When we speak of crop protection in potatoes, or any other crop for that matter, the old saying, “An ounce of prevention is worth a pound of cure,” certainly applies. One of the reasons potatoes are so expensive to produce is the fact that they are susceptible to many diseases. Fortunately, many of these disease problems can be effectively managed by insisting on high-quality certified seed. For others, like late blight and early blight, management requires a fungicide program. Symptoms produced by these two foliar diseases are easily distinguishable from one another, but their behavior is actually similar in a number of ways. For instance, they both reproduce by means of windborne spores that can travel for fairly long distances. When either disease organism has successfully infected the tissues of the host, disease becomes far more difficult to control because the pathogens are almost completely internal and are actually shielded from control measures by the host itself. This is why fungicide programs are much more effective when used to prevent the infection events from happening in the first place. More. Article by Phil Nolte, extension seed potato specialist, University of Idaho.