1. 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 University of North Carolina, Raleigh, NC Clemson University, Clemson, SC University of Georgia, Tifton, GA University of Florida, Quincey, FL Cotton Incorporated, Cary, NC

2. Determine the possible importance and etiology of infectious yeast in seed rot, internal boll rot, and tight lock of cotton. Objective

3. 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 Plant Pathogenic Yeast

4. Nematospora coryli on TSA medium

5. Nematospora coryli on PDA medium

6. Close-up of Nematospora coryli colonies

7. Colonies showing hyphae Close-up of Nematospora coryli colonies

8. Nematospora coryli: A – vegetative budding cells, B – hyphae with ascus, C – asci, D – ascospores

9. Bud cells, hyphae, and ascospores of Nematospora coryli

10. Symptoms 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.

11. Florida lock infected with Nematospora coryli Lock cross-section

12. Infected lock showing staining and restricted opening

13. Comparison of locks infected with bacteria or yeast

14. Secondary Alternaria and Cladosporium infections of locks affected by N. coryli

15. Seed rot and shriveling caused by N. coryli InfectedControl

16. Occurence of Nematospora in Field and Greenhouse Bolls* Punctured by Stink Bugs in 2005 Source of Bolls No. Bolls Observed No. With Punctures No. With Nematospora No. With >10 6 Bacteria Field Bolls 36343012 Greenhouse Bolls* Greenhouse Bolls* (SGSB collected from millet on 9/15 & 10/6) Females491486 Males411495 Nymphs12220 Greenhouse Bolls* Greenhouse Bolls* (SGSB collected from light trap on 10/5) Females10313 Males6303 * Single insects caged over bolls for 8 days. Microbial content measured 12 days after insects removed.

17. Frequency of Caged Feral Insects Transmitting Nematospora and Bacterial Pathogens to Bolls in 2006 No. of BollsNo. With Pathogen Insect*Source † TotalPuncturedNematosporaBacteriaBoth SGSBMillet999266133 BSBMillet1110742 BSBP Trap41371473 LFPBMillet98743 Total160147942711 * SGSB = Southern green stink bug; BSB = Brown stink bug; LFPB = Leaf-footed plant bug. † Collected from pearl millet by hand or from pheromone traps.

18. Effect of Insecticides on Insect Punctures and Boll Infections by Nematospora and Bacteria in 2006 % Bolls* Punctured % Punctured Bolls With StateTreatment NematosporaBacteriaBoth NCNone60 (6.0)382517 Insecticide6 (1.0)060 SCNone26 (2.0)18270 Insecticide4 (1.0)5000 GANone94 (25.1)406233 Insecticide26 (10.5)428342 FLNone62 (21.9)62238 Insecticide60 (10.6)55246 * Based on 50 bolls; ( ) indicates mean number of punctures.

19. Effects of Nematospora coryli (Seed and Fiber Development in Lock)

20. Effects of Nematospora coryli on Seed

21. Effects of Nematospora coryli (Array of Cotton Seed Weights - ST 474) * Mean of >400 bolls from 98 cultivars.

22. Effects of Nematospora coryli (Array of Cotton Seed Weights - DP 393) * Mean of >400 bolls from 98 cultivars.

23. Effect of Boll Age on Damage Caused by Nematospora Boll Age at Inoculation* (Days) % Decrease in Weight LockFiberSeed 418 19 6363934 8384136 10171518 12262528 14283028 * Fifty bolls from four cultivars.

24. Effect of Boll Age on Damage Caused by Nematospora (...continued) Boll Age at Inoculation* (Days) % Decrease in Weight LockFiberSeed 14-15455045 16-17384237 18-19363934 20-21161915 * Fifty bolls from four cultivars.

25. Effect of Boll Age on Infection and Colonization of Nematospora coryli Transmitted by Feeding of Southern Green Stink Bugs Infested Boll Age (Days) Number of Bolls* TotalInfected >10,000 cfu/gm 15-17992 18-20181410 21-23652 24-26420 27-29653 30-341510 Total574527 * Bolls examined 12 days after single feral insects from pearl millet were caged over bolls of specified ages.

26. Cultivar Reaction to Nematospora coryli

27. Cultivar Reaction to Nematospora % Reduction in Fiber Weight Susceptible CultivarsResistant Cultivars ST 5242 BR (80.1)Phyt 710 R Acala (13.7) ST 5599 BR (69.3)DP 110 RF (14.5) NG 3273 B 2 RF (63.8)BW 6896 B 2 F (15.9) BW 2038 B 2 F (63.6)FM 966 LL (16.9) BW 3255 B 2 F (61.6)DP 444 BG/RR (17.6) NG 3550 RF (60.3)AFD 5065 B 2 F (18.9) FM 960 RR (59.8)CPCSD Acala Fiesta (20.6) DP 164 B 2 RF (59.0)ST 6622 RF (21.4) Phyt 370 WR (58.2)BW 8245 B 2 F (24.8) DP 167 RF (58.1)AFD 5062 LL (24.9) ST 4357 B 2 RF (54.8)FM 958 LL (25.9) ST 4700 B 2 RF (54.8)CG 3020 B 2 RF (26.6)

28. Conclusions 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.