Pomegranates on display at the Kearney Research and Extension Center in Parlier showed clearly that it’s not just a Wonderful world, although that variety leads the growing California industry by far.
Arils, the colorful seed coats in the fruit, come in a variety of hues that were on display in a meeting room packed with a standing-room-only crowd of about 125.
The heavy turnout on a foggy November morning was an obvious indicator of the expanding interest in the fruit that covers more than 30,000 acres statewide and has a $115 million farm gate value in just Kern County, home to Paramount Farming, which has dramatically boosted interest in the crop.
At the front of the room was a small display that was far less appealing, a pomegranate whose seeds were blackened, a casualty of “black heart disease.”
Those who attended the event presented by the University of California saw and heard the good, bad and ugly of the pomegranate industry — the diversity in colorful fruit, the insects that can cause a lot of damage and fungi that can make juice or fresh fruit unpalatable.
A need for sanitary orchard practices, though not orchestrated by the speakers, emerged as one area of consensus. In short, leaving weeds, prunings and rotting fruit can open the way to unwanted infestations.
The worst insect pest in pomegranates is the omnivorous leaf roller, said Walt Bentley, a UC entomologist. “Weedy areas can be a key source,” he said, recounting his observation of a weedy orchard floor where mustard abounded and infestation was at 60 percent.
“If you’re not monitoring for it, you’re going to get stung,” Bentley said, recommending that pheromone traps be used in mid-February to attract the pest.
The cautionary words about weeds were echoed in a later talk by Claude J. Phene, a soil scientist and former director of the U.S. Department of Agriculture’s Water Management Research Laboratory in Fresno.
He pointed out that use of sub-surface drip resulted in less weed growth than use of surface irrigation, meaning it’s less likely the orchard “would store pests.” Moreover, he said, the weeds use more water and nitrogen.
Bentley warned of another pest, the katydid that can overwinter in old leaves. “It’s good to blow the leaves to the center and destroy them,’ he said, adding the pest can be controlled with the use of Success.
The katydid leaves “ice cream like scoops” into fruit, and Bentley said he has seen damage jump from 1 percent to 20 percent in just 10 days.
Bentley also cautioned against using sprays that could take out natural predators for other pomegranate pests, among them the whitefly.
“The ash whitefly will eat you alive if you take the parasite away,” he said.
Ants can protect some pests against predators, and Bentley recommends keeping them off the crop with Amdro Hydramethylnon.
Bentley cautioned against a “one-size-fits-all” approach to treating for pests in pomegranates, saying that more damage can be acceptable for the juice market than for fresh sales.
He said some pests can migrate from other crops, for example the navel orangeworm that can move from pistachios into pomegranates. Again, he recommended removal of old fruit that can harbor the pest.
Themis Michailides, a UC plant pathologist, said removing fruit can also get rid of overwintering fungi that can cause problems such as Pilidiella granati rot that affects the rind as well as the fruit’s interior.
He said botrytis stem decay, which can develop in cold storage, can be avoided if care is taken when picking fruit, clipping rather pulling the fruit and removing the stem.
With research paid for by Paramount, Michailides has been studying diseases that include “black heart,” an infection from Altenaria fungi that turns the inside of fruit black while leaving the outside appearing normal.
It’s an insidious disease because a single damaged fruit can contaminate others juiced with it, and if the fruit is sold fresh it’s obviously not received well even if it’s limited to a few pomegranates.
Another similar problem is caused by Aspergillus rot, though it is dry and powdery.
The work by Michailides is seeking to determine just when and how “black heart” infections occur, and early indications are that they happen when the crop is at full bloom. Other entry points into the fruit itself, he said, can be holes made by insects or by thorns of the pomegranate tree.
Michailides said no fungicides are registered to combat the disease, but in the laboratory effective treatments have been done with fungicides that include Pristine.
He is also studying a problem termed “tree decline” in which trees turn yellow and leaves thin, resulting in dead branches. Michailides said it’s possible that herbicide damage opens the way to spread of various fungi that ultimately can kill a tree.
The display of various varieties of pomegranates was presented by Jeff Moersfelder, greenhouse manager for the USDA’s National Clonal Germplasm Repository at UC Davis.
Moersfelder talked of annual tastings of pomegranates held in November and resembling wine tastings.
“They range from sweet to tart,” he said.
And not all the fruit arils are red. They include a yellowish seed from a variety called Haku Botan. Still, Moersfelder said, “red sells” and some alternately colored varieties might do better in a farmers market setting where tastings can be done.
He began his presentation with soft seeded types best suited for the fresh market, then proceeded to types that have harder seeds and are better aimed at the juice market.
One, the Parfianka, was termed “balanced for sweet and tart” and “excellent for fresh eating and juice.”
“It’s a favorite at tastings,” Moersfelder said.
He said the Wonderful variety amounts to about 90 percent of the market in California, adding that production was down about 30 percent for Wonderful this year. He said the fruit was not as sweet this year, likely because of cooler temperatures during the growing season.
Moersfelder said the Kara Gul has the darkest seeds and “readily gets heart rot.” He recommended researchers study it because of its heightened vulnerability.
He also showed slides of several ornamental varieties of pomegranates and one dwarf variety.
The meeting closed with comments from Maxwell Norton, UC farm advisor in Merced County. He said data from county pesticide registrations showed these acreages for five counties “with substantial planted acres of pomegranates.”
Kern County, 13,481 planted acres.
Fresno County, 5,744 planted acres.
Madera County, 5,057 planted acres.
Kings County, 4,132 planted acres.
Tulare County, 3,324 planted acres.
Norton also distributed a letter from the UC Cooperative Extension office in Merced asking for help in calling attention to cutbacks in staffing of farm advisors statewide.
“A few counties are not being staffed at minimum levels,” it read. “Madera County, for instance, is one of our nation’s major agricultural producers but they are down to one full-time advisor. Fresno County, the nation’s leading tree fruit county has no tree crop advisors. Kern County, the nation’s top almond producer has no almond advisor. This sad list goes on and on.”