Seed transmission of Bipolaris coicis, B. cynodontis, B. maydis and Curvularia lunata causing leaf blight of Job's tears.
B. coicis, B. cynodontis [Cochliobolus cynodontis], B. maydis [Cochliobolus heterostrophus] and Curvularia lunata [Cochliobolus lunatus] were leaf blight fungi detected from 45 seed samples of Coix lachryma-jobi. B. coicis was the predominant species in seed samples followed by C. lunatus, C. cynodontis and C. heterostrophus. When the seed components were plated on test tube agar, B. coicis and C. lunatus were frequently detected from various parts of the plant but not from the plumule. Seed infection with B. coicis caused seed rot, coleoptile blight and seedling blight of C. lachryma-jobi. Conidial characteristics of leaf blight fungi were as follows; B. coicis was oblavate, brown, slightly curved, 0-5 distoseptate, and 16.8-48×7.2-16.8 µm in size; B. cynodontis was fusiform, brown, slightly curved, 0-8 distoseptate, and 16.8-72×9.6-19.2 µm; C. heterostrophus was fusiform, brown, distinctly curved, 0-10 distoseptate, and 28.8-110.4×12-21.6 µm. C. lunatus was fusiform, brown, typically curved, 0-3 distoseptate, and 7.2-24×4.8-12 µm. B. coicis was highly pathogenic to C. lachryma-lobi and maize, weakly pathogenic to wheat and barley, but not pathogenic to rice. C. cynodontis was highly pathogenic to C. lachryma-jobi, maize, wheat, barley and rice. B. maydis was highly pathogenic to maize and C. lachryma-jobi, weakly pathogenic to rice, but not pathogenic to wheat and barley. C. lunatus was highly pathogenic to C. lachryma-jobi (no. 2), maize, wheat and barley, weakly pathogenic to C. lachryma-jobi (No. 1), but not pathogenic to rice. All treatments were effective to inhibition of leaf blight fungi when carboram, benoram, fludioxonil, prochloraz, thiram, and tap water treated to infected seeds.