Title: The Southern Region Small Fruit Consortium Agent Training
1The Southern Region Small Fruit ConsortiumAgent
Training
2Small Fruit Freeze ProtectionPassive or
Alternate Methods
- Gerard Krewer
- Professor of Horticulture and
- Georgia Small Fruit Specialist
- Tifton, Georgia
3Note
- This presentation is offered for educational
information. Freeze protection is subject to
many variables. The author assumes no
responsibility for the use of this information in
freeze protection. - You are welcome to use these photos, but please
acknowledge their source.
4Todays Course Outline
- Winter freeze dangers
- Species sensitivity
- Methods of protection
- Spring frost and freezes dangers
- Species sensitivity
- Methods of protection
- Your suggestions and corrections are
appreciated! - Photo on right from Nick Vorsa
5Winter Freeze Protection
- This sections covers winter freeze damage
- This is can be a major problem in the upper
South. - Only an occasional problem in the lower South.
6Average Winter Lows
- Map of SE-photograph
- Winter lows
7Occasional Low Temperatures
- Jan 21, 1985
- Ga. mountains minus 20 F
- Middle Georgia minus 10 F
- South Central Georgia zero F
- Coastal Georgia 6 F
- Citrus killed to ground level
- Flower bud damage on peaches in middle Georgia
- Some muscadine cultivars damaged in north and
middle Georgia
8Dangerous Winter Temperaturesto Plants or Flower
Buds(photo from Nick Vorsa)
- Muscadines Below 5 degrees F?
- Plasticulture strawberries Below 10 degrees F?
- Wine grapes below minus 8 F?
- Blueberries Highbush below minus 15 degrees F?
- Rabbiteyes Below 0 F? Possible bush top die back
at minus 20 degree F - Kiwi Trunk damage below 10 F?
9Types of Injury
- Trunk / Arm /Branch
- Strawberry Crowns
- Flower buds- this is a healthy one-tissue will be
dark if injuried.
10Blueberry mid-winter damageNick Vorsas photos
11Winter Freeze Injury(photo courtesy of Nick
Vorsa, Ruters Univ.)
- Two danger spots
- 1. Exposed windy locations- Ground freezes,
plants lose water but cant replace it. - 2. Low elevations are often coldest-bud injury
and bark splitting may occur on some small
fruits. - Protected hilltops and south slopes are often the
best sites to avoid winter freeze injury.
12Passive Methods of Winter Freeze Protection
- Site selection (Hill sides)
- Species selection (Very important)
- Cultivar selection (Very important)
- Keep plants healthy (Do not over crop)
- Prune in late winter (5 degree hardiness
difference) - Trunk wraps (kiwi)
- Soil banking (citrus,etc.)
- Survey bud damage before pruning
13Crop Overview
14Cultivar Selection to Avoid Winter Injury on
Blackberries
- USDA Eastern Thornless are fairly cold hardy to
about minus 5-10 F (Chester, Hull, etc.) - Western trailing killed at 10 F (Marion berry,
etc.) - Arkansas cultivars are similar to eastern
thornless in hardiness (Indian cultivars)
15Muscadine Grape Cultivar Selection(photo from
VPI and NCSU grape guide)
- In marginally cold areas plant..
- Carlos (self-fertile-wine)
- Noble (self-fertile-wine)
- Nesbitt (self-fertile-fresh)
- Summit (female flowered-fresh fruit)
16Some areas of the SE are too cold for muscadines
and bunch grapes(photo from NCSU)
17Strawberry Cultivar Selection to Avoid Winter
Injury
- Matted row is normally hardy to minus 10 F or
below - Plasticulture cultivars
- Chandler is hardy to about 0-5 degrees F
- Carmine?
- Camarosa to??
- Camarosa line, best south of Macon, Ga. to
Charleston,SC?
18Blueberry Cultivar Selection for Winter Hardiness
- Northern Highbush is the most cold hardy
- High Chill Southern Highbush?
- Rabbiteye- Can be planted up to SE Va.
- Low chill Southern Highbush (Oneal in Indiana
will crop well about one in three years?)
19Muscadine Pruning
- Prune in late winter if winter injury is a
problem.
