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.
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. 21, 2016, Canada – As potato harvest wraps up, the United Potato Growers of Canada reports conditions were generally favourable for growers across the country.
Prince Edward Island
Approximately 35 per cent of P.E.I.'s potato crop had been harvested by Thanksgiving. Beautiful weather has made for excellent harvest conditions. Overall quality going into storage to date has been good with the exception of some isolated issues such as scab. Size profile is a bit lower on some of the first crop dug but current projections are for at least an average yield. Demand has been very good and as a result, fresh shipments are ahead of last year at this time. P.E.I. has begun shipping into some markets at an earlier time frame than normal. Prices are much better that this time last year.
Excellent harvesting conditions have put the harvest percentage between 75 and 80 per cent as Oct. 7. Yields have been good with many fields in the northern region running around 375 cwt./acre and 325 to 350 cwt./acre in the southern part of the province. Fresh sheds are running product out of field to help several growers finish up. Growers and sheds seem particularly happy with the yield and quality of the Innovator variety this year, which did not seem to be as susceptible to heat and dry conditions experienced.
Excellent weather had brought the harvest to between 75 and 80 per cent completion as of Oct. 7. Many growers have only a week left, although the Lac St. Jean area will probably need two weeks. Yields are status quo, but certainly down from last year’s record setter. Quality is very good, with perhaps a smaller size profile in some areas. Movement has been very good to date. Pricing is stable and packers have agreed to leave it at current price points for now.
Ontario’s harvest was 85 per cent complete on Oct. 7. The Shelburne area, which is usually the last planted region due to a later spring with cooler soil temperatures, is about 60 per cent harvested. Growers in the province have experienced a 50 per cent yield reduction on dry land crops and a 20 per cent reduction on irrigated fields. Dry weather however does bring good storage conditions with no storage rot, so the quality of both fresh and processing spuds, is excellent. Trials this year showed some of the standard varieties performed better in the heat and drought than some of the newer ones, which exhibited secondary growth, knobs and growth cracks. Shippers also feel, chef size and larger size sku’s should bring more of a premium this year. The Ontario fresh market has been strong without the traditional downward pressure on price experienced this time of year. Virtually all of the chip harvest was in the bin by Thanksgiving.
Manitoba’s harvest was 95 per cent complete on Oct. 7. Harvest conditions were very wet after receiving three inches of rain. Quality going into storage is high with minimal rot. Gravity is high in the processing spuds with a large size profile. Yields have been remarkable, with many processing growers having a surplus over their contracts. Some fields will be disced under, due to lack of storage. Yield records in the province will probably be set this year, despite the drowned out acreage south and east of Winkler. Those growers in the path of that severe weather pattern will have large losses and crop insurance claims this year. Processing of the new crop in the months of September/October is down from 1.7 million hundredweight in 2015 to 1.2 million hundred weight in 2016. Very little open purchasing has been done yet. Fresh pricing continues to be strong with the market driven by the extreme weather and excess moisture in the Red River Valley of North Dakota.
Most of the potato crop had been harvested by Oct. 7. Some areas had seen 10 centimetres of snow in early October, with wind chills of -7 C.
For the most part, harvest conditions were excellent, and a few rain days did not cause any concern. The Central Alberta seed area did have some wet rainy days, which caused harvest to drag on, but it is now complete in that region. Seed quality is excellent – the best in years. Process quality is extremely good. There are some pink rot and soft rot issues that are being dealt with. In terms of yield, seed yield is excellent, early process yields are excellent, storage yields are just average due to a shortage of heat units at critical times in the growing season.
For the most part, B.C.’s crop was harvested by Oct. 7. There are some growers with full storages who will need to market out of field in order to wrap up. Yields and quality have been excellent. British Columbia was able to begin marketing earlier this year, which should be a big help in moving their crop through distribution channels.
Observations on the European crop
The North-western European Potato Growers (NEPG) expect production in their five countries (Netherlands, Belgium, France, Great Britain, and Germany) to be down in 2016 by 1.6 per cent compared to 2015, and 2.2 per cent compared to their five-year average. This is due to weather-related issues, even though their planted acreage increased by 4.8 per cent this year. This is a preliminary estimate, as harvest is not yet complete, but this does represent a reduction of 1,000,000 tons. Of particular interest is Belgium, with projected reductions of 12.4 per cent below 2015, and 17.8 per cent below their five-year average.
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. 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
Dec. 17, 2014, Ottawa – Statistics Canada estimates total potato production in Canada topped 102.0 million hundredweight (4.6 million tonnes) in 2014. This represents a 0.7 per cent decrease from 2013.
Potato production for 2013 is estimated at 102,704,020 hundredweight (4,658,576 tonnes), up 2.6 per cent from 2012, according to Statistics Canada.
Potato yield was 292 hundredweight per acre (32.7 tonnes per hectare), up 6.8 per cent from 2012. Harvested area was down four per cent to 351,800 acres (142,369 hectares) from 2012.
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