Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Scab

Problem
Sunken black lesions on the corm (the "bulb" of the gladiolus plant) are covered with a shiny, varnishlike material and are encircled by raised, brittle rims. Later in the season, after the corms have been planted, many tiny, raised, reddish brown specks develop on the bases of the emerging leaves. These specks become soft, elongated dead spots, which may be covered with and surrounded by a shiny, oozing material in wet weather. The leaves usually fall over.

Analysis
This disease, caused by bacteria (Pseudomonas marginata), earns its name from the scablike lesions it produces on the gladiolus corms. The bacteria penetrate the corm tissue and then move up into the stem base, producing a soft, watery rot. This decay causes the leaves to fall over. The shiny, varnishlike spots that form on the leaves and corms contain millions of bacteria. Wet, heavy soil and warm temperatures favor the rapid development of this disease. The bacteria can live for several years in infected corms and plant debris. The bacteria are spread by splashing water, and by contaminated corms, soil, tools, and insects. Severely infected plants may die.

Solution
There is no chemical control for this disease. Destroy infected corms. Remove and destroy infected plants. Plant healthy corms in well-drained soil where diseased gladioli have not grown.

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