Gary W. Moorman, Professor of Plant Pathology
|ALTERNARIA LEAF SPOT||Dark brown to black spots form on leaves. These enlarge to engulf large portions of the leaf. Spots on petioles may allow them to break.||Alternaria sensecionis||Remove infected leaves. Water in a manner that keeps leaf surfaces dry. Maintain low humidity. Apply a fungicide to protect healthy plants.|
|DOWNY MILDEW||Yellow spots on leaves become black. Sparse fungal growth may appear on the underside of infected leaves.||Plasmopara halstedii||Water in a manner that keeps leaf surfaces dry. Remove infected leaves.|
|PHYTOPHTHORA ROOT AND COLLAR ROT||Roots and stem at the soil line rot. Plants wilt and die.||Phytophthora cinnamomi, P. cryptogea, P. megasperma, and P. drechsleri||Plant in pasteurized potting mix. Apply a fungicide to protect healthy plants.|
|POWDERY MILDEW||White fungal growth forms on the leaf surface.||Golovinomyces cichoracearum (formerly Erysiphe) or Sphaerotheca fusca||Heat and ventilate to maintain low humidity at night. Apply a fungicide to protect healthy plants.|
|VIRUSES||Leaves may be mottled, have yellow spotting, dead flecks, line or ring spot patterns. Plant may be distorted, have flower color breaking, or may be stunted. Veins may be killed along with petioles and the entire plant.||Impatiens necrotic spot, streak and mosaic viruses.||Destroy infected plants. Maintain good thrips and mite control.|
Impatiens necrotic spot virus infection symptoms on leaves and stem.
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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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