Gary W. Moorman, Professor of Plant Pathology
|ALTERNARIA LEAF SPOT||Large reddish brown or purple spots, at first round to oblong but becoming irregular in shape have gray or tan centers that may drop out leaving a hole. Severely affected leaves brown, dry, and become brittle.||Alternaria zinniae||Apply chlorothalonil, iprodione, mancozeb, fludioxonil, propiconazole, or thiophanate methyl + mancozeb Whenever possible, water in a manner that keeps the leaves dry to inhibit this seedborne disease.|
|ASTER YELLOWS||Leaf-like tissue forms where flower parts should be located. Flower-like parts remain green or light green. Often flowers on only one side of the spoke show sympotms. Sepals may be very large or dwarfed.||Phytoplasma||Destroy infected plants. Control leafhoppers.|
|BACTERIAL LEAF SPOT||Spots reddish brown to dark brown, angular and with a prominent yellow halo form on leaves.||Xanthomonas campestris pv. zinniae||No sprays are effective. Whenever possible, water in a manner that keeps the leaves dry to inhibit this seedborne disease.|
|POWDERY MILDEW||White fungal growth forms on the upper surface of leaves and may form on flower petals.||Golovinomyces cichoracearum (formerly Erysiphe)||Apply myclobutanil, kresoxim methyl, fenarimol, mancozeb, piperalin, propiconazole, sulfur, thiophanate methyl + mancozeb, triadimefon, or triforine to protect plants.|
Alternaria leaf spot. Bacterial leaf spot (those with yellow halo)
Alternaria leaf spot (purple spot, no halo).
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.)|
|2||3||Dicarboximide||iprodione||12||Chipco 26GT (100-1138), Chipco 26019 (264-481), Iprodione (51036-361), Sextant (51036-361-59807)|
|Triazole||propiconazole||24||Banner MAXX (100-741), Propiconazole (51036-403), Spectator (62719-346-10404), Kestrel (66222-41-81943)|
|triadimefon||12||Strike (3125-436), Bayleton (432-1360)|
|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)|
|1 + M||thiophanate methyl + mancozeb||Zyban (58185-31)|
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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