What is the dark ring in my Cabbage?

Question

I cut my home grown cabbage in halves and some of them have a dark ring in it, what is this?

Answer 1

Cabbage and Cauliflower (Brassica) -- Ring spot (Black Blight)

  

Cause: A fungus, Mycosphaerella brassicicola, attacks cabbage, cauliflower, Brussels sprouts, and broccoli. The disease is a problem mostly with seed production. Seeds may carry the pathogen. The fungus also overwinters on infected weed and crop hosts or in residues. Spores spread by wind. Cool (59 to 70°F) moist weather favors disease development.  

Symptoms: All aboveground portions of the plant may show symptoms. Individual lesions have dark concentric rings with definite edges surrounded by a yellowish zone. Under severe attack, spots coalesce, and the entire plant may be affected and blackened. In seed stalks, the fungus causes a distortion similar to the injury caused by the herbicide 2,4-D. Dark lesions may develop on stored cabbage and may penetrate deeply.  

  

Cultural control:

Locate plant beds 1 mile or more from diseased fields.

Burn straw stacks, and plow under diseased refuse of cabbage, turnip, and rutabaga seed fields immediately after harvest and before transplanting the new crop.

Hot water seed treatment at 122°F for 30 min eliminates seedborne inoculum. Treat a small quantity of each seed lot, and test the germination before treating all the seed.



Chemical control: Some fungicides used to control downy mildew or white mold (see Cabbage and Cauliflower - Sclerotinia Stem Rot and Watery Soft Rot) also control this disease.

Bravo Ultrex at 1.4 lb/A with water to cover. 12-hr reentry.

Cabrio EG at 12 to 16 oz/A. Begin applications prior to disease development. Continue on a 7- to 14-day interval. Use the shorter interval when disease pressure is high. Do not make more than two (2) sequential applications of Cabrio EG or other Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. Do not make more than four (4) applications per season. Preharvest interval is 0 days. 12-hr reentry.

Echo 720 at 2 pt/A at 7- to 10-day intervals when disease threatens. Preharvest interval is 7 days. 12-hr reentry.