Ground Cover For New Citrus Plantings

New citrus planting method stops bugs, yields additional benefits

September 26, 2017 by Kathleen Phillips

New citrus planting method stops bugs, yields additional benefits
Raised beds covered with plastic mesh have proven to stop the life cycle of the Diaprepes root weevil on citrus trees in Texas. Scientists are now documenting other positive effects of the novel planting technique. Credit: Texas A&M AgriLife Research

A planting design that outwitted a weevil in Texas citrus groves has yielded numerous other benefits for growers and brought better quality oranges and grapefruits to consumers, experts say.

Enter the Diaprepes root weevil in 2000. The insect was found to be chewing up Texas citrus tree roots underground, then busting through the soil and up the tree to feast on leaves. Researchers began looking for a way to disrupt the weevil’s path.

By 2009, studies found all it took to stop the pest was a layer of mesh over the soil beneath the tree, according to lead scientist Dr. Mamoudou Sétamou, professor of entomology at Texas A&M University-Kingsville Citrus Center in Weslaco.

The plastic forms a barrier that the weevil cannot penetrate either from the ground up or from the tree to the soil, the researchers on the project explained, and thus the pest’s life cycle was interrupted, and it could not live there.

But after several years, Sétamou and others on the project realized that with field work, irrigation of the and washing rains, soil would become deposited on top of the plastic mesh layers. That led the team to try planting citrus trees on raised beds of soil and then covering the beds with plastic mesh. This design has proven effective in stopping Diaprepes root weevils and preventing soil accumulation to build.

And that might have been the end of the story, but the research team began to notice other benefits after years of watching for the weevils.

Dr. Olufemi Alabi, Texas A&M AgriLife Extension Service plant pathologist, Weslaco, said the planting method also has proven to save the growers money on inputs while yielding more fruit per acre.

“Traditionally, the planting density in the Rio Grande Valley is 121 trees per acre,” said Alabi, who joined the project in 2013. “With the new planting design, growers can easily increase this to 165-218 trees.”

The raised beds are 10-feet wide at the base, slope to 8 feet at the top and are about 18 inches tall, Alabi said. The plastic mesh is applied across the beds in a continuous length from one end of the row to the other.

The configuration has saved irrigation water, Alabi said, because the plastic mesh reduces evaporation from the root zone meaning less water is needed. The method also reduces the need for chemical sprays against the weevils and weeds, which can’t grow through the plastic mesh.

Alabi said now that citrus greening has also emerged as a threat against citrus production, the novel planting method is being examined as a potential aid against that disease as well.

“Our hypothesis is that the new planting design will bring young citrus trees to earlier production compared to the traditional method, so the productive capacity of the grove can be realized prior to and even in the presence of ,” said Alabi, who is collaborating on the study with Setamou, growers and the Texas Citrus Pest and Disease Management Corp. The project was funded by the U.S. Department of Agriculture-Huanglongbing Multi-Agency Coordination Group.

That study is also recording additional benefits of the planting design in 30 acres planted in the study at the Citrus Center in Weslaco and another 100 acres planted by cooperating growers, Alabi said. Another 145 acres are likely to be planted in the new style by the end of the year.

“Ironically, despite the disease and pest issues, citrus acreage in Texas has been steadily increasing the last three to four years,” Alabi said. “And more interesting is an increase in gross returns per acre due to a combination of factors, including the outputs of these research efforts.”

Almost 27,000 acres of citrus in a three-county area of the Lower Rio Grande Valley annually yield more than 9 million cartons of fresh grapefruit and oranges plus 5 million cartons of juice fruit valued at more $100 million dollars, according to Texas Citrus Mutual.

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Lemon Production in Floirda on the Rise

More Florida Citrus Producers Pondering the Lemon Pledge

Florida lemon grove
Lemons are in high demand not only for juice, but also oil.
Photo by Peter Chaires

The lemon craze certainly appears to be in full swing in Florida. Growers are gravitating to the prospect of a citrus crop that continues to produce in an HLB environment, even when surrounded by infected trees. Growers need a citrus variety that will hold on the trees and that is in relatively high demand. Though nurseries remain the primary source of information and guidance relative to planting decisions, some nurseries are reticent to engage on the issue; because like the rest of the industry, they have very little experience with lemons.