20Spring Freeze and Frost ProtectionInformation
from Carter, 1956
- Frost or hoarfrost-feathery ice crystals
- Black frost or dry freeze-below 32 degree F but
above dew point - Light freeze 29 to 32 degrees F
- Moderate freeze 25 to 28 degrees F
- Severe freeze 24 degrees F and lower
- Dr. Poling is proposing a change in terminology
- Lets get standardized
21Spring Freeze Dangers
- Preconditioning weather, low temperature
experienced, duration of freeze and bloom stage
has large effect. - Rough rule of thumb Open blackberry and southern
/ northern blueberry blooms killed at 28 degrees
F. Rabbiteyes at 29 degrees F (pistil damage),
strawberries at 30 degree F, grapes at 28-31
degree F (note that French hybrids, American
bunch grapes, muscadine will rebloom from
secondary and tertiary buds producing partial
crops or better)
22Freeze injury on vinifera grapes
- Often results in crop failure
- Photo from VPI and NCSU grape guide
23Rabbiteye Blueberry
Stage 4 Sandbur Stage
- Dangerous temperatures for rabbiteye blueberries
- Stage 4 24 F
- Stage 5/6 28-29 F
- Postbloom 29-30 F
Stage 2/3
Stage 5 Elongated But not open And Stage 6 Open
24Post bloom Freeze Damage
- Damage can occur at 28 to 29 degrees F
Note damage to top of fruit
Healthy
Damaged Note watermelon Stripes
25Mean date of last spring frostAll land is not
created equalfor spring freezes Note cold
pockets and warm pockets
26Ga. late date of 28 F in spring
27South Carolina-last date of 28 F in spring
28N.C. average date of last 32 degree temperature
in the spring
29Methods of Spring Frost and Freeze Protection
- Species selection
- Cultivar selection to avoid freeze damage
- Site Selection
- Orchard floor management
- Heating
- Protected culture
- Summer pruning
- Delayed winter pruning
- Overhead irrigation
- Wetting orchard floor
- Flooding
- Air movement
- Growth regulators
30Species Selection
- Approximate Bloom or Budbreak in South Georgia
- Strawberries mid-Feb. to late April
- Southern highbush blueberries early Feb. to
early March (varies with chilling requirement) - Rabbiteye blueberries early March to late March
- Blackberries mid to late March (varies with
chilling requirement-but also mixed buds-delays
bloom) - Muscadines late March to early April (low chill
high heat requirement for bud break)
31How Winter Chilling Effects Spring Bloom Dates on
Peaches?
- Middle Georgia 1000 chill hours, 3 days delay
for each 100 hours - South Georgia 700 chill hours, 7 days delay for
each 100 hours - N. Florida 400 chill hours, 10 days delay for
each 100 hours - Similar situtation on blueberries
Star 400 hours
Oneal 400 hours
FL86-19 V1 200 hours
Southern highbush blueberries
32Winter Chilling Map(rough estimate)
33Freeze Avoidance-Chilling Requirement Selection
- Blueberries vary from 100 to 1000 hours in
chilling requirement - Chilling satisfaction plus heat bloom
- Select cultivars with a chilling requirement
appropriate for your region
Tifblue 650 hours dormant
Climax 400 hours blooming
34However..
- The chilling requirement must be satisfied
- This is mainly an issue with peaches and
blueberries - For example Reveille blueberry in S. Ga.
- 800 hours in 500 chill hour winter, blooms late
and misses market window, poor leafing with small
berries
PEACHES
Chilling requirement satisfied-good crop
Chilling require- ment not satisfied- plucked
chicken look- Fruit abort
35Blueberries
- If you dont have overhead irrigation for freeze
protection do not plant cultivars less than 400
hours south on a line running from Atlanta to
Wilmington, NC - NHBgtREgtSHB order of bloom, but many exceptions
Northern high- bush
Low chill- Southern highbush
36Late Blooming Rabbiteyes
- Ira
- Brightwell (not so late, but some frost
resistance) - Powderblue
- Centurion
- Ochlockonee
37Radiation Freeze Control MethodsFreeze with
little or no wind
- If you go up a mountain it get colder
- However, during freezes an inversion layer
often forms- - Warm air above cold air
Warm air
Cold air
38Air Drainage
- Hill tops and south facing slopes are the warmest
during freezes - However, north slopes in the mountains may delay
bloom if plants are shaded - Often site selection is not an option
- Early blooming fruit may not be the best choice
39Spring Freezes
- High mountain effect-delays bloom on north side
of big hills or mountains - Important in mountainous areas, situation may be
different elsewhere - Hills-Hill top or south slope is warmest during a
freeze, often 4-5 degrees - Unexplained frost pockets-i.e. Grand Bay Creek
area, west Bacon pocket
- Johnson, et al 1968
- Last 28 degrees F
- Hill top, 754 ft. March 15
- SE slope,711ft. March 28
- Riverbottom,584 ft., April 12
- North slope, 724 ft., April 11
40Promoting Air Drainage and Mixing
- Cold air is heavier than warm air and will seek
the lower elevations - Cut gaps in timber about 75 feet wide every few
hundred feet to vent the field - If overhead irrigation for frost protection is
being used dont cut wind breaks on N,NW or W
41Lake Effects
- Large lakes can provide several degrees of
warming - Ocean effects
- Ocean effects may extend inward for up to 30
miles Atlantic fetch
42Orchard Floor Management
- Moist, bare compact soil is the best-close mow if
weedy - Compact bare soil verses high weeds
- As much as 4 degrees F colder during radiation
freeze - Balance moonscape with erosion control
- Organic mulches are cold!!
- Pine bark beds can be 4 degrees colder than bare
soil
43Return Stack Heaters
- Cost about 25 but may be available at low cost
from Florida - Burn about 6 gallons of diesel per night
- Up to 35-40 per acre are used with concentration
windward edge - Wind machine plus 15 heaters per acre works well.
