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Nematospora seed rot and lint stain: Distribution, Importance and Association with Hemiptera. Alois Bell, Juan Lopez, Jr., Enrique Medrano, Jack Bacheler, Jeremy Green, Phillip Roberts, Robert Kemerait, Jr., James Marois, David Wright, and Robert Nichols. USDA-ARS, College Station, TX - PowerPoint PPT Presentation
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NematosporaNematospora seed rot and lint stain: seed rot and lint stain: Distribution, Importance and Distribution, Importance and Association with HemipteraAssociation with Hemiptera
Alois Bell, Juan Lopez, Jr., Enrique Medrano, Alois Bell, Juan Lopez, Jr., Enrique Medrano, Jack Bacheler, Jeremy Green, Phillip Roberts, Jack Bacheler, Jeremy Green, Phillip Roberts,
Robert Kemerait, Jr., James Marois, David Robert Kemerait, Jr., James Marois, David Wright, and Robert NicholsWright, and Robert Nichols
USDA-ARS, College Station, TXUniversity of North Carolina, Raleigh, NC
Clemson University, Clemson, SCUniversity of Georgia, Tifton, GAUniversity of Florida, Quincey, FL
Cotton Incorporated, Cary, NC
Determine the possible importance and
etiology of infectious yeast in seed rot,
internal boll rot, and tight lock of cotton.
ObjectiveObjective
1. Belong to four closely related genera and readily produce 2-celled, needle-shaped ascospores.
2. Ashbya and Eremothecium are filamentous, whereas Holleya and Nematospora are dimorphic. Recent studies place all in Eremothecium.
3. Specifically associated with heteropterous insects, and are restricted to warmer climates.
4. Cause diseases of many families of angiosperms, usually attacking fruits or seeds pierced by bugs during feeding. Important crop hosts include cotton, okra, soybean, green bean, cowpea, citrus, pistachio, tomato, and mustard.
Introduction to PlantIntroduction to PlantPathogenic YeastPathogenic Yeast
NematosporaNematospora corylicoryli on TSA medium on TSA medium
NematosporaNematospora corylicoryli on PDA medium on PDA medium
Close-up of Nematospora coryli colonies
Colonies showing Colonies showing hyphae hyphae
Close-up of Nematospora coryli colonies
NematosporaNematospora coryli:coryli:A – vegetative budding cells, B – hyphae with ascus,A – vegetative budding cells, B – hyphae with ascus,
C – asci, D – ascosporesC – asci, D – ascospores
Bud cells, hyphae, and ascospores of Bud cells, hyphae, and ascospores of NematosporaNematospora corylicoryli
SymptomsSymptoms
1. Prior to boll opening: lint is first stained yellow and later reddish-brown and may become dry. Seed coats are discolored and embryos are killed or their development is severly inhibited.
2. At boll opening: sutures may not split completely, locks do not fluff normally and infections by secondary fungi are common, sometimes blackening the lock.
3. After opening: cotton locks are stained tan to reddish brown. Seed is shriveled with discoloration of fuzz and absence of black pigment in seed coat.
Florida lock infected with Florida lock infected with Nematospora coryliNematospora coryli
Lock cross-section
Infected lock showing staining Infected lock showing staining and restricted openingand restricted opening
Comparison of locks infected with Comparison of locks infected with bacteria or yeastbacteria or yeast
Secondary Secondary AlternariaAlternaria and and CladosporiumCladosporium infections of locks affected by infections of locks affected by N. coryliN. coryli
Seed rot and shriveling Seed rot and shriveling caused by caused by N. coryliN. coryli
Infected Control
Occurence of Occurence of NematosporaNematospora in in Field and Greenhouse Bolls* Field and Greenhouse Bolls*
Punctured by Stink Bugs in 2005Punctured by Stink Bugs in 2005
Source of Bolls
No. Bolls Observed
No. With Punctures
No. With Nematospora
No. With
>10 6 Bacteria
Field BollsField Bolls 36 34 30 12
Greenhouse Bolls*Greenhouse Bolls* (SGSB collected from millet on 9/15 & 10/6)
Females 49 14 8 6
Males 41 14 9 5
Nymphs 12 2 2 0
Greenhouse Bolls*Greenhouse Bolls* (SGSB collected from light trap on 10/5)
Females 10 3 1 3
Males 6 3 0 3
* Single insects caged over bolls for 8 days. Microbial content measured 12 days after insects removed.
Frequency of Caged Feral Insects Frequency of Caged Feral Insects Transmitting Transmitting NematosporaNematospora and and
Bacterial Pathogens to Bolls in 2006Bacterial Pathogens to Bolls in 2006No. of Bolls No. With Pathogen
Insect* Source† Total Punctured NematosporaNematospora BacteriaBacteria BothBoth
SGSB Millet 99 92 66 13 3
BSB Millet 11 10 7 4 2
BSB P Trap 41 37 14 7 3
LFPB Millet 9 8 7 4 3
Total 160 147 9494 2727 1111
* SGSB = Southern green stink bug; BSB = Brown stink bug; LFPB = Leaf-footed plant bug.
† Collected from pearl millet by hand or from pheromone traps.
