Relationships among hail net and thinning efficacy

From 2015 to 2019, several fruit-thinning compounds were tested on apple (‘Pinova’, type ‘Evelina’) grown under hail net or in open field conditions. During the five years trials, the thinning efficacy induced by the 6-benzyladenine (BA), 1-naphthyl acetic acid (NAA), amonium thiosulphate (ATS) or ethephon was similar on the trees grown under hail net as compared to “open field” conditions while Metamitron induced higher thinning effect on the trees grown under hail net, in two of the five years of experiment. Although the obtained results did not confirm the general opinion that fruit abscission is stronger under hail net, in our trials a reduced requirement for fruit thinning was required for the trees grown under hail net because of a lower fruit set registered in this circumstance.