Gary W. Moorman, Professor of Plant Pathology
|ALTERNARIA LEAF SPOT||Purplish spots form on leaves and stems.||Alternaria||Avoid overhead irrigation. Apply fungicide registered for use on this crop.|
|BACTERIAL LEAF SPOT||Small (2-5 mm) circular dead spots form on leaves and petioles. Spots have purple margins.||Pseudomonas tagetis||Destroy infected plants. Avoid overhead irrigation.|
|BOTRYTIS FLOWER BLIGHT||Flower parts brown and die. Gray masses of spores form on the infected tissue when wet.||Botrytis cinerea||Avoid overhead irrigation. Apply fungicide registered for use on this crop.|
|FUSARIUM WILT||Seedlings are killed. In older plants, black streaks darken the vascular tissue up one side of the plant. Plants wilt. Roots on the greatly reduced root system are rotted. During wet weather, salmon-colored spore masses form on infected stems.||Fusarium oxysporum||Plant in potting mix free of pathogens. Destroy infected plants.|
|LEAF BURN||The tips and margins of leaves yellow and die.||Excess boron, manganese, or molybdenum||Measure and apply micronutrient solutions carefully. Manganese should not be above 55 ppm, molybdenum above 24 ppm, or boron above 3 ppm.|
|SEPTORIA LEAF SPOT||Oval to irregular gray to black spots with tiny dots peppering their surface (fungal fruiting structures) form first on lower leaves and then spread upward.||Septoria tageticola||Avoid overhead irrigation. Apply fungicide registered for use on this crop.|
Alternaria leaf and stem spot.
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.
Visit Penn State Extension on the web at extension.psu.edu.
Where trade names appear, no discrimination is intended, and no endorsement by Penn State Cooperative Extension is implied.
This publication is available in alternative media on request.
The Pennsylvania State University is committed to the policy that all persons shall have equal access to programs, facilities, admission, and employment without regard to personal characteristics not related to ability, performance, or qualifications as determined by University policy or by state or federal authorities. It is the policy of the University to maintain an academic and work environment free of discrimination, including harassment. The Pennsylvania State University prohibits discrimination and harassment against any person because of age, ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual orientation, gender identity, or veteran status. Discrimination or harassment against faculty, staff, or students will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University, 328 Boucke Building, University Park, PA 16802-5901; Tel 814-865-4700/V, 814-863-1150/TTY.