Potato is the most important non-grain crop in the world. So, understanding the potential impacts of climate change on potato production is critical, especially for producers.
Throughout its long history, Earth has warmed and cooled time and again. Climate has changed when the planet received more or less sunlight due to subtle shifts in its orbit, as the atmosphere or surface changed, or when the Sun’s energy varied. But in the past century, experts agree that humans have also played a part in influencing the Earth’s climate.
Whether or not you believe in climate change doesn’t deter from the fact the weather is changing. It’s readily noticeable in warmer and longer seasons, and especially in the number and severity of storm activities.
So, with these changes, what are the biggest challenges we’re likely to see that will affect crop management and production of potatoes? And what can growers do to manage those challenges, starting now?
For this edition of Roundtable, Spud Smart gathered some expert opinions on climate change, and how potato growers can adapt to weather changes now, and into the future.
Our three experts are:
- David Phillips, senior climatologist, Environment Canada, Ottawa, Ont.
- Tracy Shinners-Carnelley, vice president research and quality, Peak of the Market, Winnipeg, Man.
- Michele Konschuh, potato research scientist, Alberta Agriculture and Forestry, Brooks, Alta.
“What we’ve seen certainly in the last half century and with evidence from around the world is that we’re into a pattern of warmer conditions,” says Phillips. “It doesn’t mean every day is going to be warmer, or every season, or every year or even every decade. But clearly when you stick a thermometer in the planet, and into Canada, it is showing global fever – we are seeing warmer temperatures. Nobody can deny that – even the people who don’t believe in climate change have to accept the fact we’re living through warmer times.”
We Can’t Control the Temperature
Temperatures above 30C have a range of negative effects on potatoes including slowing tuber growth and initiation, less partitioning of starch to the tubers, physiological damage to tubers (e.g. brown spots) and shortened/non-existent tuber dormancy, making tubers sprout too early.
“The problem of course is with warming, if that happens,” says Konschuh. “Potatoes are temperate crops, they don’t really like hot weather. Potatoes really prefer to be under 25C. Between 25C and 30C, they can still function, but they don’t like it. And after 30C they shut down – they close their stomates because they’re at risk of losing too much moisture for what they get in for CO2, and they can actually wilt in a moist field on a hot day because they just basically won’t open the stomates.
“We’re usually lucky in Alberta that we have cool mornings and cool nights,” she adds. “So even if we have really hot daytime temperatures, as long as we have those cool shoulder periods when there’s still daylight available, the plant can still photosynthesize. But if it’s over 30C all day long or all of the hours of the day that it’s light out, potatoes won’t thrive at all.”
The northern climate, such as what we have in most of Canada, is well suited for future potato production because the cooler temperatures, combined with the long days, provide a good environment for increasing yields. As long as the optimum temperature is between 16C and 19C, with temperatures not falling below minus 2C in the growing season, then production will be possible in these climates as long as the water requirements of 20 to 24 inches during the growing season are fulfilled.
“We have a lot of country further north that may be ideally suited to growing potatoes in the future,” says Konschuh. “The challenge there is moisture in the form of irrigation. While moving potato production north is realistic in some ways, we don’t have irrigation infrastructure beyond our current processing production area.”
There’s also a lot of talk about the problem of high carbon dioxide (CO2) because of the greenhouse effect. CO2 itself is not a huge threat to the cropping industry. Indeed, potato plants and potato crop yields are predicted to benefit from increased carbon dioxide concentrations in the atmosphere. The major benefit of increased CO2 for potatoes is an increase in their photosynthetic rates which can increase their growth rates.
“The reality is, plants like higher CO2,” says Konschuh. “In fact, in greenhouses they enrich it deliberately, and if you have higher CO2, you don’t have to have the stomates open as long for photosynthesis to occur. An enriched CO2 can actually improve plant productivity and therefore, for potatoes, it would be able to shuttle photosynthate to the tubers and potentially bulk up faster.
But We Can Control Other Factors
Methods to adapt potatoes to climate change include shifting production areas, improving water use and breeding new tolerant potato varieties, as well as other practices.
According to Shinners-Carnelley, one of the places to start is potato storage. She says she has noticed warmer seasonal weather, especially in the fall in Manitoba.
“When we talk about potato storages, potato storage is the second season of potato production,” she notes. “When you’re in the field you want to meet your yield goals. When you move your crop out of the field and put it into storage, you want to maintain your yield because it can very quickly be lost because of poor storage. In that sense, there’s a lot of investment in facilities and the equipment within storages to manage.”
