Photos and text by Debbie Roos, Agricultural Extension Agent.

This problem is showing up in cauliflower, kale, and other brassicas on a new field on an organic farm. Lower leaves are yellowing and dropping off. The veins and mid-ribs of leaves become necrotic. Leaves are sometimes cupped with necrotic margins. Leaves show some mottling and chlorosis. Severely affected plants are stunted and weak and less cold hardy - many were killed with a recent frost (see photos below). The affected area is confined to a "hot spot", radiating out from a central location. Initial pH was around 5.2 and the soil was amended in August with composted manure, hi calcium lime and wood ash. We suspect a nutritional deficiency exacerbated by acid soil.