What action can a farmer take if they notice cankers on grapes in winter?

When a farmer notices cankers on their grapevines during winter, pruning the affected areas is a proactive and effective management action to take. Cankers are typically signs of disease, which can lead to further infection and deterioration of the plant if not addressed promptly. By pruning, the farmer removes the diseased portions of the plant, which helps prevent the spread of the infection to other areas of the vine and promotes better airflow and sunlight penetration, ultimately encouraging healthier growth for the remaining parts of the plant.

Though options like applying fertilizers or biopesticides could be part of an overall management strategy, they do not directly address the immediate need to remove the infected tissue as effectively as pruning does. Sprinkling sulfur can help in some situations; however, it is generally used as a preventative measure rather than a remedial one for already affected areas. Pruning thus stands out as the most direct and beneficial action to manage the problem of cankers on grapevines during winter.