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.
Sweeper heads should be set at the manufacturer’s factory level so that wire tines are 0.125 inch off the ground. If set too low, dust from the pickup is increased substantially. Wire tines without rubber flaps on sweeper heads can reduce dust, particularly on softer soils.
Adjusting the blower spouts to match the unique conditions in the field can reduce blower passes. Adding an optional berm brush can also help minimize blower passes under many conditions.
Harvester ground speed should be reduced depending on field conditions. In orchards with loose soils, slower ground speed allows gravity to drop dirt so that growers don’t have to depend solely on fans to do it.
Under clean orchard conditions, suction fan speed can be reduced on pickup machines to dramatically reduce dust in the field without loss of harvest efficiency.
When operating near roads or homes during harvest, use the trees as a natural filter by blowing rows close to the edge into the orchard to allow dust to filter and settle out.
Stockpiling and Concealed Damage
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.