Other than some specialized lemon plantings for the fresh market and small volumes for processing, Florida has been a minor player in the lemon market since the 1962 freeze. Coke (Minute Maid) did plant some acreage in the 1960s and the Seminole Tribe of Florida followed suit in the 1970s, collectively producing an estimated 550,000 boxes of lemons. It has been reported Minute Maid abandoned its acreage in 1980s after freezes and eventually for economic reasons. However, necessity remains the mother of invention and growers now appear willing to put their frost-protection skills to the test in order to supply market demand.

Demand for the Product

Lemon demand flows from two markets: juice and oil. Lemonade and variants thereof are among the fastest growing products in the beverage category. Florida’s climate is ideal for juice production. When you add robust tree performance into the discussion, it should come as no surprise that Florida citrus growers are gravitating to lemons. What adds another dimension to the lemon conversation is the second and perhaps more important market: lemon oil. Global demand for lemon oil remains strong. This summer, the price was hovering around $24 per pound. Oil recovery and oil quality will be key factors for processing plants entering this market. Both factor into grower returns and decisions related to varieties.

Lemon tree in Florida full of fruit
Photo by Peter Chaires

Fresh vs. Processed

Undoubtedly, most of the new lemon plantings will go into the processed channel. Florida has only one fresh packinghouse running lemons. Indian River Exchange Packers (IREP) starts its season with lemons, and has a level of expertise with harvesting, packing, and marketing. Lemons require a different de-greening temperature range than other citrus, and IREP has made this investment and is well positioned to benefit from recent plantings. That being said, production of Florida lemons for the fresh market presents a load of challenges.

First, harvesting begins (depending on available volume) somewhere between mid-July and mid-August. It requires some careful planning and management to move from lemons to the next earliest varieties without a time gap. Second, like other citrus, lemons for the fresh market must be harvested when they are dry. Since lemons mature during the rainy season and cannot be harvested until early afternoon, and inevitably, the rains come in mid- to late afternoon, the balancing act can be frustrating and expensive.

Adding to the dilemma of handling in the field is the fact lemons have a high degree of susceptibility to skin breakdown. Blue and green molds and sour rot are challenges to the packinghouse.

Finally, Florida is and will likely remain a very small player in the American fresh lemon market, which means we will be a price follower rather than price leader. California and Arizona offer a longer season and retailers will not compromise those relationships. However, for those who can manage the process and the market, there may be opportunity. Bottom line: Unless the grower has a juice contract, the market will be quite limited.

Crop Insurance

RMA is in the process of considering the Florida counties that will be included in the lemon production area where risk of loss to cold weather is manageable. This currently appears to include: St. Lucie, Indian River, Polk, Hendry, Collier, Highlands, and Lee. However, specific situations can be addressed through the crop insurance program.

Current Volume and Projections

Estimations show approximately 200 to 250 acres of lemons currently in production in Florida. Over the past three years, roughly 400,000 trees have been propagated; but nearly 124,000 of those were registered for use as budwood increase. This would leave about 276,000 trees going into commercial production over the past three years. At a 140 trees per acre average – this would be another 1,970 acres of commercial lemons on the way.

This raises the question why so many increase trees are needed. It is likely that this number is too high, the likely result of nursery reporting errors. Nonetheless, even if this number is reduced significantly, it shows nurseries are ramping up for some serious lemon propagations.

 

One processor offered an incentive plan for growers to plant lemons and fully subscribed its program for 50,000 trees (resulting in average 137 trees per acre, or 365 acres). Other processors have similar incentive programs, but specifics are hard to come by. Estimates are as high as another 5,000 acres, but an additional 1,500 to 2,500 acres is more realistic. To put this in scale, USDA-National Agricultural Statistics Service shows California having approximately 41,500 acres of lemons in production and Arizona about 8,250 acres. Growers interested in planting lemons should contact their processing plant and inquire whether greater allotments of trees will be added to their tree incentive programs and how the pricing will be structured

Vetting Varieties

It is important growers verify with their processor whether there are specific lemon varieties that are preferred for their oil profile. The three main commercial lemon variety types are: ‘Bearss’ (which reportedly has fewer thorns), ‘Eureka,’ and ‘Lisbon.’ Presently, ‘Bearss’ and ‘Eureka’ appear to be the leading varieties for Florida growers. Most processing plants seem to value the oil and juice from both of these varieties. Very few ‘Lisbon’ lemons are being planted (probably due to lack of experience with the variety).

