The Downey Mildew disease (Peronospora sparsa) is one of the key challenges in roses production in Kenya today. If and when the weather is suitable (moist cloudy conditions) for its development, frequent epidemics are often encountered leading to loss of a whole flush or flushes in highly susceptible varieties.
Traditionally, the prevalence of the disease in Kenya used to be seasonal confined to the rainy periods, but this is changing throughout the year in high altitude areas where some growers have established some farms, driven by the market demand for better quality roses. This calls for careful integration of all possible downy mildew management methods, chief among them being chemicals.
Ethofin 10SC is one the newest unique chemistries now available in the Kenyan market since its successful launch in early 2011.
It is composed of Ethaboxam (100g/l) as the active ingredient and belongs to the class U5 in the FRAC code (no known resistance) implying that it can be used safely for eons. It has broad spectrum, systemic, protective and early curative, with long residual activity against the water loving fungi. Ethofin 10SC belongs to WHO class IV and is thus unlikely to cause harm if used as recommended. It is manufactured in Japan by Summit Agro international Ltd.
Mode of action
The fungicide is like a double edged sword with a dual mode of action. It inhibits the normal development of the fungi by attacking the microtubular cytoskeleton, making it weak and impossible to ramify and penetrate the plant tissues. It also interferes with the mitochondrial respiration, denying the fungi vital energy especially at the early stages of disease development, eventually killing it before causing major damages. The two modes of actions make it hard for the fungi to develop resistance against Ethofin 10SC, confirming it to be smarter than the Fungi.
Application rate and timing
For best results, farmers should apply Ethofin 10SC early in the disease cycle before the signs are advanced. Since Ethofin 10SC has both systemic and translaminar movement in the plant tissues ensuring good acquisition by the target fungus, it assures the grower maximum protection against Downey mildew because the disease is also systemic.
In roses, a rate of 1.5-2.0lts/ha repeated after 7 days is recommended. Do not under or overdose and remember to rotate with molecules that have different modes of action after two end-to-end applications to avoid resistance development.
Roses tolerate Ethofin 10SC well when used at the recommended dosage, however growers should conduct sensitivity tests before full scale application.
Except strong alkaline materials, Ethofin 10SC mixes well with most insecticides and fungicides. It is prudent however, to conduct a test before spraying. It is also compatible with many biological control agents and beneficials and is therefore suitable for inclusion in IPM programmes.