Some apple growers can get nervous about using chemical fruit thinners. However, Sam Boyce, operations manager at a Goulburn Valley orchard, says the savings in manual thinning and early market sales benefits are simply too great to ignore.

Mr Boyce works at the MJ Hall and Sons properties at Toolamba, near Shepparton. At the “home farm”, Gala, Pink Lady and Granny Smith apple varieties, as well as plums and some pears, are grown over about 65 hectares.

Mr Boyce has worked closely with industry consultant Nic Finger to fine-tune their chemical thinning program, which is now producing strong benefits.

“The ideal result is to reduce the fruit number as close as possible to our post-thinning target,” he said. “It’s getting it near to the point where we have dropped too much fruit because that’s the greatest cost saving in thinning.

“We are putting on quite high rates (of thinners), and some people can’t believe how much we are applying, but our hand thinning costs have reduced by more than 30 per cent.

“Yes, we are investing strongly per hectare in chemical thinning, but we are saving much more per hectare in manual thinning costs. And instead of looking at the chemical cost per hectare, we look at it as $2–$3 per bin, and to make that back in profit is very easy.”

He said a key part of their chemical thinning program in recent years had been the addition of Brevis fruit thinner from Adama Australia for the Gala apples.

“Gala is a different beast, and once you get your head around it, you realise you have to throw everything at it. It’s a very sticky apple tree, and it needs a hard pruning regime,” Mr Boyce said.

“We tweaked some things with a few other thinners and added Brevis, and it’s now a solid part of our program for Gala.”

Containing the unique active ingredient, metamitron, a non-hormonal agent that inhibits photosynthesis, Brevis has become a key secondary thinning tool for apple growers and can also be applied in pears.

Aided by Adama Australia’s clever online decision support tool, BreviSmart, it can be applied across a wider growth interval (8–16mm central fruitlet diameter) and temperature range (10–25°C) than alternative fruit thinners.

BreviSmart uses an algorithm that harnesses important factors such as location, variety and fruitlet size, along with weather, that can influence Brevis’ efficacy in predicting a recommended application window.

“Our program in the Gala would be four to five flower thinning sprays, including ATS (ammonium thiosulfate). Once it’s at fruit set, we then use 6-BA at 8–10mm followed by Brevis at 12–16mm fruit size,’’ Mr Boyce said.

“Brevis has brought the capability to use a product with a different mode of action after fruit set. Our only other option is another 6-BA, which drops less fruit than Brevis, and so we don’t get the result we are after.”

He said that even if the strong thinning program reduced yield by 10 per cent but increased the fruit size, it would still be effective.

“You pick up the 10 per cent in the fruit size without doubt,” Mr Boyce said.

“If we drop more fruit than anyone else but achieve better size and quality and get it into the market, then it’s a benefit. We go hard early for early size and colour, to get it to market early, to get early money.

“The earlier you get fruit off the tree, the more energy the tree is putting into the remaining fruit.”

Charles Martin, agronomist with Nutrien Ag Solutions at Shepparton, said another benefit with Brevis compared with alternatives was that it did not promote tree growth for further pruning, making it ideal for applications on mature trees.

He said applications also had a limited impact on beneficial predators.

Mr Martin was involved in a Brevis trial in apples with a Cobram grower last season.

BreviSmart was used to determine the optimum application timing, which was at the 8–10mm fruit size stage in September when it was applied at the high rate of 2.2 kilograms/ha over a full block.

“BreviSmart was definitely a handy tool, and the application showed a strong benefit compared with hand thinning,” Mr Martin said.

“Initially, the grower was concerned that the Brevis application had dropped too much fruit, but later on it looked good and they were very happy with the yield.”

He said another positive with Brevis was that it did not remove fruit clusters, whereas alternative fruit thinners can.