Effect of Insecticides on Effect of Insecticides on Insect Punctures and Boll Infections by Insect Punctures and Boll Infections by
NematosporaNematospora and Bacteria in 2006 and Bacteria in 2006
% Bolls*
Punctured
% Punctured Bolls With
State TreatmentNematospora Bacteria Both
NC None 60 (6.0) 38 25 17
InsecticideInsecticide 6 (1.0) 0 6 0
SC None 26 (2.0) 18 27 0
InsecticideInsecticide 4 (1.0) 50 0 0
GA None 94 (25.1) 40 62 33
InsecticideInsecticide 26 (10.5) 42 83 42
FL None 62 (21.9) 62 23 8
InsecticideInsecticide 60 (10.6) 55 24 6* Based on 50 bolls; ( ) indicates mean number of punctures.
Effects of Effects of Nematospora coryliNematospora coryli(Seed and Fiber Development in Lock)(Seed and Fiber Development in Lock)
0
100
200
300
400
500
600
700
800
900
mg
/lo
ck
Seed CottonWeight
Cotton SeedWeight
Fiber Weight
Measurement/Lock
ControlInoculated
Effects of Effects of Nematospora coryliNematospora coryli on Seed on Seed
0
20
40
60
80
100
120
Re
lati
ve
Am
ou
nt
No. Seed/Lock Seed Weight(mg)
% Fiber
Measurement
ControlInoculated
Effects of Effects of Nematospora coryliNematospora coryli(Array of Cotton Seed Weights - (Array of Cotton Seed Weights - ST 474ST 474))
0
2
4
6
8
10
12
14
16
* M
ea
n S
ee
d W
eig
ht
(mg
)
1 2 3 4 5 6 7
Seed Number
ControlInoculated
* Mean of >400 bolls from 98 cultivars.
Effects of Effects of Nematospora coryliNematospora coryli(Array of Cotton Seed Weights - (Array of Cotton Seed Weights - DP 393DP 393))
0
2
4
6
8
10
12
14
16
* M
ea
n S
ee
d W
eig
ht
(mg
)
1 2 3 4 5 6 7 8
Seed Number
ControlInoculated
* Mean of >400 bolls from 98 cultivars.
Effect of Boll Age on Damage Effect of Boll Age on Damage Caused by Caused by NematosporaNematospora
Boll Age at Inoculation*
(Days)
% Decrease in Weight
Lock Fiber Seed
4 18 18 19
6 36 39 34
8 38 41 36
10 17 15 18
12 26 25 28
14 28 30 28
* Fifty bolls from four cultivars.
Effect of Boll Age on Damage Effect of Boll Age on Damage Caused by Caused by Nematospora Nematospora (...continued)(...continued)
Boll Age at Inoculation*
(Days)
% Decrease in Weight
Lock Fiber Seed
14-15 45 50 45
16-17 38 42 37
18-19 36 39 34
20-21 16 19 15
* Fifty bolls from four cultivars.
Effect of Boll Age on Infection and Colonization of Effect of Boll Age on Infection and Colonization of Nematospora coryliNematospora coryli Transmitted by Feeding of Transmitted by Feeding of
Southern Green Stink BugsSouthern Green Stink Bugs
Infested Boll
Age (Days)
Number of Bolls*
Total InfectedInfected >10,000 cfu/gm>10,000 cfu/gm
15-17 9 9 2
18-20 18 14 10
21-23 6 5 2
24-26 4 2 0
27-29 6 5 3
30-34 15 10 10
Total 57 4545 2727* Bolls examined 12 days after single feral insects from pearl millet were caged over bolls of specified ages.
Cultivar Reaction toCultivar Reaction to Nematospora coryliNematospora coryli
0
5
10
15
20
25
Fre
qu
en
cy o
f C
ult
ivars
% Reduction in Seed Cotton Weight
Cultivar Reaction to Cultivar Reaction to NematosporaNematospora % Reduction in Fiber Weight
Susceptible Cultivars Resistant Cultivars
ST 5242 BR (80.1) Phyt 710 R Acala (13.7)
ST 5599 BR (69.3) DP 110 RF (14.5)
NG 3273 B2RF (63.8) BW 6896 B2F (15.9)
BW 2038 B2F (63.6) FM 966 LL (16.9)
BW 3255 B2F (61.6) DP 444 BG/RR (17.6)
NG 3550 RF (60.3) AFD 5065 B2F (18.9)
FM 960 RR (59.8) CPCSD Acala Fiesta (20.6)
DP 164 B2RF (59.0) ST 6622 RF (21.4)
Phyt 370 WR (58.2) BW 8245 B2F (24.8)
DP 167 RF (58.1) AFD 5062 LL (24.9)
ST 4357 B2RF (54.8) FM 958 LL (25.9)
ST 4700 B2RF (54.8) CG 3020 B2RF (26.6)
ConclusionsConclusions
1. Nematospora occurs in many bolls punctured by bugs during feeding.
2. A high percentage of feral insects carry Nematospora which may persist and be transmitted repeatedly.
3. Most cultivars are highly susceptible to Nematospora and suffer loses of 40-60% of the fiber, as well as reducing seed quality.
4. Insect control is the best way to prevent infection, although improved cultivar resistance may be possible.
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