Protection
This article was republished from a 1999 article in Top Crop Manager.

The basic principles of potato storage have not changed much over the years. The computer age has allowed growers to more precisely control their humidity and ventilation operations, but the need to minimize disease, cool the pile, reduce shrinkage and preserve the crop until shipment remains essentially the same.

Every storage situation is different, according to John Walsh a former potato storage management specialist for the New Brunswick Department of Agriculture and now an agronomist with McCain Foods in Florenceville. However, he has a basic strategy that he shares with growers, which holds true for most situations: growers can adjust to suit their operation.

“There could be 1000 management situations,” Walsh explains. “But we've developed a strategy for storage management that begins with evaluating the crop for rot potential. For example, if a grower sees late blight late in the growing season, a flag should go up. If soil is saturated for more than 24 hours, another flag goes up. If there is rain during harvest — another flag. If rot is seen during harvest, that's another flag. If there are no flags, the grower can go ahead and start curing the crop. If a grower only has one flag, only a couple days of drying will be needed. If there are two flags, a couple weeks of drying may be necessary. If there are three flags, it would be best to turn the humidifier off, turn the fans on, and leave them that way because it could take more than two months to dry the crop. In the end, a little extra shrink is better than potatoes flowing out the door!”

The goal of all growers is to prevent rot from infecting the entire warehouse. Once taken care of, there are four steps to follow: curing, cooling, holding and removal of the crop from storage. If all are accomplished with no problems, a grower has completed the second stage of crop production, the first being the actual growing of the crop.

The curing process helps heal wounds and set the skin on the tubers, reducing any opportunity for disease to infect them. Walsh says the curing process is slightly different depending on how the potato is to be used. In the case of processing potatoes, he says, a colour evaluation must be made first and then the curing process can begin. “Tablestock and seed can cure for two to three weeks at 50 degrees F, while chip and French fry potatoes should cure for three to six weeks at 55 degrees F,” he reminds growers. “Once curing is over, growers begin the cooling process by dropping the temperature two to three degrees a week for tablestock and seed, and one to two degrees a week for processing potatoes.”

When cooling is complete, the potatoes are held at the recommended temperature for each type until delivery to processors or consumers. Processing potatoes may require warming to 55 degrees F for a few weeks before delivery to improve colour, otherwise the important thing is to maintain uniform conditions. Walsh says as long as rot is controlled, many problems facing growers will be manageable. However, he admits there is little growers can do to minimize the effects of rhizoctonia or silver scurf once they have infected the storage. He maintains growers need to concern themselves more with wet rots and dry rots because, with effective cooling, curing and holding, they can be minimized.

Some products will help control dry rot, but they have limited use due to resistance to the control product. Ross McQueen, a potato pathologist in the Faculty of Agricultural and Food Sciences at the University of Manitoba in Winnipeg, says thiabendazole has been effective on dry rot, but resistance is beginning to appear in Western Canada. “We're currently working with chlorine dioxide to control secondary infections that come from late blight,” he says. In this trial method, “The chlorine dioxide is delivered through the humidity system.” He says the method shows promise because it reduces the populations of the bacteria that cause rots that result from late blight.

Walsh recommends growers minimize dirt and mud going into storage as well as avoiding over-filling warehouses.

Occasionally, growers try to fine-tune their storage operations to reduce disease by using multiple ventilation systems or opting for newer insulating materials, but the basic principle of good storage remains the same, says Walsh. “Work continues to develop expert systems to run the computers that manage the storage,” he says, “but the basics remain the best management system.”

A grower who has developed his own expert system is Keith Kuhl of Southern Manitoba Potato Company of Winkler, Man. He says after trying a number of computer environmental control systems, including “a cumbersome program” from a technology company in the U.S., he met with a local electrical company and developed his own system. “Ours is a much simpler system than any others that are on the market,” he says. “We determine a long-term goal for each warehouse and the computer is adjusted to maintain temperature and humidity until the planned shipping date.”

Kuhl says his company ships 12 months of the year and, as a result, his crop is managed with that in mind from the time it is planted. “In the cooling process, we know what our long-term plan is for that crop, so each bin may be treated differently depending on the market or delivery date.”

However, despite an efficient, easy-to-use computer program, Kuhl relies on regular visual inspections using temperature probes and his nose to sniff out any problems. “A good manager should rely on his sensory perception,” he says. “If you detect sour smells, you know you might have some problems in that bin.” For damage control, he may use the chlorine dioxide product, Purogene, in his ventilation system, but he would prefer to eliminate potential problems before this step is needed. This product recently received an extension of its 'emergency use' registration until June 2000.

Finally, the trick for successful storage is to never quit monitoring the warehouse. Take note of any 'flags' as the crop is being put into storage and adjust humidity and ventilation to minimize problems. Then, throughout the winter, maintain systems and monitor the crop to eliminate any surprises when the trucks start loading to take the crop to its final destination.

