1. Step 1. You dig up the roots of these suspect plants and examine them. What are you looking for?

2. Step 2. You don’t find any of the things listed in step 1, or certainly nothing serious enough to kill the plant. So you clip through stem just below ground level (half an inch below the stem base) and look at the cross section. This is a scouting step for which diseases?

3. Step 2 continued. You  look at the clipped cross section and find this. What is it?

4. Step 3. You check the cross section and don’t find anything, but upon closer examination, the plant looks like this. What is the cause?