Tips To Avoid Potato Bruising

As we head toward another harvest season and the mad rush it entails, now might be a good time for a few reminders and a short refresher on potato tuber bruising.

Mechanical damage to potato tubers can take the form of nicks, cuts, skinning, and bruising. All of these forms of damage can affect the final quality of your potatoes as well as the storability of the crop. In general, any type of damage that breaks the skin of the tuber is a concern because such damage provides a potential entry point for one or another of the long list of disease organisms that cause storage rots.

While nicks, cuts, and skinning are all relatively superficial (though some cuts can be very severe), bruising usually involves damage to fairly substantial portions of the tuber and may also go fairly deep. To make matters worse, some bruises remain invisible until the damaged tubers are cut.

Bruising Types
Three types of bruising occur in potato tubers. Two of these types of bruises, shatter bruise and blackspot bruise, are generally associated with the rigors of harvest, though potatoes can suffer bruise damage anytime they’re handled. The third type of pressure bruise actually occurs in the storage facility while the tubers are stationary.

Figure 1. Shatter bruise can be seen without cutting into the tuber. Tissue separation and periderm damage occur in potatoes harvested and handled when pulp temperatures are too cold. Photo(s) Credit: Dr Nora Olsen, University of Idaho, Kimberly.
Figure 1. Shatter bruise can be seen without cutting into the tuber. Tissue separation and periderm damage occur in potatoes harvested and handled when pulp temperatures are too cold. Photo(s) Credit: Dr Nora Olsen, University of Idaho, Kimberly.

1. Shatter bruise is the one type of bruise that can be observed without actually cutting into the tuber and examining the internal tissues. Shatter bruise is characterized by cracks and fissures in the tuber that break the skin (Figure 1). This type of bruise occurs readily in crisp, turgid tubers or those with a high-solid content and is often associated with potatoes that are harvested and handled when pulp temperatures are too cold.

Turgid tuber tissues respond to a physical blow by rebounding. As these forces reverberate through the tuber, they actually tear the tuber tissues apart, resulting in fissures in the tuber flesh and cracks in the skin.

2. Blackspot bruise is quite a bit different. In this case, the periderm and the somewhat more resilient tissues just beneath it will deform in response to a physical blow, but in this case, the skin doesn’t break, and the tuber tissues don’t get ripped apart. Instead, the energy from the mechanical insult is delivered to tissues deeper in the tuber. The damaged internal cells leak some of their cellular contents, and the enzymes and substrates released react with one another resulting in the internal grey to black discoloration associated with this bruise type (Figure 2).

Figure 2. Blackspot bruise, caused by a physical blow, is favored by warmer pulp temperatures and dry conditions.
Figure 2. Blackspot bruise, caused by a physical blow, is favored by warmer pulp temperatures and dry conditions.

Blackspot bruise is favored by warmer pulp temperatures or dry conditions that tend to leave tubers in a more flaccid state. It also appears more commonly near the stem end of the tuber.

3. Pressure bruise is very similar to blackspot in that tissue damage inside the tuber leads to discolored internal tissues. In this case, however, the mechanical force is supplied by the sheer weight of the potato pile bearing down on tubers at or near the bottom of the pile. External symptoms may appear in the form of flattened areas on the outside of affected tubers.

Recommendations For Management
Management begins with proper adjustment and operation of harvesting equipment and placement of padding in problem areas of the handling equipment. Avoid drops of more than 6 inches. Harvesting tubers in the recommended pulp temperature range of 45o F to 65o F will also help to reduce damage.

In general, both shatter bruise and blackspot bruise increase when pulp temperatures are too cold. Management of pressure bruise requires high humidity in the storage facility although reducing pile height — keep below 18 feet — can also minimize this type of bruise.

