Organic production of a new Australian-bred scab resistant apple in Queensland, Australia

Abstract

The first crop of organically grown Australian-bred scab resistant apples (Malus × domestica Borkh.) has been produced at an experimental site in Queensland, Australia, characterised by sandy soils and a warm, summer rainfall climate. The planting is in its fourth leaf and consists of one hectare of trees of 'RS103-130'. This selection from the Department of Primary Industries and Fisheries, Queensland (DPI&F) apple breeding program is a midseason apple resistant to apple scab (caused by Venturia inaequalis). All trees are planted on 'MM.106' rootstock at 5.0m x 1.8m spacing (1111 trees/hectare). With minimal lime sulphur and wettable sulphur sprays, no apple scab has occurred on leaves or fruit of 'RS103-130'. Apple scab infected 4.6% of 'Galaxy' (comparator variety) fruit in the first cropping season. The most significant causes of insect damage to fruit have been native budworms (Heliocoverpa punctigera) and Light Brown Apple Moth (Epiphyas posvittana), however spinosad applications and pheromone disruption are providing effective management of these pests. White clover (Trifolium repens) planted in the alleyways is growing prolifically and appears to be attracting damaging insects, including western flower thrip (Frankliniella occidentalis), away from the trees. Kangaroos (Macropus spp.) have been a problem, attracted to the lush groundcover in dry autumn months and damaging growing points and foliage. Fruit set at the site is excellent and has necessitated some hand thinning. In an experiment to compare the effectiveness of weed mat and sugar cane mulch in weed control, and the effect of supplementary organic compost on tree growth and productivity, larger apples were produced from trees treated with organic compost and sugar cane mulch. Drought and hail are the two primary factors affecting the productivity of organic and conventional apple orchards in Queensland. Hail netting is essential to guarantee the supply of fruit; it moderates the effect of drought and helps control some pest problems.