Joe Ceravolo, along with his brother Tony, runs Ceravolo orchards.

Their grandfather immigrated to Australia in the 1950s and bought a block of land in Ashton SA, which is still used today for their packing shed and juicing facilities.

The Ceravolos now have several properties spanning across the Adelaide Hills, from Nairne, Woodside and Echunga, and another at Myponga on the Fleurieu Peninsula. Growing a variety of pome and stonefruit on the property, they have around 15 hectares set aside for cherries.

Joe Ceravolo said there were challenges facing growing cherries in this region.

"One of the key challenges is that we can often get quite cold days during flowering, which can restrict bee flights and therefore have a significant impact on pollination and subsequently on fruit set.”

Mr Ceravolo's agronomist suggested he try ReTain from Sumitomo. ReTain is a naturally occurring plant growth regulator which blocks ethylene production and delays senescence, keeping the flowers viable for longer.

Mr Ceravolo said that in some varieties, the flower might only be viable for 24 hours and if this coincides with a cold day and reduced bee flights it could be extremely detrimental to fruit set.

"Our hope was that by using ReTain, we could keep the flower viable for an extra day or two, greatly increasing the chance for pollination and fertilisation.”

Mr Ceravolo trialled Re-Tain on an acre (0.4ha) of Stella cherries, treating a third of the crop with ReTain, a third with ReTain and a dormancy breaker and leaving a third untreated.

The results were striking.

Trial pays off

The area treated with ReTain alone, produced 30–40 per cent more fruit than the untreated and the area treated with ReTain and a dormancy breaker produced about 60 per cent more fruit than the untreated.

These results certainly meant that the investment in ReTain produced a significant return.

Mr Ceravolo gave the following advice to other cherry growers who may be considering ReTain but were still undecided:

"I would say that if they have any varieties that are poor at setting fruit or where they are susceptible to short flowering periods, they would be mad not to give it a go.”

ReTain can be used to extend flower viability in cherries by delaying flower and stigmatic senescence, thereby offering a better chance for pollination and fertilisation under poor set conditions which may result in better fruit set.

Timing of ReTain application may impact results as applications too early (pre-bloom) or too late (full bloom or later) will significantly reduce efficacy of the treatment.

Application must be made between 30–60 per cent flowering/bloom.