New plant growth regulator promotes red colouration in bi-colour apples

Blush trials - Gala. Left Gala Control.  Right Gala Blush.

For the first time this fall, Canadian apple growers have the opportunity to use Blush plant growth regulator (PGR).  American competitors have had access to the product since 2014.  

With the active ingredient prohydrojasom, a naturally occurring plant hormone, the product promotes red colouration in bi-colour apples such as Fuji, Gala, Honeycrisp, Ambrosia , Paula Red and Pink Lady. If it’s a rainy, cool fall, it could make a difference in grading.  

“This product hastens the accumulation of anthocyanins,” says Jim Kruger, northeastern representative for Fine Americas, Inc. who presented to Ontario’s Georgian Bay growers in late July. Anthocyanins are red pigments that belong to a class of molecules called flavonoids. Along with stimulating fruit colouration, anthocyanins act as powerful antioxidants.  

The PGR does not affect firmness, sugar levels or ethylene production. It’s sprayed within seven to 28 days of harvest, along with a non-ionic surfactact. While no trials have been conducted in Canada, apple growers in both New York state and Washington state attest to the product’s value. Colouring is a complicated process, they note, with the product working well under cooler conditons.  

For growers who use other PGRs to manage fruit maturation and ripening, there is no concern in mixing two products.  Blush PGR can counter the effect of “colour drag” from other harvest management products. Kruger suggests using a tight spray interval of seven to 10 days.  “The longer out you can apply the product before harvest, the more consistent the results,” says Kruger.  

In many apple growing areas, droughty conditions have prevailed this season. “If you were to give emotions to an apple, you can imagine that the last thing it would worry about is colour,” says Kruger. “It just wants to protect the seed, survive and say my job is done for the year.”  

One side benefit of Blush PGR is improved harvest efficiency. It can increase the percentage of packable fruit in the early part of the season, spreading labour costs.Blush PGR is available to Canadian apple growers through N.M. Bartlett.  According to Sean Bartlett, sales representative, the product has a fit for bi-coloured fruit. 

“Growers in the northeast generally get fairly good colouring in the fall due to the warm days and warm nights,” he says. “However we have trouble achieving enough colour to get away from multiple picks. The hope with this new product is that we have another tool to help achieve more uniform colouring, more consistent yields and greater tray fruit. 

Early indications are that growers plan to try the product on Fuji, Honeycrisp, Ambrosia, McIntosh and a few others. For certain varieties, it may be harder to justify the expense.  

“Macs, for instance, do not fetch the money a Honeycrisp apple would but if we can pick 15 per cent more on the first pick or pick everything on the tree at once, we are starting to save significant dollars,” says Bartlett. “I would say southwestern Ontario growers would definitely see a benefit on certain varieties such as Honeycrisp which is challenged to colour properly.”

In Ontario, it’s been a hot and droughty summer, but apple growers need the cool nights in September to get good colouring. Otherwise, the colouring tends to bleach out. The use of Retain PGR will mitigate this colouring process. All growers have blocks that don’t receive as much colouring as they would like. 

We are recommending growers stay at the high rate suggested by the manufacturer, with two applications spaced a few weeks apart,” says Bartlett. “The first application should be going on 35-42 days before anticipated harvest. With this timing in mind, you want to make sure that the apples have already started to colour. This product will not turn a green apple red. I would also recommend that growers apply their first spray before applying Retain to get the product working best as possible.”

If the product is part of a tank mix, it should be mixed with a non-ionic surfactant for improved uptake. It can also be tankmixed with Retain with no issue, in which case growers should substitute the non-ionic surfactant for a silicone surfactant. 

“So for the launch year, I hope growers will walk before they run,” says Bartlett. “Start with the high rate and work backwards and try some different trials on your farm with different varieties and timings. We are all learning how Blush PGR works in the  northeast and we want to make sure it does the best job possible.” 

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Thursday, August 25, 2016
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