Johnny Starling, Nichols Farms general manager, hopes to start shaking pistachio trees in the second week of September — but right now, he’s not sure how many will get a second shake.
“The majority of our mature trees have a lighter crop than last year,” he says of the company’s 1,650 acres, most of which are located in western Tulare County and eastern Kings County, with the rest on the West Side of the San Joaquin Valley near Coalinga.
“From what I’ve seen and heard, growers on the West Side have a heavier crop than we’re seeing in our orchards,” he says. “We have some variation in uniformity that may have been caused by weather during bloom.”
His big concern now is an increased threat from navel orangeworm (NOW). “We’ve already seen them when almond hulls started splitting,” he says. He started pre-harvest treatment for NOW in late July.
With the likelihood of a smaller crop this year, the impact of worm damage on quality and profits will be that much greater, Starling says.
The problem stems from difficulties with orchard sanitation this past winter. Shaking almond and pistachio mummies, which harbor overwintering NOW navel orangeworm larvae, was next to impossible. “We just couldn’t get the machines to shake them all off,” he says. “Also, in some orchards we needed to send a pole crew through to hand-knock them to the ground. It was very frustrating.”
Even though he used flail mowers to destroy mummies on the ground, dry winter weather slowed rotting of those nuts. In most of the orchards he was able to winter flood irrigate, not only to build up the water reservoir but to also to help rot mummies. Normally, he sprays for NOW about three times per year. If a delayed harvest runs into the fall flight of the moths, he’ll treat again, if needed.
That brings up an issue that has come to the forefront in the past few years: maximum residue levels (MRL). Countries will reject nuts if pesticide residue levels exceed their established maximum. Sometimes, he says, that can occur even when a registered pesticide is used far outside of the pre-harvest interval (PHI). For example, a material could be applied 21 days out, versus up to the 14-day PHI listed on the label.
“You want to use a gangbuster material to control the insects, but then you can have a potential MRL problem,” Starling says. “And, an insecticide’s MRL can vary from one country to another. This is just one more thing to worry growers and processors.”
So far, fungal disease pressure seems to be under control with the farm’s standard fungicide program. Although he usually sees some botrysphaeria and lower limb dieback in his orchards, his main threat, year in and year out, is alternaria.
A high temperature, combined with irrigation, causes humidity levels in an orchard to skyrocket and increases the threat of alternaria by creating an ideal environment for the disease-causing fungi to thrive. Starling manages that problem by shortening and alternating irrigation runs.
Since a light production year should reduce stress on his trees this season, he is cautiously optimistic about controlling the alternaria pressure. “In anticipation of a large crop next year, we will be doing a number of things to control the disease this fall,” he says.
One is running a chisel down every other row of trees, about a foot or so out from the drip line, to a depth of 30 inches or more, to reduce humidity in the orchard by improving drainage. Another is to improve soil structure and reduce levels of harmful salts by encouraging deeper penetration of gypsum, which Starling sidedresses along the drip lines.
He tried chiseling last year on 40 acres, based on results of University of California trials and the experience of growers who have done the practice. It root prunes, but it also encourages new root growth.
“This worked well, and it doesn’t seem to have hurt the trees,” Starling says. “We’re going to try it again this fall in some other fields. If it continues to show good results, we plan to continue doing it on a rotation basis.”