The ‘Harvey’ lemon, another Florida variety, is thought to be good for fresh packing, but its value for processing is still under evaluation.

New Twist to Freeze Protection

Lemon trees are susceptible to damage and loss of bloom due to freeze. Proper use of microjet irrigation will certainly improve one’s odds, but one grower is taking a different twist. He has been growing lemons successfully in Lake County for almost 20 years. His lemons are utilized in processing. He plants all of his trees as rooted cuttings, so that if the trees freeze to the ground, they come back as lemons and he is able to recover more quickly.

Fine Tuning Citrus Nutrition

How Florida Growers are Fine-Tuning Citrus Fertility

 

Citrus growers have always scrutinized their plant nutrition programs, but with HLB now in the mix, that scrutiny is on hyperdrive. And the programs are sort of like fingerprints — each different based on individual circumstances. Over the years, growers have honed in approaches that appear to be helping infected trees stay as productive as possible.

Water barrel graphic depicting Liebig's law of the minimum
The barrel depicting Liebig’s law of the minimum has become a common sight in citrus fertilizer presentations.
Graphic courtesy of UF/IFAS

Sharing Insights

In the spirit of open dialogue to help the industry fight the scourge of HLB, many growers are sharing what is working or not in their fertility programs. Once such grower is Marty McKenna who farms with his brother, Pat. He recently spoke at Florida Citrus Mutual’s Citrus Industry Annual Conference on McKenna Bros.’ fertilizer program and its successes.

He began by crediting Maury Boyd for bringing attention to Liebig’s law of the minimum, which states: the rate of growth of a plant, the size to which it grows, and its overall health depend on the amount of the scarcest of its essential nutrients that is available to it.

Both McKenna and Boyd are past winners of Florida GrowerSM magazine’s Citrus Achievement Award.

“Our situation is we are 100% infected with HLB,” McKenna told conference attendees. “We quickly realized we are not going to stay in business if we spent more than we were taking in. So, we had these two issues as we tried to get in the right direction to stay in business.”

McKenna said his brother Pat drove down to visit Ed English’s grove to observe his program of applying micronutrients to the root system, which was appearing to have success.

2016 Florida Grower Citrus Achievement Award winner Marty McKenna
Marty McKenna
Photo by Frank Giles

“As he was driving back, Pat called me and said, ‘Marty, I just saw the prettiest Valencia orange grove I have seen in 10 years,’” he said.
After the visit, the brothers began trying figure out a way to duplicate the program on their groves.

“It is not a one size fits all, but the beauty of minor elements applied on the ground in the presence of greening is anybody can try it,” McKenna says. “I think it is important that you can utilize the equipment you already have in groves with this approach.”

The McKennas have been using fertigation for more than 30 years. This guided their program to deliver minor elements to the roots via fertigation. After a lot of trial and error and tracking, they developed a 5-0-7 mix.

“It is basically an all nitrate fertilizer program,” McKenna said. “We alternate this due to the [Liebig’s law of the minimum] with a 5-4-7 mix, which has the boron, molybdenum, and phosphate. So, we are alternating these applications weekly [weather permitting].”

The program is more expensive than more conventional approaches. McKenna said they were backing off a little on nitrogen and would likely be below 200 pounds per acre, or perhaps even less than 150 pounds per acre given the right conditions. The brothers also are dialing back the intensity of their psyllid control applications to free up dollars for the fertilizer program.
McKenna continues to further supplement trees with a foliar nutrition program.

Hybrid Approach

Understanding the importance of root health and providing a steady source of nutrition, Rob Atchley, General Manager of Groves for Duda Citrus Division, and his team have developed a hybrid fertilizer program that focuses on the benefits of controlled-release fertilizers.

Rob Atchley
Rob Atchley

From 2013 to 2015, Duda put in a number of large plantings. The homogenous prill slow release materials they used were safe enough to put in tree holes at planting and provided a steady source of early nutrition and cut down on leeching.

