modifications and additions to high tunnels for improved environmental control
TRANSCRIPT
Jason McAfee
Curt Rom, Luke Freeman, Heather Friedrich, Spencer Fiser, Julia Stover
Donn Johnson, Barbara Lewis, Jennie Popp, Elena Garcia
Modifications and Additions to High Tunnels for Improved Environmental
Control
Background
High Tunnels are being studied and used for• Environmental protection
• Freezes, frosts, rains• Season extension of berry crops
• Advance the spring crop• Extend the fall crop
• Pest exclusion
The Need for High Tunnel Modifications/Additions
Temperature Management• Appropriate passive heating and cooling; sidewall, doors, and ventilation• More heat accumulation within appropriate temperature range in late winter and early
spring to promote early bloom and harvest• More heat accumulation within appropriate temperature range in late fall into early
winter to extend harvest• More protection in early spring and late fall to protect flowers/fruit• Reduce heat in the summer months; Cooling options for late summer months• Exclusions for pest control
Sub-studies for Potential Tunnel Modifications/Additions to Extend, Protect Crops1. Tunnels in Tunnels (TnT)
• Build temporary TnT in order to provide additional environmental modification of the tunnel system in spring and fall to provide more heat accumulation and retention
2. Summer Shading • Apply shade over plant canopies to reduce heat stress and potentially delay
flowering in primocane fruiting blackberry and raspberry
3. Overhead Mist Systems (preliminary results)• Install overhead mist lines as an add-on to existing irrigation line to help cool
during severe heat
4. Screening to reduce insect pests
Spring Frosts by Region
One single layer of poly provides one hardiness zone of protection
Source: www.hightunnels.org
Sub-study 1. Tunnels in Tunnels (TnT)
Research and Objectives• Spring Production Systems – Floricane berries
1. Increase heat unit accumulation to advance the crop2. Provide increased frost/freeze protection during freezing
events during early season bloom – protecting flowers
• Fall Production Systems – Primocane berries1. Increase heat unit accumulation to maintain flowering
longer through the season2. Increase heat unit accumulation to sustain fruit
maturation3. Provide increased frost/freeze protection during freezing
events during fruit ripening – protecting fruit
Effects of TnT on Spring ‘Natchez’ Blackberry Yield
6/13 6/18 6/23 6/28 7/3 7/8 7/13 7/18 7/230
2000
4000
6000
8000
10000
12000
14000
16000
18000
2013
TNTHTFD
Date
Cum
ulati
ve Y
ield
(g p
er 1
0ft p
lot)
19,363 lbs/A
15,549 lbs/A
3,766 lbs/A
N=3
5/26 6/5 6/15 6/25 7/5 7/15 7/250
5000
10000
15000
20000
25000
2014
TNTHTFD
Date
Cum
ulati
ve Y
ield
(g p
er 1
0ft p
lot)
10,030 lbs/A
22,897 lbs/A
28,334 lbs/A
N=3
Effect of TnT on Spring ‘Natchez’ Blackberry Quality
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
Berry Weight (g)
Treatment
gram
s
N=3
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
01020304050607080
Marketable Yield (%)
Treatment
%
N=3
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
9.0
9.5
10.0
10.5
11.0
11.5
12.0
Soluble Solids
Treatment
brix
N=3
2013 2014
TnT Study Seasonal Summary
Spring• TnT has potential to increase yields 1-2 weeks earlier than HT, 2-3 weeks earlier than field
• Growers may want to consider having a combination of both TnT and HT when considering windows of production in spring
• Both TnT and HT protect the crop during poor weather conditions such as wet springs, late frosts
• TnT can limit pollination
