By Kathryn Carter, Fruit Specialist, OMAFRA and John Warbick, Engineer, OMAFRA
It has been a long cool start to spring, and we are seeing green tissue and pre-bloom stages in tree fruit this week.
Temperatures for this week’s forecast should not pose an issue with frost. However, as fruit tree development continues buds and blooms will become more vulnerable to frost. Frost damage will vary between orchards, cultivars, crops and stages of development. As flowers begin to swell and expand into blossoms, they become less resistant to freeze injury. Buds that develop slowly tend to be more resistant. The table below shows the average temperatures required to kill 10 percent and 90 percent of buds. Keep in mind that weather conditions preceding cold nights can affect bud hardiness. Prolonged cool weather tends to increase bud hardiness during the early stages of bud development.
Wind machines have been shown to provide protection during overnight frost events. However, some neighbours may be disturbed by the noise produced. Here are some neighbourly Best Management Practices for wind machine operation.
- Explain to neighbours living within 125 m of a machine how and why wind machines operate, consider providing a copy of OMAFRA factsheet (listed below).
- Consider creating an early warning system to remind neighbours about possible wind machine use. Give neighbours a 24-hour cellphone number to call.
- Set machines closest to the neighbours to be the last on and the first off.
- Be diligent operating wind machines on farms where you do not live, as you are not always there to hear if and how they operate.
- Use best management practices to determine when to start wind machines.
- Do not operate wind machines during high winds.
For more information on the use of wind machines refer to OMAFRA Factsheet 10-045 Wind Machines for Minimizing Cold Injury to Horticultural Crops: http://www.omafra.gov.on.ca/english/engineer/facts/10-045.htm
For other strategies to mitigate the risk of frost see: http://www.omafra.gov.on.ca/english/crops/facts/weather-frost.htm.
Pome Fruit - Apples
Apples | Silver Tip | Green Tip | 1/2 " green | Tight Cluster | First Pink | Full Pink | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -8.9 -9.4 -16.7 | -8.9 -7.8 -12.2 | -5.6 -5.0 -9.4 | -2.8 -2.8 -6.1 | -2.8 -2.2 -4.4 | -2.2 -2.2 -3.9 | -2.2 -2.2 -3.9 | -1.7 -2.2 -3.9 | -1.7 -2.2 -3.9 |
Pome Fruit - Pears
Pears | Bud Swell | Bud Burst | Tight Cluster | First White | Full White | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -7.8 -9.4 -17.8 | -5.0 -6.7 -14.4 | -4.4 -4.4 -9.4 | -2.2 -3.9 -7.2 | -1.7 -3.3 -5.6 | -1.7 -2.8 -5.0 | -1.7 -2.2 -4.4 | -1.1 -2.2 -4.4 |
Stone Fruit - Apricots
Apricots | Bud Swell | Bud Burst | Red Tip | First White | First Bloom | Full Bloom | In the Shuck | Green Fruit |
|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -- -9.4 -- | -5.0 -6.7 -17.8 | -- -5.6 -12.8 | -3.9 -4.4 -10.0 | -- -3.9 -7.2 | -2.2 -2.8 -5.6 | -- -2.8 -4.4 | -0.6 -2.2 -3.9 |
Pome Fruit - Pears
Pears | Bud Swell | Bud Burst | Tight Cluster | First White | Full White | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -7.8 -9.4 -17.8 | -5.0 -6.7 -14.4 | -4.4 -4.4 -9.4 | -2.2 -3.9 -7.2 | -1.7 -3.3 -5.6 | -1.7 -2.8 -5.0 | -1.7 -2.2 -4.4 | -1.1 -2.2 -4.4 |
Stone Fruit - Peaches
Peaches | Bud Swell | Calyx Green | Calyx Red | First Pink | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -5.0 -7.8 -17.2 | -- -6.1 -15.0 | -- -5.0 -12.8 | -3.9 -3.9 -9.4 | -- -3.3 -6.1 | -2.8 -2.8 -4.4 | -1.1 -2.2 -3.9 |
Stone Fruit - European Plums
European Plums | Bud Swell | Side White | Tip Green | Tight Cluster | First White | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -- -10.0 -17.8 | -- -8.3 -16.1 | -- -6.7 -13.9 | -- -4.4 -8.9 | -5.0 -3.3 -5.6 | -2.8 -2.8 -5.0 | -2.8 -2.2 -5.0 | -1.1 -2.2 -5.0 |
Stone Fruit - Sweet Cherries
Sweet Cherries | Bud Swell | Side Green | Green Tip | Tight Cluster | Open Cluster | First White | First Bloom | Full Bloom | Post Bloom |
|---|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -5.0 -8.3 -15.0 | -5.0 -5.6 -12.8 | -3.9 -3.9 -10.0 | -2.2 -3.3 -8.3 | -2.2 -2.8 -6.1 | -1.7 -2.8 -4.4 | -1.7 -2.2 -3.9 | -1.7 -2.2 -3.9 | -1.1 -2.2 -3.9 |
Stone Fruit - Tart Cherries
Tart Cherries | Bud Swell | Side Green | Green Tip | Tight Cluster | Open Cluster | First White | First Bloom | Full Bloom |
|---|---|---|---|---|---|---|---|---|
Old Temperature 10% Kill 90% Kill | -9.4 -17.8 | -4.4 -12.2 | -3.3 -5.6 | -3.3 -4.4 | -2.2 -4.4 | -2.2 -4.4 | -2.2 -4.4 | -2.2 -4.4 |