Strategizing for fall strawberry production

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Day-neutral strawberries grow best when placed in crowned, raised beds and protected by plastic. Photo courtesy of Pam Fisher/Fisher Berry Crop Consulting

by Courtney Llewellyn

The sweet treat of strawberries tends to be an alluring draw for many customers. As growers, it would be wonderful to be able to offer them more than one season per year. Work has been advancing on making autumn strawberry production more and more efficient and profitable.

Day-neutral strawberries – those that will continue to set and ripen until a hard frost puts them into dormancy – can provide that opportunity. Pam Fisher of Fisher Berry Crop Consulting presented her knowledge on these fruits during the recent Great Lakes Expo, based on observations she made working with about a dozen farmers. They grew about 350 – 400 acres of day-neutral strawberries along Lake Erie, up to Ottawa and beyond.

The first thing she did was compare traditional June-bearing (short-day) strawberry varieties to day-neutrals. The June-bearing fruits initiate flower buds when days are short and temperatures are cool; they provide one crop per year; and they’re dormant in winter. Day-neutral varieties, however, initiate flower buds when temperatures are cool, regardless of day length; they offer multiple crops per year in flushes; and are semi-dormant in winter. “Day-neutrals are very sensitive to high temperatures, however,” Fisher pointed out. The more northerly latitudes may have better success in growing these strawberries because of that.

Because of the success growers have been seeing with these fruits, consumers are starting to learn fresh strawberries are available almost all year long. Fisher said the majority are sold via on-farm and farmers markets, and they provide an added revenue stream for growers with multiple berry and vegetable crops. Growing day-neutrals also helps those looking to sell to grocery and large retail markets, since they help provide more consistent production. However, these growers will always be in competition with those from California, where much produce is steadily grown year-round.

“The day-neutral strawberry didn’t take off in Ontario until varieties had good shelf life and flavor,” Fisher said. Some of the most successful varieties include Albion, San Andreas, Seascape, Monterey, Portola and Evie 2; currently being trialed are Murano, Cabrillo, Victor, Valliant and Royal Royce.

“They all have their strengths and weaknesses,” Fisher noted. While Albion tends to have great flavor and quality, with a high percentage of marketable fruit, its yields are lower than Seascape and winter hardiness can be an issue. San Andreas provides large fruit and excellent quality, good flavor, very vigorous plants, higher yields than Albion and is noticeably more resistant to leaf diseases, according to Fisher. It is, however, more susceptible to botrytis.

“Regardless of what variety you choose, it’s important to order early,” Fisher said. There are two ways to plant – bare root, which is common up north, as well as plug plants, which are planted in late summer/early autumn. She noted some growers will utilize bare root, planted plugs and dormant plugs in order to be able to grow all year long.

Planting & Growing

Day-neutrals are grown in raised beds using plastic coverings. Black plastic provides early warmth, while white plastic means the beds will be cooler in summer. Fisher said some growers use both colors for temperature control. She’s observed two to four rows per bed with plants staggered in 12-by-12-inch spacing, with beds usually four to six feet apart. “With all this plastic and heavier soil types, it’s important to shape a crown,” she noted. Grass is planted between the rows.

When planting bare roots, Fisher recommended doing so as early as you can, and definitely before the June-bearing fields (late April – early May). Pay close attention to soil moisture and planting depth. It’s a good idea to test soils and add some fertilizer before planting.

Irrigation and crop nutrition will be critically important. Fisher said strawberries respond well to “spoon feeding” – small, measured doses of nutrients. They will have a relatively high demand for potassium. Leaf analysis will allow growers to adjust micronutrients as needed. “More frequent, small doses of fertilizer is better than big slugs,” she said.

When removing early bloom, wait until the plants are established (usually about four to six weeks after planting) and take the whole truss. Fisher said to also remove runners because they compete with crown and flower development – and this can become very labor intensive as plants grow.

There should be the potential of 18,000 – 22,000 pounds of strawberries per acre. “Plan to harvest for 16 to 20 weeks,” Fisher said. “It’s like milking cows. There’s no rest.”

As for weed management in day-neutrals, growers will want to keep planting holes as small as possible, and hand weeding around plants may be necessary. Spraying herbicide in the alleys, or using herbicide and straw in the alleys, helps, as does investing in shields for water nozzles.

“In insect and disease management, it’s a long growing season, and there are several important pests, but not as many products to choose from [for control],” Fisher said. “You will most likely have to spray weekly.” Specifically, the tarnished plant bug tends to damage blooms and green fruit, so it’s important to catch first summer generation, as it can be devastating. Another pest is flower thrips, which presented a problem in the warmest parts of Ontario. They caused fruit to become bronzed and cracked. Fortunately, Fisher said, pirate bugs love to eat thrips (and alyssum will lure in pirate bugs and other beneficial insects).

Spotted wing drosophila, a major pest for many fruit growers, is also an ever-present threat. SWD causes bruises and soft spots, resulting in unmarketable fruit, so Fisher recommended using all the tools at your disposal to manage it.

She added that the plant diseases day-neutrals face are similar to those for June-bearing fruits.

Once the long harvesting season is over, it’s important to safely overwinter the day-neutrals using row covers put in place in late October and November. “Even with covers, plants can look pretty tough in the spring,” Fisher said. “The earliest bloom is usually small and frosty and runty, but that’s okay.” Covers may need to go on and off often in early spring.

Do You Dare with Day-Neutrals?

“The input costs can be high, but harvests can be high as well,” Fisher summed up. The more expensive inputs can include plant density, plastic mulch, drip irrigation and row covers. It’s labor intensive too, with the hand planting and blossom and runner removal. The daily harvest goes on for an extended period, and early crops are susceptible to frost.

“But once you start growing day-neutrals, you’ll find there’s more ways to expand the season even further, with high tunnels, mini tunnels and substrate growing,” she said. And that expanded season means new products for your market, appeasing consumers who want locally grown produce all year (including strawberries) and being able to charge higher prices – and day-neutrals can compensate for early season losses. Many growers will already have the infrastructure in place for strawberries.

If you’re considering adding day-neutral strawberries to your operation, Fisher recommended linking up with the North American Strawberry Growers Association (nasga.org) for more information.

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