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
Potato virus Y (PVY) affects both yield and the quality of the crop, making it one of the most dangerous diseases faced by commercial potato producers. Spread by aphids and through infected seed lots, PVY has been managed with varying levels of success by Canadian growers for many years, but the rise of more aggressive and faster-spreading strains has made it even more challenging to control.
Published in Diseases

Syngenta Canada Inc. has received registration for Revus fungicide as a potato seed treatment for the suppression of pink rot and control of seed‑borne late blight in potatoes.

Pink rot is a devastating, soil-borne disease caused by the pathogen Phytophthora erythroseptica that thrives in wet, poorly drained soils. Infection typically takes place pre-harvest, as the pathogen enters tubers through the stem end and lenticels.

Tubers infected with pink rot will often decay during harvest and handling, which allows the pathogen to spread quickly from infected tubers to healthy tubers while in storage.

“Every field has the potential for pink rot,” says Brady Code, eastern technical lead with Syngenta Canada. “It takes a very small number of infected tubers going over harvest equipment or getting by on the belt to put an entire season of work in jeopardy, and leave growers with far fewer healthy potatoes to ship.”

Revus contains the active ingredient mandipropamid (Group 40), and works by protecting the daughter tubers from becoming infected with pink rot. It also provides control of seed-borne late blight (Phytophthora infestans), according to a company press release. 

Revus is applied at 5.9-11.8 mL per cwt of seed (13-26 mL/100 kg of seed).

Following a seed treatment application of Revus fungicide, the first foliar fungicide application should be a product that does not contain a Group 40 active ingredient.

Maximum Residue Limits (MRLs) for mandipropamid have been established for markets including Canada, the United States, Japan, and South Korea, in support of the seed treatment use pattern.

Published in Seed Treatment
The International Plant Nutrition Institute (IPNI), J.R. Simplot Company, and Tennessee State University have collaborated on a new publication that provides readers with access to a unique collection of hundreds of high-resolution photographs that document a wide range of nutrient deficiency symptoms in potato plants. 
Published in Agronomy
EU-funded scientists have discovered genetic markers that could allow potatoes to be selected for their ability to be stored at low temperatures, keeping them fresh and avoiding the use of anti-sprouting chemicals.
Published in Research
Chemicals in the leaves of potato plants, produced naturally by the plant, may hold the key to a new way in controlling Colorado potato beetles. Agriculture and Agri-Food Canada (AAFC) research scientist, Helen Tai (pictured here) has turned to the leaves growing on wild potato relatives – leaves that Colorado potato beetles won’t eat – as a new approach to keep the pest away.
Published in News
After a final holding temperature is achieved in storage, it is important to ventilate properly in order to manage the byproducts of respiration, ensure a uniform temperature and an ideal environment for the duration of the storage period, which will maximize the value of the crop.
Published in Storage

Usually wet seasons favour crop development, but incidence of storage rots is a concern, especially if rainfall occurs late in the growing season, advises Eugenia Banks, Ontario potato specialist.

Published in Storage
Lso (zebra chip pathogen) has been detected in small numbers of potato psyllids in two sites in Alberta, but no zebra chip symptoms or pathogen has been found in any potato plant tissue yet.

During three years of sampling for potato psyllids (Bactericera cockerelli) across Canada, we found
small numbers in Alberta (2015-2017, increasing annually), Saskatchewan (first time in 2016), and
Manitoba (first adults, 2016). No potato psyllids have been found on sample cards from any sites
east of Manitoba.

In southern Alberta, the range of potato psyllids has expanded to sites throughout the potatogrowing area, where in 2017 they appeared on sampling cards of over 70 per cent of 45 sites regularly sampled (we thank the growers for co-operation and access to University of Lethbridge samplers at 45 sites, with a minimum of 4 sampling cards per field, and Crop Diversification Centre South for managing two additional sites and sending sample cards). For the full story, click here

Published in Crop Protection
Syngenta Canada Inc. has announced Orondis Ultra fungicide is now available in a premix formulation for added convenience.
Published in Diseases
For the first time, evidence of the zebra chip pathogen has been found in potato fields in southern Alberta.

An infected potato psyllid insect carries the Lso (Candidatus Liberibacter solanacearum) pathogen that can cause zebra chip disease in potato crops.

Zebra chip has affected potato crops in the U.S., Mexico and New Zealand and caused millions of dollars in losses. Potatoes with zebra chip develop unsightly dark lines when fried, making affected potatoes unsellable.

The first detection of Lso came from sampling cards collected at one site south of Highway 3, near Lethbridge, Alta. For the full story, click here
Published in Diseases

Researchers are hoping Canadian potato growers will soon be able to use an innovative approach to control wireworms. This method uses just a few grams of insecticide per hectare applied to cereal seeds that are planted along with untreated seed potatoes. It provides very good wireworm control for the whole growing season, with a lower environmental risk than currently available insecticide options.

