The Chronicle Herald (Provincial)
Researchers track viability of frost fans
Steve Ells remembers June 4, 2018, well.
A severe frost caused more than $30 million worth of damage to crops across the province as temperatures plunged while plants were experiencing a growth spurt following some warm weather in May and early June. The mercury dropped to -1.87 C in Kentville and remained below freezing for a significant time.
Ells, who owns and manages Ellslea Farms Limited in Sheffield Mills, said the company is just getting back to full production this year after the vineyard lost about 60 per cent of its production in 2018 due to the spring freeze event.
“It was devastating for us. We’re still actually just coming out of the effects of it,” he said.
Ells is intrigued by research underway at Agriculture and Agri-food Canada’s Kentville Research and Development Centre that may provide some insight into the effectiveness of using a fan as a risk-management tool.
“All the research they can do that can help us mitigate climate change is valuable to the industry,” said Ells, who is also the Grape Growers Association of Nova Scotia president.
The latest research has scientists in Kentville using a portable frost fan at its vineyard.
“They’re not novel; they’re not new,” plant physiologist Harrison Wright said of frost fans, noting the Kentville researchers are gathering data to determine the fan’s effectiveness in Nova Scotia. “It’s really more of a regional question, like how useful could a frost fan be here?”
HISTORY
The Kentville facility planted a one-hectare vineyard in 2016 to conduct various research trials.
“There’s a long history of wine grape research here,” Wright said, noting there are trials dating back about a
century.
The vineyard was in its third season when the 2018 frost event occurred. The third year is often the first crop worth harvesting to produce wine, but this vineyard was being used for research purposes.
“I am glad we weren’t having to rely on the income from that crop that year,” Wright said. “If we were a grower, and that had happened to us, that would have been a very lean year.”
The 2018 frost impacted a variety of crops, including wild blueberries, apples and Christmas trees. Farmers began asking themselves how they could protect their crops from a reoccurrence, and the research facility decided to study a fan’s effectiveness.
THE SCIENCE
The fan could provide a solution to radiation frost by drawing warmer air from above to the ground and creating air movement so frost cannot settle and damage crops.
How low the temperature reaches and how long it remains at that level are factors that determine how much damage will be seen following a frost event.
Wright said the 2018 event saw low temperatures remain for a long time.
“That was the coldest June temperature on record (at the Kentville station), and again those records go back to 1913,” Wright said. “It was devastating.”
Wright said while they believe the fan helps somewhat, more data needs to be collected to determine trends.
“It won’t help in all situations,” he said. “It’s not the answer to all your frost problems. It’s just one more tool to use.”
Cost is one obstacle keeping some farmers from investing in the technology, but Ells said it is something his company is looking at buying after undergoing an expansion during the past 10 years.
“The fans are pretty effective and they’re almost standard pieces of equipment in some vineyards in the Okanagan and the Niagara Region,” he said. “I see that as probably a risk-management tool that we will purchase in the future.”
Other techniques are used worldwide, such as vineyard candles, smudge pots, heated wires and helicopters.
IN USE
There are some wind machines already in use in Nova Scotia.
One can be seen in an apple orchard along Highway 1 near the border of Waterville and South Berwick. It was there when Lloyd Dyck purchased the property in 1999.
“I’ve never really used it for what it was supposed to be used for,” he said. “I’m not a fan of it.”
The owner of Apples and Spice Orchard said it takes a lot of energy to move the gaspowered fan’s large blades.
“In my mind, they are a dangerous piece of machinery if they are installed in such a tight area as mine,” he said.
Dyck said he decided to take a different approach to help protect his orchard. It included pruning the trees, making sure the grasses are mowed, opening up the edges of the orchard and planting the rows north-south to increase airflow.
“In areas that have thousands of hectares of flat land, you have the ability to plan your air movement with greater precision,” he said. “In areas like the Annapolis Valley, with our valleys and high spots, topography and orchard layout must be considered. Since cold air is heavier than warm air and has the same hydrodynamic features as water, it will flow to collect in lower areas. These are the most susceptible areas for frost damage, namely, the bottoms of valleys or depressions in rolling land and flat lands.”
Ellslea’s vineyard has two sections, one about 20 metres higher than the other. The higher elevated area was less impacted in 2018.