GLADIOLUS SCAB
Pseudomonas syringae
  F A C T S H E E T

Introduction

The Gladiolus scab is caused by the bacterium Pseudomonas syringae.

Symptoms

Lesions on corms are pale yellow, water-soaked circular spots, deepening to black or nearly black. These eventually become sunken with raised brittle margins that are scab-like and exude a gummy amber substance.


Figure 1: Symptoms of gladiolus Scab. (provided by Cornell University)
Figure 2: Foliar symptoms. (provided by Cornell University)

Disease Cycle

Bacteria over-winter on corms. Shortly after planting, tiny reddish raised specks appear on leaves, mostly near the base. These enlarge to dark sunken spots which grow together into large areas, causing either firm or soft rots of the neck or the basal parts. Injury to the corm by bulb mites, grubs, or wireworms may increase in the incidence of Gladiolus scab.

Management Strategies

Examine corms before planting, and plant only quality corms that are free of disease or insect injury. Dry corms well before storage and over-winter in a cool (40-45°F) well-ventilated place.

Created, KLS, 1/01; Updated, SLJ, 3/09

This publication may contain pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, sold, and/or applied in New York State must be registered with the New York State Department of Environmental Conservation (DEC). Questions concerning the legality and/or registration status for pesticide use in New York State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. READ THE LABEL BEFORE APPLYING ANY PESTICIDE. __________________________________________________________________________________
The Plant Disease Diagnostic Clinic at Cornell University is located at 334 Plant Science Building, Ithaca, NY, 14853. Phone: 607-255-7850, Fax: 607-255-4471, Email: kls13@cornell.edu or slj2@cornell.edu