44Small Fires
- Many small fires are needed per acre 20-40
- Candles used in Europe
- Large fires create chimney effect and bring in
cold air - 1 gallon fuel oil 14,000 BTUs
- 15 pounds of dry pine
- 10 pounds of charcoal
45Frost Dragon
- Propane heater that blows hot air
- Will provide several degrees protection in some
situations
46Row Covers
- Very successful on strawberries
- Covered in Dr. Polings talk
- Difficult to use on larger plants under windy
conditions without a frame - Working well in W.Va. For western blackberries.
Keeps plants from mid-winter dessication - Dr. Fumi Takeda
47Low Tunnels
- Low tunnels are often use in areas with low labor
cost for strawberry production
48High Tunnels
- Becoming extremely popular in major small fruit
producing areas - Used in combination with heat source during
severe freezes - Protects from rain as well
49High Tunnels on Blueberries
- Used in Spain and California to protect from
freezes and advance ripening
50Hail Mesh
- Hail mesh is commonly used in areas with hail
problems - Provides a few degrees protection
- Frost dragon plus hail mesh can be used together
51Wetting Orchard Floor Before a Freeze
- Moist, compact soil collects and releases more
heat than dry soil - Raises humidity in the field
- Not recommended on strawberries-succulent crop
52Flooding
- Commonly used in bedded citrus in flat woods in
Fla. - Has been used with success in Ga. blueberries
- Several degrees protection??
53Summer Pruning
- Delays bloom by one week or more
- Flowers form later and bloom later
- Southern highbush can be pruned about June 1 in
S. Ga. - Rabbiteyes can be pruned about Aug. 1
54Summer Pruning
- In high density blueberries in S.Ga.,up to 70 of
the canopy can be fall wood. - Bloom can be delayed several weeks on fall wood.
- Rabbiteyes, one week bloom delay is typical
- Benefits limited on rabbiteyes-cant be pruned
unit about Aug. 1 in S. Ga. - Limited fall regrowth
Fall wood-bloom delayed
Spring wood Blooming occurring
55Delayed winter pruning
- Pruning can be conducted up to full bloom on
peaches - Could also be used on blueberries
- Pruning the lowest chilling or most freeze
sensitive cultivars last. - Adjust crop load after spring freezes
56Blueberry Growth Regulators
- Fall ethephon for bloom delay on blueberry.
- Registered for use in Ga. and Ala. (not cleared
in other states) - Has worked well in Ga. on Climax and southern
highbush - Has not work in Michigan
- Gibberellic acid for freeze rescue
- Registered nationwide
- Very effective on processed berries
57Spring Freezes
- Dangerous temperatures for blueberries
- Stage 4 24 F
- Stage 5/6 28-29 F
- Postbloom 29-30 F
58Gibberellic acid for freeze rescue in blueberries
- Type 1 Damage Different flower and fruit tissues
freeze at different temperatures
CorollagtPistilgtOvulegtFlesh - Type 2 DamageTip of corolla may be damaged at
stage 4 or 5 and never open, preventing
pollination
Ovules or seed killed but flesh alive.
59Type One DamagePistil killed-prevents pollination
PiP
Pi
60Freeze Damage to Pistil
- Typically at about 29 degrees F
- Corolla shows damage
- Pistil girdled at base
- Flesh of berry alive
- Apply gibberellic acid just after the freeze
- Repeat 10 days to 14 days later
61Blueberry Flower Photo from Nick Vorsa
Slide from Nick Vorsa
62Type 2 Damage Freeze Damage to Tips of Unopened
Flowers
- Typically caused by temperatures around 26
degrees or lower - Ovaries are still hardy, but corollas are tender
- Wait about one week until flower moves into what
would be stage 5, then make first gibberellic
acid application
Brown tips
63Gibberillic acid freeze rescue responseGood for
processing berries
64Cryoprotectants
- Do any work?????????????????
- Please let me know
- Gerard Krewer
- Gkrewer_at_uga.edu
- 229-392-1388
65Foam
- Being tested on strawberries in some locations
- Photo from foam web site
66Whats working in the real world?
- Dont be afraid to be Dr. Doom
- Every farmer cant be a fruit grower-Maybe
vegetables or ornamentals are better?? - Overhead irrigation (very successful)
- Avoidance (very successful to successful)
- Orchard floor management (successful for slight
freezes)
67Whats working in the real world
- Strawberry Row Covers (successful on light or
moderate freezes if heavy weight) - Post harvest hedging on southern highbush
- Gibberellic acid on processing blueberries
(successful for light freezes at stage 5/6 or
moderate freezes at stage 4) - Fall applied ethephon for bloom delay (successful
in south Georgia- failed in Michigan)
68Crop Insurance
- Becoming more widely available
- Tom Earley will be seeking input on crop
insurance at the blueberry session. - Jeanne Lindsey with USDA crop insurance will be
speaking at the muscadine meeting
69Thanks To
- Dr. Tom Monaco- Director of the Southern Region
Small Fruit Consortium - Mr. H.C. Spivey and Southern Ag and Turf
- Mr. Giles Padgett-Wilkes and Point Source
Irrigation - USDA Risk Management
- American Agrifabrics
- Atmore Industries
- Others who sent samples