Growing Magazine - August, 2014

FEATURES

Citrus on the Fast Track

By Curt Harler


University of Florida citrus breeders Jude Grosser (left) and Fred Gmitter pose in their tissue culture room.
PHOTO COURTESY OF NEW VARIETIES DEVELOPMENT & MANAGEMENT CORP. BACKGROUND PHOTO BY ERCANEROL/THINKSTOCK.COM.

When it comes to speed, NASCAR drivers have nothing on the citrus breeding program at the University of Florida's Institute of Food and Agricultural Sciences. The Plant Improvement Team is taking several new citrus varieties on the fast track.

Better yet, growers can join forces with breeders through the New Varieties Development & Management Corp. in Maitland, Florida. NVDMC's program, called Fast Track, allows growers to take new varieties for a spin right in their own groves.

Fast Track includes oranges, orange hybrids, tangerine and mandarin hybrids, grapefruit and pummelo hybrids, and acidic fruits.

"Our industry is in an absolute panic since we are so far behind in fresh varieties," said Quentin Roe, president of William G. Roe & Sons, Winter Haven, Florida. They have made a decision to test all of the sweet mandarin and tangerine varieties that come out, focusing on the dwarfing rootstocks like US-897.

Roe encourages all grove owners to join other growers. "Spend a few bucks and get into the program," he said.

"The program is a big help to growers. It's another tool growers have to look at opportunities," said Tom Hammond, owner/operator of Hammond Groves, Inc., Vero Beach, Florida.

J. Peter Chaires, executive director of NVDMC, works closely with IFAS and Florida Foundation Seed Producers on this innovative program that lets growers register to plant between five and 30 trees of experimental fresh citrus selections. Through the Fast Track program, commercial growers become part of the trial process and provide feedback that will inform release and commercialization decisions.

"My sense is that growers need to have a competitive product to put in the marketplace right now, right away," Hammond said. The holy grail for him would be a seedless, easy-to-peel variety. His market is clamoring for one.

Hammond understands the need to research a variety before rolling it out. He was one of the growers involved with the Spanish clementine that flopped 15 years ago when it turned out that Mediterranean varieties are not suited to Florida and become seedy. But he said, "The quicker we can see a variety in our groves, the better."

Now growers will be an integral part of the release and commercialization process. The purpose of the Fast Track program is to reduce the time necessary to evaluate and release promising new varieties. The program is for fresh fruit varieties only.

The first group of cultivars is just now heading into commercial groves, noted Dr. Fred Gmitter Jr., citrus geneticist at the UF Citrus Research and Education Center in Lake Alfred, Florida. Time will tell whether they succeed under grove conditions.

Gmitter said, "At the moment, it is too early to tell. The first trees are just going into the ground."

On the fast track

Registration for the first nine IFAS Fast Track scion selections opened on August 2, 2013, and closed on January 29 of this year. Sixty-one Florida growers registered for the program.

In that group of nine cultivars there are five mandarins, three seedless oranges and the UF 914 grapefruit cultivar. The latter has great potential to change the medical community's advice to people on statins and other blood pressure medications to avoid grapefruit, since the three most active problem chemicals in grapefruit juice are either at very low levels or nonexistent in UF 914.

"I'd say a grower who is not engaged with Fast Track and is not participating in the program will find themselves economically and developmentally behind the curve," Roe said.

In the past, when a new citrus selection showed promise, it would be entered into replicated field trials on a wide range of commercial rootstocks and under multiple growing conditions.

"While this process remains valuable for the collection of data, growers wanted a way to speed up this process," Chaires explained. When NVDMC sponsors variety display days with IFAS - events where growers, packers, processors, marketers and fruit enthusiasts evaluate and score the new selections - the results tell breeders and producers whether the fruit has promise.

"But we know little else," Chaires said. "All of the questions that a grower might reasonably ask have not yet been answered."

Growers wanted a process where they could register to grow new selections of interest, evaluate their potential in real-world commercial conditions, and decide for themselves which ones, if any, are viable.



Seedless and easy to peel, UF 950 is one of the first seedless mandarins in the Fast Track program.
PHOTOS COURTESY OF IFAS.

Enter the Fast Track model.

Fast Track is a three-tier system. Tier 1 is the trial and evaluation stage. Growers become part of a grower group for the selections they choose. There is a nominal fee to participate. Growers choose only the selections of interest to them.

Selections that prove to have commercial potential will move to Tier 2. This is the commercial stage, but is only for the growers who participated in Tier 1.

In return for their assistance in the trial process, growers who elect to plant a variety that moves to Tier 2 get a five-year head start and a reduced tree fee (royalty).

"However, no growers are left behind," Chaires said. "All growers can elect to register to grow the variety at Tier 3 after the expiration of the head start."

