Ideal growing conditions, optimum fertility, pest and disease control – all these things are crucial to ensure a high-yielding, healthy crop. But before the seed goes in the ground, it’s crucial growers ensure the seed they’re planting is as healthy as possible.
For this edition of Roundtable, Spud Smart gathered some expert opinions on why it’s important potato growers plant the best seed they can get their hands on.
Our five experts are:
- AJ Bussan, senior production agronomist, Wysocki Produce Farm, Wisconsin.
- Michel Camps, commercial potato grower, CP Farms Ltd., Barnwell, Alta.
- Steven Johnson, crops specialist and extension professor at the University of Maine.
- Russell Jonk, co-owner and operator of seed potato producer Swansfleet Alliance, Swan Lake, Man.
- Shaun Pelkey, manager of agromony at McCain Foods’ Valley Farms, Grand Falls, N.B.
“Seed is the cornerstone of potato production,” notes Steven Johnson. “The same production costs are put into a crop from poor seed as in a crop from good seed, but the yields can be drastically different.”
Shaun Pelkey agrees, adding that healthy seed ensures plant stand, plant health and yield potential is maximized. “No management practices can compensate for planting seed that is high on virus, bacterial and fungal diseases.”
According to AJ Bussan, healthy seed ensures lower seed piece decay, and more uniform dormancy break, emergence and stands. “As well, healthy seed means rapid growth and good tuber sets, more uniform tuber size profiles and higher overall yields.”
But how is high-quality, healthy seed determined? The Canadian Food Inspection Agency (CFIA) regulates and inspects all commercial seed sold in Canada, but that is only part of determining seed quality. For instance, virus and other disease testing are important factors to consider.
“Talking with your seed grower and asking them about practices they use, and having a look at their facilities and equipment, will tell you a lot about how the seed was produced,” notes Russell Jonk.
Michel Camps does just that. The commercial potato grower in southern Alberta has developed good relationships with his seed growers. “I usually make a point to go and visit my seed growers in the growing season, and then again in November, when we will look at the crop in storage,” he says. “That gives me a good idea about what size profile we’re dealing with. Also, it’s a good time to check the seed to ensure there aren’t any disease issues.”
Seed potatoes are inspected the year before planting by government inspectors and determined to have at least a minimum level of quality. They have to meet certification standards or they won’t be certified for planting the next year. There is also post-harvest testing in addition to the growing crop inspection.
“In New Brunswick, seed health is determined through two visual seed inspections by government-regulated seed inspectors during the growing season,” explains Pelkey. “Each seed lot must meet the certification standards set for each field generation. New Brunswick also implemented a virus cap for seed, set at four per cent. All seed lots must be PHT [post-harvest tested] at an accredited lab. No seed can be planted if the PHT is higher than four per cent.”
It’s apparent early on that having a good relationship with your seed grower is imperative to ensuring you get only healthy seed. Not only does a seed grower want you as a customer from year to year, his or her reputation is on the line.
“If a seed grower and customer work together, they can better predict your needs and keep you informed of any changes in variety, quantity or quality,” says Jonk, citing the seed grower perspective. “You need to trust your seed grower and trust they are going to be there for your future needs. Have a good relationship means working together for the long-term sustainability of both farms involved.”
As a potato producer, Camps agrees. In the 15 years he and his family have been producing commercial potato crops, they have only had to reject a seed potato lot one time.
“Each year, I make a point of going to pick up that first load myself, so as to confirm that what I saw in the field the previous summer and what I saw in the winter in the storage is actually what I get on my truck,” he says. “But one year, with a baby on the way, I couldn’t pick up that first load. We ended up getting three loads delivered, and they all had severe Fusarium. It was far below not only my standards, but for sure the CFIA standards.”
Pelkey’s take, from the industry side, is similar. “Seed purchasers need to have complete confidence that their seed is being produced from growers who have proven track records of producing high quality seed potatoes using proper management practices,” he notes. “Buyers need to be able to visit their seed grower during the growing season, at harvest and also during storage to ensure there will be no unexpected surprises once seed has been delivered.”
Indeed, if there are issues at seed delivery, it is often too late. The relationship between the seed grower and buyer needs to be open with both parties interacting frequently.
Bussan’s advice is to develop long-term relationships and understand what the seed grower’s goals are in raising their seed crop. “Visit the seed farm during the summer if you can. Request and read all of the certification reports for that crop. If you aren’t finding the seed that is working for you, investigate other sources and seed growers. The seed grower that works for you is out there, maybe in your own backyard.”
Speaking of storage, do adverse storage conditions affect seed stock? You bet, says Johnson.
“Adverse storage conditions age seed. Fluctuating temperatures, too high carbon dioxide levels and improper air flow all stress seed, thereby aging it.”
