Over the next week most growers across P.E.I. should start harvesting and storing potatoes, Donald said. Farmers will get a better idea of the yield closer to Halloween when the harvest ends. READ MORE
Harvest management, in large part, is bruise management. Bruising also affects tuber quality significantly. In order to harvest potatoes with minimum tuber damage, growers need to implement digging, handling and storage management practices that maintain the crop quality for as long as possible after harvest.
Assuming all harvest and handling equipment are mechanically ready to harvest the crop with minimum bruising, there are several tips to preserve the quality of potatoes crop during harvest:
- Timely Vine Killing. Killing the vines when tubers are mature makes harvesting easier by reducing the total vine mass moving through the harvester. This allows an easier separation of tubers from vines.
- Timely Harvest. Potatoes intended for long term storage should not be harvested until the vines have been dead for at least 14 days to allow for full skin set to occur.
- Soil Moisture. Optimal harvest conditions are at 60-65% available soil moisture.
- Tuber Pulp Temperature. Optimal pulp temperatures for harvest are from 500F to 600F. Proper pulp temperature is critical; tubers are very sensitive to bruising when the pulp temperature is below 450F. If pulp temperatures are above 650F, tubers become very susceptible to soft rot and Pythium leak. Pulp temperatures above 70°F increase the risk of pink rot tremendously no matter how gently you handle the tubers if there is inoculum in the soil.
- Tuber Hydration. An intermediate level of tuber hydration results in the least bruising. Overhydrated tubers dug from wet soil are highly sensitive to shatter bruising especially when the pulp temperature is below 450F. In addition, tubers harvested from cold, wet soil are more difficult to cure and more prone to breakdown in storage. Slightly dehydrated tubers dug from dry soil are highly sensitive to blackspot bruising.
- Reducing Blackspot Bruising. Irrigate soil that is excessively dry before digging to prevent tuber dehydration and blackspot bruising.
- Bruise Detection Devices. Try to keep the volume of soil and tubers moving through the digger at capacity at all points of the machine. If bruising is noticeable, use a bruise detection device to determine where in the machinery the tubers are being bruised.
- Do not harvest potatoes from low, poorly drained areas of a field where water may have accumulated and/or dig tests have indicated the presence of tubers infected with late blight.
- Train all employees on how to reduce bruising. Harvester operators must be continually on the lookout for equipment problems that may be damaging tubers. Ideally, growers should implement a bruise management program that includes all aspects of potato production from planting through harvest.
- Harvest when day temperatures are not too warm to avoid tuber infections. Storage rots develop very rapidly at high temperatures and spread easily in storage. If potatoes are harvested at temperatures above 27o C and cool off slowly in storage, the likelihood of storage rots is increased. If warm weather is forecast, dig the crop early in the morning when it is not so warm.
The warm conditions has slowed the harvest of some processing fields, to prevent bringing warm tubers into storage. The seasonal accumulated precipitation has been 50-70% of normal in the potato growing areas (Fig1). The soils are generally on the dry side (Fig 2), but irrigated fields have sufficient moisture for a good harvest. READ MORE
Nov. 29, 2016, Canada – Canada's potato production was 105.2 million hundredweight (4.7 million tonnes) in 2016, up 0.5 per cent from 2015, according to the latest report from Statistics Canada.
Production in British Columbia increased 41.8 per cent to 315 hundredweight per acre. Ontario, which experienced extreme summer heat and drought, saw production and yield fall 17.2 per cent compared with a year earlier.
Harvested area edged down 0.2 per cent from 2015.
In 2016, Prince Edward Island represented 24.5 per cent of total potato production and Manitoba represented 21.3 per cent.
Some P.E.I. potato farmers have had to wait longer than usual to finish their harvest because of recent wet weather, according to the P.E.I. Potato Board. | READ MORE
Ambra variety potatoes harvested by C&V Farms in October. Photo courtesy of Eugenia Banks.
Oct. 27, 2016, Ontario – Each growing season is different, but the 2016 season was unlike any season seen before in Ontario. Planting started later than usual due to the cold weather. The early crop planted by the middle of April in southwestern Ontario took more than three weeks to emerge due to cool soil temperatures. Growers were caught off guard when snow fell by the middle of May. The season was off to a bumpy start.
There was only limited rain up to the end of May. Then the heat and drought started relentlessly – too early in the season.
Studies have shown that a healthy crop of potatoes needs an inch of rain a week. That adds up to about 16 inches of rain from May through August for the potato crop to show its full potential. Environment Canada data indicates that the water deficit in Norfolk, Simcoe and Dufferin counties was above 60 per cent. Norfolk County was the hardest hit by the heat and drought, with a total rainfall close to four inches near Delhi.