"Fast Track has taken a process that was taking 40-plus years to introduce new varieties and gotten it to the point where growers can test new selections on a 10-year cycle," Roe explained. And there are some promising lines to see.



A 3-year-old reset of Valencia on UFR-17 in an area with heavy HLB/blight pressure at the Lee Alligator Grove, located east of St. Cloud, Florida.

Promising lines

Grove owners will be excited about C4-16-12, a sweet orange-like hybrid. The trees look a lot like sweet orange trees and are small/medium-sized, so they can be used in high-density plantings. While its cold hardiness is unknown, Dr. Jude Grosser, UF professor of citrus breeding and genetics, says it should be at least as good as sweet orange.

"Although 8 percent trifoliate orange, the juice from this selection cannot be distinguished from orange juice," Grosser noted. The juice of C4-16-12 has a high Brix rating. The fruit is seedless and has a thin rind, making it perfect for juicing.



Adult asian citrus psyllids on a citrus stem. The insect is the vector for huanglongbing or citrus greening, a disease that is devastating the citrus industry.
PHOTO BY PEGGY GREB, COURTESY OF USDA-ARS.

"Last year, we had a fruit splitting problem following a 6-inch rain," Grosser said. They still need to determine if this is a problem that has to be managed.

C4-16-12 looks to be resistant to canker, Grosser added.

The UFR-17 rootstock is getting some buzz in the groves. It is a "tetrazyg" hybrid of Nova + HB pummelo x sour orange + Carrizo.

"We have limited horticultural performance data," Grosser cautioned. Before the recent release of UFR-17, there were 16 other rootstocks released because of their potential tolerance to huanglongbing (HLB or citrus greening), which threatens to wipe out Florida's citrus industry. UFR-17 might be called an "extra," but it could find its way to the big time.

As HLB became an issue, researchers noted that some rootstocks made a difference in terms of frequency of infection and severity of symptoms. With UFR-17, young trees show a reduced frequency of HLB infection, and infected trees show reduced symptoms when grown with a good nutrition program.

While the common varieties planted today are quite HLB-prone - with infection rates as high as 70 percent - there are experimental rootstocks with infection rates below 7 percent.

Selecting for greening resistance at an early stage means producers will not have as much to worry about in the decades to come. However, those early positive results - 7 percent infection rates - are due to serendipity, not to any inherent resistance. (For more on the greening problem, see the April 2014 disease control column at http://www.growingmagazine.com/article-10650.aspx.)

At present, these lines are only being grown in Tier 1 for more evaluation. "None of these will be available to producers until at least one grower moves to Tier 2," Grosser noted.

Pushing pummelos

Florida has a long history of producing citrus for the processed market; pummelos may find a spot in the fresh market. Since about 90 percent of Florida's citrus goes to juice or other processed applications, the crystal ball for pummelos is hazy. Citrus growers are wondering where pummelos will fit best in a grove manager's strategy. Will they allow spreading out the harvest from the usual orange-grapefruit time frame?

Hammond is cautious. While he's looking at pummelos, it's not a huge focus in his market. "It's a tighter market than easy-peel," he said.

However, Hammond Groves is evaluating several varieties to get a sense of how they will do under its grove conditions.

Will pummelos see broad adoption? "The industry will have to answer those questions," Grosser said. "I believe they have potential in specialty shops, roadside stands and Whole Foods-type stores."

"Critical mass is necessary for any line of processed product, and the jury is still out whether Florida growers will embrace pummelo production," Chaires said. Florida can produce very high-quality pummelos, but so far, despite high scores in evaluations, pummelos have received limited attention.

"There is tremendous genetic diversity in pummelo," Chaires pointed out.

Roe is quite aware of that. One promising variety offered resistance to greening. "But I didn't like the flavor," he said. "There is always a fine line with balancing all the different characteristics."

Roe has looked at several selections and is focusing the grove's testing on a couple of them.

The future of pummelo in Florida is up in the air. "The quality of the fruit is exceptional, but we do not yet have trees in the ground," Chaires said.

Cutting time

"This model was co-developed by IFAS' Plant Improvement Team, NVDMC and Florida Foundation Seed Producers, Inc.," Chaires explained. The organizations hope the Fast Track program will significantly reduce the amount of time necessary for new selections to move to the commercial stage.

"We are very excited about this program," he added.

Another reason Roe encourages fellow growers to get involved is that it broadens the test bed, giving everyone a chance to see how lots of varieties perform.

"I think what we've done with Fast Track, in the greater world of plant breeding, is just brilliant," Roe said.

"I think the seedless, easy-to-peel market will be great for Florida," Hammond said. "Everyone wants a citrus like a banana that they can just peel and eat. When we get the right one for Florida, it will be something that will really help our markets."

Curt Harler, who has a B.S. in agriculture from Penn State University and an M.S. in ag from Ohio State University, is a full-time freelance writer specializing in green topics.