Pairing PGRs In Pears Helps Control Vigor

Vigor – it’s something pear growers constantly struggle with. Bending and tying branches, planting higher-density orchards, altering canopy architecture – all these things can help growers calm the vigor, but as Todd Einhorn, Associate Professor of Horticulture at Oregon State University says, these horticultural practices are only part of the remedy.

A pear tree treated with ReTain 14 days after bloom show PGR vigor control. (Photo credit: Todd Einhorn)
A pear tree treated with ReTain 14 days after bloom show PGR vigor control. (Photo credit: Todd Einhorn)

“It’s just extraordinarily difficult to control the vigor in ‘Anjou’ and we need solutions.”

Einhorn is studying the effects of plant growth regulators (PGRs) on controlling pear varieties. The vigor of young ‘Anjou’ can slow down early productivity. Two. The other popular winter varieties — ‘Bosc,’ and ‘Comice,’ are biennial bearers and ‘Comice’ in particular is a shy bearer, but still quite vigorous.

Where a PGR might be used to control vigor in ‘Anjou,’ a PGR would be needed to improve fruit-set with ‘Bosc’ and ‘Comice.’

Einhorn has studied using ReTain (Valent) to improve the fruit-set of ‘Anjou’ and shy bearers such as ‘Comice.’ The label suggests an application around bloom. However, ReTain is more effective if applied 7 to 10 days or so after bloom when ethylene production of developing fruitlets is markedly increasing. “When we wait and hold off for seven to 10 days after, we get about a 75% chance of increasing fruit-set,” he says.

Although there are times where no improvement has been seen, Einhorn says the vast improvement three-fourths of the time adequately makes up for the times when it doesn’t. He is currently developing research to understand the factors responsible for the inconsistent response.

Taking A Fresh Look
Studies on prohexadione calcium have shown some sensitivity with certain varieties such as ‘Bosc’ and ‘Bartlett.’ Einhorn says previous research with Apogee (BASF) had shown negative effects on return bloom of ‘Bosc’ and fruit size of ‘Bartlett’, and it was enough to have the label removed for pear.

Although several studies have shown Apogee’s effective shoot growth control, it can cause a 10% to 30% reduction in return bloom in ‘Anjou,’ and with a vigorous ‘Anjou,’ that reduction may not necessarily be a bad thing.

Einhorn is studying prohexadione calcium in another PGR, Kudos (Fine Americas), as a way to control ‘Anjou.’

“‘Anjou’ is extremely vigorous, in part because they don’t tend to set fruit early in their life so there’s a lot of horsepower,” he says. “We don’t have sufficient dwarfing roots to control the growth. More than any other cultivar, it needs help with controlling vigor in order to facilitate high-density

An untreated control tree. (Photo credit: Todd Einhorn)
An untreated control tree. (Photo credit: Todd Einhorn)

plantings.”

Understanding some of the data with ‘Anjou’ and Apogee, Einhorn and his team suspected that if the number of flowers were reduced with an application of prohexadione calcium, it could give the tree an increase in fruit-set efficiency for the remaining blooms.

Improving Return Bloom
For now, Einhorn says he will be examining the effect of Kudos on other varieties.

He is also studying ethephon around 45 days after bloom to improve flowering, which he says helps negate the effect ofprohexadione calcium. So, an application of prohexadione calcium could be applied to control vigor, and ethephon would assure return bloom would not be adversely affected in varieties that it may be a concern, such as ‘Anjou,’ ‘Bosc,’ and ‘Comice.’

“We’re getting a very nice effect on increasing return bloom, consistently around 20% to 30% partnering it with Kudos and when we were doing the Apogee work,” he says. “It’s essentially negated the effect of prohexadione calcium on reducing return bloom,” he says.

Ethephon products are currently not labeled for use with pear.

Einhorn says the PGR work is only a part of a larger portfolio of options for growers. He says often pear growers are reluctant to plant ‘Anjou’ in higher-density systems, simply because of how much trouble it can be to control the vigor.

Einhorn’s group is studying dwarfing rootstocks, root pruning, tighter in-row spacing, training systems, and canopy structuring — all component of the bigger picture of pear growing.

“The PGR approach is just one tool that we’re ultimately wanting to implement into a whole program for controlling vigor and improving cropping,” he says. “PGRs are just one tool to try to get out a sustainable, systematic approach to controlling vigor.

 