Where available, irrigation was the order of the day during the summer. However, growers could not keep up with irrigation due to the extremely high evapo-transpiration rate. Irrigation increased the cost of production dramatically. By July, there were reports of some irrigation ponds that were completely empty and not filling up. One producer said, “With the heat and drought we are experiencing, irrigation is simply keeping the crop alive. Rain water does way more for the crop than irrigation.”
There were many days in June, July and August when the temperatures were above 30 C. Such heat puts the potato plants in a dormant state, unable to photosynthesize efficiently, the activity that keeps plants functioning well.
Some rainfall by the middle of August did not help the early crop, which was too far gone to benefit from rain.
Ontario Potato Distributing in Alliston started packing early potatoes from Leamington on July 19. Quality was excellent. The harvest of the early crop continued in August but yields were down at least 50 per cent in non-irrigated fields. In irrigated fields, yield reduction was at least 35 per cent.
Dry weather brings good quality. Diseases such as late blight, pink rot and leak did not develop. These diseases, also known as storage rots, reduce quality and can cause significant storage losses.
Hot, dry weather also induces second growth. A few table varieties with short dormancy aged rapidly in the field and showed some sprouting before harvest.
Mark VanOostrum reports that the chip processing crop yielded as low as 60 per cent of normal yield. The best yields were reported from the Shelburne area in the late-planted crop and late-season varieties. Harvest was difficult, because it took more than five to six weeks to get good skin set after topkill or natural death. Because the fall was very warm, storages temperatures are just starting to drop below 13 C. Typically, the temperature would have been down to 9 C on many bins for a few weeks by this time of the year. Higher storage temperatures will age the crop (one that was already aged in the field due to the heat and drought).
The processing of the storage crop started earlier than anytime in recent history due to the shortage of field fry crop. Some heat necrosis was seen in Atlantics, but minimal in other varieties. So far, the quality of the storage crop has been very good. Some stem end sugar defect is present, but less than normal for this early in the storage season. One real concern is how the long-term effect of the heat and drought stress affect the chipping quality. Stem end sugar defect incidence and severity is highly correlated with extreme heat, and the question remains: will we be able to burn off all the stem end? Also, the heat and drought stress is correlated with chemical and physical aging. Will a variety that typically has a seven-month life span be shortened by weeks or months? Time will tell.
By Thanksgiving, nearly all the table and processing crop had been dug and stored with no risk of storage rots.
Ontario potato growers will remember 2016 as one of the hottest and driest year in Ontario. Our potato growers should be commended for their resilience and capacity to produce a high-quality crop in what was an extremely difficult growing season.
Oct. 6, 2016, Ontario – A quick survey indicated that about 80 per cent of the provincial potato crop has been harvested by Oct. 5, according to Eugenia Banks, Ontario potato specialist.
On the chipping front, Mark Van Oostrum from WD Potato expects that most processing growers will be done by Thanksgiving.
Growers in the Simcoe, Ont., area are close to completing the harvest. Joe Lach, who farms near Delhi, Ont., will finish this coming week, and told Banks his remaining potato crop is all sold.
About 60 per cent of the acreage near Shelburne, Ont., has been dug. This area plants a bit later than other areas due to cooler spring weather and lower soil temperature.
On Oct. 5, Banks harvested a variety trial in Honeywood, Ont. Standard processing varieties such as Lamoka (chipping) and Waneta (chipping and table) did very well. There was no second growth or tuber malformations. By contrast, many of the new varieties under evaluation showed the effects of a hot, dry summer: second growth, bottlenecks, cracks and knobs. 2016 was a great year to see how new varieties perform under heat and water stress.
Sept. 29, 2016 – Second growth is a physiological potato problem induced by soil temperatures of 24 C or above and water stress. These two factors interact to limit the tuber growth rate, causing second growth. Inadequate soil moisture alone does not result in the initiation of second growth.
Heat and drought prevailed during the 2016 Ontario growing season, which explains why second growth has been reported in some fields.
Potato varieties differ in their susceptibility to second growth. European varieties appear to be more susceptible because they were bred and evaluated in countries where the growing seasons are rarely hot.
There are three distinct types of second growth:
Tuber chaining: A series of small tubers are produced on a single stolon.
Heat sprouts: Sprouts develop from stolons or daughter tubers. The sprouts may emerge from the hills developing into leafy stems.
Secondary Tuber: Small tubers form on daughter tubers. The secondary tubers are formed on short sprouts or directly on the tuber surface. This disorder is usually associated with physiologically old potatoes. High temperatures and water stress during the growing season are major factors contributing to the physiological aging of potatoes.
Cultural practices that promote uniform growth of plants and tubers throughout the season help minimize second growth. Among them are:
● Do not plant physiologically old seed in cold, dry soil.
● Space seed pieces as uniformly as possible at planting.
