Monday, September 17, 2018

Almond Harvest a Nutty Time of the Year for Growers

The almond harvest is in full swing as summer gives way to autumn this week.

California almond growers are poised to set another record-breaking year, harvesting 2.45 billion pounds from more than 1 million bearing acres, according to predictions earlier this summer by the USDA’s National Agricultural Statistics Service. The haul is a 7.9 percent increase from 2017.

Field scout Jenna Mayfield points out growers were worried the winter freeze would reduce yields this year. However, that hasn’t been the case.

“There hasn’t been a lot of pest pressure this season,” Jenna says. “Some growers will be harvesting into late October.”

Sweepers often work larger farms first over smaller farms.
Jenna points out growers plant at least two different almond varieties for cross pollination and each variety will mature differently – thus an encore tree shaking.

In California, growers produce 30 different almond varieties – although 10 varieties make up 70 percent of the state’s production.  All varieties fall under three general classifications – Nonpareil, California and Mission.

Right now, growers aren’t ready to relax. There is a lot of work left to do. And there is a lot to worry about before the last nut is picked up and sent off to the processor.

Normally, after the almonds are shaken off the trees the nuts will remain on the ground to dry for about a week. Growers try to pick up the nuts as soon as possible to avoid pest damage. Jenna says the heat and humidity trapped under the orchard canopy can prolong the drying process on the ground, leaving the almonds vulnerable to pest damage.

Ants are a problem when nuts are drying on the ground.
Currently, some growers are grappling with ants parading around nuts on the orchard floor, Jenna says. The longer the nuts are on the ground to dry, the more ant damage can be expected. But these growers operate small orchards and must wait for equipment operators to schedule a sweeper to collect the harvested nuts. “The large operations either have their own harvesting equipment or take priority over the smaller farms,” Jenna explains.

Almond processors will grade the quality of harvested nuts.
Meanwhile, Jenna joins UC extension advisers in espousing the benefits of taking harvest samples. “How do you know the true effectiveness of your pest management program when 4-5% of damaged nuts may be removed by the harvest process?” Merced County UC Cooperative pomologist David Doll writes in an Almond Doctor blog post. “Collect nuts from the ground after shaking but before windrowing and pick-up.”

 For several years, Jenna has collected almond samples for growers. She will crack open the nuts to check for pest damage and report her findings to growers. These harvest samples will let growers know what pests are in their orchards and compare these results with the nut damage results from the huller. The information helps growers prepare next season’s orchard management strategy.

UC Integrated Pest Management recommends taking 500 nuts from each orchard block as a representative sample. Jenna tries to collect nuts quickly, trying not to leave them on the ground too long. Otherwise, ants might get to some of the nuts and skew the findings. 

Almond samples collected from an orchard.
Here is how UC Integrated Pest Management describes pest damage:
       * Peach twig borer (PTB) and navel orangeworm (NOW) often like to infest the same nut. But NOW bores into the nut and PTB doesn’t. The NOW damage will cover over the PTB damage. NOW damage is represented by webbing and powder-like remnants.
  •       Ant damage is evident by the big bites taken out of the kernel – like something took a miniature melon ball spoon and took a scoop out, according to Jenna.
  •     Leaffooted bugs will leave dark spots on the kernel.
  •    Peach twig borer leaves shallow channels and groves on the surface.
  •   The Oriental fruit moth also produces shallow channels and surface groves.
“Knowing the damage that occurs provides the ability to develop the most cost-effective way to manage orchard pests,” Doll writes in his post. “

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