Diseases on Cauliflower

Major diseases observed on Cauliflower (Brassica oleracea)

1. Club Root

This disease causes swelling and malformation of the root which restricts nutrient and water flow in the plant. This disease is caused by a fungus Plasmodiophora brassicae.The club root fungus enters the plant through roots. It is very difficult to curb the infestation by this disease, as it continue to infest on the land for a longer duration. When the plant rot, the fungal spores are released in the soil which may live for 10 to 20 years and infect other plants. There are few steps to control it.

* It is important to avoid planting the plant in infested field for nearly 7 years.
* We need to avoid using the fungus infected manure to avoid the crop infestation.
* It is important that we use crop rotation and field rotation. We need to ensure that all the equipments are clean and disinfected before using on non contaminated land.
* Proper Weed Management is very important so that it does not increase the level of manifestation.
* Application of lime to maintain pH of 7.2 is important to prevent attack by fungus. In order to make sure that the transplants are clubroot fungus free, transfer the transplant in sterile soil. Also we need to make sure that we don’t plant the infected plant with the healthy ones.

2. Downey Mildew

fig: Downy Mildew

fig: Downy Mildew

It is caused by Peronospora parasitica fungus and infected plant shows white fuzzy patches on head, leaves and stems and also causes browning of the curd and leaf. This fungus is able to survive for 2 years approximately. It is very important to control this disease which can be done by crop rotation with any other plant and also by treating the field with plant debris.

3. Black Leg

fig: Black Leg

It it is caused by fungus Phoma lingam. Symptoms can be recognized with spots on the stem along with purple border. The plants may ultimately die from wilting. It can be controlled by hot water treatment of the seeds as well as 4 year crop rotation is highly effective in crop rotation.

4. Grey and Black Leaf Spot

fig: Grey leaf spots

These diseases are seed and soil borne identified by small spots on the leaf and forms a hole like appearance. This disease is favored by cold temperature, high humidity and rain and decays the cauliflower. Grey Leaf Spot and Black Leaf spot is caused by Alternaria brassicae and Alternaria brassicola respectively. It can be controlled by by treating the seeds with hot water. It can also be avoided through long rotations and can also be incorporated by debris incorporation.

5. Black Rot

fig: Black Rot

It is caused by Xanthomonas campestris, which is favored by rain. It causes yellowing of the tissue. It can be controlled by treating the seeds with hot as well as crop rotation.

6. Damping Off

fig: Damping off

It is caused by Rhizoctonia Solani and is a soil borne fungus disease which attacks the seedlings. It generally does not affect plants that reached three to four leaf stage. In order to control spreading of this disease, the field needs to be ploughed properly before planting cauliflower. It is important to avoid over watering of the field. It is important to take care that the plants are not stressed.

fig: Damping off

7. Bacterial Soft Rot

This disease is caused by a bacteria Pectobacteria carotovora & Pseudomonas spp. In the mature crop the soft internal tissue of the stem may disintegrate, reducing it to a bad smelling slimy mess. In winter cauliflower the curd may show brown discolored patches resembling frost injury. The biggest problem from bacterial soft rot is the invasion through wounds to which cauliflower curds are very susceptible during cutting and subsequent packing. Infection begins as a small, yellow water soaked specks in the florets, and as decay progresses the florets become increasingly discoloured and water soaked. To control it, avoid the damage during cutting and packing. Once the cool crops are cut it is necessary to immediate storage at low temperature for the storage.