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Nematospora seed rot and lint stain: Distribution, Importance and Association with Hemiptera

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

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Nematospora seed rot and lint stain: Distribution, Importance and Association with Hemiptera

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

  3. Introduction to PlantPathogenic Yeast 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.

  4. Nematosporacoryli on TSA medium

  5. Nematosporacoryli on PDA medium

  6. Close-up of Nematospora coryli colonies

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

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

  9. Bud cells, hyphae, and ascospores of Nematosporacoryli

  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. Lock cross-section Florida lock infected with Nematospora coryli

  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 Infected Control

  16. Occurence of Nematospora in Field and Greenhouse Bolls* Punctured by Stink Bugs in 2005 * 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 * 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 * 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 * Fifty bolls from four cultivars.

  24. Effect of Boll Age on Damage Caused by Nematospora (...continued) * 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 * Bolls examined 12 days after single feral insects from pearl millet were caged over bolls of specified ages.

  26. Cultivar Reaction toNematospora coryli

  27. Cultivar Reaction to Nematospora

  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.

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