Not every storage is equipped with refrigeration. But storage bins intended for long-term storage do have refrigeration. With warmer fall temperatures in some parts of the country already occurring, Shinners-Carnelley says refrigeration is a must.
“One of the things that I’m suggesting to growers is they start thinking about how they adapt to these warmer harvest periods,” she advises. “So as growers are looking at their storage facilities, if they have capacity with refrigeration, be mindful to think, ‘I maybe have to turn my refrigeration on in the fall.’ Maybe it’s something they’ve never done before so it’s not something they think about. But if they’ve got that capacity, there could be a benefit there. Further to that, as growers are looking for long-term investment in their farm in terms of replacing storages or building new storages, maybe this is something for them to think about in terms of how do we mitigate that risk? Well, maybe it’s ensuring that we’ve got storage capacity that can be able to manage these warm harvest temperatures and be able to get that cool air into those potatoes early and set the foundation for a good storage crop.”
Other fall considerations include fall bedding. This management strategy is something that is widely done in Alberta, but not so much in other areas of Canada. Fall bedding allows for soil preparation work to be done when growers irrigation, broadcast fertilizer as needed, plow and then form beds into which they plant potatoes the following spring.
In addition, falling bedding can reduce the risk of soil erosion in the winter months, which is helpful when there is little to no snow cover over winter, and it also allows warming of the hills a little earlier in spring, giving growers a bit of a jumpstart on the crop.
“Growers can try to stretch their planting season by having those hills dry out and warm up a little faster in spring so they can get in the ground sooner,” says Konschuh. “This certainly helps if your growing season is a little shorter on the tail end in the fall, such as if a frost comes earlier. Growers can really stretch out the growing season by getting those plants in early into fall bedded areas.”
Konschuh also says growers can alter their planting depth and hill size – things to adjust to insulate the crop.
“Essentially, it’s a big insulation layer – which can work for and against you. If you put a great big cold hill on top of potato in the spring, you’re going to delay emergence. If you have a deep hill or a wide hill, you actually buffer some of the external temperature effects. And once that canopy closes in, you have a little bit more modified climate within the crop. So, I think hill size and structure can help mitigate some of the effects of heat.”
Konschuh says she and her colleagues have also done some work with bed planting. That’s where instead of having two rows or four rows in a 12-foot span, you would have six rows in that span and you would plant where the furrow used to be. The area would be filled in with soil and there would be stagger-planted potatoes there.
“It wasn’t widely adopted because it involves a lot of moving of soil and it would mean some equipment changes,” notes Konschuh. “It’s a production system change, not just one difference in planting. But bed planting could potentially mitigate some of those temperature-dependent changes as well because you’re insulating the bed.”
Pest and Disease Monitoring
Changing climate will certainly have effects on pests and diseases of potato. This is already apparent in some pest issues, including Colorado potato beetle (CPB) and, more recently, potato psyllid. With the former, warming temperatures mean the beetles will be able to overwinter much more successfully than they do even now.
“As well, if early springs become the norm, these beetles will emerge earlier, and that will extend their lifecycle,” says Shinners-Carnelley. “It’s extending that period of time that growers have to worry about the economic damage they (CPB) can create.”
Meanwhile, during the past three years of sampling for potato psyllids across Canada, researchers have found small numbers in Alberta, Saskatchewan and Manitoba.
While not damaging on their own, psyllids can carry the zebra chip pathogen, which causes dark stripes in potato tubers and makes them unsellable and unsuitable for processing and consumption. In 2017, the zebra chip pathogen was detected in small numbers of potato psyllids in two sites in Alberta, but no zebra chip symptoms or pathogen was found in any potato plant tissue.
“If our climate changes, we may see larger populations of some of those disease organisms that vector viruses or bacteria. But sometimes it’s an indirect impact,” says Konschuh. “For psyllid, they’re more concerned about weeds that it can overwinter on. So, if we have a climate change that affects our weed population, then we might see more pests.
“The potato tuber moth hasn’t made it here yet that we know of, and we are watching that with interest in the states, because it could potentially get this far north,” she adds. “Typically, winter takes care of a lot of the pests and so unless they’re overwintering in a storage, we’ve been quite lucky. We’re going to have to be scouting and watching a little bit more for pests and diseases.”
