Identifying Harmful Broccoli Diseases

Broccoli is a popular vegetable in many home gardens. With its uniquely textured head and rich green color, it is a refreshing vegetable to be found in any garden. Broccoli is rich in vitamins A and C and is regarded as a cancer-fighting food. It is best to sow seeds early in the spring to give the heads adequate time to mature before hot weather sets in. This will also help prevent broccoli bolting which usually occurs in hot weather. It is important that you know how to identify potential diseases that may attack your broccoli. This will help you realize better quality of the crop as well as higher yields. Following is a disease guide.

Downy Mildew

Wet and cool weather encourages downy mildew. It usually occurs in the spring. Symptoms include light, powdery patches on leaves and shoots. The fungal infection causes discoloration of leaves and curd. Avoid overhead irrigation. Make sure you create good air circulation for the crop to reduce humidity. Use a fungicide on seedlings to prevent infection.


This commonly attacks broccoli as well as other vegetables in the cabbage family. The disease is encouraged in wet and rainy conditions. It spreads very rapidly so early detection is crucial in controlling it. Seedlings are usually attacked more frequently although the disease can strike the plant at any other stage. Small brown lesions appear on the stems with a purplish-black border. The lesions extend upwards on the stem and also sink deeper as they progress. They also extend below the soil where they attack the roots causing the plant to become weak and die. Avoid working the field during wet weather as this encourages rapid spread. Do not over-water the crop as this creates soggy conditions which encourages the fungal infection. It s best to plant seed varieties that are disease free. Remove all diseased plants and destroy.

Soft Rot

This bacterial infection commonly affects the leaves. The disease is more likely where warm and wet conditions prevail. Leaves become yellow starting from the edges and moving towards the center. The infection causes the leaf veins and plant stems to turn black. As the infection increases, the broccoli head develops brown sunken areas of rotting matter which rapidly extend. Much defoliation takes place especially for the more mature plants. Proper growth is inhibited. Plants remain small or die prematurely. It is best to plant disease resistant varieties as a preventive measure. Also, crop rotation is helpful. Rotate crops every 2 years.

Black Rot

It is one of the more serious broccoli diseases. Black rot is encouraged particularly where temperatures and humidity are high. Infected seeds or plants usually carry the disease causing bacteria. Early symptoms usually include yellow V-shaped lesions on the leaves. Lesions target the leaf veins. As the lesions enlarge, veins become brown or black and the leaves begin to wilt. Black rot causes huge losses as it reduces the crop quality and lowers yields drastically. Avoid overhead irrigation. You can also contain the spread of the disease by not working the field when wet. It is best to use disease-free seed varieties. Practice crop rotation every 3 to 4 years.