Weather Damage

Hail damage depending on the intensity of the storm will generally cause injury primarily in the upper canopy. Damage symptoms include: leaf shredding and stem bruising, stem and leaf-stalk kinking (i.e. sharp bending), stem and leaf-stalk breakage and loss of stem tops and leaves.

Within a few days recovery can take place. Kinked stems right themselves by "goose-necking" from the kinks. Where stem tops and leaves are severely damaged or lost, auxiliary branch development took place at nodes below the damaged area. Auxiliary branches quickly produced inflorescences. Seed yields would be below potential but depending on the time of year and stage of the crop may not be as severe as first might be expected. Plants that are kinked over may right themselves and produce seed but may cause a harvesting problem because they will be below the harvesting level and cannot be captured.

All varieties will have a range of male only plants that do not produce seed. These should not be included in plant counts when establishing yield estimations as they produce pollen only and no grain.

Stalk Breakage

Hemp grows very quickly (Chart 7) in the early part of the season. During this elongation period, the fibre in the stalk is not particularly strong. Strong winds and rain during this period can cause the crop to lodge or worse, break the stalks. As with hail damage the plant will strive to recover. The head will kink and continue to grow upwards. In the fall there will be a wide range of head height which makes it very difficult to be able to harvest the entire potential yield.

Excess Moisture

Excessive rainfall and saturated soil conditions that persist for several days are very detrimental for hemp development. Hemp plants turn yellow and cease development -- the most severely affected die. As the soil drains, some plants resume growth, but a poor, yellowish, stunted and non-thrifty condition will persist throughout the season. Many fields in 2004 and 2005 suffered from these conditions. As a result stands were poor, weed problems were prevalent and yields were low.