Can plants be saved in a farm planting once late blight starts to develop?
Yes. Potato growers usually are able to effectively control late blight. It is easier to manage late blight on a farm than in a garden because of the fungicides that can be used. Farmers can use fungicides able to move within the leaf that the spray lands on; some fungicides can move into stems and new growth. Farmers also have sprayers that can achieve better coverage of plant tissue than hand sprayers. As with a garden, success is affected by whether or not fungicides were applied before symptoms were seen and how severely the crop is initially affected if fungicides were not applied. Typically farmers begin applying a broad-spectrum, contact fungicide when conditions are favorable for late blight, inspect their crops regularly, and when symptoms are found start applying fungicides with specific activity for late blight. They also manage the usual initial source of the pathogen: affected tubers from the previous year or used as seed. See also answer to previous question.
