Grow corms on clean land.

Rotate plantings if corm stocks are infested with Fusarium, so that the soil is planted to gladiolus not oftener than once every 3 or 4 years.

Replace diseased stocks with healthy corms, never mixing healthy with diseased stock.

Cut off tops at harvest and avoid bruising corms.

Soak mechanically harvested corms 10 minutes immediately after digging in a solution of 3 pounds Dowicide B in 50 gallons water.

Cure corms at temperatures between 80 and 90 F. for a week immediately after corms are dug.

Avoid too rapid drying of corms. Remove old corm and roots from new corm within 2 weeks after digging. Dust corms with Spergon wettable powder as they are cleaned.

Pick out diseased corms and treat sound ones immediately before planting in a 1/2-percent solution of Lysol for 2 hours or a 1/8-percent solution of N. I. Ceresan for 15 minutes.

Rogue diseased plants as soon as they can be identified.

Grow disease-resistant varieties.

Use nitrogen fertilizers sparingly, if at all; never place them in the planting furrow and always add phosphate fertilizer with the nitrogen. For soils where potash is needed, ratios of 1-3-2 or 1-3-3 are often advised.

THE GLADIOLUS BOTRYTIS, B. gladiolorum, has been present in this country at least since 1940 and before that in Europe. The fungus causes a spotting and rotting of all parts of the plant. The disease, which is favored by cool moist weather, has been destructive in Eastern and Southern States, in States bordering the Great Lakes, and in places along the Pacific coast.

The relation of weather to the severity of the botrytis disease in gladiolus-growing g areas of the United States was pointed out by W. D. McClellan, Kenneth F. Baker, and C. J. Gould. During the unusually wet, cool seasons of 1950 and 1951, destructive outbreaks of the disease occurred for the first time in the Midwest, indicating that the disease may appear in all our important gladiolus-growing areas during long rainy spells and at the lower temperatures that usually accompany such weather.

The disease is primarily a corm-rotting problem in northern bulb-growing areas. In southern flower-growing areas it causes most damage as a rot of flowers in transit to northern markets. In all areas, particularly along the Pacific coast, the disease may cause severe damage by the spotting and rotting of leaves.

The three types of leaf spots are large, round to oval, brown spots; smaller, pale-brown spots with reddish-brown margins; and very small, rusty-brown spots, which usually show only on the exposed side of the leaf. Smaller spots predominate, especially during drier, warmer weather and on the more resistant varieties.

Large and small spots also occur on the flower stem. At first they are pale brown, then dark brown. A soft rotting at the bases of florets may follow after a heavy rain. The petals of most varieties are very susceptible. When spores are placed on wet petals in the evening, one may see by the following morning, translucent, water-soaked spots, pin-point in size. As the spots increase in size, the watery, dead tissue turns light brown. In a moist, cool atmosphere, the whole flower becomes slimy with the rot. Flowers that show no spots when cut and packed may be ruined as a result of the spread of botrytis infection in transit or storage.

Stalk or neck rot caused by Botrytis may develop at any stage of growth but is most common after the flowers are cut. Infection may spread down the stalk and into the corm, giving rise to dark-brown spots, irregular in shape and size and most numerous on the upper surface. The leaf scar rings may be lined with small black spots. When corms are cured at about 85 F. for a week immediately after they are dug, the infections generally become inactive and remain shallow. Without the use of artificial heat, the surface infections frequently extend through the vascular tissue to invade the core and eventually the whole corm, causing a soft, spongy rot. In some varieties the diseased vascular tissue is tubelike and can be lifted out cleanly.

Core infections may originate at the top of the corm or at the base. Core rot usually spreads out along the vascular bundles to involve the whole corm. Infection at the top is usually the extension of rotting from the flower stem remnant. Basal infection is believed to result from the previous year's infection of the mother corm.

Corm infection has persisted from year to year without any sign of the disease on the growing plants. As the rotted corms dry out, they shrink only slightly. Botrytis-rotted corms are soft and spongy, with white mold among the rotted tissues and on the surface of the corm. Nests of rotted corms with white mold occur in stored corms. Infection often spreads from one corm to those in contact with it.

The fungus produces sclerotia, the resting bodies. They are oval, flat, black, and about one-eighth to one-fourth inch long. Sclerotia may live in the soil for many years before germinating to produce the spores that initiate infection in each growing season. Sclerotia are formed on rotting tissue in the field, in refuse piles, and on rotted corms in storage. They are commonly found at the time of corm harvest on plants killed by the disease and are located between leaves just above ground and in the hollow flower stems of plants from which spikes were cut.

Botrytis disease is easily identified by the clear, pin-point spots on petals, the spore signs on leaf spots and dead florets, the sclerotia on the stalks and corms, and the soft rotted corms with white mold.

Spores are produced in grapelike bunches on the ends of short "hairs" that have the fuzzy appearance of velvet, especially when wet with dew. Spores are usually found only on brown dead tissue. Dead petals on an old spike standing in the field may produce countless thousands of spores daily for weeks.

AS THE DISEASE is carried in corms, it may not be practical to prevent its introduction to a farm or an area. It would be impractical to eradicate the disease from areas where it has been epidemic. It has been amply demonstrated, however, that the disease can be controlled effectively by protecting the plants with zineb or nabam fungicides. Arthur Holloman, Jr., and Roy A. Young in Oregon reported that ferbam is also effective, but may be less desirable on flower spikes because of the black spray residue. The fungicidal spray or dust is applied every 3 or 4 days in wet weather. To protect rapidly growing leaves and spikes, applications are made as often as every other day in plantings where the disease is already present. Dusting is most useful for renewing protection between showers and when speed of application is important.