Weather Risks: Strategies
to Mitigate the Risk of Insufficient Moisture
Table of Contents
For more information
- What it is
- When it occurs
- Where it occurs
- What can you do
This is the 2nd in a series to help 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.
Insufficient moisture is one of the main weather risks for tree
fruit growers. Access to water during important physiological
stages of tree and fruit growth is required for optimal performance
of fruit crops. Shortage of moisture during critical periods of
crop growth and fruit development affects both yields and sizing
of produce, affecting the volume of production and average price
of fruit. The trend to plant high density orchards has intensified
this effect. With erratic weather patterns increasing, availability
of water is becoming more critical for growing quality fruit.
What it is
Fruit trees need water to grow, maintain tree health, and produce
quality fruit. Insufficient moisture can cause: reduced growth,
shoot dieback, reduction in fruit size, reduced tree establishment
(young trees), negative impacts on fruit quality, reduction in
fruit bud production (and crops in subsequent years), nutrient
deficiencies, increased winter injury, increase in biennial bearing,
and increase in physiological disorders (bitter pit). Access to
water can keep trees growing through drought periods and increase
their resistance to stress factors.
When it occurs
Insufficient moisture can occur anytime during the growing season
when the tree needs moisture. Critical periods for moisture include
bloom, seed set, fruit sizing, fruit bud initiation, fruit ripening
and tree hardening. Information on determining irrigation needs
for fruit crops in Ontario can be in the OMAFRA factsheet, Monitoring
Soil Moisture to Improve Irrigation Decisions. Information on
the use of irrigation in agriculture can be found on the OMAFRA
Where it occurs
Dry conditions can occur in orchards across Ontario, but the effects
are worse on sandier soils with low-water holding capacity (eg.
low organic matter). Hot temperatures will exacerate the problem
due to increased evapotranspiration losses from the trees. Peaches
and nectarines are more vulnerable to insufficient moisture, as
are trees on dwarfing rootstock that have limited rooting area (eg.
apples on M9 size rootstock, sweet cherries on Gisela). Intensive
orchard systems with trees planted at higher densities have competition
between trees and will need supplemental water.
What can you do
Some of these potential mitigation strategies may help reduce or
eliminate damage due to insufficient moisture:
- 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.
- Supplemental irrigation:
When properly applied, both trickle and overhead irrigation will
reduce tree stress, increase fruit size, quality and yields. Trickle
irrigation is more expensive to install and is best installed
when the orchard is planted, but is easier to use when needed.
It can also be used to fertigate. Overhead systems require extra
labour to move equipment, and work best if permanent header systems
are installed for easy access to water. Trickle irrigation is
also more efficient in water use than overhead irrigation which
loses more water through evaporation. A Permit to Take Water is
needed if more than 50 000 L/day are used per day, as well as
a dependable water source that should be monitored for quality.
There are maintenance costs and costs of water to consider.
- Under-tree mulch: These
mulches can have the same result as irrigation, because they conserve
soil moisture, cool the rooting zone, and improve fruit size,
quality and yield. Mulches can provide nutrients and may host
beneficial insects, but are also attractive to rodents. Mulch
materials may be expensive, not easy to source, and likely need
re-application over time. In some cases, they may encourage late
growth of trees and winter injury.
- Add soil organic matter before planting:
Adding manure, compost, cover crops, straw, mulch or
any organic matter before planting will increase the water-holding
capacity of your soil. There is a cost to either purchasing materials
or growing it as a cover crop, but it can improve tree growth,
provide nutrients for the tree, and add resilience in the event
of a dry season.
- Build additional water storage:
Structures to store water available in the off-season may be expensive,
but well worth it in critical dry summers. A well-designed structure
is needed, and access for livestock and the public should be restricted
to ensure safety. Be sure your insurance company is aware of your
Growing quality fruit in today's intensive plantings is an increasing
challenge with changing weather patterns, increasing evapotranspiration
in summer's heat, and reduced rainfall. Growers need to ensure that
water is available during critical periods in tree growth and fruit
development. Access to water has become more important in producing
high volumes of high quality fruit for today's markets.
For More Information
For more information:
Toll Free: 1-877-424-1300