Gary W. Moorman, Professor of Plant Pathology
|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. Do not use thiophanate methyl on plants suspected of being infected with Curvularia.|
|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.|
|NEMATODES||Root system is small. Plants are stunted and flower late. Galls may form at nodes. Fusarium yellows may be severe.||Meloidognye, Pratylenchus, Trichodorus, Belonolaimus, Ditylenchus, Hemicyliophora, Rotylenchus||Plant in soil that has been steamed or chemically pasteurized. Maintain good weed control.|
|SCAB||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 maneb + zinc 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.|
Cucumber mosaic virus symptoms on leaves and flowers.
Active Ingredients and Trade Names of the Chemicals
|FRAC Group No.||Risk Level||Class||Active ingredient||REI Restricted Entry Interval||Trade names (EPA Reg. no.)|
|1||3||Benzimidazole||thiophanate methyl||12||3336 (1001-69), OHP 6672 (51036-329-59807), Fungo Flo (51036-329-59807), Systec 1998 (48234-12)|
|2||3||Dicarboximide||iprodione||12||Chipco 26GT (100-1138), Chipco 26019 (264-481), Iprodione (51036-361), Sextant (51036-361-59807)|
|M||1||Chloronitrile||chlorothalonil||48||Daconil (50534-9), Exotherm Termil (70-223)|
|12||Echo (60063-7), PathGuard (60063-7-499), Concorde (72167-24-1812), Pegasus (72167-24-1812)|
|Dithiocarbamate||mancozeb||24||Dithane (707-180), FORE (707-87), Pentathlon (1818-251)|
|manganese + zinc||24||Protect T/O (1001-65)|
Fungicides and Fungicide Resistance Management - Certain fungicides, usually systemic fungicides, are said to be 'at risk' to the development of resistance if they are used repeatedly. See the Risk Level in the above table (1 = low risk; 3 = high risk). The Fungicide Resistance Action Committee has developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action (See http://www.frac.info/frac/index.htm ). It is recommended that chemicals at high risk be used sparingly and in rotation or mixed with chemicals with different modes of actions (different FRAC number).
Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
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