There is no reason to be caught unawares by blight

Disease Control
Late Blight on potato leaf

Prevention is better than cure.  That is an old saying which remains relevant today, especially when it comes to diseases on potatoes.  A lot of emphasis is placed on the preventative control of diseases for this very reason.

This is not sales talk: laboratory trials conducted with SDHI-products have shown very poor control of early blight on potatoes even when application was done 2 days after inoculation.  At this stage no symptoms are visually present.  Preventative control of early blight on potatoes is extremely important for effective control.

Early Blight Risk Conditions Lambert Bay

Figure 1 Early blight risk for Lamberts Bay over different seasons.  A Disease Risk Value of lower than 1 indicates a low risk for the disease.

According to the data it looks like the risk for ealy blight for the current season has been higher than the past 2 seasons.

Late Blight risk conditions Warden

Figure 2  Late blight risk for Warden over different seasons.  A Disease Risk Value of lower than 1 indicates a low risk for the disease.

In the Warden area the risk for late blight on potatoes was the highest during the 2018/19 season. 

Another challenge for (potato) farmers today is rising input costs.  It is very true for potato farmers where production costs have increased tremendously over the last decade, with produce prices remaining relatively constant.  In the current conditions, unnecessary applications of fertilizer, pesticides or other inputs can simply not be afforded and maximum return on investment should be realized.

The question is then: how do you prevent unnecessary inputs but still manage diseases preventatively?

Syngenta has recently added a service for potato producers which warns growers of conditions conducive for disease development.  The diseases included is early and late blight on potatoes.

The services combine data from weather forecasts and disease risk models to create warnings for certain weather stations or areas around a weather station. 

Producers can register for the service here where they can choose for which months they want to receive alerts (no sense to get warnings when you don’t have a crop growing) for each weather station they want to receive alerts for.  Alerts are then sent out on Mondays and Thursdays with a 5-day risk forecast.  When no risk is expected for the next 5 days, no warning will be received.  Alerts can be received via email or WhatsApp and also includes other information like spraying conditions, etc.

Blight on Potatoes

For any queries your Syngenta distributor or sales manager can be contacted, or you can send an email to