Very dry storage or heavily bruised seed can age a seed lot, causing higher stem and tuber counts. “It also may cause poor stands for a number of reasons,” says Bussan. “The same can be said for heavily sprouted seed.”
Pelkey notes that seed stock is stored cooler than a processing crop. “Seed is often stored long term, up to eight months, so storage has to be designed to minimize tuber breakdown and tuber sprouting with proper temperature and ventilation,” he says. “Storage temperature in particular is critical as it affects water loss, respiration and sprouting.”
Adds Jonk: “Just as with a commercial crop, proper ventilation, temperature control and humidity are crucial.”
If you use poor quality seed, what can you expect from your crop? According to Johnson, if you use poor quality seed, “your bar is already lowered. Poor, erratic emergence and seed-piece decay are some of the symptoms of poor quality seed. Here in Maine, some seed lots with Dickeya were a total loss and were plowed in.”
Planting poor quality seed can limit plant emergence, which in turn affects plant stands and overall yield potential. “Growers need plants to maintain desired stem numbers,” says Pelkey. “Poor stands will cause less competition between plants, which will affect desired tuber size at harvest. Seed breakdown could also happen, and if virus levels are high, that will also limit yield potential.”
The physiological condition of seed plays a part as well. Johnson states there is a huge difference in a crop produced from physiologically young versus physiologically old seed.
“Seed age can have a big impact on the performance of a seed lot, and this relationship is pretty well understood,” says Jonk. “The problem is predicting and accurately measuring seed physiological age in a particular lot.”
Physiological condition also determines if your seed is dormant or not, notes Bussan. “Emergence and stands can be affected positively or adversely. Stem numbers and tuber sets can vary.”
There are many factors in play when it comes to physiological condition, with storage management being one of the most important. Different regions and growing season lengths require different seed vigour, so there is not a single recipe that will work everywhere.
“Seed that was handled rough and stored in a warmer environment will be physiologically older than seed that was harvested mature, with limited bruising and skinning, and stored cooler,” says Pelkey. “Growers are encouraged to collect seed from their seed supplier in March, and perform a ‘grow out’ test to see how the seed sprouts. This will help growers decide how they handle and store the seed when it is received. Processing growers would prefer ‘young’ seed so it performs well and has lots of vigour towards the end of the growing season.”
Ensuring healthy seed stays healthy includes proper handling. According to Pelkey, keeping harvesters and unloading lines full and minimizing transfers or drops to less than six inches is important.
“Any damage that occurs during harvest or handling, such as bruising, mechanical damage or skinning, will affect how the seed is able to be stored, thus affecting the performance of the crop the following season,” he says. “Also, disinfecting between varieties and seed lots, and keeping the seed cutting equipment sharp will also help ensure disease spread is minimized.”
Jonk notes that bruises and cracks are entry points for disease. “If you are cutting the seed, warm it slightly beforehand to reduce damage to the seed during the process. Pile cut seed five to six feet high, with lots of ventilation to ensure suberization. When it comes time to plant, try to match the seed temperature to the ground temperature or as close as practically possible.”
Camps handles his seed potatoes with extra care. Once they’re picked up from the seed grower, usually six weeks before planting, they’re preconditioned in one of their own clean, disinfected storages.
“We try to maintain the seed grower storage temperature. So let’s say the seed comes in at 40 F – we try to maintain that seed at 40 F until we have all our seed in storage,” he says. “That might take a week to 10 days to bring all our seed in. So we try to maintain that storage temperature throughout that time. Then, we start to slowly warm up the temperature to about 55 F, which is the temperature we want it at for cutting.”
Camps adds that he plants his seed immediately after cutting to eliminate another handling and potential disease entering because of that handling.
Johnson says cut seed should be stored at 50 to 60 degrees F for two weeks, at 80 to 90 per cent relative humidity. Cut seed should not have free water on it, and it should have air movement in the range of 10 to 30 cubic feet per minute per ton.
So how do growers find that perfect seed stock? Pelkey says growers need to be proactive. “Asking questions to your seed supplier is crucial. Ask questions, such as, what class seed will I be receiving? What were the PHT virus levels? Can we see a copy of the field inspection reports from CFIA? How was the seed stored?
“Also ask the seed grower if he is able to size the seed. And if it is a new seed source, what were their management practices during the growing season,” adds Pelkey.
Seed lots that have minimal mixture, low virus readings, little or no tuber diseases or defects are out there, says Johnson. “Developing that relationship with the grower actually producing the seed is the first step.”
With 1,000 acres of potatoes to plant each year, Camps sums it up best. “Seed is probably the most important input in our fields. We can fix fertilizer, we can fix weeds, we can fix a lot of stuff. But we cannot fix poor seed.”