Alternaria leaf spot
![Focus of disease.](https://vegcropshotline.org/wp-content/uploads/2023/02/PXL_20220802_170410114-225x300.jpg)
Figure 3. The roughly round area of diseased broccoli transplants observed here represents a focus of disease. Alternaria leaf spot probably started on a transplant in the center of this area and spread to surrounding seedlings.