Dealing With Severe Weather in Horticulture Crops - Frequently Asked Questions

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 Summer storms can cause a lot of damage to horticulture crops, with high winds, excess rain, hail or other weather extremes. These can result in losses ranging from minor losses (a few leaves lost here and there, with minor yield effect) to complete crop loss. Damage can be in the form of physical damage to plants, that causes reduced productivity, yield and quality, or may result in an increased incidence of disease. While producers cannot prevent storms and the conditions associated with them, there are sometimes things that can be done to minimize the impact of the events.

Excess water is often a problem with summer storms. When water falls rapidly, in high amounts, gradual infiltration into the soil is virtually non-existent. Water runs off and accumulates in low-lying areas. Saturated or flooded soils can increase the incidence of root rot. Producers should attempt to remove excess water from the fields, if possible, usually through pumping. Removal of excess water allows the soil to return to a state of equilibrium and reduces the damage to plant roots. Producers must also deal with the conditions that remain after the water has been removed. As water moves rapidly into and then out of a soil profile, mobile nutrients such as nitrogen are removed, often resulting in a deficiency situation. Producers must estimate the amount of nutrients that may have been lost and determine the needs of the crop. A supplemental application of nitrogen may be required, either through fertigation or a broadcast application.

While excess water can be a significant problem in fields, dealing with a small flooded area should not affect the management of the overall crop. Producers should attempt to provide all that is needed for the greater area, while minimizing the effect of the smaller area. This would include appropriately timed irrigation applications, nutrient applications, or harvest timing.

Hail can cause severe damage to crops, depending on the size of the hail, the duration of the event, and the growth stage of the crop. Producers must determine the extent of the damage, in terms of leaf loss or physical damage. They should also consider the weather following the hail. If growth conditions are good following hail, and there is sufficient time for crops to recover, the plants may compensate. Damage can result in increased disease incidence or a yield loss due to a reduction in leaf area.

In crops like potatoes, fungicide applications combined with an application of nutrients can help to reduce losses. Plants should also be managed to compensate for changes in maturity and quality factors.

All crops should be monitored for the development of diseases such as soft rot or other diseases associated with physical damage.

High winds can also cause damage in different crops. Nursery crops can experience limb or tree breakage, resulting in deformed and unsaleable trees. Wind can also cause raspberry canes to be snapped off or abraded by contact with other canes (increase in disease infection). Wind-blown particles can cause superficial damage to various crops, which can reduce saleability. Wind, combined with heavy rains, can also result in lodging in various crops, complicating harvest operations and lowering crop quality. In some cases, injury or damage due to wind can be minimized by additional supports (e.g. trellises in the case of raspberries). Shelter can also reduce damage due to wind-blown particles.

Lightning can damage horticulture crops, although the frequency of occurrence is fairly limited. Damage to mature trees might be more common, resulting in tree death. Lightning strikes in fields usually produces a circular area of dead or dying plants.

Other extremes
Sometimes summer storms result from rapid shifts in temperature. If temperatures drop rapidly to very low temperatures, cold temperature or chilling injury can occur. This is more common in spring or late summer, and can be dealt with using frost protection irrigation or microclimate modification.

Prepared by Ag-Info Centre, Alberta Agriculture & Forestry

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For more information about the content of this document, contact Robert Spencer.
This document is maintained by Brenda McLellan.
This information published to the web on July 15, 2005.
Last Reviewed/Revised on August 20, 2018.