Kuhl says he is always ready to adjust his plans. For example, if a problem is found in a field slated for 10 months of storage, he may decide to move those tubers out of storage earlier than he had planned. He also says he selectively harvests to reduce problems. If the season has been wet and low areas are still wet, he may choose not to harvest those areas. He might also harvest them separately and store them in a different bin where the curing/cooling process can be adjusted to meet the needs of those tubers. If he sees a higher percentage of culls in a field, he may monitor that crop more diligently when it is in storage. He suggests keeping good records at harvest, noting the conditions of harvest and the pulp temperature of the potatoes going into storage and recording any disease potential.

“Storage management is like managing a completely separate crop,” says McQueen. “There are multiple factors growers need to take into account and manage the storage accordingly.” Savvy growers, like Kuhl, understand this concept and try to remain on their toes when their potatoes are in the bin although the basic storage principles remain the same.
Published in Storage
2018 saw fewer problems with wireworm in Atlantic Canadian potato fields than past years, according to Christine Noronha, a research scientist for Agriculture and Agri-Food Canada based in Prince Edward Island. But this doesn’t mean the problem has gone away.
Published in Diseases
It’s not about how you start, it’s how you finish – and this potato season is not over yet. Canadian potato producers endured a tough harvest season, especially Prairie and east coast producers who were faced with abnormally cold wet weather that delayed harvest until early November.
Published in Storage
For potato growers, one of the most concerning and costly diseases is late blight, caused by the pathogen Phytophthora infestans. Estimated to cost almost $10 billion per year worldwide, late blight spreads by spores and can spread quickly in a field. Post-harvest losses can be substantial if infected tubers are harvested and stockpiled. Like other disease pathogens, new strains and novel genotypes of P. infestans have emerged over the past few years, creating new challenges for commercial potato growers.
Published in Diseases
Scouting and monitoring help reduce yield and quality losses and can save time and money. Diseases can manifest during the growing season, or at and after harvest, therefore scouting and monitoring can help identify diseases early in the cropping or storage cycle when it may still be possible to slow down or stop their spread. Regular scouting and monitoring of potato crops throughout the growing season and during storage are essential to good integrated pest management (IPM) programs.
Published in Diseases
A number of Ontario potato growers began noticing moist grey and brown lesions around wounds and the stem ends in their harvested potatoes in the fall – the first signs of Pythium leak. Measures to minimize the potential problem were initiated because, if the crop isn’t managed carefully as it is placed into storage, a season of hard work can be lost.
Published in Diseases
Eugenia Banks, Ontario potato specialist, attended a BASF meeting discussing several pesticides for potatoes will be coming through the pipeline for producers.
Published in Chemicals
The impact of the difficult harvest on the industry will be felt across all sectors - seed, table stock and processing. Crop stress, reduced yields and unharvested acres will all contribute to a national decline in potato production.
Published in Business Management
Lorraine MacKinnon, PEI potato industry coordinator with the Department of Agriculture and Fisheries, says it’s not a nice position to be in now to start contemplating potential issues going forward with storage after a difficult harvest. MacKinnon created a checklist for producers to use during their daily warehouse visits that help identify symptoms of larger problems. Storage problems are better tackled sooner rather than later.
Published in Storage
Ontario corn producers are dealing with high-DON (deoxynivalenol) in grain corn this year. High amounts of the mycotoxin are harmful to animals, so high-DON corn is unsuitable for feed and producers have limited end use options.
Published in Crop Protection
Syngenta Canada Inc. announces the launch of Minecto Pro foliar-applied insecticide for broad-spectrum control of key pests in potatoes, apples, pears, and a variety of vegetable crops. 
Published in News
Syngenta Canada announces the registration of Vibrance Ultra Potato as a new seed treatment for the suppression of pink rot and control of other seed and soil-borne diseases, including late blight. 
Published in News
Health Canada is proposing to cancel all uses of mancozeb, except for use on greenhouse tobacco, due to unacceptable risks to human health and the environment. The re-evaluation removes the exception that allowed foliar application of mancozeb on potatoes.
Published in News
Pythium leak has been observed in a number of fields in Ontario this harvest season, according to Eugenia Banks, potato specialist with the Ontario Potato Board.
Published in Diseases
Black cutworms were found in a number of fields near Delhi, Ont., on July 26, according to Eugenia Banks' latest potato update. 
Published in Pest Control
Potato farmers in P.E.I. are planting more mustard to ward off wireworm and boost crop yield. 
Published in Crop Protection
The Pest Management Regulatory Agency (PMRA) completed its re-evaluation of mancozeb and found the continued registration of products containing mancozeb acceptable for foliar application to potatoes in Canada.
Published in Diseases
Agriculture and Agri-Food Canada researchers in Fredericton, N.B. are exploring environmentally friendly solutions to manage Potato Early Dying complex (PED), a disease that is limiting yields in many potato fields in eastern Canada.

