Stone Fruit: Avoiding Cherry Fruit Cracking Is A Balancing Act

Greg LangWater is certainly critical to growing large sweet cherries, but too much of a good thing results in fruit cracking. In recent years, scientists have been studying the various steps involved in how cherry fruit crack, and have realized that cracking can result from prolonged exposure to water in the root zone as well as rainwater on the fruit (or even postharvest from water on the packing line).

Let’s first consider the classic scenario of too much rainwater on the fruit. The first encounter of a raindrop with fruit is likely on the top of the fruit. From here, the water droplets will either flow to the lowest point on the top of the fruit — the fruit “bowl” where the stem is attached to the fruit — or the lowest point on the bottom of the fruit, the tip (see figure). Droplets pool in the bowl around the stem, and thus even after the rain event is over, there is prolonged contact with, and uptake into, the fruit flesh in this region.

Dr. Lars Sekse (Plant Bioforsk, Norway) and Professor Mortiz Knoche (Leibniz University, Germany) showed that as cherries begin the final period of rapid fruit growth, the cuticle becomes thinner and microcracks appear. Contact with water aggravates microcrack formation. With prolonged contact, too much surface water is absorbed, the flesh swells in this localized area, and bowl or shoulder cracks result.

Similarly, droplets running off the fruit collect at the tip until there is enough water to drip off (see figure). Thus, again there is prolonged contact, which can result in tip cracks. This is also the part of the fruit where the flower style was attached until fruit set, leaving a small scar that generally is not as elastic as the fruit cuticle. Varieties with prominent stylar scars tend to be more prone to such tip cracks than varieties with small scars.

A third potential area of the fruit skin that may incur prolonged contact with rainwater is where two or more fruit in a cluster are touching (see figure), creating a surface tension that prolongs water contact with the surfaces of both fruits. This can result in cracks where the fruit touch, along the fruit sides or lower shoulders.

Clearly, duration of rain contact with any of these fruit surfaces is directly related to how much water is absorbed into the local areas of fruit flesh, resulting in cracking when the flesh swells more than the fruit skin can stretch. Thus, reducing this duration, as by blowing water off of fruit with helicopters or airblast sprayers, can be done following rain events. Eliminating rain contact with the fruit with orchard tent covers or high tunnels can prevent this type of fruit cracking entirely.

Fruit Need Not Be Wet To Crack
sweet cherry crackingFor uncovered orchards, the uptake of water through the fruit cuticle can be slowed by the application of water-repelling (hydrophobic) fruit coatings — for example, Parka or RainGard. These generally need to be applied more than once to assure the coating remains intact during rapid Stage III fruit growth. Similarly, the application of an osmotic salt, such as calcium chloride, will reduce the osmotic differential between the pure rainwater on the fruit skin and the fruit flesh, which slows uptake. These also need to be reapplied, possibly even during prolonged rain events, since they are water soluble and can wash off.

The more recently characterized cracking scenario is that of too much water (from rain or irrigation) in the soil. In our high tunnel and retractable-roof cherry-covering-system studies at Michigan State University, we have maintained absolutely dry fruit, yet still found cracking can occur when rainwater flowing off the tunnel covers drained onto the soil and saturated the root zone. As we tested high-frequency/low-duration trickle irrigation scheduling, we also caused cracking from excessive root zone saturation, particularly during climatic periods of low evapotranspiration. Soon after we observed these phenomena, Dr. Penny Measham (University of Tasmania) reported that this root-driven water uptake into the fruit is the primary cause of side-cracks (see figure).

Water taken up by the roots is transpired mainly through the leaves, but if the evapotranspiration rate is low, more water is drawn into the fruit. This explains why some hydrophobic fruit coatings may exacerbate fruit cracking in certain situations, if the coatings reduce leaf transpiration and the rootzone becomes saturated. Likewise, orchard covers that raise humidity within the canopy, reducing transpiration, can exacerbate fruit cracking if soil moisture is excessive.

Therefore, methods to improve rootzone drainage, such as modifying surface drainage (planting on berms or raised beds) or installing subsurface drainage tiles, can be helpful for reducing rain-cracking potential, in addition to the use of orchard covers or fruit coatings. Scheduling irrigation to only meet evaporative demand is preferred. This is easier to accomplish in high density cherry orchards with micro-irrigation systems and with smaller trees having smaller root systems, than with large trees that have correspondingly large root zones.

