Disease	Symptoms	Pathogen/Cause	Management
Botrytis Blight	Brown spots that may have reddish margins develop on leaves. Spots can be very small to over 1/2 inch in diameter. Similar spots on stems become soft and rot in wet weather. Small, clear spots on petals become brown. A neck rot may occur at the soil line. Small black granules (sclerotia) form on the surface of the infected corms.	Botrytis gladiolorum	Do not plant infected corms. Purchase corms that were treated with hot water and fungicides. Apply mancozeb, chlorothalonil, iprodione, or vinclozolin to protect growing plants.
Curvularia Leaf Spot	Long, rectangular spots on leaves are tan with a brown margin and yellow halo. Concentric rings form within the enlarging spots. Corms rot.	Curvularia trifolli f. sp. gladioli	Do not plant infected corms. Plant in pasteurized soil. Apply mancozeb or chlorothalonil to protect plants.
Fusarium Yellows	Roots have brown spots or general rot. Older leaves yellow. Flower size, shape and color may be abnormal. Flowers may not develop while stalks are curved in an S-shape. Corms rot from the center outward. Oval, sunken spots on the corm surface are brown and may have concentric rings.	Fusarium oxysporum f. sp. gladioli	Do not plant infected corms. Maintain a soil pH of 6.6-7.0 and use nitrate as the nitrogen source when fertilizing.
Scab	Brown spotting occurs on leaves. Brown, round, sunken areas with raised edges are on corms. A soft rot of the neck develops.	Pseudomonas marginata	Do not plant infected corms. Disinfest cutting knives frequently. Maintain good mite and insect control. Water in a manner that keeps leaf surfaces dry. Avoid working on wet plants.
Stemphylium Leaf Spot	Small, round yellow spots have a distinct reddish center when held up to the light. Mature leaves have the most spotting.	Stemphylium botryosum	Apply mancozeb, ziram, or chlorothalonil before any disease begins.
Stromatinia Dry Rot	Corm scales are brown and may appear shredded. Small reddish-brown spots on the surface of the corm can be removed, leaving a clean, shallow, sunken area. Corms are dry, hard, and mummified. Clusters of plants are killed by neck rot.	Stromatinia gladioli	Do not plant infected corms. Purchase corms that have been treated with hot water and fungicides. Plant in soil that has been pasteurized with chemical fumigants or steam. If infection is noted after planting, apply PCNB or vinclozolin until flower production is complete. Then discard corms.
Viruses	Flowers are small, distorted or have color breaking. Leaf tissue may be mottled, have white flecks, or reddish blotches.	Bean yellow mosaic, cucumber mosaic, tomato ringspot, tobacco ringspot	Maintain good insect control. Plant in pasteurized soil free of nematodes and weeds. Destroy infected plants as soon as they are found.

Fungicides mentioned above:

COMMON NAME	TRADE NAME
captan	Captan
chlorothalonil	Daconil 2787
copper	Kocide, Basicop, Microsperse
iprodione	Chipco 26019
mancozeb	Dithane, Protect T/O
mancozeb + copper	Junction
PCNB	Terraclor, Defend
thiophanate methyl	Clearys 3336, Domain, SysTec
ziram	Ziram