Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 1999
Publication Date: N/A
Interpretive Summary: Gray mold, a fungus disease caused by Botrytis cinerea, parasitizes many kinds of crops in greenhouses and costs growers millions of dollars in losses annually. Calcium chloride (CaCl2), a common salt, was tested as an alternative control agent and compared with mancozeb, a registered fungicide. Gray mold was reduced with CaCl2 and mancozeb over a 4 week period in a greenhouse. Leaf burn or phytotoxicity was recorded on plants sprayed with CaCl2 and mancozeb at higher concentrations. Plants remained salable with chemical treatment. CaCl2, if included as part of a integrated disease management program, could provide relief for growers from gray mold disease as a relatively inexpensive control and would permit immediate access to greenhouses after spraying, as opposed to conventional fungicides which require up to 48 hours before worker re-entry into these confined areas.
Technical Abstract: The efficacy of calcium chloride (CaCl2) was compared with mancozeb, a conventional fungicide, for control of gray mold disease caused by Botrytis cinerea on rooted cuttings of tuberous Begonia in greenhouse tests. The fungicides were applied as topical sprays at 14 day intervals. Disease severity and phytotoxicity were evaluated at regular intervals over a 4 week period using a modified Horsfall-Barett scale. Both CaCl2 and mancozeb significantly decreased disease severity based on the area under the disease progress curves (AUDPC). Efficacy of mancozeb was not significantly different from that of CaCl2. Mancozeb\sprays clearly deposited visible residues on the foliage of plants whereas such residues were not observed on the plants treated with 0.25% CaCl2. Neither fungicide affected flowering and symptoms of phytotoxicity were not observed.