Topics: , , ,

Leave a Reply

Fruits Stories
Andrew (left) and Steve Beilstein use an air dancer, pictured in the background, as a bird-scaring device at The Blueberry Patch in Lexington, OH.  (Photo credit: Gary Gao)
Berries
July 27, 2016
Bird Damage Plagues Most Fruit Growers
There’s no silver bullet, but here are several techniques to annoy and deter birds. Read More
precision ag vision conference
Citrus
July 27, 2016
Ag Tech Is Hot On Horticulture; Get A Handle On What This Means For You
As evidenced by the recent AgTech Summit hosted by Forbes magazine in Salinas, CA, action in precision farming and the Read More
cash money in hand
Citrus
July 27, 2016
Stockholders OK Dow, DuPont Merger
Companies intend to separate into three, independent companies. Read More
Tall Spindle Axe featured
Stone Fruit
July 26, 2016
Take A Closer Look At The Tall Spindle Axe Training System
One of the more traditional three-dimensional canopies, Tall Spindle Axe data shows consistent early and sustained yields. Read More
Workers picking in a Florida strawberry field
Berries
July 26, 2016
Wish Farms Commits $100K To Food Safety Cause
Central Florida berry operation will donate $20,000 annually over the next five years to fund various research projects backed by the Center for Produce Safety. Read More
Spanish speaking employees
Fruits
July 26, 2016
Popular Spanish-Speaking Fruit Summer Tour Returns
Second-annual tour designed to educate Spanish-speaking employees or farmworkers on fruit growing practices. Read More
Feature Im-Perfect-Wal-Mart-Fruit-Apples (Photo credit: Walmart)
Apples & Pears
July 26, 2016
Walmart Begins Selling So-Called ‘Ugly Fruit’
Cosmetically challenged apples are the company’s first foray into a global movement to cut food waste. Read More
The Latest
Farm Management
July 29, 2016
Obama Signs GMO Labeling Law
The law is praised by major grower groups because it avoids a patchwork of state laws and provides clarity going forward. Read More
Citrus
July 28, 2016
Florida’s Medicinal Cannabis Venture Off…
The state’s first dispensary of product comes online in Tallahassee, others waiting for the green light. Read More
Citrus
July 27, 2016
Ag Tech Is Hot On Horticulture; Get A Ha…
As evidenced by the recent AgTech Summit hosted by Forbes magazine in Salinas, CA, action in precision farming and the Read More
Citrus
July 27, 2016
Stockholders OK Dow, DuPont Merger
Companies intend to separate into three, independent companies. Read More
Fruits
July 26, 2016
Popular Spanish-Speaking Fruit Summer To…
Second-annual tour designed to educate Spanish-speaking employees or farmworkers on fruit growing practices. Read More
Crop Protection
July 25, 2016
Study: GMO Ban Would Hurt Economy And En…
Food prices and greenhouse gas emissions would rise, according to paper by Purdue University agricultural economist. Read More
Farm Management
July 25, 2016
Seven Reasons You Need To Attend The Uni…
Education sessions and Capitol Hill visits will focus on key issues, such as labor, facing the fresh produce industry. Read More
Crop Protection
July 25, 2016
Organic Insect Control Product Available…
The mycoinsecticide is EPA registered and controls a variety of insect pests. Read More
Citrus
July 21, 2016
Farm Labor Delays Taking Toll On Crops […
When it comes down to it, we have a choice to make. We either have to import our labor, or we'll have to import our food. Read More
Citrus
July 20, 2016
My First Trip To Cuba Proves Fruitful
The five-day journey was enlightening, providing participants with a better perspective of the state of agriculture in this country 90 miles off Florida’s coast. Read More
Citrus
July 19, 2016
Funds Allocated To Address Impact Of Cli…
NIFA announces $8.4 for study and development of new approaches to mitigate effects of climate change. Read More
Citrus
July 18, 2016
USDA Awards More Than $26 Million For Af…
The funding is to support more than 400 rental units in four states. Read More
Business Planning
July 18, 2016
Financial Fortitude Key For Small Farm S…
Local threats like citrus greening create additional challenges for many of Florida's more modest enterprises. Read More
Citrus
July 18, 2016
Bayer Ups Bid To Buy Monsanto
Reports indicate new offer at nearly $65 billion. Read More
Farm Management
July 14, 2016
House Passes GMO Labeling Legislation
The measure will be sent to President Obama, who is expected to sign the bill into law. Read More
Citrus
July 14, 2016
Look Up! Farming’s Future Is Comin…
FAA's recent ruling regarding unmanned aircraft systems is good news for business. Read More
Fruits
July 14, 2016
Hail Hits Northern Michigan
Growers encouraged to act quickly while trees and plants are susceptible to disease infection. Read More
Citrus
July 13, 2016
Farm Credit Celebrates 100 Years Of Serv…
Lending institution plays a critical role in sustaining Florida agriculture. Read More
[gravityform id="62" title="false" description="false"]