How To Identify and Prevent Botrytis

There are more than 50 different species of botrytis, also known as gray or brown mold, or bacterial soft rot, which can wreak havoc on numerous plants, including ornamentals, fruits and vegetables.

Asparagus, beans, carrots, celery, eggplants, grapes, lettuce, peppers, raspberries, strawberries, and tomatoes are just some of the plants commonly affected by the dreaded botrytis.

Botrytis is a cool-season disease that affects both outdoor and indoor gardens. It is common in every climate and geographical location, aside from possibly the Arctic and Antarctic regions.

This destructive fungus can quickly destroy an otherwise healthy garden due to its ability to spread rapidly. In fact, many gardeners refer to this fungus as bud rot or fruit rot because of its ability to quickly rot those sections of the plant.

Both indoor and outdoor horticulturists should be on the lookout for botrytis, especially during the cooler months of the year.

A better understanding of identifying the conditions favorable to botrytis, and being able to catch any infection in the early stages, gives growers a fighting chance against one of the worst pathogens to plague gardeners.

Identifying Botrytis

Botrytis mainly affects tender tissues, such as flowers, fruits, and seedlings, but it can enter the plant’s tissue through pruning scars or other distressed or wounded tissues. Lower, shaded sections of a plant are usually the first to show signs of a botrytis infection.

The first sign shown by a plant with an infection is a water-soaked browning area. The distinctive browning is universal, regardless of the type of plant affected. Once a grower has seen this distinctive browning, it becomes fairly easy to identify later.

After the initial browning, a silver gray fuzzy mat will develop on or around the brown tissue. Upon closer inspection, the fuzzy mat will look like thousands of tiny balls.

These tiny balls are actually spores that fly up like dust if the area is disturbed. The rest of the plant may show signs of illness such as yellowing leaves or buds.

In extreme cases, or when high humidity is prevalent, a brown, slimy substance, which is actually decimated plant tissue, can appear. The time of the year will play a part in the identification of the botrytis beast.

As mentioned earlier, botrytis commonly occurs during the cooler parts of the season. Growers should be on the lookout during fall and winter months, especially in a greenhouse or indoor garden where fresh air for the garden is taken from the outside.

Outdoor growers need to pay extra close attention to their plants during late summer and early fall.

Botrytis commonly affects outdoor crops when temperatures turn cooler and rain is more prevalent. Moisture from rain, artificial waterings and dew can all accelerate the growth of this fungus.

Preventing Botrytis in Your Growroom

As with many garden pathogens, prevention is the key to avoiding botrytis. Keeping a clean room and removing any dying or dead plant material is a good first step for any grower. In a sense, botrytis is an environmental disease, meaning it can only develop when the environmental conditions are conducive to its growth.

Prevention of botrytis is easier for indoor horticulturists because they have more control over environmental conditions.

Humidity is the largest contributing variable to botrytis in an indoor garden. As long as the humidity is kept below 55%, botrytis is unlikely to develop. The other contributing environmental factor is temperature.

Botrytis can only germinate on damp or wet plant tissue in temperatures between 50 to 70°F. However, once the fungus has developed, it can withstand a larger range of temperature and humidity.

Botrytis grows most rapidly in lower temperatures with high humidity. For the indoor grower, the best prevention is to maintain a lower humidity in the growing environment, especially during fruiting and flowering stages.

To be extra safe, an indoor grower should keep temperatures on the warmer side and monitor the dark-cycle temperature.

A heater may be needed during the dark cycle to minimize the temperature variance and reduce the possibility of condensation.

A ventilation system with atmospheric controllers allows an indoor grower to ensure environmental conditions are in check and are not inviting infection.

Oscillating fans that create good air flow within the room will help keep the room’s humidity uniform.

Another way an indoor grower can prevent botrytis is by using a filtration system or other air purification system. HEPA filters enable growers to filter out many spores commonly found in the air.

This will greatly reduce the chance of developing botrytis and other pathogens. Be sure to place the filter in a bag and remove it from the growing area before gently removing it for cleaning.

Filters trap many spores that are still viable and, in some cases, growers inadvertently expose their gardens to all sorts of nasty things when they remove the intake filter for cleaning.

Air purification systems offer another way for growers to eliminate spores from the growing space. Photocatalytic air purifiers are the best option for indoor growers looking to eliminate air-borne molds because they completely destroy the spores and do not trap any viable pathogens.

If you choose to use a photocatalytic air purifier, be sure to note if it produces ozone. High levels of ozone can be harmful to people and plants when it becomes concentrated in an enclosed area like a growroom. This can be counterproductive to the plants and dangerous to the grower.

 

Source exerpt: Maximum Yield,2/28/2020,"Beating Botrytis: How to Identify, Prevent & Treat a Common Crop Ailment"https://www.maximumyield.com/beating-botrytis-how-to-identify-prevent-treat-a-common-crop-ailment/2/1261