’ve achieved it relatively easily on a difficult cultivar.”
The Orchard of the Future at Bokveldskloof dispelled many of the myths about M.9 rootstocks. “People said, M.9 can’t grow in South Africa, doesn’t like our warm climate, doesn’t have a good root system, needs excellent soil, doesn’t grow enough. There’s an argument that M.9 is more management intensive. That’s all nonsense,” asserts Pohl.
In the trial orchard, M.9 Nic29 has performed well on poor soil with an unfavourable aspect. “If I could get it to work here, there are few places on this farm where it won’t work.”
The conclusion from the Orchard of the Future at Bokveldskloof is that both the semi-vigorous M.7 and the dwarfing M.9 Nic29 rootstocks can deliver high-quality Fuji apples when planted at higher than conventional densities. All treatments yielded higher tonnages by sixth leaf than the historical average of the farm, with the best results obtained from M.7 at 3.25 by 1.2 metres. Results from other Orchards of the Future suggest that adding shade-net would likely have improved pack-outs.
Pohl has begun to plant new orchards with M.9 at 3.25 by 1.0 metres for vigorous cultivars, and a little closer in the row for less vigorous cultivars. He thinks there is still a place for M.7 in situations where soil quality is poor or the cultivar doesn’t grow strongly. However, he is convinced that there is no going back from high-density planting.
Image: Hendrik Pohl.
Supplied by Anna Mouton.
Table 1 The Bokveldskloof Orchard of the Future at a glance
|M.7 and M.9 Nic29
|Spindle central leader
Table 2 The four treatments at the Bokveldskloof Orchard of the Future
|Spacing in m
|3.25 x 1.2
|3.0 x 0.8
|3.25 x 1.2
|3.0 x 0.8
|Tree height at planting in m
|Trees per ha
|Block size in ha
The orchard team
Retief du Toit