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- There is expanding interest in pomegranates that cover more than 30,000 acres of California and have a $115 million farm gate value in just Kern County, home to Paramount Farming, which has dramatically boosted interest in the crop.
- Growers and consultants were told 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.
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.
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.