This week, the question was: What is wrong with the stem and lower petioles of this cabbage plant?
This plant is suffering from Sclerotinia white mold (caused by the fungus Sclerotinia sclerotiorum), also called Sclerotinia stem rot. This disease is commonly observed this time of year as temperatures begin to warm up. It develops a mass of white fungal growth on the stems and lower leaves of its host plant as well as black-colored sclerotia. The sclerotia are much larger than the similar disease, Southern blight (Athelia rolfsii), which is also sometimes referred to as white mold. Sclerotinia white mold affects a wide range of crops, though we mostly see it on brassicas here in SC. This is because our soil temperatures during the summer, when other crops are in the ground, are usually too warm for the sclerotia to germinate. For more info, take a look at this site.