Effects of a photoselective netting system on Fuji and Jonagold apples in a Mediterranean orchard

An assessment of a red photoselective netting system on apple production was conducted in a Mediterranean semi-arid climate. For two seasons, blocks of trees from an early bearing (cv Jonagold) and late bearing (cv Fuji) cultivars were covered to full canopy with red photoselective nets with 20% shading factor and an exclusion mesh size of 5.2 × 2.1 mm in an experimental orchard and compared to uncovered blocks of trees in the same orchard. The influence of nets on microclimate was assessed by measuring light intensity, Photosynthetic active radiation (PAR), Air temperature and relative humidity. An average decrease of 22.8% in light intensity along with a reduction in the average PAR radiation incidence by 23% improved the leaves photosynthesis efficiency with no influence on air temperature and relative humidity. The nets, installed after petal fall, had no significant influence on annual shoot growth and fruit set. At harvest, apples taken from netted trees were better graded than in the control in terms of both quality and quantity. Fruit weight, size and color blush were significantly higher in apples grown under nets compared to uncovered ones in both cultivars. While apple firmness was slightly lower under nets, no significant differences were reported in terms of sugar content and malic acid between both treatments. Nets significantly reduced the population of codling moth and the fruit damages caused by this pest without use of insecticides. Nets also decreased the amount of fruit fly caught in traps. No differences were recorded in terms of powdery mildew occurrence, aphids, mites and leafminer populations between both treatments. At last, nets also protected apples from sunburn and bird damages. To our knowledge, this is the first overall assessment of apple production in a pest-exclusion setting using red photoselective nets. © 2019 Elsevier B.V.