Higher yields, threat management key pistachio issues

Higher yields, threat management key pistachio issues

The California pistachio industry did not exactly dodge two bullets in 2014 – a drought and low chilling levels – but it was not mortally wounded either. The nearly 514 million pounds of pistachios harvested last year was the third highest total ever - exceeding estimates ranging from the low 400 million range to 500 million pounds. 

The California pistachio industry did not exactly dodge two bullets in 2014 – a drought and low chilling levels – but it was certainly not mortally wounded.

The nearly 514 million pounds of pistachios harvested last year was the third highest total ever and it exceeded estimates that ranged from the low 400 million range to 500 million.

 “People were quite shocked,” said Bob Klein, manager of the California Pistachio Research Board. “That’s not to minimize what some people experienced in their orchards.

“Overall, we did much better than expected but not as well as we could have.”

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Absent the two challenges, Klein said, acreage totals and the previous year’s crop pointed toward a harvest that could have been a whopping 650 million to 700 million pounds.

Klein opened the Statewide Pistachio Day in Visalia with a brief look at the shots fired across the bow last year and a forecast that this year that could be “not radically different than last year . . .  but pistachios tend to surprise.”

Keep the guard up

Other speakers at the first full-day conference for the annual Statewide Pistachio Day talked of ways growers can keep their guards up against some relatively new pests and diseases and others that have been around much longer.

Klein said one of the challenges this year could relate to the European Union defining phosphite, which is used in many orchards, as a residue. That’s significant because the EU takes 25 percent of the industry’s crop. Klein recommended checking with processors on the issue and seeking alternatives.

Jennifer Randall, an entomologist with New Mexico State University, talked of efforts by researchers – including some in the southern San Joaquin Valley - to get a handle on pistachio bushy top syndrome.

Randall said nearly 45,000 acres of pistachios - 2 million trees - planted on UCB-1 rootstock in California and Arizona from 2011-2014 showed symptoms of the disease that she and others traced to the bacterium Rhodococcus.

Growers confirm

At least two growers interviewed during a break between speakers said they have encountered the disease in their orchards. Jack Efird, who farms south of Fresno, said he wants to learn at what stage trees should be pulled. Rich Kreps, a Madera County grower and plant nutrition consultant, said he has had to pull out an orchard twice due to the disease.

Randall said researchers that include Elizabeth Fichtner, a University of California farm advisor in Tulare County, are looking at issues that include whether there is a cure for infected trees, whether it is safe to replant in the same holes from which infected trees were removed, and how likely bacteria is to be transmitted by farming tools that include pruning shears and grafting knives.

Symptoms include stunted growth, shortened internodes, swollen lateral buds, and atypical bushy growth. The symptoms may not be fully apparent until the second or third year.

Pistachio threats 

Themis Michailides, plant pathologist with UC Davis, talked of foliar and fruit diseases that are far from newcomers to the state.

He said Altenaria late blight can be addressed by changing irrigation practices (to use of drip), increasing orchard ventilation, and avoiding cover crops.

Michailides said Botryosphaeria, a fungus that kills shoots and clusters and reduces yields, can be spread by moving water, insects, birds, pollen and pruning equipment.

Older pistachio trees are most affected, pruning is important and bloom, spring, and summer sprays are needed. He said it’s best to spray before or after rains.

Nutrient management in pistachios was discussed by Patrick Brown, a professor in plant sciences at UC Davis. He said the topic takes on added importance as the state adopts requirements for nitrogen budgeting to cut down on nitrates in the groundwater.

Brown said nutrients are taken up in water “only by active roots on trees with leaves.” For efficiency’s sake, he recommended following “the four R’s” – applying nutrients in the right rate, at the right time, in the right place, and using the right fertilizer source.

He said leaf sampling is a good monitoring tool but not a good management tool.

Ramping up mating disruption

Management of Navel orangeworm (NOW) in pistachio is a perennial problem drawing the attention of people like Brad Higbee, director of entomology research for Paramount Farming Co.

Higbee said Paramount has ramped up its use of mating disruption to supplement pesticide applications and other practices to cut down on NOW damage. From 800 acres of almonds in which puffers were placed in 2009, the company has moved to between 35,000-40,000 acres of both pistachios and almonds where mating disruption is used.

Higbee said mating disruption is a “good fit” for orchards where current insecticide programs are not sufficient.

Over the years, the pheromone based puffers have become easier to use, said Candice Rogers, a Sutter account manager, at the company’s display booth. “You just turn on a switch and hang them in a tree,” Rogers said.

Better nut prices are helping drive grower interest in the mating disruption devices, she added.

Higbee said resistance by the NOW to pyrethroids is being gauged.

Monitoring techniques

David Haviland, a UC farm advisor in Kern County, said monitoring techniques can determine when best to spray for the NOW pest based on a formula that calculates degree days based on a “biofix,” an indicator of the development state for the insect.

He said spraying at hull split in late July or August should be a priority over other timings.

Several speakers discussed the need for sanitation – removal or destruction of mummies that can harbor the pest.

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