- Botrytis cinerea: The Life Cycle
- Botrytis cinerea: Identify damage
- Control successfully Botrytis and drive away gray mold
- Botrytis Clever prevention
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Botrytis cinerea is one of the most common plant-damaging fungi. We introduce the annoying fungus and show how to fight it successfully.
Who doesn't know the gray mold growth on the beloved strawberries? This is mostly caused by Botrytis cinerea, the gray mold. With a little knowledge about the fungus, you can prevent or control the infestation. We'll show you how, so you can enjoy your plants for a long time.
The fungus Botrytis cinerea is a wound and weakness parasite and is extremely adaptable, which is why it has a strong tendency to develop resistance. It is one of the most difficult pathogens to control and can cause us concern on various plants in our garden.
Botrytis cinerea: The Life Cycle
This fungus belongs to the class Ascomycetes (Ascomycetes) and has a wide range of host plants. This class owes its name to the shape of its reproductive organs. The sac fungi include 45,000 different species and are therefore the largest and most important group among the real mushrooms. The Ascomycetes also include apple scab (Venturia inaequalis), ergot (Secale cornutum) or the brush mold (Penicillium), known from antibiotic production.
The conidia (asexual fungal spores) form on the decaying areas. Gray mold conidia are spread by wind or spray, infecting new plant tissue. Infection occurs when there is prolonged moisture. The infection then spreads through the fruit and plant. The well-known gray mold lawn can then be observed on strawberries. However, the fruit can also be infected directly.
The fungus hibernates on organic material and in the spring begins to develop again. Sclerotia are formed as a permanent form, but the fungus can also overwinter as mycelium on dead plant parts. Sclerotia are hard permanent formsof mushrooms that are very resistant to drought or cold, this allows mushrooms to stay in a dormant stage for a long time until optimal conditions are restored for them. The development is started by the humid conditions in spring and with that the growth of the fungus starts again and with it the formation of new spores.
An overview of the development cycle of the gray roan:
- There are sclerotia in the soil that can survive there for a long time.
- The fungus can also survive as mycelium on organic material.
- From these sources, the spores spread and infect our plants.
- Dispersal is by wind or spray.
- A gray layer of fungi develops on the plants, on which spores also form.
- Humidity and temperatures between 20 and 28 °C are optimal for gray mold.
Botrytis cinerea: Identify damage
As its name suggests, a flat, mouse-grey lawn of fungi forms when gray mold infests it. This mushroom lawn has the habit of dusting heavily. The tissues of the plants die off, and brown spots also form on the leaves and fruits. The fruits look rather glassy at the beginning. So-called ghost spots can appear on tomatoes. A bright center forms and around this center, with some distance, a bright ring.
The fungus can occur on all parts of the plant. Soft fruits and flowers are particularly affected, but shoots and woody parts can also come into contact with gray mold.
Crops that are particularly susceptible are tomatoes, cucumbers, onions and lettuce. When it comes to berries, the gray mold is particularly interested in strawberries, raspberries, gooseberries and blackberries and does not stop at our ornamental plants. Roses, tulips, rhododendrons and hydrangeas are just some of the affected ornamental plants in our gardens.
Control successfully Botrytis and drive away gray mold
There are several approaches to controlling gray mold. Here we show you tips and tricks for prevention and various countermeasures.
Control Botrytis cinerea: Suitable pesticides
Chemical control of Botrytis cinerea is somewhat problematic. This fungus is extremely adaptable and can grow very quicklydevelop resistance. Therefore, you should first apply our preventive and natural control measures before resorting to chemical control. Studies on raspberries from northern Germany show that 100% resistance can develop after just five years.
If you don't see a way out, the following active ingredients can promise success:
- Trifloxystrobin
- Cyprodinil
- Fludioxonil
- Soil fungus Gliocladium catenulatum
Use caution when using pesticides. Always follow directions for use, especially personal safety and dosage.
Control Botrytis cinerea: Natural measures
Several methods against gray mold have also proven themselves in a natural way. On the one hand, the use of various liquid manure and teas to combat and prevent it should be mentioned, since many of these remedies are plant strengtheners. He althy and strong plants will not be attacked by disease as quickly as plants in a weakened state.
For example, horsetail broth can be sprayed on for strength. In the case of strawberries, dip the roots in horsetail broth before planting, support growth later with diluted nettle manure and defoliate the plants a little if the stand is very dense. Find out more about horsetail broth and nettle manure here.
But it is important that you look for a new location for the strawberries after three years at the latest. Since the strawberry flowers are affected, you can dust them with rock flour to reduce the infestation. The rock flour can also be applied to the soil as a fertilizer - especially on acidic soils as a soil improver. But don't overdo it with fertilization. A lot of nitrogen can promote fungal infections, so use it sparingly.
Botrytis Clever prevention
Since the fungus survives the winter on organic material, we have the first point of attack. Remove dead plant parts, these are full of spores and will only infect more plants. It is important to have as few sources of infection in the garden as possible.
Particularly importantis also dealing with humidity, which humidity favors Botrytis. Therefore, the planting distance between your plants should not be too narrow. A larger distance promotes good air circulation and promotes faster drying. Varieties that develop smaller leaves also help, as they dry off faster.
You should also pay special attention to your casting practice. Do not water from above, this will wet the whole plant and create optimal conditions for fungal infection. Therefore, it is best to water the plants where they really need moisture - namely on the ground. If you work with irrigation systems, rely on drip irrigation.
Be careful when using straw with strawberries. Of course it is practical if the strawberries are not full of soil, but you should not spread the straw around the strawberry plants from the beginning. It is sufficient if you spread it on the ground shortly before or during flowering. Unfortunately, there are no strawberry varieties resistant to Botrytis.
Also ensure crop rotation in your garden and change the location of your ornamental plants regularly. In the vegetable patch, a mixed culture with garlic or onions can have a preventative effect. The mustard oils in these plants act against the fungus. You can also leave the garlic and onion residues in the garden and incorporate them into the soil. The mustard oils are effective against various pathogens and pests.
If you have a glass house, you should make sure that the humidity is not too high and that no dew forms on the leaves. Regular ventilation or the use of automatic windows is particularly important.
A special storage tip: Cool the harvested fruit, especially berries, quickly to 0 to 3 °C. This keeps them fresh longer, otherwise potentially infected fruits could cover your entire harvest with the gray mold lawn. Also try not to touch the fruit as much as possible and not to damage it.
Preventing Botrytis: A Brief Summary
- Remove infested and dead plant parts
- Larger plant spacing
- Do not water from above but close to the ground
- Put the straw on the ground only after the strawberry blossom
- Crop rotation and relocation
- Mixed culture with garlic
Tip: To strengthen the plants most commonly susceptible to botrytis and make them more resistant, we recommend our Plantura organic tomato fertilizer. This is ideal for vegetables and berries and has a high potassium content.