Stone Fruit Update

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