De Rust

Laying the groundwork for success

The first priority when planning a new orchard is to select the rootstock and scion. Soil scientist Mico Stander recommended ordering at least two years in advance to ensure that you receive top-quality trees. He also advised surveying the soil before deciding on the rootstock.

Stander explained that they tested three times more soil samples than the traditional ameliorant-block method requires. The ameliorant-block method determines the average soil conditions so that blanket amelioration can be applied. This can lead to inappropriate applications in certain areas of a block.

The site at De Rust was ameliorated using variable-rate spreaders that allow fine-scaled matching of applications to soil conditions. Stander stressed that the goal is not to save money – at De Rust, they ended up applying 24% more lime and 30% more phosphate than they would have given, based on the ameliorant-block method.

Soil preparation consisted of ripping both downhill and crosswise to counter the effect of clay tongues that trap water. Drainage was installed and Stander noted that they opted to round up rather than down on drainage. He highlighted the importance of rapid removal of water after spring rains to allow tractor access.

Nutrition and irrigation

The site is windy, so each tree is irrigated by a 20 /h micro-sprinkler to optimise water distribution. One micro per tree also reduces the impact should a micro become blocked.

Deficit irrigation was implemented from around January to slow vegetative growth in the second leaf. This has stimulated root growth and the trees have good root distribution and density up to their drip line. Stander likes to see thin roots – he referred to them as thinner than spaghetti – that are responsive to the environment and efficient at absorbing water and nutrients.

Nutrition started with a granular programme in spring, as it was raining. The advantage of granular fertilisers is that they can be applied with variable-rate spreaders. This allows the grower to fine-tune nutrition.

Fertilisation gradually switched to a liquid programme as irrigation increased during the season. Stander reported that the trees did not complete their nitrogen programme in the second leaf, as growth was too vigorous. Fertilisation was stopped around the end of the calendar year.

Stander noted that soil amelioration is part of the nutrition programme and that growers should ask their nutrition consultant to attend to both.

The first and second seasons

The nursery trees were in cold storage before planting and treated with 4% Dormex after planting. Pruning of the trees in the first leaf was minimal. Some weaker trees were topped and laterals that did not obey the 1:3-thickness rule were removed toward the end of October up to mid-November.

Nieuwoudt explained that he prefers to leave a slight stub – three buds – when removing laterals. The tree is likely to produce two or more shoots from this stub and these grow less vigorously than the single shoot produced when cutting to the branch collar. Two shoots can be reduced to one later if they are balanced. Or they can both be allowed to spur.

New shoots were pinched in the second half of December to encourage the formation of reproductive growth. Nieuwoudt also believes that manipulating branch angles to promote bearing is essential even in higher-density plantings. Elastics or toothpicks pay for themselves if they bring fruiting forward by a year.
The leaders were headed at the start of the second leaf to encourage branching in the tops of the trees. The treetops were treated with 3% Dormex a week later and the entire tree was treated after another week. No chemical thinning or growth regulators were applied.

Pruning in the second leaf was mostly aimed at thinning where necessary, and at encouraging branching. Nieuwoudt demonstrated how cropping reduced shoot elongation from approximately 70 cm in the first leaf to only 10 – 20 cm in the second leaf. This shows that the vigour of G.778 can be effectively controlled with fruit.

Balancing growth and crop load

Nieuwoudt bases crop-load targets on trunk diameter. The average trunk diameter measured 30 cm above the orchard-floor level in the second leaf, was about 14 cm in late January – this had increased to 16 cm by early June. Leader growth by late January was 47 – 55 cm with another 15 -20 cm by early June.

At the planting density of this orchard, trees with a trunk diameter of 16 cm have the potential to carry 100 tonnes/ha in the third leaf. But Nieuwoudt is planning on a conservative 60 – 65 tonnes/ha in the third leaf to allow for more canopy development at the top of the trees.

Lateral shoots will be pruned to 60 – 70 cm between trees and 70 – 75 cm in the work row in late November. This inevitably involves fruitlets ending up on the orchard floor. So Nieuwoudt warned against leaving it too late – pruners are understandably reluctant to cut away bigger fruit.

Stander also pointed out that delaying pruning to save fruitlets for this season can result in shading bearing wood while it is supposed to be developing flower buds for next season.

Nieuwoudt is satisfied with the fruit colour and quality obtained in the second leaf. Culling in the orchard was only 6.5% and mainly due to sunburn and weevil and guinea-fowl damage. This is in line with the goal of producing quality – 85% Pink Ladies regardless of tonnages.

Acknowledgements

Thanks to the Clüver family for hosting the visit, and technical advisers Piet Nieuwoudt of Fruit Tree Services and Mico Stander of Agrimotion for leading the discussion.