| | Air movement within an orchard or planting can significantly impact commercial fruit production. An excess or lack of air movement can result in physical or physiological damage to sensitive plant parts and impact yield and marketable quality.
Excess air movement
Wind is often associated with excessive amounts of air movement in a berry planting. High winds can break tree limbs, disperse straw and snow cover used for cold protection and disrupt field equipment (e.g. mulch, drip tape, etc.).
Excess air movement can result in physical damage to plants and fruit (chafing/rubbing, bruising, windfall), and prolonged exposure to prevailing winds increases the risk of desiccation. High winds accelerate water movement through crop plants, resulting in increased water use.
High winds can prevent or reduce pollinating insect activity. For example, honeybee flight is reduced when average wind speeds exceed 16 km/hr or gust above 24 km/hr.
Plantings should be oriented to compensate for prevailing winds and adequate shelterbelts should be in place. Slowing down air movement will prevent damage (breakage, physical contact between fruit, etc.) and can increase snow accumulation. One metre of height (protection) will provide 10 metres of sheltered area.
Inadequate air movement
While too much air movement can be problematic, no air movement is equally undesirable. A lack of air movement can result in a build up of disease and insect pests, an increase in relative humidity, and an increased risk of frost damage.
Fields and orchards should be oriented to allow some air drainage within the planting, so that cold air does not settle at night and damage emerging flowers and sensitive plant parts (e.g. Saskatoons). Fields should follow the contour of the land. Planting on a slope of 1 to 5% will allow a sufficient amount of air drainage and reduce the risk of frost injury.
Shelterbelts should not completely restrict airflow. A build up of humidity can accelerate disease and insect development. Leaving some gaps in the shelterbelt will reduce problems due to excess air movement, while allowing some airflow and ventilation of the planting.
Inadequately pruned plantings can result in elevated disease levels, as humidity and temperature can build up within the microclimatic zone of the tree canopy without sufficient air movement.
Air movement and ventilation should be maintained throughout all plantings. Proper consideration should be given when planning or establishing a new planting.
Prepared by Robert Spencer, Alberta Ag-Info Centre, Alberta Agriculture and Forestry. |
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