Angular Leaf Spot on Zinnia
Friday, 15 July 2005 12:10
Angular leaf spot caused by Xanthomonas campestris pv. zinniae. Bacterial diseases are most aggressive in hot weather as bacterial growth is favored by high temperatures. Overhead or sprinkler irrigation aggravates bacterial blights. Xanthomonas species are carried on seed; start with pathogen-free seed. If treated seed is not available-seed can be treated with a dilute bleach solution (10%) for 15 to 30 minutes or hot water. Be sure to test a small batch of seed for sensitivity to these treatments. Practice strict sanitation and rigorous scouting to identify and remove infected plants in the early stages before the pathogen spreads. Few bactericides are available and effectiveness varies. Chemicals registered for Xanthomonas on zinnia growing outdoors include Champ, Champion, Kocide, KOP-Hydroxide, Aliette, Fosphite, and Riverdale Magellan.
See photo: Angular Leaf Spot on Zinnia
Link to: UMass Diagnostic Lab (information on sending samples)
Bess Dicklow, UMass Diagnostic Lab
