Weather Risks: Strategies
to Mitigate the Risk of Excessive Moisture
Table of Contents
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- What it is
- When it occurs
- Where it occurs
- What can you do
This in the 6th in a series to help Apple apple and tender fruit
growers in Ontario face many weather risks that can damage their
trees and crops. It is important for growers to recognize the
weather risks for their own location, and develop strategies to
reduce or eliminate the impact on their business operation.
What it is
Excessive rainfall, over-irrigation or poor drainage can cause
flooding, soil compaction and erosion in orchards. Excess moisture
may increase the incidence of: root rots, splitting/cracking of
fruit (eg. sweet cherries), diseases, winter injury, vegetative
growth, soil compaction, nutrient deficiencies and tree mortality.
Excessive moisture can also restrict root development resulting
in decreased yields and plant vigour, and makinges the trees more
vulnerable to tipping over due to high winds or heavy crop loads.
Unmanaged water runoff can result in sediment loading into streams
and open outlet drains having a negative impact on water quality.
When it occurs
Excessive moisture can occur anytime during the growing season.
It is common to have excessive moisture in the late fall or in spring
before budbreak, and luckily tree roots are most tolerant of flooded
soils at this time. However, strong weather fronts, including thunderstorms
or hurricanes can bring large downpours at any time. Sometimes,
consequentive rainy days of small amounts of rainfall will keep
the orchards wet enough to cause problems.
Where it occurs
Excessive moisture is one of the main weather risks for tree fruit
growers. Excess moisture can have a negative impact on tree health,
disease and susceptibility to winter injury.
What can you do
Some of these potential mitigation strategies may help reduce or
eliminate damage due to winter injury:
- Production insurance (PI):
Production insurance is purchased before the season, and can give
you peace of mind that at least some of your input costs will
be covered if your crop is reduced by insufficient moisture. Your
premiums will depend on the coverage you choose, your claim history,
and the yield potentials of your orchards. Over time, your premiums
can be reduced if you are lucky enough not to have claims. However,
some growers struggle with the premium costs (especially in their
start-up years or if they have claims) and the fact that PI is
not intended to fully cover your loss, either in yield or price.
There is also the problem of reduced coverage levels in the years
after your crop is reduced, due to the effect of the loss on your
long-term average yields. Also, spot loss insurance is not available,
so growers with multiple orchard sites may be penalized when good
yields occur on the non-damaged sites.
- Site selection: Avoiding
planting in low-lying areas or soils which may be prone to waterlogging.
Areas that are poorly drained due to ponding, compact sub-soils,
seepage from up slopes and high water table should be improved
prior to planting, or avoided. If choice of site is limited to
soils with one or more of these problems then attempts should
be made to improve the soil prior to planting.
- Drainage: Surface and
subsurface drainage can be used to manage water movement in vineyardsorchards.
Install tile drainage in the orchard and check tile in older orchards
to ensure they are working well. Heavier soils may need benefit
froma French drains (channels of gravel from the surface to the
tile drains) to improve drainage.
- Land preparation: Be aware
of surface water flow and grade the orchard to manage water and
prevent flooding. Heavier soils may need the application of gravel
to improve drainage.
- Compaction and erosion:
Traffic through the orchard with equipment under moist or wet
soil conditions can cause soil structure problems such as compaction.
After heavy rains allow soil to drain before driving through the
orchard when possible. Where possible select light weight equipment,
and reduce tire pressure to minimize compaction.
- Cover crops or orchard sod:
Cover crops and sod row middles can help to absorb moisture throughout
the growing season and may help trees or prepare for winter. They
also prevent leaching losses by tying up nutrients in organic
form over winter, and releasing the spring when the trees can
- Efficient use of irrigation:
Monitor soil moisture levels when irrigating to avoid excessive
Managing water in orchards is an increasing challenge with changing
weather patterns. Growers need to be prepared to deal with excess
moisture to ensure tree growth and fruit development.
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