By Elizabeth Ashby
It has really only been about two decades since farmers in Florida decided to tackle the tough task of growing blueberries commercially in the state. Unlike other states to the North, Florida’s climate holds great promise for getting the fruit to market much earlier.
But to capitalize on that earlier production cycle, growers also have to overcome a whole host of other obstacles: a soil not conducive to the crop; an increased threat of freezes; and a blueberry bush that isn’t strong enough for mechanical harvesting.
Varieties that make the cut
Dr. Paul Lyrene, professor of horticultural sciences with the University of Florida, Gainesville, has been working with blueberries since 1977. He was trained as a plant breeder, had worked in south Florida as a sugar cane breeder for three years, and then got the opportunity to move to Gainesville.
“I thought it was an interesting crop and Gainesville was an interesting place,” Lyrene says.
When he first started his blueberry research, almost all the blueberries in Florida were the rabbiteye variety, which ripens from May 20 through early August, Lyrene says. The variety is native in the panhandle and southeastern Florida, is draught tolerant, vigorous and has a high yield. At that time, all the blueberries in the state were sold at pick-your-own operations, and there were about 300 or 400 acres of rabbiteyes in the state, he says.
Today, the industry has turned almost entirely to the southern highbush blueberry because of the variety’s earlier ripening schedule, which continues to get harder and harder to define, Lyrene says.
“Historically, the season has been April 1 through May 20, but it is harder to define because we have varieties that have been ripening for more than a month already under plastic in Gainesville. As the industry has moved farther south, there is even some March production,” Lyrene says.
Dr. Jeff Williamson, fruit & nut specialist with the UF/IFAS Horticultural Sciences Department, says a lot of Florida growers who are growing for commercial markets grow the southern highbush because of the high price they get for that early season fruit.
“The prices for commercial blueberries are five times a good early in the spring than they are in the summer,” Williamson says. But, he adds the southern highbush is a lot more difficult to grow. Rabbiteyes, on the other hand, are very resilient, he says, adding, “In fact, it is difficult to kill them once they become established.”
Lyrene says the most common southern highbush varieties in Florida are the Emerald, Jewel and Star because they have the fewest problems.
“[The University has] about 15 varieties we have released, and each one has one or more problems. A good variety is like putting together the best bush with the proper harvest time, it gets ripe at the right time and then along with it is has berry qualities growers need that have to due with harvesting and packing and post-harvest life. Then, of course, consumers need to be satisfied with the flavor, texture and appearance,” Lyrene says.
The university normally releases about a variety a year. Lyrene says he plans to put several new ones out this coming year if they make it through the cold spring and look good.
Prepping the proper soil
Once growers select the variety they wish to plant, soil preparation is key. Researchers say it is difficult to find soil that blueberries are happy with across the state. The fruit need acidic soil, but they also need a very course texture that is always moist but never saturated, Lyrene says.
Jerry Mixon of SunnyRidge Farm Inc., Winter Haven, says there are still many growers using sulphate-based nitrogens to assist them with their pH control.
“We amend our soils heavily with sulfur, peat moss. That hasn’t changed a lot,” he says. “I am continually amazed at the willingness of growers to try blueberries on such diverse soil types. You go from great rich soils of South Carolina and Georgia to sandy soils of Florida, and growers are still being entrepreneurial enough.”
Lyrene says blueberries, like most plants, need nitrogen, phosphorous, magnesium and other nutrients, and the main trick with blueberries is that they have very shallow roots and are often grown on raised beds. This requires very light but frequent fertilization. That is why he and other scientist recommend fertigation. “If it rains 3 or 4 inches, you leach all the fertilizer out of the soil for blueberries,” he says.
Mixon says more growers are looking into drip irrigation to put water and nutrients where the plants need it. This not only helps solve the soil dilemma; it also tackles disease problems. “Most of our current maladies are waterborne,” he says. “If you have water on top of the bush, it trickles down to the lower parts of bush with overhead irrigation. Drip should clear that up a bit.”
As new diseases appear, scientists and growers look for answers. Mixon says the Florida Blueberry Growers Association, Hawthorne, received some special grants through the new farm bill to devote to research. He serves as director of the association.
