Botrytis Cinerea (Bud Rot)

Last Updated: August 13, 2018

Definition - What does Botrytis Cinerea (Bud Rot) mean?

Botrytis cinerea is a fungus that afflicts many types of plants. It is one of the main causes of moldy marijuana plants. Left unchecked, it will result in a condition known as bud rot.

A necrotrophic fungus, Botrytis cinerea is extremely common on wine grapes and cannabis. It attacks cannabis at all stages of growth and can be devastating to a crop.

Marijuana plants afflicted with the fungus can perish within one week. The fungus typically thrives when the weather is cool but the humidity is high. The mold of the Botrytis cinerea is the most noticeable on the moist areas of the plant.

MaximumYield explains Botrytis Cinerea (Bud Rot)

Botrytis cinerea is often just referred to as gray mold. The spores of the fungus are spread by the wind. They enter the plant via a small tear or external wound in the plant’s tissue. It often burrows into the marijuana plant’s stems right where the stem meets the soil.

Once inside the stem, the fungus starts to rot the stem tissue and the plant falls over which is referred to as ‘damp off’. Once the plant’s stem has been infected, the fungus then spreads to the marijuana buds. The plant’s leaves turn brown and the plant wilts. The buds become covered in a fine gray fur. As the fungus progresses, the buds start to rot and turn into a slimy mess.

Prevention is the key to controlling Botrytis cinerea. You should keep your plants dry and warm. Ideally, the grow room temperature should be maintained over 70 degrees Fahrenheit and the relative humidity maintained below 50 percent.

If a plant becomes infected with Botrytis cinerea, it should be discarded. Infected plants may be treated with a copper sulfate fungicide. However, oftentimes the plant is a complete write-off. Burning and spraying the plants with sulfur also reduces the airborne spores of the fungus.

This definition was written in the context of Cannabis
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