Identifying hull split is critical in an almond integrated pest management program. If summer navel orangeworm applications are necessary, they are timed relative to the beginning of hull split and the occurrence of egg laying.
Hull split also exposes nuts to peach twig borer invasion and hull rot fungi. The longer the nuts remain on the tree after hull split, the longer the interval that they are exposed to these invaders. Therefore, harvest your almond crop as early as possible to reduce the time it will be exposed to these pests and to avoid complications caused by early rains. If the threat of navel orangeworm is severe, the orchard can be harvested twice; once to remove the early ripening nuts and the second time to remove the later ripening ones.
The exact timing of hull split initiation is complicated. Ripening does not occur in all fruit simultaneously. It begins in the upper and outer 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 95 to 100% of the hulls have split.
Check for initiation of hull split:
- Check harvest timing for your variety. The start of almond harvest varies from year to year and district to district, but usually begins in early to mid-August.
- Check for the beginning of hull split in early to mid-July.
- Use pole pruners to cut small branches from the top southwest portion of 5 to 6 trees in the orchard and see if hull split has begun.
Once hull split initiation is determined:
- Continue monitoring trees until 95 to100% of the fruit at eye level are visibly split.
- Shake a few trees to determine if nut removal is satisfactory. If not, try again in a few days.
- Harvest blocks with poorest sanitation first.
 Unsplit almond |
 Initial separation stage |
 Deep V, unsplit stage |
 Almond hull split, less than 3/8 inch |
 Initial drying stage |
 Completely dry stage |