Yellow-brown patches on Cymbidium sinense leaves and withered leaf tips: disease or unsuitable soil and water?
The leaves of Cymbidium sinense have irregular yellow-brown patches and the leaf tips are withered and dry. Is it disease or failure to adapt to the soil and water?
This should be damage from anthracnose, a common disease of Cymbidium sinense. It is relatively severe in flower nurseries in the south, and it now also occurs in Beijing, Tianjin and other places.
Control methods: (1) In the early stage of the disease, when there are not many diseased leaves, the diseased leaves can be cut off and then sprayed with 50% amobam aqueous solution at 800 times dilution or 75% chlorothalonil wettable powder at 50-800 times dilution to prevent the disease from developing. When spraying, spray the flower pot, soil surface and plant together, once every 7-10 days, for 3-4 times in succession.
(2) During cultivation and management, insist on spraying 0.5%-1% Bordeaux mixture every 10-15 days to prevent the disease.
(3) For cultivation in flower nurseries or greenhouses, before placing the plants, the site should first be sprayed with 65% zineb wettable powder at 400 times dilution for sterilization and disinfection to reduce disease incidence, especially for sites where Cymbidium sinense has been grown for many years.
(4) Newly introduced cultivars should be quarantined and grown separately from the original Cymbidium sinense group. Only after confirming that there is no disease should they be placed together with the group for care, so as to avoid bringing in pathogens.
Control methods: (1) In the early stage of the disease, when there are not many diseased leaves, the diseased leaves can be cut off and then sprayed with 50% amobam aqueous solution at 800 times dilution or 75% chlorothalonil wettable powder at 50-800 times dilution to prevent the disease from developing. When spraying, spray the flower pot, soil surface and plant together, once every 7-10 days, for 3-4 times in succession.
(2) During cultivation and management, insist on spraying 0.5%-1% Bordeaux mixture every 10-15 days to prevent the disease.
(3) For cultivation in flower nurseries or greenhouses, before placing the plants, the site should first be sprayed with 65% zineb wettable powder at 400 times dilution for sterilization and disinfection to reduce disease incidence, especially for sites where Cymbidium sinense has been grown for many years.
(4) Newly introduced cultivars should be quarantined and grown separately from the original Cymbidium sinense group. Only after confirming that there is no disease should they be placed together with the group for care, so as to avoid bringing in pathogens.