Late blight is one of those diseases that is high on the radar of potato researchers and agronomists.
“If we have a hot, dry year, we’re less at risk than if we have a moist, hot year,” says Konschuh. “If we’re cold, we’re more at risk for other types of diseases that affect the plants when they don’t grow fast enough, for instance, Rhizoctonia or botrytis or other opportunistic diseases that will affect the plant with a change in the climate.”
Many regions in the country have late blight forecasting programs to help growers better understand what their late blight risk is. There has been a lot of research work done to show which late blight strains thrive in which relative humidity and different temperature conditions.
“We put that information into a model, measure the weather data and out comes the disease risk,” says Shinners-Carnelley. “What we’re seeing more recently is late blight activity in the field even under conditions where it’s drier and where the temperature is warmer than what we thought late blight liked. Because of that, we’re seeing these pathogens still doing quite well in environments once thought would not be conducive to their development and spread.”
Another observation by the industry is seeing newer strains of late blight that have been around for perhaps five or six years that do very well in 30C weather.
“That was not the case in these older strains of late blight,” notes Shinners-Carnelley. “As we see our climate changing in whatever ways, the extremes of temperatures or warmer seasons, these pathogens and pests do a great job in adapting to that as well.
“That change is happening so it’s challenging our knowledge of what we thought we knew about them. And of course, making sure that we’re staying up on that information to be effective in managing them going forward.”
Shinners-Carnelley says the industry is working together with Rick Peters, research scientist with Agriculture and Agri-Food Canada in P.E.I., to support his research that is looking at developing data to help better understand what the environmental parameters are that these new strains of late blight do well in.
“He’s got some experiments under way right now,” she notes. “The ultimate goal of that is to be able to take the data he’s generating and update the late blight forecasting models. This will allow growers to take that information and provide them with a more accurate disease risk so they can respond.”
Finally, plant breeding is ongoing in the potato industry, and as the climate continues to change, breeders will be looking at new and improved varieties to mitigate growing and storage challenges.
“We have varieties that are on the market now that are a little bit environmentally susceptible,” says Konschuh. For instance, Russet Burbank is susceptible to inconsistent watering or too much heat, developing odd-shaped tubers or sugar ends.
“One of the things we’re trying to do when we do breeding program work is we bring other varieties in and we compare them to those standards and we see what does better,” she says. “We’re looking for things that don’t have heat necrosis, and things that aren’t as sensitive to the water disruptions, and things that aren’t going to change their physiology with a little bit of a temperature change.
“We’re looking for things that are a little bit more forgiving to grow, and still have good yield and good quality attributes. We’re also looking at water use efficiency and nutrient use efficiency.”
All three experts agree that growers should not relax when it comes to crop scouting and observation, to look for problems such as diseases and pests, and to gauge temperature fluctuations.
“Don’t count on weather observations from your nearby airport only,” says Phillips. “I can’t imagine a farmer today who doesn’t have his own set of instrumentation in his fields, in his plots, looking at the microclimates, looking at the state of the crop, what is the drought like, what is the flooding like, how much more rain do you need.
“If we can improve on the understanding, the knowledge by improving the data… the more data we have, the better strategies and tactics that we can incorporate by having real time monitoring of conditions. Not waiting for the end of the month to get the numbers to come in, but to get a sense of where you are right now so that you can get ahead of the issue.”
Growers today are also using more satellite imagery, more drones and even radar to be able to take that basic data and turn it into information for decision making. For instance, variable rate irrigation (VRI) is one tool.
“Some growers are using VRI to help them apply water where the plants need it most, and not watering low spots or wet spots,” says Konschuh.
At the end of the day, potato growers can easily adapt to a changing climate, as they have been doing for many years already. The secret is to stay on top of new and improved agronomic practices, scouting and storage technologies, and new potato varieties adapted for whatever part of the country you are in.
“The potato industry is a very dynamic one, it’s an intense industry with the type of crop that’s grown,” says Shinners-Carnelley. “Growers will adapt, that’s just what they’ve always done. There’s always been challenges they’ve had to adapt to.”
Phillips agrees. “Growers are optimistic, they will try things and experiment with things; they’re not always standing still. I think that’s good. I feel those people who are willing to change will come out tops in terms of winners with regards to the kinds of changes we’ve seen in climate. And we haven’t seen anything yet. We have seen some changes that are miniscule compared to the kinds of changes that we’re going to see in the decades or in this particular century.”