Mar 18, 2016
Retirement won’t curb Flore’s knowledge sharing

Michigan State University (MSU) horticulture professor Jim Flore is retiring this year, but not before reminding growers of the progress he has observed in the industry during a 40-year career.

Flore was honored in 2015 as the Cherry Industry Person of the Year by the Cherry Marketing Institute (CMI), an award that goes to individuals who have shown exemplary support for the industry. Flore received his bachelor’s, master’s and doctoral degrees from MSU, and has been a faculty member at his alma mater since 1974. He has devoted much of his career to the advancement of the Michigan fruit industry.

In presenting the award last July, Phil Korson, CMI executive director, said Flore has played an instrumental role in helping cherry growers remain on the cutting edge while encouraging sustainable growing practices.

“Jim has provided leadership to the cherry industry throughout his career,” Korson said. “A person dedicated to cherry research and the advancement of science, Jim has been a visionary leader who has been instrumental in the industry.”

Flore was born in Benton Harbor, Michigan, and raised on a fruit and vegetable farm in Bainbridge Township. His parents were progressive farmers who produced 17 crops, including sweet and tart cherries. They were early adopters of frost irrigation for strawberries and grapes and the mechanical harvest of cherries. His father was also instrumental in the early organization of growers through Great Lakes Cherry.

Flore was asked to speak at the recent Southwest Michigan Horticulture Days in Benton Harbor.

Afterward, he recapped his talk in an interview with Fruit Growers News.

Flore most recently has been working on a project that has shown the ability to delay cherry and apple bloom by up to 10 days in the spring. In Michigan, that is music to the ears of fruit growers, who have experienced devastating losses due to unseasonably warm temperatures followed by late frosts.

Flore is using a spray method traditionally used in high-density orchards for the application of fertilizer, to apply a fine mist of water on the trees. The water cools the tree buds, slowing growth and development. Flore said the practice could theoretically provide the water necessary for cooling with a tiny fraction of the amounts used by a conventional sprinkler.

“Along the way we have looked at cold hardiness – we fingerprinted cold hardiness for 30 years with peach and cherry,” Flore said. “And more recently, because of the earlier springs – but not a similar earliness in the last spring frost – we’ve found that we’ve had a lot of problems with spring frost, so if we could delay bloom that would be a pretty good thing.

“We found that the only thing that causes growth of the buds in spring is temperature, so if we can cool the buds we could delay them, and we developed a system by using mist and programming in the temperature and humidity to look at evaporation that we would be able to apply a mist to the tree, evaporative cool the bud and delay the bud break by seven to 10 days. I think that might be economical in the future.”

Having grown up on a fruit farm in southwest Michigan, Flore said, “I knew that I always wanted to go into horticulture. I have a very basic degree. So I know the basics pretty well.

Ishara Rijal worked with Jim Flore on a spray method to delay cherry and apple bloom by up to 10 days in the spring. Photo: Michigan State University
Ishara Rijal worked with Jim Flore on a spray method to delay cherry and apple bloom by up to 10 days in the spring. Photo: Michigan State University

“When I first got here I noticed not many people were working on cherry physiology – a few people on peach physiology, but not many people on cherry physiology. I decided one of the things that we needed to know from a basic point of view, does photosynthesis limit yield or not, and if we would look at that main building block, photosynthesis, we would know a lot about how much light we needed, temperature, humidity and many of the growing factors.

So a lot of the things that I’ve done are basic and work on that basis. But along the way we had to learn a lot of things. So let’s first take light. How much light does it take to produce a cherry? How should the light be distributed in canopies? So we first looked at thresholds for light, not only for single fruit, but within the canopies.

“We looked at different planting spacings, and eventually we proved that the amount of yield was directly related to the amount of light that could be absorbed by an acre of land,” Flore said. “Along the way we found there are also thresholds. That means that after a certain point, yield may increase but quality does not, and it starts to decrease.

“I talked a lot about distribution of light in canopies and how it related to both cherry and peach production, what optimum shape and spacing should be and after that, we talked about what might be the ideal type of an orchard.

“We started to look at – since we knew what we needed as far as the amount of carbon needed to develop fruit –we wanted to find out what some damage thresholds might be, meaning at what point does damage to the leaf, either biotic or abiotic, start to affect the production. Before we could do that, we have to know what the leaf-to-fruit ratio should be for optimizing production. We looked at that for different crops.

“Beyond that, we started to look at how much damage we could have to a leaf before we compromised photosynthesis. For most fruit leaves you can tolerate 10 percent damage between leaves if you’re not right at the limit of the number of leaves per fruit. If you’re a little bit more, then you have some compensation that you can work with, so that’s really important to know.

“The second thing that we looked at was timing. When does the insult on the foliage affect growth and production the most, and for almost all fruit crops the earlier you have the insult – either it be by biological or environmental –
the greater the effect. So that means that if you’re trying to control a certain type of insect, it’s probably more important to do earlier than later.

“We also looked quite extensively at flooding damage,” Flore said. “We find that because a lot of our soils are sandy but they’re clean tilled, the drainage was not very good, and we found that sensitivity to high water table was pretty great in tart cherry. In fact, if you’ve got much more than four to six days of flooding, with lack of oxygen, you can have some pretty detrimental effects.

“The other thing I tried to do today is indicate some of the things that we might have learned 30 to 40 years ago that finally are applicable today,” Flore said. “One of  them would be mechanical harvest of cherries. We were at the ground floor of looking at the use of ethephon for mechanical harvest, and recently – the last five or six years – growers were saying ‘What we really want to do with some of our brine fruit is harvest the fruit with the stem on. It’s worth more money to the grower, sometimes three to four times more, but how can we do that?’

“And we looked at some of our old data, and what we found was that if we wait until the fruit is about 4.5 to 5 grams to shake, and before the fruit retention force of the lower abscission zone is so low that the fruit falls off at the bottom, we could mechanically harvest, and what would happen is we swing the fruit such that it rips off at the pedestal and the branch and the stem stays on. We’ve had great success on some varieties if we started with 4.5 grams.

“So for some fruit, sweet cherries, we have a window of three to seven days where we can mechanically harvest.”

Flore said he will retire in July, but will maintain an office at MSU.

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