Efficacy of salts against fungal diseases in glasshouse crops.
The constant input of chemical fungicides against foliar diseases in glasshouse crops has instigated research on alternative control substances. Various salts have been mentioned in the literature and we have tested several bicarbonates, sulphates and phosphates against powdery mildew fungi in cucumber, tomato, sweet pepper and rose and against Bremia lactucae in lettuce. The experiments were run according to EPPO guidelines for efficacy in glasshouses of Applied Plant Research (PPO). Plants were sprayed weekly and disease and yield were assessed. In cucumber, NaHCO3, KHCO3, MgSO4 and MnSO4 all reduced powdery mildew significantly, with MnSO4 as the most effective agent. In tomato, MgSO4, MnSO4 and KH2PO4 all reduced powdery mildew by approx. 40% whereas NaHCO3 and KHCO3 gave approx. 95% control. In pepper, NaHCO3 controlled Leveillula taurica by 50-90% compared to the untreated control. In rose, the efficacy of KH2PO4, MnSO4, MgSO4, NaHCO3 and KHCO3 against powdery mildew differed between cultivars. In general, the bicarbonates were the most effective compounds. In lettuce, NaHCO3 reduced Bremia severity by 70 to 80%. The conclusion of this range of experiments is that especially bicarbonates can be a good alternative for control of foliar fungal diseases in glasshouse crops. The effective concentration is not causing any symptoms of phytotoxicity, provided that spraying is not done at high irradiation conditions. Bicarbonates have been submitted for the Dutch list of exceptions on the Pesticide Law.
Dik
A J
AJ
Applied Plant Research business unit Horticulture (PPO), P.O. Box 8, 2670 AA Naaldwijk, The Netherlands. Aleid.Dik@WUR.NL
van der Gaag
D J
DJ
van Slooten
M A
MA
D001203:Ascomycota / Q000187:drug effects / Q000254:growth & development / Q000472:pathogenicity; D001639:Bicarbonates / Q000494:pharmacology*; D002212:Capsicum / Q000382:microbiology; D018556:Crops, Agricultural / Q000382:microbiology*; D018553:Cucumis sativus / Q000382:microbiology; D005658:Fungi / Q000187:drug effects / Q000254:growth & development* / Q000472:pathogenicity; D018551:Solanum lycopersicum / Q000382:microbiology; D010710:Phosphates / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D011897:Random Allocation; D027826:Rosa / Q000382:microbiology; D013431:Sulfates / Q000494:pharmacology*
D001639:Bicarbonates; D010710:Phosphates; D013431:Sulfates