Published in Crop Protection

Just because black cutworms don’t overwinter in Canada doesn’t mean they aren’t a threat to potato crops. The insects spend their winters in the southern United States but travel north on low-level jet streams and, once they cross the border into Canada, they look for a tasty food source. Black cutworm moths prefer some of the weeds that grow in and around fields and, while potatoes are not their favourite food, they will adapt and can wreak havoc on an unmonitored field.

A researcher at the University of Minnesota says the cutworms’ new interest in potatoes could be the result of a change in potential host plants. If the moth’s desired weed is being well controlled in a field, it will eat what is available where the wind sets it down.

“Black cutworm moths are active flyers,” explains Ian MacRae, the extension entomologist at the university’s Crookston research station. “These insects can travel hundreds of miles in a short period of time aided by an extremely efficient bug highway [a jet stream].”

MacRae says if the wind and temperature are conducive and Canadian potato producers are able to get their crop planted in good conditions, there is a chance the moths will arrive about the same time as the plants are emerging. The possibility exists that early arrival could spawn a second generation of the insects later in the season. He says, once landed, reproduction occurs when the moths lay eggs. The emerging larvae will feed on the foliage, but once at the fourth or fifth larval stage they will begin actively eating near the base of the host plant, cutting it off.

“The first you might notice a cutworm problem will be plants that are cut at the base or wilting,” MacRae explains. “At night, the worms burrow into the soil and if the tubers are close to the surface, they will burrow into the tuber. They can do more damage to tubers in dry conditions because cracks in the soil will give the cutworms access to what is underneath.”

Damage to potato crops early in the season can be a greater problem because the young plants will not recover from being chewed off. There is a possibility that the seed piece might send up another shoot, but the crop will be set back. MacRae suggests early scouting will help identify the problem and allow time for control. There are effective insecticides for control of black cutworm and there are sources of natural mortality, such as predators or parasitic wasps. Birds may be less effective because of the location of the worms and their habit of eating at night.

“If you find yourself at a threshold of about 30 per cent of your plants cut, you may want to apply an insecticide,” MacRae says. “If defoliation is this high, it may be that natural mortality sources are not functioning well.”

Ensure proper identification of the larvae as black cutworms so the correct product can be chosen for control. Combining regular field scouting with pheromone or light traps to catch the male moths is an effective way to identify the insects.

“When scouting, look for stalks at an odd angle or wilting,” MacRae suggests. “Look in the evening when the cutworms come out to feed, and look as much as a half metre away from the plant because they are good walkers. Black cutworms are aptly named because they are a dark caterpillar with a waxy appearance. They will often curl into a C if disturbed. They hang out during the day under clods of soil or in cracks.”

MacRae says climate change may be the reason black cutworms are being seen farther north. He doesn’t believe they will begin to overwinter in Ontario or the Prairies, but a warmer climate means they develop faster and may overwinter in more northern states, making the migration north earlier and causing greater problems.

“Black cutworms have certainly become a problem in Ontario in the last few years,” MacRae says. “They can be a significant pest issue.”

MacRae adds there are some cultural practices that may minimize the impact of black cutworms when they arrive. Planting late can put new, young plants directly on a collision course with the moths and their offspring, so plant early, if possible. He says controlling weeds will reduce the areas where the moths might lay eggs. Growers in the United States use pre-plant tillage to turn over the soil to destroy potential habitat.

To date, there is no accurate monitoring system in place for potato crops, according to MacRae, but the cutworms also like corn and the corn growers in some states, such as Iowa, have a black cutworm monitoring network. “The moths seem to appear in Ontario about three weeks after they are seen in the United States,” he says. Ontario growers could tap into the monitoring networks south of the border and use that information as an early warning system, he suggests.

Black cutworms could be considered a stealthy yield robber because by the time you begin to notice a problem, it could be a challenge to execute effective control. The best defence is early and frequent field scouting and adopting cultural practices that could minimize the attractiveness of the crop. MacRae believes Canadian potato growers will see black cutworm more often in the coming years, so preparation for and understanding of the pest is a wise approach. 

 

Published in Crop Protection
There’s no current technology to detect acrylamide precursors quickly and without destroying the spud, but a new technique developed by Lien Smeesters from the University of Brussels might help weed out potentially toxic potatoes before they even go to market. In Smeesters’ design, a laser uses infrared light to detect acrylamide, which scatters the light in a unique pattern, instructing the machine to knock the toxic potato out of circulation. | READ MORE

Published in Diseases

Nov. 28, 2016, Prince Edward Island – Health Canada's proposal to phase out a pesticide over three years will have a significant impact on Island farmers looking to control the Colorado potato beetle, says the P.E.I. Potato Board. | READ MORE

Published in Pest Control

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!).

