Diseases
Creative solutions are needed in the battle against bacterial diseases in potato. In people, most bacterial diseases are treated with antibiotics, but due to the rise in resistant bacterial strains, that option, apart from a few exceptions, is off the table for field-scale agriculture.
Published in Diseases
Earlier this year, Syngenta Canada announced the launch of Orondis Gold Potato fungicide for the suppression of two common storage diseases, pink rot and Pythium leak, in potatoes.
Published in Chemicals
Orondis Potato Gold has been registered as an in-furrow treatment at planting for pink rot and Pythium leak or as a foliar application to control late blight. It’s one or the other, not both. So, what’s the best choice?
Published in Chemicals
As of Feb. 5, 2019, 250 Canadian potato growers have participated in the Canadian Potato Council’s survey on mancozeb use, which will be submitted to the Pest Management Regulatory Agency (PMRA) to assist with the re-evaluation of the fungicide.

The proposed final re-evaluation decision for mancozeb, which suggests cancelling all uses of mancozeb except on tobacco due to unacceptable risks to human health and the environment, was published on Oct. 5, 2018, with a three-month consultation period. The Canadian Horticultural Council and the Canadian Potato Council were granted an additional 60-day period after the consultation deadline to gather more information on how growers use mancozeb for horticultural crops, including potatoes.

The council released a survey that Canadian growers could complete online or by hard copy to gather more information during this period. The purpose of the survey is to gather grower provided data that is “highly representative of how mancozeb is used in potato production overall across Canada and within each province.”

“Specifically, mancozeb use rates, number of applications, the use of aerial application under irrigated and non-irrigated potato production and the effectiveness of chemical and non-chemical alternative controls will be determined,” explained David Jones, manager of potato industry coordination with the Canadian Potato Council.

As of Jan. 25, 2019 , only 16 of 135 total survey responses were from Manitoba. During Manitoba Potato Production Days in Brandon, producers, especially from the province and Alberta, were encouraged to participate in the survey to include how they use mancozeb so the PMRA could make a nuanced decision.

In the Prairie provinces, producers often use aerial applications for fungicides because of the nature of the landscape and the lower population compared to Eastern Canada. “But Manitoba has higher humidity, somewhat similar to some of the eastern provinces, so we’ve got a situation where we have a lot of fungicide applications due to our climate, but we also do those by air because of our topography,” said Darin Gibson, president and research agronomist at Gaia Consulting and presenter at Manitoba Potato Production Days.

The grower survey sought to include the variety of ways producers use the fungicide so that PMRA’s decision would be reflective of the fungicide’s use in Canada. “[Aerial applications] will be considered differently and I’m not sure how that affects the final outcome, but it’s important that PMRA has the best information possible about how these products are used across the country, otherwise they make assumptions about the worst case scenario,” Gibson said.

“[The survey’s] highly representative data will provide quantitative information that PMRA can use to verify or correct assumptions that they have previously used in their assessment of risk associated with mancozeb use in potatoes,” Jones added. “The desired outcome is that the collected data will contribute to revised risk assessments that are favourable to the continued use of mancozeb in potatoes.”

The proposed re-evaluation decision removed the original exception that allowed for foliar application of mancozeb on potatoes and will have a great impact on potato growers.

Currently, mancozeb is one of the most economical broad-spectrum fungicides for early and late blight. Not only is the price point attractive, but because it is a multi-site fungicide, there is a low risk of diseases developing resistance to mancozeb.

“One of the problems is when you lose some of these products to regulatory issues, you end up depending on some of these single-site fungicides, which have a much higher risk of resistance,” Gibson said.

Currently, multi-site fungicides, like mancozeb, chlorothalonil, or metiram, are the base for any potato fungicide program because there’s little risk of diseases developing resistance to these fungicides. Gibson explained that if mancozeb is removed from the growers’ toolbox, growers would have to switch to single-site products, such as either an early blight product or a late blight product. The cost of production will increase because growers will have to tank mix two products; each of those products being more expensive than mancozeb.

Mancozeb is not banned in the European Union or in the United States, having undergone its own re-evaluations in those countries in 2018 and 2005 respectively. Gibson said he’s cautiously optimistic. “It's going to end up in somewhat of a compromise where it'll be maybe three to five applications, hopefully more, but I'm optimistic that it's not going to end up at zero.”

The mancozeb use survey is available until Feb. 8, with anything submitted on Feb. 8 being accepted.

Since the low Prairie producers response numbers reported at the end of January, Jones said growers organizations in Manitoba and Alberta (KPPA, Peak, PGA) have made good effort to remind growers directly about the importance of participating in the Council’s survey. “The response from growers in Alberta and Manitoba has been excellent, representing about a third of the total responses received to date. The response rate is similar to the percentage of planted acres in those two provinces as a percentage of the total Canadian acres planted. This would indicate that the survey responses are highly indicative of potato production in Alberta and Manitoba,” Jones said.

“It's an important issue for Manitoba growers and it's just one of the important tools that growers have for protecting their potato crop and if they were to lose that one, they'll still be able to grow potatoes, but it's going to be more difficult and more expensive,” Gibson said. “So it's really important that growers get their information to the Hort Council so that can be passed on to PMRA, so they can hopefully keep an important tool for their production.”

The survey is available online, or by hard copy that could be submitted via email or fax. To complete the survey, visit www.surveymonkey.com/r/TWW76JJ.
Published in News
Syngenta Canada announced the launch of Orondis Gold Potato fungicide for the suppression of two common storage diseases, pink rot and Pythium leak, in potatoes, on Jan. 14, 2019.
Published in News
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
Zebra chip is a serious disease that can kill potato plants, significantly reduce yields, and make infected tubers unmarketable. It was first documented in Mexico in 1994 and in Texas in 2000. Since then, it has spread northward through much of the Western United States, as well as to Central America and New Zealand.
Published in Diseases
A biopesticide for managing common scab would be an exciting advance for two key reasons, explains Dr. Martin Filion with the Université de Moncton.
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
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
Prairie and east coast potato producers endured a prolonged harvest of excessive rain and cold temperatures. After a difficult harvest, it’s time to look ahead to the storage season.
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 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
Research that would help determine what species and strains of the common scab bacterium are prevalent in Ontario is underway, according to Eugenia Banks, potato specialist with the Ontario Potato Board.
Published in Diseases
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
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