● Apply an adequate amount of fertilizers.
● Maintain uniform soil moisture sufficient to meet crop needs (this was easier said than done this past season!).
Sept. 23, 2017, Prince Edward Island – Harvest is underway in Prince Edward Island. Greg Donald, general manager of the P.E.I. Potato Board, estimates less than five per cent of the Island's crop is out of the ground at this point, mostly right into production or onto the fresh market. | READ MORE
Nov. 20, 2015, Canada – Potato production in Canada increased 4.1 per cent from 2014 to an estimated 104.8 million hundredweight (4.8 million tonnes) in 2015, according to the latest report from Statistics Canada.
Manitoba accounted for 57.2 per cent of this increase while Quebec was responsible for 29.1 per cent. Production was 1.3 per cent above the average level seen from 2001 to 2015.
Harvested area edged up 0.4 per cent from 2014.
Prince Edward Island represented 23.7 per cent of total potato production in 2015 and Manitoba represented 20.6 per cent.
Nov. 16, 2015, Prince Edward Island – Potato harvest is nearly finished in Prince Edward Island, and the manager of the P.E.I. Potato Board expects yield will be down a bit across the Island this year due to dry conditions through much of the growing season. CBC News reports. | READ MORE
October 29, 2015, Charlottetown, PEI – As P.E.I.'s potato harvest winds up, there's a distinctly different look to many Island warehouses: they've installed shiny new metal detectors, at a cost of between $50,000 to half a million dollars each.
Last fall, steel needles and other sharp metal objects were detected in P.E.I. potatoes at processing plants and in bags sold throughout Atlantic Canada. A number of metal objects were found in potatoes again this spring. READ MORE
Best practices for potato storage begins with disease prevention in the field and good agronomics. Although practices and disease concerns may have changed over time, the basic principles of managing potato production and storage haven’t changed much.
“Whatever is happening in the field is going to have an impact on storage,” Eugenia Banks, potato specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) in Guelph, Ont., says. “If the crop is growing well, not stressed and harvested two weeks after killing the top growth, and the potatoes are mature with adequate skin set and no bruising, then everything should go really well. However, Mother Nature doesn’t always help, and wet conditions at harvest is bad for diseases such as late blight or pink rot and others. I think the expression ‘potato storage is not a hospital’ is great advice, as whatever goes into storage is not going to get better.”
Over the past several decades, potato production has seen a lot of changes. According to Lawrence Kawchuk, research scientist with Agriculture and Agri-Food Canada (AAFC) in Lethbridge, Alta., three big changes are pesticide resistance, the emergence of new diseases and the re-emergence of old diseases.
“Pesticide resistance remains an issue as pathogens such as Fusarium continue to develop resistance. There are also market sensitivities to pesticides and a growing interest in moving away from their use, and reducing economic and other trade costs,” he says. Also, one of the new devastating diseases of concern is zebra chip, “which has been found in Idaho and Washington, but so far monitoring programs have not yet identified the disease in Canada.”
Kawchuk says the re-emergence of late blight, a historic disease of potatoes, is due to a variety of changes, including new strains. “A lot of resources have been allocated to monitoring changes in the late blight population and helping growers respond to keep it at low levels and protect potatoes in storage,” he notes. “In the last couple of years, backyard garden tomatoes have been identified as the primary source of late blight in Canada and the U.S.”
Strategies to reduce the risk of late blight include encouraging gardeners to select resistant tomato varieties and quickly remove and dispose of any diseased plants. If the disease is not controlled, it will contaminate neighbouring fields downwind. Indeed, there is evidence of the pathogen moving 30 to 50 kilometres in the air in a single day, and perhaps more under very windy conditions.
According to Banks, an integrated pest management (IPM) program continues to be a best management practice for growers for disease prevention, including field monitoring, adequate soil moisture and fertilization, and timely application of crop protection products. “Rotation of chemical products is an important part of an IPM program, particularly to address resistance concerns, [as] Fusarium has developed different degrees of resistance to most of the chemicals currently registered for control,” she notes. “As well, storage diseases including Fusarium, late blight, soft rot, pythium leak and pink rot continue to be management issues for growers. However, there are various phosphorous acid products registered as a post harvest treatment to control late blight when potatoes go into storage. Several foliar applied fungicides for late blight and other diseases are available, and there is a new biopesticide registered, Serenade SOIL, for in-furrow application for suppression of pythium leak, pink rot, rhizoctonia, silver scurf and Fusarium dry rot.” Serenade SOIL applied as a post-harvest treatment may reduce silver scurf in storage.”
Potatoes are produced for various markets, and some potatoes are harvested during the summer and processed immediately into French fries or chips, or packaged and sent to markets and retail stores. Some potato production includes varieties that are grown later into the fall and stored for a longer duration in large temperature-controlled storage buildings.