 

 

Published in Crop Protection

Sept. 29, 2016, Ontario – The potato IPM training module, an educational tool with information for the common insect pests, diseases, viruses and disorders of potatoes in Ontario, is now available online. | READ MORE

Published in Diseases

August 26, 2016 -  According to Dr. Vikram Bisht, of Manitoba Agriculture, aphid counts in weeks 8 in all but one sample were low. There was one Green Peach Aphid (GPA) trapped in southern seed growing area, but not anywhere else. Potato aphids were trapped in southern and central areas. One field showed a sudden influx of aphids, probably from nearby crops being harvested or desiccated. There were low counts of Aster leafhoppers were trapped in all seed areas.

Some of the seed fields are being desiccated, so Bisht reports there will be one more week of aphid monitoring. The results from suction and pan traps in seed fields for the 6th and 7th week of sampling can be seen in a chart (please click here):

In 2016 season, as in 2015, as part of the Canadian Hort Council, Growing Forward 2, Canadian Potato Psyllid and Zebra Chip Monitoring Network project, yellow sticky cards are being sent to Dan Johnson, Univ of Lethbridge. One potato psyllid adult was confirmed today (August 22) in a card (in field July 12-18) from Northfolk-Treherne Rural Municipality. This is the first find for 2016 in a province outside Alberta.

North Dakota has also reported occurrence of potato psyllids in their fields. "We have confirmed that psyllids are present potato fields in western ND. Psyllids are the vector of zebra chip disease and can do damage without the Lso bacterium (Gary Secor, NDSU)".

Published in Diseases

August 15, 2016 - New late blight finds were reported on potato from Carman, Winkler areas and on tomato crops east of East of Portage and east of Highway #75, according to Vikram Bisht. Frequent fungicide applications are being applied to control the disease; and in one case the tomato plants have been pulled out and destroyed.

Samples have been collected for strain identification. All of the previous samples, tested by Lethbridge Research and Development Center were determined to be US-23 strain.

"There is increasing metalaxyl insensitivity in the Pi from these samples and the use of Ridomil would probably have only marginal benefit," says Bisht.

It is important, he continues, to scout for late blight, especially in low lying, irrigation pivot center, wheel tracks of irrigation systems (guns/pivots), tree-line protected areas and under hydro-power lines (areas where applicators may have difficulty covering).

It is also critical at this time to monitor potato and tomato plants in home gardens. The DSVs (late blight risk values) accumulated over 7-days at various weather stations suggest mostly moderate risk in most of the province. There is forecast for rain and risk of thunderstorms today afternoon in many potato growing areas. Full fungicide coverage of foliage in high risk areas should be maintained.

Due to continued high moisture levels in many fields, it may be helpful to harvest the low lying areas last, so it will be easier to manage the storages.

Also, a post-harvest treatment with phosphorus acid / phosphite fungicide could be considered for such fields, adds Bisht.

Published in Diseases

Heat edema has been observed in Ontario, and should disappear when humidex values drop below 30 C. Photo courtesy of Eugenia Banks.

 

July 27, 2016, Ontario – Two potato problems have developed due to high temperatures, writes Eugenia Banks in her latest Ontario potato update.

Fusarium wilt
The long and relentless heat wave that is affecting Ontario has provided favorable conditions for diseases and physiological problems that we do not often see. One of them is Fusarium wilt caused by Fusarium oxysporum, a relatively common soil fungus that thrives when soil temperatures are around 29 C. 

A grower found patches of Fusarium wilt this year in a field of Andovers. Also wilted plants here and there were noticeable in the field. The base of the stems emerging from the seed was woody. At ground level the stems were dark brown, rotten or hollowed but did not have a strong fishy smell. The upper part of the stems was still green but wilted. Most of the plants pulled had rotten seed, but with no fishy smell.

Gary Secor from North Dakota State University helped with the identification of this problem. He isolated Fusarium oxysporum from the diseased stems. There was no sign of blackleg, dickeya or verticillium. 

How to control this disease? 
Fusarium oxysporum is more prevalent in very hot summers, just like our 2016 growing season. There is nothing that can be done about the weather, but: 

● Avoid ammonium nitrogen as a source of N 

● Keep potassium levels adequate 

● Acid soils favour Fusarium wilt. Liming soils help, but may increase the risk of common scab. 

Heat edema
This problem has been observed in two fields of the variety Canela Russet, growing in two different production areas. Small bumps form on the leaves that, with time, rupture leaving round, brown necrotic spots. The centres of the spots often drop out leaving holes in the leaves. Holes in leaves usually means insect feeding, but there were no insects in the fields. Ian MacRae, an entomologist at the University of Minnesota, did not think that the holes looked like insect feeding. Jeff Miller from Miller Research in Idaho suggested heat edema, a physiological disorder. Edema is related to water retention (see page 122 in the Potato Field Guide), but heat edema is different. The cells expand trying to diffuse the heat and eventually rupture. Because it is a physiological problem, heat edema should disappear when humidex values (temperature plus humidity) drop below 30 C. Yesterday, I checked one of the fields and noticed that, because of the hot weather, necrotic spots were developing on new leaves. 

Prolonged heat waves bring all sorts of different problems to potato plants. Working with potatoes is a never-ending learning experience! 

 

Published in Diseases
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