Topics: ,

Leave a Reply

Apples & Pears Stories
Apples & Pears
May 2, 2017
Washington Apple Industry Giants Merge
Chelan Fresh and Borton Fruit combine; total sales volume increases by nearly half. Read More
Apples & Pears
May 1, 2017
May Day, May Day – Look Out for Fire Blight
Now that spring has really sprung, a Washington State University expert says it’s time for apple growers to do their homework. Read More
Apples & Pears
April 26, 2017
Debunking the Myth of Calcium and Fruit Quality
Nutrient management and crop quality clearly go hand in hand. But not always in the ways you might think. In Read More
Apples & Pears
April 24, 2017
Researcher Uncovers the Origins of ‘Honeycrisp’ Apple
Thanks to the scientific data available through gene sequencing, a graduate student unlocks the mystery parentage. Read More
Apples & Pears
April 21, 2017
Interpera Congress Heads to Pacific Northwest in June
International pear conference comes to the U.S. for the first time. Read More
Apples & Pears
April 19, 2017
Young Apple Growers Meet with Lawmakers
Apple leaders from across the country discuss ag issues such as labor, trade, and research. Read More
Apples & Pears
April 18, 2017
Researchers Say it is Time to Scout for Apple Diseases
With bloom underway, the risk for fire blight and scab are high. Read More
Apples & Pears
April 6, 2017
‘Envy’ Top Variety in USApple Tournament
The ‘Royal Gala’ and ‘Braeburn’ cross is a slam-dunk winner in Apple Madness bracket tournament. Read More
Apples & Pears
April 3, 2017
Jim Allen, Matt Wells Join New York Apple Sales
Allen named Vice President of Marketing and Wells named Director of Field Service. Read More
Apples & Pears
March 28, 2017
Washington State University Offers Powdery Mildew Management Tips
Opening buds may be exposed to overwintering inoculum as temperatures begin to rise. Read More
Apples & Pears
March 27, 2017
It’s a Family Reunion at IFTA
Some of my fondest memories on the road are at IFTA conferences. Read More
Apples & Pears
March 27, 2017
Out of this World Expectations for ‘Cosmic Crisp’ Apple
With millions of trees going into PNW orchards, Washington State growers are betting big on ‘Cosmic Crisp'. The shift in varieties planted and more took center stage when the International Fruit Tree’s Annual Conference met in Wenatchee, WA. Read More
Apples & Pears
March 25, 2017
Two MAIA Releases Available for Growers, Hobbyists
‘Crunch-A-Bunch’ is an early ‘GoldRush’ and ‘Bakers Delight’ is a secret ingredient for baking. Read More
Apples & Pears
March 21, 2017
Two More Lost Apple Varieties Found In Steptoe Butte
Amateur apple detective strikes again with two more finds in abandoned orchards near state park. Read More
Apples & Pears
March 11, 2017
Stark Bro’s Debuts Two New ‘Honeycrisp’ Crosses
Both ‘Stark Ruby Darling’ and ‘Stark Scarlet Crush’ boast sweetness, crunch, and non-browning attributes. Read More
The Latest
Apples & Pears
May 23, 2017
Grower Shares Personal Impact of Labor S…
USApple leader Phil Glaize of Virginia stresses need for reform with current labor regulations, programs at Congressional briefing on agriculture labor crisis. Read More
Apples & Pears
May 15, 2017
U.S. Apple Board Member Stresses Labor R…
Michigan apple grower says agriculture’s future depends on Farm Bill funding. Read More
Apples & Pears
May 8, 2017
Abundant Robotics Gets $10M Investment f…
The goal is to pick apples with the same, if not better, fruit quality than traditional harvesting. Read More
Apples & Pears
May 2, 2017
Washington Apple Industry Giants Merge
Chelan Fresh and Borton Fruit combine; total sales volume increases by nearly half. Read More
Apples & Pears
May 1, 2017
May Day, May Day – Look Out for Fire Bli…
Now that spring has really sprung, a Washington State University expert says it’s time for apple growers to do their homework. Read More
Apples & Pears
April 26, 2017
Debunking the Myth of Calcium and Fruit …
Nutrient management and crop quality clearly go hand in hand. But not always in the ways you might think. In Read More
Apples & Pears
April 24, 2017
Researcher Uncovers the Origins of ‘Hone…
Thanks to the scientific data available through gene sequencing, a graduate student unlocks the mystery parentage. Read More
Apples & Pears
April 21, 2017
Interpera Congress Heads to Pacific Nort…
International pear conference comes to the U.S. for the first time. Read More
Apples & Pears
April 19, 2017
Young Apple Growers Meet with Lawmakers
Apple leaders from across the country discuss ag issues such as labor, trade, and research. Read More
Apples & Pears
April 18, 2017
Researchers Say it is Time to Scout for …
With bloom underway, the risk for fire blight and scab are high. Read More
Apples & Pears
April 6, 2017
‘Envy’ Top Variety in USApple Tournament
The ‘Royal Gala’ and ‘Braeburn’ cross is a slam-dunk winner in Apple Madness bracket tournament. Read More
Apples & Pears
April 3, 2017
Jim Allen, Matt Wells Join New York Appl…
Allen named Vice President of Marketing and Wells named Director of Field Service. Read More
Apples & Pears
March 28, 2017
Washington State University Offers Powde…
Opening buds may be exposed to overwintering inoculum as temperatures begin to rise. Read More
Apples & Pears
March 27, 2017
It’s a Family Reunion at IFTA
Some of my fondest memories on the road are at IFTA conferences. Read More
Apples & Pears
March 27, 2017
Out of this World Expectations for ̵…
With millions of trees going into PNW orchards, Washington State growers are betting big on ‘Cosmic Crisp'. The shift in varieties planted and more took center stage when the International Fruit Tree’s Annual Conference met in Wenatchee, WA. Read More
Apples & Pears
March 25, 2017
Two MAIA Releases Available for Growers,…
‘Crunch-A-Bunch’ is an early ‘GoldRush’ and ‘Bakers Delight’ is a secret ingredient for baking. Read More
Apples & Pears
March 21, 2017
Two More Lost Apple Varieties Found In S…
Amateur apple detective strikes again with two more finds in abandoned orchards near state park. Read More
Apples & Pears
March 11, 2017
Stark Bro’s Debuts Two New ‘Honeycrisp’ …
Both ‘Stark Ruby Darling’ and ‘Stark Scarlet Crush’ boast sweetness, crunch, and non-browning attributes. Read More