High density production systems for Australian-bred scab resistant apples (AP08008)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Apple scab (colloquially known as black spot), was a major fungal disease of apples worldwide, and costed the Australian industry upwards of $10 million annually in chemical control and fruit losses. New apple varieties resistant to scab were bred by the Department of Agriculture, Fisheries and Forestry, Queensland (DAFF, Qld).

‘Kalei’ was the first scab-resistant apple to be released from this program, and was publically launched in May 2012. Apple and Pear Australia Ltd (APAL) signed a licence agreement with DAFF, Qld to commercialise ‘Kalei’.

‘Kalei’ was an attractive, crisp, sweet, juicy red apple maturing just before Pink LadyTM. It retained firmness and crispness after long-term storage and when left at room temperature for three weeks.

A one hectare block of trees was established at Applethorpe Research Station, Queensland to evaluate the productivity of six scab-resistant apple selections, including ‘Kalei’, in high density plantings under semi-commercial conditions. High density planting systems and appropriate tree management were critical to increasing the productivity of Australian apple orchards.

No sprays for apple scab control (apart from green tip copper) were applied. Since planting, all six scab-resistant apple selections showed no leaf or fruit symptoms of apple scab, despite the presence of the disease in the orchard. ‘Granny Smith’ and ‘Pink Lady’TM trees planted as pollenisers showed moderate to severe incidence of scab on fruit over the previous two seasons.

Trees of ‘Kalei’ were well-suited to high density planting (upwards of 2000 trees/ha). The semi-spur growth habit of ‘Kalei’ trees was easy for growers to manage, and yields of 60-70 tonnes/ha/annum could be expected from fully mature trees. ‘Kalei’ could be a large apple (> 200 g) if trees were under-cropped. ‘Kalei’ was also tolerant to Alternaria disease and western flower thrip, and could be grown both conventionally and organically.

Trees of a second scab-resistant apple selection, maturing just after ‘Gala’, yielded 60 t/ha in 2012 (7th leaf), with over 90 per cent packouts of first grade apples. Early fruitlet thinning was essential to minimise the production of small fruit in this variety, which would be the next scab-resistant apple to be commercialised.

The first ‘Kalei’ trees for commercial planting should be available through APAL (Coregeo) in winter 2013.