“By putting it down in the hole, the fertilizer stays right there with the tree, and we’ve had very good luck with,” Atchley says. “Beyond that on the young trees, we use a lot of foliar nutrition, which goes out about every three to four weeks.”

The controlled-release fertilizer and foliar program carried the young trees to about year two. Atchley then moved on to what he calls a hybrid fertilizer approach, which combines conventional fertilizers with controlled-release fertilizers, along with foliar applications. “We apply dry fertilizer at the normal times most growers do (January, April, and October),” he says. “We vary my percentage of controlled-release fertilizer to match the weather patterns for certain times of the year. We also rely heavily on soil and leaf sampling to direct our applications. When you are spending that much on sampling, you don’t really want to use a cookie-cutter approach to fertilization.”

Atchley says the combination of their hybrid fertilizer program and continued strong commitment to psyllid control is paying off in Duda’s groves.

Ag is Sustainable

Americans say agriculture is sustainable, favor incentives over regs

From the notion of a modern farm or ranch being economically able to sustain a family, to the idea of working with the land in a manner that supports food and fiber production for future generations, sustainability means different things to different people. Even in agricultural circles, definitions of sustainability run far afield, from the environment to economics.

A recent Morning Consult poll asked 1,917 registered voters to give their opinions regarding agriculture and sustainability. One definition of sustainable agriculture was offered, generally, as defined by the 1977 and 1990 farm bills, a system of agriculture that will satisfy human food and fiber needs, enhance environmental quality, use resources efficiently, sustain the economic viability of farmers and benefit society as a whole. 

Almost everyone supports sustainability, by one definition or another. And, while the background noise around this discussion might sometimes suggest otherwise, many Americans think agriculture and farming are among the nation’s most sustainable sectors.

Democrats and Republicans actually agreed on many points in the survey. For starters, 80 percent of Republicans said they agreed that modern agriculture is sustainable, as did 76 percent of Democrats. There was strong bipartisan support for incentives related to environmental sustainability versus outright government regulation. Sixty-five percent of Republicans and 63 percent of Democrats favored cooperative incentives that allow government and farmers to work together to address issues, versus 13 percent of Republicans and 15 percent of Democrats who favored more farm regulation.

Fifty-nine percent of respondents said they trust farmers to make the right decisions when it comes to sustainability, while just 24 percent wanted government to make the call. Seventeen percent said they did not know or had no opinion. Across party lines, the majority of respondents expressed trust in farmers over government mandates, with Republicans at 67 to 18, Democrats at 55 to 30 and independents at 55 to 23.

By nearly a five-to-one margin, respondents said cooperative incentives would boost environmental sustainability in agriculture over additional government regulations—62 to 13 percent. Again, there was agreement across party lines, with 65 vs. 13 percent of Republicans and 63 vs. 15 percent of Democrats favoring incentives. More respondents (46 vs. 26 percent) said additional government regulations would hurt sustainability on American farms rather than improve it.

Farmers are winning the popular vote. Agriculture and farming ranked as the most favorable industry section among those offered to respondents. Seventy-eight percent ranked it favorable, compared to 76 percent for the technology sector, 73 percent for the hospitality industry, 67 percent for manufacturing, 60 percent for energy, 43 percent for the pharmaceutical industry and 54 percent for airlines.

Agriculture also drew the highest marks when respondents were asked whether it was more “good” than “bad” regarding environmental sustainability—56 percent said good, 13 said bad, 19 percent said equal and 11 percent did not know or had no opinion. The technology industry came in second with 47 percent good and 15 percent bad.

A whopping 80 percent of respondents said they strongly or somewhat agreed with the statement that “the true success of an environmentally sustainable farming practice depends on whether that practice also leads to economic opportunity for the farmer.” Seventy-five percent of respondents said they were more likely to say modern agriculture is sustainable with the knowledge that a common goal among farmers and ranchers is to leave the land in better shape for the next generation. Likewise, 72 percent said they were more likely to say modern agriculture is sustainable with the knowledge that many farms and ranchers have been operated for generations, and some for more than a century.

The public “gets” it, even if zealots don’t. America’s farmers and ranchers need to build on that reservoir of trust by sharing their stories of what really happens in the countryside. They need to explain the in-the-field work they are doing to protect natural resources while providing for their families. Americans trust you. Show them why they should continue to do so.