• HT significantly increased berry weight across two growing seasons, TnT increased for one
• TnT and HT both significantly increased marketable yield percentage compared to field both seasons
• Field showed significantly greater sugar content in both seasons
• Adequate pollination and excessive daily temperatures have been limitation to TNT
• TNT requires additional management and labor
Effects of TnT on Fall ‘Prime-Ark 45’ Blackberry Yield
7/20 7/30 8/9 8/19 8/29 9/8 9/18 9/28 10/8 10/18 10/280
1000
2000
3000
4000
5000
6000
7000
2014
TNT
HT
FD
Date
Cum
ulati
ve Y
ield
(gra
ms p
er 1
0ft p
lots
)
= ~7,446 lbs/A
= ~7,030 lbs/A
= ~4,672 lbs/A
*lbs/A calculated at 8 ft row spacing N=3
8/14 9/3 9/23 10/13 11/2 11/22 12/120
2000
4000
6000
8000
10000
12000
2013
TNT
HT
FD
Date
Cum
ulati
ve Y
ield
(gra
ms p
er 1
0ft p
lots
) = ~12,308 lbs/A
= ~11,889 lbs/A
= ~7,090 lbs/A
*lbs/A calculated at 8 ft row spacing N=3
Effect of TnT on Fall ‘Prime-Ark 45’ Blackberry Quality
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Berry Weight (g)
Treatment
gram
s
N=3
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
01020304050607080
Marketable Yield (%)
Treatment
%
N=3
FD HT TNT FD HT TNT2013 2013 2013 2014 2014 2014
7.0
7.5
8.0
8.5
9.0
9.5
Soluble Solids
Treatment
brix
N=3
TnT Study Seasonal Summary
Fall• TnT and HT significantly increased yield by ~40% for an extended fall season
• TnT and HT significantly increased yields on average 30-40% for a short fall season (early frost)
• TnT and HT showed increased berry weight although variable between seasons
• HT significantly increased sugar content for both growing seasons, TnT showed greater than field in one season
• TNT requires additional management and labor
TnT Schematic and Addition of Heating
Methanol chafing dish burners1/50sqftBurn 6-7 hrs
Effect of high tunnel and tunnel in tunnel (TnT) on daily average temperature over a 1 month period October-November, 2013.
10/25
10/26
10/27
10/28
10/29
10/30
10/31
11/111/2
11/311/4
11/511/6
11/711/8
11/911/1
011/1
111/1
211/1
311/1
411/1
511/1
611/1
711/1
811/1
911/2
011/2
111/2
211/2
311/2
411/2
5-10
-5
0
5
10
15
20
25
Field High Tunnel TnT
Time
Tem
p oC
10/25
10/26
10/27
10/28
10/29
10/30
10/31
11/111/2
11/311/4
11/511/6
11/711/8
11/911/1
011/1
111/1
211/1
311/1
411/1
511/1
611/1
711/1
811/1
911/2
011/2
111/2
211/2
311/2
411/2
5-10
-5
0
5
10
15
20
Field High Tunnel TnT
Time
Tem
p oC
Effect of high tunnel and tunnel in tunnel on daily low temperature over a 1 month period October-November, 2013.
Heating No Heating
7 degree savings
5 degree savings
3 degree savings
Effect of high tunnel and tunnel in tunnel on ambient temperature difference over a 1 month period October-November, 2013.
10/25
10/26
10/27
10/28
10/29
10/30
10/31
11/111/2
11/311/4
11/511/6
11/711/8
11/911/1
011/1
111/1
211/1
311/1
411/1
511/1
611/1
711/1
811/1
911/2
011/2
111/2
211/2
311/2
411/2
5-10
-5
0
5
10
Field High Tunnel TnT
Time
Tem
p oC
Heating
Heating
No Heating
Effect of high tunnel and tunnel in tunnel on temperatures over a 1 month period October-November, 2013.
Avg. Temp
(oC)Avg. Minimum Temp
(oC)Ambient Temp Difference
(oC)Freeze Exposure
(hrs/day)
Trt N Mean N Mean N Mean N Mean
TnT 96 14.3 aZ 96 6a 96 1.8 a 96 0.4 b
HT 96 12.1 b 96 4.3 b 96 0.1 b 96 1.2 ab
Field 96 10.6 c 96 4.2 b 96 0 b 96 2 a
Prob > F <0.0001 0.035 0.0004 <0.0001
Z Mean separation using LSD for comparisons and means followed by different letters are significantly different, α=0.05.
Effect of high tunnel and tunnel in tunnel on temperature with supplemental heating over a 48 hour period November 12-13, 2013.