Topics: ,

Leave a Reply

Potatoes Stories
PotatoesNortheast Poised To Increase Sweet Potato Production
July 15, 2015
In the first study of the performance of modern sweet potato cultivars in northern regions, University of New Hampshire (UNH) Read More
PotatoesNominations Open To Fill Board Seats For U.S. Potato Board’s 2016-2019 Term
July 7, 2015
Fifty-four board members will be elected or re-elected to fill open seats on the United States Potato Board. Read More
PotatoesInnovative Technology Is Necessary For Potato Growers To Be Sustainable [Opinion]
June 30, 2015
Historically, there has often been opposition or fear of new agricultural technologies and today is no different, but it is critical that growers have access to technologies that meet consumer demand while using less land and conserving soil, water, and energy. Read More
PotatoesBlack Gold Farms Kicks Off Red Potato Harvest In Southeast Missouri
June 26, 2015
American Vegetable Grower magazine’s Top 100 Grower Black Gold Farms kicked off fresh red potato harvest in Southeast Missouri this Read More
PotatoesPotato Field Day To Focus On Seed Lot Evaluations, Crop Protection
June 16, 2015
Attendees will be able to participate in one of two concurrent sessions. Read More
Potatoes2014 Fall Potato Harvest Estimated To Be Slightly Larger Than 2013
June 15, 2015
According to a recent USDA report, potato harvest in 2014 is the second-highest production level noticed in the last decade. Read More
PotatoesCrop Transition Conference In The Twin Cities
June 2, 2015
Potato growers and industry leaders are invited to attend the 2015 Crop Transition Conference in Bloomington, MN, June 17-18. The Read More
The Latest
PotatoesLate Blight Confirmed In Areas Of Idaho; Number Of Pota…
July 31, 2015
The number of potato psyllids decline while additional fields are noted as having late blight. Read More
PotatoesPotato Production And The Environmental Component Of Pl…
July 29, 2015
Part of being prepared for unusual weather patterns means being on the lookout for problematic pathogens and other pests. Read More
Late blight shown in a tomato
Disease ControlLate Blight Identified In Indiana, Michigan
July 28, 2015
A potato field in Michigan and a potato and tomato field in Indiana have documented the disease. Read More
PotatoesNortheast Poised To Increase Sweet Potato Production
July 15, 2015
In the first study of the performance of modern sweet potato cultivars in northern regions, University of New Hampshire (UNH) Read More
PotatoesNominations Open To Fill Board Seats For U.S. Potato Bo…
July 7, 2015
Fifty-four board members will be elected or re-elected to fill open seats on the United States Potato Board. Read More
PotatoesInnovative Technology Is Necessary For Potato Growers T…
June 30, 2015
Historically, there has often been opposition or fear of new agricultural technologies and today is no different, but it is critical that growers have access to technologies that meet consumer demand while using less land and conserving soil, water, and energy. Read More
PotatoesBlack Gold Farms Kicks Off Red Potato Harvest In Southe…
June 26, 2015
American Vegetable Grower magazine’s Top 100 Grower Black Gold Farms kicked off fresh red potato harvest in Southeast Missouri this Read More
PotatoesPotato Field Day To Focus On Seed Lot Evaluations, Crop…
June 16, 2015
Attendees will be able to participate in one of two concurrent sessions. Read More
Potatoes2014 Fall Potato Harvest Estimated To Be Slightly Large…
June 15, 2015
According to a recent USDA report, potato harvest in 2014 is the second-highest production level noticed in the last decade. Read More
PotatoesCrop Transition Conference In The Twin Cities
June 2, 2015
Potato growers and industry leaders are invited to attend the 2015 Crop Transition Conference in Bloomington, MN, June 17-18. The Read More
PotatoesNational Potato Council Accepting Scholarship Applicati…
June 2, 2015
The National Potato Council (NPC) is accepting applications for a $10,000 graduate-level scholarship to be applied toward the 2015-2016 academic Read More
PotatoesGMO Potatoes: A Solution To Key Production Challenges? …
May 31, 2015
The North American potato industry is a complex and wonderful entity. Like everything in the world of agriculture, this industry Read More
PotatoesAnother Genetically Engineered Potato To Be Evaluated
May 6, 2015
A petition from J.R. Simplot is seeking deregulation of a potato genetically engineered (GE) for late blight resistance, low acrylamide potential, reduced black spot bruising, and lowered reducing sugars. Read More
Phytophthora spore under a microscope
Disease ControlResearchers Find Silver Lining In Phytophthora Fight
May 5, 2015
A team of researchers from the University of Florida, University of Central Florida, and the New Jersey Institute of Technology Read More
PotatoesNorthwest Region Potato Stocks Hit 87.2 Million Hundred…
April 29, 2015
Potato stocks in Idaho on April 1, 2015 totaled 50.0 million cwt., according to a USDA National Agricultural Statistics Service Read More
PotatoesPotato Board’s Past Chairman Reflects On Year Of Servic…
April 8, 2015
New chairman was on the Potato Board’s International Marketing Committee and was a secretary/treasurer of the Northern Plains Potato Growers Association.    Read More
PotatoesResearchers Find Gene That Defends Against Late Blight
April 7, 2015
Scientists say a protein in the gene will make the late blight pathogen less likely to overcome resistance. Read More
PotatoesNew Dual-Purpose Potato Variety Released
March 31, 2015
The russet-skinned variety from the University of Maine and the Maine Potato Board boasts high yields. Read More