High-density citrus planting

When you are told the experimental citrus grove you have planted is like no other in the country, you know it is a sign of the times and changes brought on by citrus greening. That’s what Horace Durrance was told about the 14-acre block of super high-density (SHD) trees planted on his Lost Lake Groves property near Lake Placid.

Durrance has been working closely with Dr. Clay Pederson, managing director of Agromillora Florida, on the project. As a third-generation citrus grower, Durrance says planting 908 trees per acre in the grove is a huge departure from the traditional 100 trees per acre planted by previous generations. But he is willing to give it a try for one simple reason—economics.

“My father and grandfather would probably roll over in their graves, knowing I am putting this many trees in the ground per acre,” Durrance jokes. “Back before greening came along, 100 trees per acre worked fine for generations, but now the economics just don’t work, as greening has reduced yields in traditional spacing and densities.”

Lost Lake’s super high-density citrus grove was planted in May 2018. While it remains to be seen if the experiment will be a success, early growth is impressive. Trees already are reaching about 4 feet in height and have developed an extensive root system.

In Lost Lake’s super high-density citrus grove, trees are planted on 12-foot by 4-foot spacing. Several varieties and rootstocks are being tested in the planting. Trees are planted on dwarfing rootstocks because the idea is to manage and grow them almost into a hedge, similar to how apple and olive orchards are grown today, minus the trellis.

According to Pederson, they are taking what they have learned in other super high-density plantings from across the world and applying that knowledge in Lost Lake’s grove.

“One of the things that helped Agromillora get established as a company was propagating super high-density olive groves in Europe 25 years ago. We have talked about high density around the world, and here in Florida, for years. But what we are doing with Lost Lake Groves is a different way of approaching super high-density.”

Durrance says from a production standpoint, he is not treating super high-density citrus trees much differently than new resets in his conventional grove. There are a few exceptions to this, including his irrigation placement of one microjet for every two trees since the spacing is so close.

In addition, imidacloprid is being applied with a 1,000-gallon rear sprayer pulled behind a tractor going down every other row rather than using a hand-pump applicator, which is used on resets.

“You have 908 trees per acre, so that is a lot of hand pumping for our field workers,” Durrance says.

For weed control, Durrance built a herbicide boom to attach behind a John Deere Gator.

“I don’t have a disk that will fit the super high-density grove, so I am mowing it more than my conventional spacing,” he says.

Lost Lake Groves is testing various rootstock/scion combinations in its 14-acre super high-density grove. It is critical to utilize dwarfing rootstocks in the planting. Here are the various combinations being evaluated. The trees were produced by Agromillora using tissue culture technology, but the super high-density concept can be deployed with any nursery tree.

‘Vernia’ on US-897

‘Vernia’ on UFR-06

‘Valquarius’ on US-897

‘Valquarius’ on UFR-06

Frank Giles is editor of Florida Grower

American ag, wins and losses

Late last week China announced an additional 10 percent tariffs on $100 billion of U.S. goods including apples, pears and cherries, according to multiple reports. This is as the U.S. tariffs on Chinese goods were set to kick in Sept. 1.

This also comes on the heels of a newly released document from USDA’s Office of the Chief Economist, detailing how estimated damage from trade disruptions was calculated for its support package for farmers. These damages from trade disruptions include $318 million in pistachios, almonds, walnuts, pecans, hazelnuts, and macadamia nuts; $111 million in sweet cherries and $70 million in grapes.

But there is some good news, as Japan has recently agreed to a trade deal with the U.S. which will include agriculture products. While the details are still being worked on, Western Growers president and CEO Tom Nassif quickly applauded the deal.

“Tariff equity for U.S. fresh produce is one of our most important international trade priorities, with Japanese tariffs on American agricultural products reaching as high as 35 percent for some commodities. Of equal importance is the need for sanitary and phytosanitary (SPS) reforms, as Japan’s current SPS regulatory regime prohibits many high-quality U.S. fruits, vegetables, and tree nuts from entering the Japanese market,” Nassif said.

Christina Herrick is the Senior Editor of American Fruit Grower magazine and Western Fruit Grower magazine

Mites versus Florida strawberries

Florida Grower magazine hosted a tour of farms in Central Florida late last year. One of the stops was at JayMar Produce—a strawberry operation near Plant City. JayMar’s production manager, Dwight Rainwater, showed tour attendees how various technologies and products are being deployed on the farm.

One practice was the use of predatory mites in the strawberry fields to help manage two-spotted spider mites. He commented that he was a skeptic at first but now is a big believer in their effectiveness and use in the crop.

Chris Crockett, director of Research and Grower Services for Highland Precision Ag, works with Rainwater and other growers. The company provides various precision, data management, field scouting, and crop recommendation services. He says a few of his strawberry-growing clients are now using predatory mites. Greenhouse and hothouse growers use them heavily, and Crockett expects the emerging medical cannabis industry will be a big user of the mites. Blueberry growers in the state are beginning to experiment with their use as well. Koppert Biological Systems and Biobest are the major U.S. suppliers of predatory mites.

So, can predatory mites get the job done in strawberry plantings? Crockett says yes, when applied correctly. Most commercial mite suppliers recommend applications begin when the first signs of spider mites start to appear in the fields.

Some growers use predatory mites more as a preventative, which Crockett says is advisable if the farm does not have a thorough scouting and field mapping program. Other growers rely on spot treatments in problem areas.

Another critical factor in predatory mite performance is applying them in the right conditions. Temperature and relative humidity play an important role in their survival and ability to reproduce. Florida is fortunate to have relatively high temperatures and humidity throughout much of the season. This allows the use of persimilis for most of that period of time.

The effect of insecticide applications on predatory mites should also be taken into account. Crockett says he uses a mortality scale to determine potential harm caused to predatory mites by different chemicals. The scale runs from one to four. A product ranked one on the scale is least lethal and four is most lethal.

“For a grower like Dwight, he will not apply an insecticide that is a four on the scale unless he absolutely has to because some other pest is taking down the farm,” Crockett says. “We also consider the predatory mites’ susceptibility to different chemicals. For example, californicus is a little more tolerant than persimilis to certain pesticides.”

Frank Giles

Florida peanut and chocolate cupcakes


1½ cups Florida peanuts, toasted, salted and coarsely chopped

6 ounces dark chocolate, broken into pieces

1 chocolate cake mix, store bought or homemade

Chocolate frosting, store bought or homemade


Coarsely chop the peanuts and set aside. Prepare cupcake batter using box mix instructions, and fold in half of the chopped peanuts. Once the batter is prepared, place cupcake liners in the cupcake pan and fill ¾ full. Bake according to cupcake batter instructions and set aside to cool completely. Place chocolate pieces in an oven-safe glass bowl. Set the bowl atop a small sauce pot with a half cup of simmering water, to create a double boiler. Stir continuously until the chocolate is melted and smooth. Carefully remove the bowl from the heat (caution: it will be hot). Frost the cooled cupcakes and sprinkle the remaining chopped peanuts on top. Drizzle with the melted chocolate and serve.



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