Control measures

The control of potato late blight must combine various preventive measures:

• prefer resistant or tolerant cultivars, when available;

• use healthy seed tubers;

• destroy waste piles and groundkeepers in the adjacent crops, which can serve as a primary inoculum reservoir;

• ensure effective ridging and nitrogen fertilisation;

• chemical preventive protection of the foliage should be applied during all the growing period whenever required by the disease pressure. Numerous fungicides are effective against potato late blight and must be used according to their recommendations and their mode of action: contact fungicides (e.g. dithiocarbamates, copper-based products and others), translaminar or systemic fungicides. Care should be taken concerning the risk of the resistance of P. infestans natural populations to certain fungicides, in particular with systemic fungicides used in fields where late blight is already present;

• during the growing period, it is highly recommended to take account of the local weather forecast and of blight warnings issued by the blight monitoring services to adapt the fungicide protection. Unless the environment of a potato crop can be regularly inspected to check for the absence of the disease, it is advisable to subscribe to the local specialised warning system or to have a personal Decision Support System for field advice; this tool is available in most European countries;

• in order to protect the crop until tubers are harvested, fungicide protection must be carried out up to the time of haulm destruction.