“I’ve been working on potatoes for decades and continue to be amazed at the advancements in potato storage,” Kawchuk says. “Growers can now store high-quality potatoes for several months, and still have good quality products for the market 10 or 11 months later. Quality is everything to the market today, as the potato market is quite saturated.”
Advancements in handling and storage
Growers today have access to various technologies to protect healthy potatoes going into storage and over the long term. Advanced technologies for controlling ventilation, relative humidity, temperature and other factors are available. Many technologies can be managed remotely from computers and smart phones, helping growers easily monitor storage conditions.
“There is a wide range of advanced technologies and equipment available, but the number one priority of all new storage technologies and facilities today is to save energy,” Banks explains. “One of the new field technologies that is proving to be very useful is the Impact Recording Device (IRD), which helps detect where in the harvesting and handling process potatoes suffer bruising. The device is the shape of a potato and as it passes through the harvesting, conveyors, transportation and handling processes, it records where impacts and bruising are occurring.”
She adds eliminating bruising is key to reducing the incidence of serious diseases such as Fusarium dry rot and soft rot. Fusarium, which is a difficult pathogen to control, is always ready to penetrate potatoes if they have bruises or wounds, and then soft rot will follow, attacking potatoes infected with Fusarium. The device costs about $5000, but it pays off and helps growers optimize their system quickly to prevent bruising. The device is available through Techmark Inc. based in Michigan, which also carries a wide range of potato storage technology, equipment and devices.
Potato breeding and varietal development advancements continue to focus on bruising and disease resistance to improve potato quality and storage. The Potato Research Centre in Fredericton, N.B. holds the Canadian Potato Genetic Resources germplasm collection and leads some of the variety development in Canada.
“There are new varieties being released constantly with improved traits,” Banks says. “For example, Simplot in the U.S. recently received USDA approval for the release of Innate varieties, which are improved versions of existing potato varieties created through a proprietary biotechnology process called Innate.” Innate potatoes contain genes from wild and cultivated potatoes. According to Simplot, these potatoes pose no environmental risk, create no harm to other species, and grow just like conventional potatoes in extensive field tests. The first generation of Innate potatoes includes Russet Burbank, Ranger Russet and Atlantic. They are tolerant to black spot bruising and pressure bruising, and they produce less acrylamide after frying. Simplot expects to soon add resistance to late blight.
“Another similar technology, Cisgenesis, uses natural genes (cisgenes) from wild potatoes, and is being used to improve disease resistance in plant breeding,” Banks adds. “However, questions remain whether or not these potatoes are going to be accepted by growers and consumers. The technology is there to offer good improvements, but the consumer also has to be considered.”
Some of the new varieties have improved cold tolerance and can be kept in storage longer. This impacts sugar content and issues with French fry and chip quality, including discoloration when fried.
“Another emphasis is on the development of varieties resistant to common scab, one of the main production problems in Ontario and Quebec,” Banks says. “The use of resistant varieties is the only reliable control method. A new scab resistant variety, Whitney, was recently released, and hopefully we will have more resistant varieties in the years to come. However, the breeding process is not easy, and it usually takes plant breeders 10 to 12 years to develop, evaluate and release a new commercial potato variety.”
“This is a very exciting time for the potato industry,” Kawchuk adds. “If we can keep inputs on the lower side as we have traditionally, and with continued advancements in varieties, technology and storage enhancements, markets will continue to expand. There are huge opportunities opening up in Asian-Pacific markets, with over 50 per cent of Alberta potatoes, for example, currently being shipped offshore.”
Kawchuk says advanced plant breeding techniques using molecular approaches will become more commonplace in the next five to 10 years. “Science has been completely revolutionized with low-cost genome sequencing and the understanding of how genes function. This is a real game-changer and has the potential to eliminate the use of pesticides in the future. These new advancements will allow growers to produce healthier products on a consistent basis by eliminating disease, improving storage quality and increasing access to new markets in the future.”
Storage research is ongoing
Fifteen years ago, “The future of fighting disease in storage” was published in a special edition of Potatoes in Canada, a sister publication to Top Crop Manager magazine. The story highlighted several new research projects that were underway at the time, which could potentially help growers maintain crop health in the field and in storage.
Some of the research projects highlighted in that story, such as biological controls and new varietal development, are still underway today. And what was a concern 15 years ago, namely the risk of fungicide resistance, remains a management issue for growers today. Then, like now, growers are encouraged to rotate between products with different modes of action.
Other research 15 years ago focused on storage disease control alternatives, such as ozone generators, ultraviolet light and irradiation. “However, those alternatives such as ultraviolet light, irradiation, ozone or the use of volatile compounds, never resulted in commercial use,” Banks notes.
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