Riverina pruning workshops

Riverina growers prune to improve fruit quality

Last year there was strong grower interest at two Riverina pruning workshops facilitated by NSW DPI. The Griffith and Leeton events focused on pruning citrus trees to give growers greater financial returns for their crop. Guest speakers were Daniel Lazar (E.E. Muir & Sons) and David Davies (Stihl).

Andrew Creek, NSW DPI Citrus Development Officer presented data from a Griffith pruning trial and pack-outs from the Dareton Agricultural Research and Advisory Station. Andrew focused on the improved returns achieved by pruning. Pruned treatments had increased class #1 pack out, regulated crop load and fruit size improved to the desired grades for export. Andrew also reported a 10% reduction in albedo break down from pruned trees (Figure 1).

Figure 1. Navel orange showing signs of albedo breakdown.

Pruning also resulted in different fluorescence types (Figure 2), which is important because fruit produced from a leafy fluorescence on a strong bearing branch is usually 15% larger than those borne on a weaker bearing branch of a leafless inflorescence (Krajewski and Pittaway 2000).

Left: Window and skeleton pruned trees had leafy inflorescences; Right: Unpruned control trees had a higher proportion of white blossom and leaf less inflorescence

Andrew also reported data from the NSW DPI research station at Dareton. The unpruned, midseason navels from the navel clone block returned $324 per tonne in 2018 compared to an annually pruned Atwood block on the station that returned $758 per tonne. While the financial return is good for class #1 fruit, an expense of $1.00 per tree for hand pruning is easily justified.

David Davies from Stihl discussed chainsaw maintenance and practical tips on sharpening the fine chains of professional arborist type saws. Attendees took interest in the discussion about the battery-operated chainsaws and how to get the longest life from their battery (Figure 3). The battery chainsaw cut as quickly as the arborist petrol saw. The advantages of the battery saw includes no exhaust fumes, no messing around with petrol and fuel mixes and they are super quiet compared to a petrol chainsaw. Battery work time varies with the work rate and the size of cuts. Larger batteries may hold a greater charge however they increase the weight of the saw. During pruning work, an AP300 lasts for about 2.5 hours while chunk pruning citrus trees. For heavier cutting, like preparing hedged trees for reworking, expect 5 battery swaps in 8 hours.

Figure 3. David Davies outlines chainsaw maintenance at the pruning workshop.

With the assistance of Mildura Fruit Company (MFC), Mr Daniel Lazar (E.E. Muir & Sons) spent a couple of days in the Riverina visiting growers in June 2019. Daniel presented at both the Griffith and Leeton citrus pruning workshops. As the former manager of Sunmar Orchards at Ellerslie, Daniel consistently achieved some of the best navel orange pack-outs of all suppliers to MFC. Pruning workshop attendees enjoyed discussing pruning and nutrition management with Daniel (Figures 4 and 5).

Daniel Lazar discusses citrus pruning methods at the Griffith workshop.

Daniel Lazar discusses citrus pruning methods at the Leeton workshop.

Daniel uses a chunk pruning style annually, immediately after harvest. He invested considerable time training a few staff on the different pruning methods required to account for the variability between varieties and blocks on the farm. Staff were well renumerated for the laborious work, lifting saws all day. The pruning team became very skilled and returned every season to prune the trees. The cost of pruning varied with citrus variety and tree size, however Daniel stated, “the 80 cents invested in each tree annually with pruning improved the fruit’s value, keeps the fruit cleaner and had the farm consistently cropping high yields.”

The crop management section of the NSW DPI citrus website has pruning videos. There is also an article on citrus pruning and a 'High-density planting and pruning case study: Sunmar Orchards, Sunraysia'. https://www.dpi.nsw.gov.au/agriculture/horticulture/citrus

NSW DPI thank the sponsors of the pruning workshop event – Mildura Fruit Company, E.E. Muir & Sons, Stihl Australia and especially the growers who hosted the workshops, Mario Marin at Yoogali and the owners of VillaRosa at Leeton.

Reference

Krajewski A and Pittaway T. 2000. Manipulation of citrus flowering and fruiting by pruning. Proceedings of the International Society of Citriculture IX Congress. 357–360.