0:002:00
4:006:00
8:0010:00
12:0014:00
16:0018:00
20:0022:00
0:002:00
4:006:00
8:0010:00
12:0014:00
16:0018:00
20:0022:00
-10
-5
0
5
10
15
20
25
30
35
40
Field High Tunnel TnT
Time
Tem
p oC
Heat Started
Daytime Daytime
Effect of high tunnel and tunnel in tunnel on ambient temperature difference with supplemental heating over a 48 hour period November 12-13, 2013.
0:002:00
4:006:00
8:0010:00
12:0014:00
16:0018:00
20:0022:00
0:002:00
4:006:00
8:0010:00
12:0014:00
16:0018:00
20:0022:00
-10
-5
0
5
10
15
20
25
Field High Tunnel TnT
Time
Tem
p oC
Heat Started
Daytime
Table 3. Effect of high tunnel and tunnel in tunnel on temperatures with supplemental heating over a 48 hour period November 12-13, 2013.
Avg. Temp (oC) Avg. Minimum Temp (oC)Ambient Temp Difference
(oC) Freeze Exposure (hrs)
Trt N Mean N Mean N Mean N Mean
TnT 6 15.1 aZ 6 1.3 a 6 7.1 a 6 0.5 c
HT 6 9.8 b 6 -3.1 b 6 2.8 b 6 4.3 b
Field 6 4.4 c 6 -5.8 b 6 0 c 6 7.7 a
Prob > F <0.0001 0.0009 <0.0001 0.003Z Mean separation using LSD for comparisons and means followed by different letters are significantly different, α=0.05.
TnT Study Summary
High Tunnels • Provide increased daily heat accumulation• Provide minimal night time heat conservation during a frost event• Provide some heat retention with the addition of supplemental heating
TnT • Provide increased daily heat accumulation over tunnels• Provide increased heat conservation during a frost event• Provide significantly more heat retention with the addition of supplemental
heating
Sub-study 2. High Tunnel Shading of Brambles
Research Objectives• Focus: Fall high tunnel study• Problem: poor flower formation and fruit
set due to heat in July and August• Solution: Delaying flowering and reducing
heat stress may have potential to increase marketable yields and extend harvest
• Shade structures placed over plant canopies of both blackberry and raspberry ~July 1 for 30 days to reduce heat stress and delay flowering
Effects of Shade on ‘Prime-Ark 45’Blackberry Yield
8/14 9/3 9/23 10/13 11/2 11/22 12/120
1000
2000
3000
4000
5000
6000
2013
No ShadeShade
Date
Cum
ulati
ve Y
ield
(g p
er 1
0ft p
lots
)
N=3
= ~6,809 lbs/A
= ~4,360 lbs/A
*lbs/A calculated at 8 ft row spacing
7/20 7/30 8/9 8/19 8/29 9/8 9/18 9/28 10/8 10/18 10/280
1000
2000
3000
4000
5000
6000
7000
2014
No ShadeShade
Date
Cum
ulati
ve Y
ield
(g p
er 1
0ft p
lots
)
N=3
= ~7,588 lbs/A
= ~5,604 lbs/A
*lbs/A calculated at 8 ft row spacing
Effects of Shade on ‘Prime-Ark 45’Blackberry Quality
NoShade Shade NoShade Shade2013 2013 2014 2014
0
1
2
3
4
5
6
7
8
Berry Weight (g)
Treatment
gram
s
N=3
NoShade Shade NoShade Shade2013 2013 2014 2014
0102030405060708090
Marketable Yield (%)
Treatment
%
N=3
NoShade Shade NoShade Shade2013 2013 2014 2014
6
8
10
Soluble Solids
Treatment
brix
N=3
Effects of Shade on Raspberry Yield
7/5 7/25 8/14 9/3 9/23 10/13 11/2 11/22 12/120
500
1000
1500
2000
2500
2013
No ShadeShade
Date
Cum
ulati
ve Y
ield
(g p
er 1
0ft p
lots
)
N=3
= ~2,471 lbs/A
= ~1,787 lbs/A
*lbs/A calculated at 8 ft row spacing
Effects of Shade on ‘Nantahala’ Raspberry Quality
NoShade Shade0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Berry Weight (g)
Treatment
gram
s
NoShade Shade0.0
10.020.030.040.050.060.070.080.0
Marketable Yield (%)
Treatment
%
N=3
NoShade Shade0.0
1.5
3.0
4.5
6.0
7.5
9.0
10.5
12.0
Soluble Solids
Treatment
brix
N=3
N=3
HT Shade Study Summary and Conclusions for Blackberry
• Shading with small structures ~1 month before fruiting showed no effect on reducing heat during flowering
• This may be different with whole tunnel shading.
