Monday, June 24, 2013

In the Long Haul, Hull Split Timing is Critical in Almonds

 Tick tock, tick tock. Tick tock, tick tock.

While almond growers aren’t sitting idly by the clock, they certainly are playing a waiting game trying to figure out the timing of hull split, says our almond field scout Jenna Horine. So far, she hasn’t seen it arrive yet in various orchards in the northern San Joaquin Valley.
Almonds are experiencing rapid growth this season.

However, almond experts say the rapid growing season has accelerated the process and the start of hull split is likely to come this week for some growers, especially those with the early varieties. Normally, growers start checking for hull split in early to mid-July.

So how hard can it be to identify hull split initiation? The green hull starts to split, exposing the brown shell inside. Soon, it will be time for harvest.

Here is an unsplit almond.
It’s a little trickier than that. Says UC IPM: The exact timing of hull split initiation is complicated. Ripening does not occur simultaneously. It begins in the upper and outer most parts of the tree, in the southwest quadrant, later extending through the lower and inner sections (nuts at eye level will be less mature than those at the tree tops.) Almonds should be harvested when the hulls on 95 to 100 % of the nuts on the tree nuts on the tree have split.”

This photograph shows the initiation of hull split.
-  UC IPM photos
Of course, growers have to deal with those pesky pests. Determining the beginning of hull split is critical for integrated pest management and if a summer treatment for the dreaded navel orangeworm is needed. Applications are timed with start of hull split and NOW egg laying. Hull split also leaves the almonds vulnerable to peach twig borer and hull rot fungi.

These almonds are  at hull split.
Years of field trials have demonstrated the importance of timing sprays for nonpareils during the first 10 percent of hulls splitting, according to Walt Bentley, retired entomologist and UC IPM emeritus.  The later the spray timing, the poorer the insect control.  Over the past two years there has only been one orchard with greater than 2 percent damage.  Walt says your history of damage and this year’s mummy load is an indicator for the need of an insecticide application.  These sprays serve to reduce NOW numbers in the next generation (August to September).  The third generation is the one that produces significant levels of infestation.
Read more about how to identify hull split  at UC IPM online. You also get more information online about managing navel orangeworm.

Growers need to monitor for navel orangeworm.
During her field scouting rounds last week, Jenna found only one orchard dealing with mite issues, which could have been related to water stress. While the grower flood irrigated a week earlier, the water apparently didn’t go deep into the ground. The grower and his pest control advisor dug into the ground and found hard pan only five feet down. The recent hot weather contributed to the water stress, she says.

Meanwhile, field scout Carlos Silva says most alfalfa growers have completed their third cutting and left border strips to create a habitat for pests to stay out of nearby cotton fields. Cotton continues to progress well with no major lygus concerns at the moment.

This week, Carlos may start taking petiole samples to determine nitrogen levels in cotton plants. Nitrogen is an important nutrient for cotton production.


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