—Mace Thornton is executive director of communications at the American Farm Bureau Federation

Early Valencias

Varieties: Replacing Hamlins with Early Valencias

early valencias

University of Florida/Institute of Food and Agricultural Sciences plant breeder Jude Grosser makes a case for Florida’s citrus industry replacing Hamlin oranges with early-maturing Valencia oranges that he and others are developing.

“I think that’s a no-brainer because Hamlins are having a really bad time with greening, and orange juice sales are declining,” Grosser says. “Hamlin is half our juice. It’s half of the NFC (not-from-concentrate) product and yet it has inadequate color and flavor to make a Grade A product on its own. It has to be blended with Valencia. So you can imagine what a boost to the quality of our product it would be if you replaced all the Hamlins with Valencias. You’re going to have better color in the bottle; it’s going to be more attractive. And when somebody buys it, takes it home and drinks it, the flavor’s better and so they’re going to want to come back and buy more of it.”

Grosser mentions some existing early Valencias that have had a higher ratio than Hamlins at Christmastime and even at Thanksgiving. Traditional Valencias aren’t harvested until late winter or early spring. “They’re (the early Valencias) not home runs against HLB, but again with the right rootstock and nutrition program, they should be able to work,” he says.

Grosser’s comments address some of the biggest issues facing the Florida citrus industry. Approximately 95 percent of Florida’s oranges go into orange juice, and HLB, also known as citrus greening, has greatly reduced the state’s citrus acreage and production. HLB was discovered in Florida in 2005. There is no known cure, and most growers have struggled to find production programs that let them remain profitable in the face of the disease.

Citrus Leprosis

Citrus Leprosis Rears Its Ugly Head: Know the Details

With citrus leprosis a re-emerging threat to citrus, know the details of the disease.

Citrus Leprosis Details

  • Appearance: “On symptomatic fruit, the spots are usually brown, reddish-brown or tan-colored. The lesions on fruit are limited to the fruit rind only and do not extend into the fruit sections.” And “The symptoms of leprosis are distinctive; however, they could be confused with citrus canker lesions on leaves, fruit and twigs.” Testing confirms the disease.
  • Impact: “Left untreated, leprosis disease will kill a mature citrus tree in about four years. Leprosis affects all citrus types (sweet orange, mandarin, lemon, grapefruit and citranges) as well as Swinglea glutinosa, a citrus relative.”
  • Transmission: “The disease is spread by Brevipalpus mites, commonly called broad mites. The Brevipalpus mites have a broad host range with over 900 plant hosts reported from 513 genera.”
  • Treatment: “Mite control is essential for the control of leprosis. In Brazil, where leprosis has been endemic for many years, 12 or more miticide applications are made yearly. Leprosis-infected trees can be recovered with the pruning of the symptomatic branches, followed by good mite control, but the pruning of individual trees is expensive.”

HLB management

By Jaci Schrekengost

As huanglongbing (HLB) continues to decimate citrus crops, researchers continue to search for new, efficient ways growers can manage the disease.

HLB, also known as citrus greening disease, is vectored by the Asian citrus psyllid. The disease affects the entire tree, including the roots and fruit.

Tripti Vashisth, assistant professor and citrus Extension specialist at the University of Florida (UF), says one main concern with HLB is nutrition based on the size of the roots in HLB-infected trees. She says another researcher found HLB-infected trees have smaller root mass compared to trees that are not infected.

The concern with smaller root mass in these trees is whether they are moving the same amount of nutrients as the trees that do not have HLB.

According to the UF Institute of Food and Agricultural Sciences Citrus Extension website (http://www.crec.ifas.ufl.edu/extension/greening/index.shtml), “Root systems of infected trees are often poorly developed, and new root growth may be suppressed.”

Vashisth says in a new greenhouse study that she and other researchers conducted, it was actually concluded that the roots in HLB-infected trees move nutrients more efficiently than trees that do not have HLB. The issue with nutrients not reaching the top of the tree is due to the smaller mass of the roots.

The way to solve this concern is to allow a constant supply of nutrients to the HLB-infected trees, Vashisth says. “Continuous supply of fertilizer in any form is working best,” she says.