SynopsisBarley stripe mosaic virus has caused severe losses in spring wheat yields and moderate losses in test-weights in experimental trials in Montana since 1956. Field readings for incidence of virus show the disease has increased in Pilot and Centana, has about maintained itself in Rescue, and has decreased in Lee, C.I. 13041, C.I. 13042, Supreme, and Thatcher. Greenhouse plantings showed that storage had little or no effect on the percentage of seed which carried the virus.

Symptoms, method of infection, course of the disease, influence of environment and the control of smut in Gladiolus were described. In the first year (S1) spores adhering to scales of corms and cormels or present in the soil caused infection, generally without conspicuous symptoms. The optimum soil temperature for infection was 20°C, the maximum about 24° and the minimum below 12°. Latent mycelium could be seen microscopically in the flesh of lifted corms with or without macroscopically visible symptoms (sori).During storage at 13°-20° (in S1B) the mycelium. grew slowly to the top of the corm.In the second year (S2) symptoms appeared in parts above soil, only if the soil was cooler than about 20° and the mycelium reached the apical buds in time. At 24° the mycelium remained latent in the corms giving rise to apparently healthy plants. At 28° the fungus in the mother corm was inactivated and offspring was completely free of pathogen. A dip in an organic Hg fungicide before planting killed smut spores present in or on the corm's scales. Mycelium in the corm's flesh was killed in hot water (30-60 min at 47°), by prolonged soaking or anaerobic treatment or by dry storage at 34° for several weeks. Complete control in corms could thus be obtained by combining treatment with hot water and disinfection before planting.Dry spores survived 30 min. at 60° but were killed after soaking in water at 53°C. As cormels could stand more heat than corms, 24-h soaking in water followed by hot-water treatment for 30 min. at 53° or 55° gave complete control.

Symptoms, method of infection, course of the disease, influence of environment and the control of smut in Gladiolus were described. In the first year (S1) spores adhering to scales of corms and cormels or present in the soil caused infection, generally without conspicuous symptoms. The optimum soil temperature for infection was 20°C, the maximum about 24° and the minimum below 12°. Latent mycelium could be seen microscopically in the flesh of lifted corms with or without macroscopically visible symptoms (sori).During storage at 13°-20° (in S1B) the mycelium. grew slowly to the top of the corm.In the second year (S2) symptoms appeared in parts above soil, only if the soil was cooler than about 20° and the mycelium reached the apical buds in time. At 24° the mycelium remained latent in the corms giving rise to apparently healthy plants. At 28° the fungus in the mother corm was inactivated and offspring was completely free of pathogen. A dip in an organic Hg fungicide before planting killed smut spores present in or on the corm's scales. Mycelium in the corm's flesh was killed in hot water (30-60 min at 47°), by prolonged soaking or anaerobic treatment or by dry storage at 34° for several weeks. Complete control in corms could thus be obtained by combining treatment with hot water and disinfection before planting.Dry spores survived 30 min. at 60° but were killed after soaking in water at 53°C. As cormels could stand more heat than corms, 24-h soaking in water followed by hot-water treatment for 30 min. at 53° or 55° gave complete control.