Obj. 1A Hybrid Susceptibility to SCA: Do thresholds differ with ‘S’ and ‘R’ hybrids Sorghum – Sugarcane Aphid Research Exchange Meeting Dallas, TX January 3 – 4, 2017 Name Affiliation Trial Location David Kerns Texas A&M AgriLife Ext. Winnsboro, LA Nick Seiter University of Arkansas Monticello, AR Alana Jacobson Auburn Headland, AL Michael Brewer John Gordy Texas A&M AgriLife Res./Ext Corpus Christi, TX * Rosenberg, TX * Gainesville, TX * * Additional data partly financed by Texas Grain Sorghum Board
Transcript
Obj. 1A Hybrid Susceptibility to SCA:
Do thresholds differ with ‘S’ and ‘R’ hybrids
Sorghum – Sugarcane Aphid Research Exchange Meeting
Dallas, TX
January 3 – 4, 2017
Name Affiliation Trial Location
David Kerns Texas A&M AgriLife Ext. Winnsboro, LA
Nick Seiter University of Arkansas Monticello, AR
Alana Jacobson Auburn Headland, AL
Michael Brewer
John Gordy
Texas A&M AgriLife
Res./Ext
Corpus Christi, TX *
Rosenberg, TX *
Gainesville, TX *
* Additional data partly financed by Texas Grain Sorghum Board
Introduction
Commercial hybrids vary in response to
aphids and aphid abundance varies
1. Are ‘R’ hybrids susceptible to
sugarcane aphid within range of
aphid pressure experienced in the
U.S. (do they experience yield loss)?
2. Do we need to adjust thresholds for
‘S’ and ‘R’ hybrids?
Current thresholds • Vegetative: EILs: 50-200 aphids/leaf for ‘S’ hybrids
ET: 35-125 aphids/leaf for ‘S’ (4 hybrids, 5 states, dryland/irrig)
• Vegetative: 20 to 30% of plants infested with
established colonies and honeydew present
Materials & Methods
• Aphid pressure by V5 to V9
Sivanto (4 oz/ac) and Transform (1 oz/ac)
50, 125, 300 sca/leaf, UTC
• Hybrids: common ‘S’ and multiple ‘R’ (> 3)
• 4 reps, small plots, factorial (> 48 plots)
• Measurements
– Weekly aphid cts on 20 top/bottom leaves
• Count < 30, 10s > 30, 100s >500
• Max. aphid/leaf, Cum. Aphid-day/leaf
• Leaf injury weekly, stand counts, days to 50% flower
• Yield (lb/acre)
Location Hybrid Maturity Water Presumed
susceptibility
Winnsboro
LA
REV9782
DKS 38-88
DKS 37-07
Med/Full
Early Late/Med
Early
irrigated Highly Tolerant (?)
Susceptible
Highly Tolerant (R)
Monticello,
AR
84P80 (P)
DKS 38-88
83P17
DKS 37-07
Med/Full
Early Late/Med
Full
Early
Irrigated Susceptible
Susceptible
Highly Tolerant (?)
Highly Tolerant (R)
Headland,
AL
84P80 (P)
DKS 38-88
83P17
DKS 37-07
Med/Full
Early Late/Med
Full
Early
Irrigated Susceptible
Susceptible
Highly Tolerant (?)
Highly Tolerant (R)
Corpus
Christi,
Rosenberg
Gainesville
DKS 48-07
DKS 38-88
DKS 37-07
DKS 53-67
SP 7715
BH 4100
Med
Early Late/Med
Early
Full
Full
Med/Full
dryland,
good
moisture
Highly Tolerant (R)
Susceptible
Highly Tolerant (R)
Susceptible
Highly Tolerant (R)
Highly Tolerant (R)
Hybrids
yield
0
1000
2000
3000
4000
5000
max
0 100 200 300 400 500 600 700 800
AR Hybrid ET Factorial - 2016 Summary - Yield=Max by hybridHybrid=DK3888
yield
0
1000
2000
3000
4000
5000
max
0 100 200 300 400 500 600 700 800
AR Hybrid ET Factorial - 2016 Summary - Yield=Max by hybridHybrid=P84P80
Arkansas: Yield -- Max aphid (highest aphid pressure)
84P80 (S)
P = 0.001
slope= --5.36
Inter = 4503
R2 = 0.54
DKS3888 (S)
P = 0.04
slope= --3.67
Inter = 3604
R2 = 0.26
yield
0
1000
2000
3000
4000
5000
max
0 100 200 300 400 500 600 700 800
AR Hybrid ET Factorial - 2016 Summary - Yield=MAX by hybridHybrid=DK3707
DKS3707
P = 0.77
slope= -flat
Inter = 4067
Max aphids/leaf
yield
0
1000
2000
3000
4000
5000
max
0 100 200 300 400 500 600 700 800
AR Hybrid ET Factorial - 2016 Summary - Yield=MAX by hybridHybrid=P83P17
