What Are the Common Problems with the Plant?
Another good diagnostic perspective is to consider a plants common problems. All plants have their own set of diseases, insect problems, and cultural dilemmas; there are no problem-free plants. Ponder-ing these common quandaries can create somewhat of a bias, especially if you are seeing something new, but it helps rule certain problems out. For example, fire blight, caused by the bacterium Erwinia amylovora, causes a blighting of shoots that result in discolored leaves and a curling of the shoot often characterized as a shepherds crook. This symptom is helpful in considering fire blight as a possibility. However, such symptoms can also be caused on many plants by far simpler problems, such as moisture stress, resulting in leaf and shoot wilting. For which plants should fire blight be considered a possibility? As it turns out, fire blight occurs only on plants in the rose family (rosaceae). So, if you see a crabapple, firethorn, or mountain ash with a shepherds crook symptom, fire blig