“The growers association was privileged to get a grant from the current farm bill. They are working with several growers scattered throughout the state. The FBGA has our current block grant, and we are applying for second block grant to fund research on mechanical harvesting and disease understanding,” Mixon says. “Several farms have taken an acre of their fields and will run them with similar care-taking methods. They will get results in three to four years.”
Evolving production practices
Williamson says no matter which variety growers select, they need at least two cultivars grown close together for cross-pollination, and three or four would be even better because the more mixing of pollen you get the better fruit set and the bigger the fruit will be.
When growers first took a stab at blueberries, they were trying to develop unique production practices and test methods that might work in Florida that wouldn’t in other growing regions. But over the years, researchers say growers are getting ever more conventional.
“Growers tried all different types of patterns, but now they look like ones in North Carolina and New Jersey,” Lyrene says. “The rows are 10 feet apart and plants are 3 feet apart within the row.”
Mixon says most of SunnyRidge’s growers work between 1,700 and 2,200 plants per acre.
Lyrene says an experienced grower with good yields can produce about 8,000 pounds of blueberries per acre in a year, which starts about the third year after planting.
Growers also have a duel irrigation system with overhead irrigation for freeze protection and drip for applying fertilizer and irrigation water, he says.
To increase yield per acre, some growers are using plastic tunnels, Lyrene says. This moves the harvest peak back to a more favorable harvest window, but also offers some additional benefits. For example, it allows growers to pick the fruit when it is raining outside, and berries are a lighter blue color because rain doesn’t wash off the fruit’s natural wax. Lyrene says this is a fairly small segment of Florida’s production due to high cost of buying and managing the tunnels, which are about 10 feet tall, each one enclosing about three to four rows.
Williamson says the university just planted four rows of blueberries for an organic trial. To help with weed control, the scientists put a ground cloth under the pine bark.
“Rabbiteye show great potential for that in our climate in Florida. You could grow these with minimal pesticide use or organically,” he says.
Potential for mechanical harvesting
Lyrene says about half the world’s blueberries are sold as a processed product, and those are frozen and harvested by machine. Of the fresh blueberries in North America, about 20 percent are harvested by machine and the rest by hand. But mechanical harvesting in Florida hasn’t been too popular so far.
“The price of the berries has been so high, growers don’t want to be dropping a fraction of the crop on the ground,” Lyrene says. “But as production increases and value goes down, I think we will move to machine more and more.”
With that change, though, comes a major increase in cost. Mechanical harvesting requires redesigning a fairly large aspect of the production system, including using different varieties, pruning methods and more, he says.
“Our bushes are not bread for mechanical harvesting,” Mixon says. “We are two decade old industry, which is very young. How will these current varieties handle the rigors of mechanical harvesting, as well as the long growing season we have down here and disease control? Most of our current varieties are not nearly of the firmness that a normal mechanical harvested berry would have.”
Mixon says there also are other reasons why mechanical harvesting will take a while to become widely used: most of the state’s varieties don’t yield high enough volumes to afford losing a portion of the crop. He also says as long as growers have hand labor available, why not use it.
“One day it will happen I think, but we will see where it will take us,” Mixon says.
Watch a virtual field day about blueberries at http://virtualfieldday.ifas.ufl.edu/suwanneevalley/orchard/blueberries.shtml
Overhead drip irrigation systems came in handy this winter when Florida growers faced freezing temperatures that threatened the life and their southern highbush blueberry plants and the fruit the plants had set.
Dr. Paul Lyrene, professor of horticultural sciences with the University of Florida, Gainesville, says growers were trying to save their plants the Feb. 3, 4 and 5 when temperatures around 19 F hit Alachua County. He says where the wind stayed around 5 miles per hour, the temperatures stayed around 24 F.
“Both combinations are at the far lower limit of where we can protect open flowers with the irrigation systems we have, but I think if all the pumps and pipes and emitters ran as designed, we should have been able to scrape by, but barely,” he says.
This bout of cold weather came on the heels of other freezing temperatures that hit the state in January. Several nights throughout the two months, growers ran overhead sprinklers to form ice to insulate the bushes, similar to the method employed by strawberry growers. “This has been one of the coldest winters we have on record that I can remember,” Mixon says. “Growers earned their keep this year.”