Weather Risks: Strategies to Mitigate the Risk of Insufficient Moisture

Table of Contents

  1. Introduction
  2. What it is
  3. When it occurs
  4. Where it occurs
  5. What can you do
  6. Summary
  7. For more information

Introduction

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 website.

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:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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 storage.

Summary

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
E-mail: ag.info.omafra@ontario.ca
Author: Leslie Huffman - Apple Specialist/OMAFRA; Kathryn Carter, Tender Fruit and Grape Specialist/OMAFRA
Creation Date: 05 February 2013
Last Reviewed: 05 February 2013