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Small potatoes require unique production

Small potato production is expanding in Saskatchewan to meet increased market demand for “creamer” potatoes with a target size of 20 mm to 40 mm in diameter. Specialty potato companies, such as The Little Potato Company of Edmonton,  have found new culinary markets for so-called “little” potatoes. Now growers in Saskatchewan are taking notice, particularly in the irrigated region of Outlook.

However, small potato production is markedly different from conventional potato production and has a unique set of requirements, including suitable varieties, special equipment and agronomic practices that differ from large potato production in several key ways.

According to Jazeem Wahab, horticultural crops agronomist at Agriculture and Agri-Food Canada’s (AAFC) Saskatoon Research Centre, small potatoes are emerging as a higher-value option for the producer and another culinary choice for the consumer. However, growing small potatoes presents challenges to growers. “We have to develop cost-effective agronomic production practices that can produce the size and grade of small potatoes the market demands,” Wahab says.

Since 2006, Wahab has headed up a long-term study analyzing the effects of seed tuber size, seed spacing and harvest timing on growth and yield of small potatoes in Saskatchewan. He says many factors influence production of high-quality small potatoes, including weather, irrigation, harvest timing and variety. “Not one factor operates independently – we have to take a holistic approach,” he says.

The project received support from Saskatchewan’s Agriculture Development Fund from 2007 to 2009, as well as some funding from The Little Potato Company. Wahab hopes to continue the study this year with AAFC funding.

According to Saskatchewan’s Ministry of Agriculture, the project was initially aimed at “finding the best small potato germplasm and developing cost-effective and cultivar-specific agronomic practices for producing small potatoes,” as well as determining the potential for producing small potatoes from commercial table potato cultivars.

Studies under the project’s umbrella included the screening of creamer clones developed by AAFC potato breeders and identifying commercial potato cultivars suited for small potato production.

The project aims to benefit Saskatchewan’s potato industry by bringing greater revenue to the province’s producers through the higher-value small potatoes, which also increase the accessibility of lucrative urban markets. Small potato production is also more cost-effective, as small potatoes are harvested earlier than conventional large potatoes, and thus require fewer inputs such as pesticides.

Wahab and his team of researchers analyzed the impact of seed tuber size, seed spacing, harvest and top kill timing under irrigated conditions on three proprietary small potato varieties – Baby Boomer, Piccolo and Blushing Belle – as well as a few commercial and table standard large potato varieties, including AC Peregrine and Norland.

Larger tuber seeds for bigger yields

In one study, six seed tuber sizes were used in the study’s treatments, ranging in size from as small as 20 mm to as large as 50 mm in diameter. “In general, we found the larger the seed tuber, the bigger the yields,” Wahab says. Larger seed tubers also tended to decrease tuber size.

Two seed spacings were studied: 15 cm and 20 cm, respectively, between seed piece plantings. In general terms, closer spacings resulted in higher marketable yields, although Wahab says more data is needed. “I’ll be working on consolidating data from the years of the study to come up with recommendations,” he says. “What I can say is that some years, closer spacing yielded significantly higher, and some years it did not. The year that it did not respond well, it was very hot – weather can have a significant impact.”

In another study focused on harvest timing, one top-kill stage was used in the first year, based on tuber development of the different cultivars. Three top-kill stages were used in the second year, at 10, 11 and 12 weeks after planting.

Wahab says harvest timing depends on variables such as weather, but harvesting after 10 weeks usually results in a reasonably good small potato yield. “A nine-week harvest results in very low yields, a 10-week harvest in fairly good yields. At 11 weeks you get some larger potatoes, depending on the variety,” he says.

The team also studied the effects of harvest timing on some standard commercial varieties, such as Norland and AC Peregrine red potato varieties. What they discovered was AC Peregrine could also be grown for the small potato market if harvested early. But even though such adaptability would seem to make varieties like AC Peregrine attractive for commercial growers hoping to break into the small potato market, Wahab says most growers cannot afford to grow potatoes for both markets, as small potato production requires specialized equipment.

Before small potato production can grow into a major player in Canada’s potato industry, more suitable varieties will be needed, Wahab says. “The traditional varieties that are grown on a commercial scale have been bred to grow large. The number one thing we need is the best varieties for this particular purpose.”

Wahab believes small potatoes have a bright future in Canada, even though small potato production is still considered “niche.”