Almonds should be harvested as soon as possible after they have matured to avoid quality loss and to minimize exposure to navel orangeworm and the subsequent potential for aflatoxin contamination.
After the crop is mechanically shaken to the ground, the nuts are raked into windrows and allowed to dry naturally, ideally to a hull moisture content that does not exceed 12%, or a kernel moisture content that does not exceed 6%, which can take anywhere from a few days up to two weeks.
A harvest sample taken after shaking and before the crop is windrowed will provide a progress report of that season’s IPM program, and will indicate what pests are in the orchard, which will, in turn, help determine the management activities for the next year.
Pickup machines sweep the windrows into carts or trailers for transportation to a huller/sheller facility. With the large crops of recent years, it has become more and more common for almonds to be stockpiled, either in the orchard or at the huller/shellers. To avoid insect damage, stockpiles should be monitored and fumigated if necessary.
Reducing Dust at Harvest
Improving air quality in California, especially in the San Joaquin Valley, is a major issue for all residents. Sweepers and pickup machines can create a significant amount of airborne particles (PM10). Almond Board of California–funded research has developed numerous methods growers can use to reduce dust at harvest, such as changing sweeper head height, reducing the number of blower passes, using metal tines, and reducing pickup machine speed. In addition, equipment manufacturers have made changes to the sweepers and pickup machines to reduce the amount of visible and PM10 dust emitted.
Everyone involved in the growing and harvesting of California Almonds should be aware that dust affects all who are present at harvest, including workers, neighbors and the community.
Below are three quick steps based on Almond Board-funded research findings, to reduce harvest dust.
Start with a clean orchard. Clean orchard floors make all dust management practices easier. Clean floors help you reduce suction fan speed on pickup machines. That can knock a lot of dust out of the process without losing harvest efficiency.
Plan your route. Take every opportunity to blow dust back into the orchard using the tree canopy as a natural filter. Note that the trees and their canopies can help capture dust before it reaches roads and homes. Plan your passes and travel direction to direct dust away from roads, homes and sensitive locations such as schools, hospitals and day-care centers. If you are near a busy road, consider placing traffic signs to warn motorists of harvest activities.
Go slow. Taking almond harvester ground speeds down a notch is a big help with dust reduction. A pickup speed of 1.5 miles per hour cuts dust by 50% compared to 3 miles per hour. Note how conditions change from orchard to orchard and from early to late harvest. Adjust ground speed to match conditions. In loose soil conditions, slower ground speed lets gravity do more of the work by separating dirt from the crop meaning harvester fans produce less dust.
Maintaining California Almonds that are stockpiled requires careful management to avoid contamination and damage that can reduce kernel quality and lead to food safety concerns. The key issues in stockpile management are moisture and temperature.
The following documents provide guidelines for managing moisture in the stockpile and minimizing concealed damage that can result from harvest rains and excess moisture.