• Shade with small significantly reduced flowering (not pollination)• Shade with small structures significantly increased cumulative yield on average
30-40% over two growing seasons• Shade with small structures increased berry weight in blackberry but could be
contributed to lower yields (further statistical analysis needed)• Shade with small structures significantly increased marketable yield percentage
in one growing season but not enough to justify cost and labor of shading• Shade had no effect on fruit sugar content
HT Shade Study Summary for Raspberry
• Shading ~1 month prior to expected yields significantly increased yield in ‘Nantahala’ raspberry by ~30% for one growing season
• Additional season of data needed to conclude effect on yield• Shade with small structures reduced overall raspberry quality by
significantly reducing berry size and marketable yield percentage• Shade did not have any effect on sugar content of raspberry• Reducing the amount of shade may have potential to increase fruit
quality• Shading shows potential for fall raspberry production
Sub-study 3. High Tunnel Cooling with Mister/Foggers
Research Objectives• Focus: Summer cooling of primocane fruiting blackberries• Problem: Screening tunnels results in excess heat retention and
accumulation. • Solution: Use misters or foggers to reduce plant stress and promote early
flowering for fall production of primocane bearing blackberries• Provide a means of cooling a tunnel enclosed with insect screening• Provide a better environment for flowering and berry development
• Attach water mister/fogger system into existing irrigation line• Mist the high tunnel at different time intervals to provide cooling during late
summer
Effect of Misters/Foggers on Max Air Temp of a High Tunnel
4:48 AM 7:12 AM 9:36 AM 12:00 PM 2:24 PM 4:48 PM 7:12 PM20.0
25.0
30.0
35.0
40.0
45.0
AmbientHT 1-hr MistContinuous MistHT No Mist
Time
Avg
Hour
ly T
emp
oC
Continuous Mist Period
1-hr Mist Period
N=4
Effect of Misters/Foggers on Max Air Temp of a High Tunnel
N=4
4:48 AM7:12 AM
9:36 AM12:00 PM
2:24 PM4:48 PM
7:12 PM9:36 PM
12:00 AM
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
36.0
38.0
40.0
42.0
44.0
46.0
AmbientHT 1-hr MistContinuous MistHT No Mist
Time
Avg
Hou
rly
Max
Tem
p oC
Continuous Mist Period
1-hr Mist Period
Effect of Misters/Foggers on Ambient Temperature Difference for Max Air Temp of a High Tunnel
N=4
4:48 AM7:12 AM
9:36 AM12:00 PM
2:24 PM4:48 PM
7:12 PM9:36 PM
12:00 AM
-12
-9
-6
-3
0
3
6
AmbientHT 1-hr MistContinuous MistHT No Mist
Time
Avg
Hou
rly
Max
Tem
p oC
HT Cooling Misters/Foggers Summary
• Misting for 1-hour had only a short term, and no long term significant effect on decreasing air temperature in a high tunnel
• Pulsing and repeated 1 mists was not tested
• Continuous misting significantly decreased air temperature in a high tunnel • Continuous misting wetted plants which could reduce berry quality or increase
disease• Leaf wetting may reduce mites
• Adjustments for this year’s experiment will include:• Decreasing mister/foggers output rate from 1 GPH to 0.5 GPH• Change from misters to foggers• Install battery operated timer for hourly intervals • Install vents for better air circulation
What have we learned?
• TnT can be a good tool for growers for enhancing and protecting seasonal bramble yields
• Growers should consider TnT as a tool for increasing early spring yields
• TnT has potential to be a good tool in the fall for protecting and extending harvest but will vary by year
• TnT is not outperforming HT in fall production
• HT can serve as a form of crop insurance for growers during seasonal occurrence of bad weather (wet springs, late frosts)
• Shading mid-late summer for fall primocane producing blackberry is NOT recommended
• Shading mid-late summer for fall raspberry production should be considered and additional seasons of data needed to confirm
• High tunnel cooling via mister/foggers has potential but will need further modifications and testing
Thank you!Questions?