PED is a disease complex caused by a combination of a fungal disease (Verticillium wilt) and root-lesion nematodes.

With few available treatments, a process called biofumigation is being used by some growers to manage PED. The process involves tilling mustard plants into the soil at a specific stage of growth with enough heat and moisture in the ground to induce a chemical breakdown of the plant material.

“As the mustard decomposes, it releases a chemical that reduces Verticillium wilt pathogens without adverse effects on the environment,” explains Dahu Chen, AAFC plant pathologist at the Fredericton Research and Development Centre.

As a side-effect, mustard biofumigation also delivers green compost into the soil, improving soil health. There is some evidence that the severity of PED symptoms is reduced in healthy soils.

“The disease has been around for a long time, but it is now identified to be a major factor limiting tuber yield in New Brunswick,” says Chen, who is studying the problem with colleague, AAFC researcher Bernie Zebarth. 

“The pathogen can survive in the soil for a long time, even through the harshest winter conditions of eastern Canada,” explains Chen.

Chen and Zebarth are now working with industry partners, including Potatoes NB and McCain Foods Canada, to determine the effectiveness of mustard biofumigation through trials in commercial fields.

In addition, crop rotations that reduce the severity of PED symptoms are being examined in New Brunswick and Prince Edward Island by Potatoes NB, McCain Foods Canada, the PEIPotatoBoard, the NB Department of Agriculture, Aquaculture and Fisheries and the PEI Department of Agriculture.

Dr Chen examines leaves of potato plant
Dahu Chen, AAFC plant pathologist, examines the leaves of a potato plant for signs of disease. (Photo courtesy of AAFC)



Published in Diseases
Eight spore traps have been set up in potato fields across Ontario to help detect spores of late blight, according to Eugenia Banks' latest potato update.

Two spore traps are located in the Shelburne-Melancthon areas at D & C Vander Zaag Farms Ltd. and two others in the Alliston area at Mark and Shawn Murphy Farms. In the Delhi area, two spore traps are set up at Joe Lach's Farm and Fancy Pak Brand Inc. The final two spore traps are located in the Leamington area at Harry Bradley and Sons Farm. 

Alliance Agri-Turf, Bayer CropScience, FS Partners, Holmes Agro and Syngenta provided funding for the 2018 late blight spore trap project. 

A&L Laboratories in London, Ont. will conduct the polymerase chain reaction (PCR) tests to identify the presence of late blight spores.

The results will be shared with growers and positive PCR tests indicate the presence of spores. Early detection helps alert growers to add late blight-specific fungicides into their mix.

In the past two years, Eugenia Banks, a former potato specialist for the Ontario Ministry of Agriculture, Food and Rural Affaris (OMAFRA), led a project evaluating passive spore trapping technology to help growers improve late blight management. The project recorded positive results. Spores were detected 15 days on average before late blight lesions were seen in a few fields. A previous Potatoes in Canada article goes indepth into the project and how effective spore traps are for preventing late blight

“Spore traps represent another tool to be added to the potato growers’ arsenal to combat late blight,” Banks says. “If late blight spores are not detected by the traps, growers should still follow a preventative fungicide program and apply a fungicide spray before rows close. Also, fields should be scouted regularly.”
Published in Crop Protection
Wild potatoes acquired from a gene bank in Germany six years ago are producing promising results for Agriculture and Agri-Food Canada researchers trying to develop superior Canadian varieties with resistance to some of the most problematic potato diseases. 


Stronger potato varieties will increase yields for Canadian growers, which translates into higher profits.

Dr. Benoit Bizimungu, head of potato breeding at the Fredericton Research and Development Centre, said a number of hybrids bred from these wild varieties could be ready for industry trials next year. 

Bizimungu selected the German plants because of superior traits such as high yield, as well as strong natural resistance to PVY, late blight, drought, and insects like the Colorado potato beetle.

“Although the primary interest was multiple disease resistance and high yield potential, a number of progenies show a nice deep yellow flesh color, which is usually associated with carotenoids,” Bizimungu explains. This is great news for consumers who want more antioxidants in their diet.

“What is really exciting is that some of these wild species have never been used in potato breeding before now,” he says. “Using these new parents broadens the genetic base.”

“It’s good to have multiple sources for breeding, especially for things like late blight where it keeps changing.”

Dr. Bizimungu obtained this unique plant material as a result of his collaboration with potato geneticist Dr. Ramona Thieme of the Julius Kuhn-lnstitut (JKI) at the Federal Research Centre for Cultivated Plants in Braunschweig, Germany.

The imported species come from wild potato cultivars that originated in South America, the birthplace of the potato. 

Published in Traits and Genetics
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