Early induction of pear drop using ethephon

In recent years the acreage of 'Conference' pear has been steadily increasing in Belgium reaching above 10,000 ha and rendering it the most important fruit in terms of production and economic value. However, this strong growth can sometimes have unfavourable effects. In 2014 the climatological conditions during pear bloom as well as during the rest of the season were excellent. Consequently, there was a risk of overproduction and the prices of pears were decreasing rapidly. The Russian embargo in August 2014 on Belgian pears worsened the situation and the European non-harvest regulation or intervention became effective to avoid destabilization of the European fruit market. The question arose as to how the non-harvested pears can be forced to drop early because the growers want to economize on the harvest cost and avoid further energy investment by the trees in fruit development. Trials were initiated at pcfruit on several cultivars using Ethephon 480^® SL (480 g L^‑1 ethephon), which yields the plant hormone ethylene that enhances fruit abscission. Variable ethephon doses (0.5 to 2.0 L ha^‑1 or 480 to 1920 ppm, respectively) and number (1 to 2) of applications at harvest to induce early pear drop were tested. One application of 1.0 L ha^‑1 (960 ppm) ethephon hastened fruit drop by 2 weeks in 'Conference' and up to 3-4 weeks in 'Doyenné du Comice' compared to their respective natural fruit drop. A second application of ethephon after a first one at harvest does not further accelerate pear drop. A strong storm in June 2016 and several subsequent hailstorms caused severe damage on pears necessitating fast removal of the pears from the trees. However, trials at pcfruit in that year clearly demonstrated that ethephon applications one and two months before harvest (up to 2.0 L ha^‑1 or 1920 ppm) cannot induce a significant pear drop.