Sunflowers are among the most popular plants of all because of their striking appearance. Unfortunately, various diseases and pests can spoil the appearance.
The sunflower is a very robust and hardy plant. If it doesn't get enough water despite the persistent heat, it lets its leaves droop - a clear sign that you need to water it. Afterwards the plant recovers quite quickly.
It is different with the various diseases and pests that can attack the sunflower. It is often fungi that damage the plant. In this article we explain how to detect pests and diseases in your sunflowers and what treatment is appropriate.
Pests on Sunflowers
Sunflowers are less likely to be attacked by pests than diseases. The pests are the typical animals:
- Lice
- Bugs
- miner moths
- caterpillars
You can usually recognize the harmful animals by their feeding spots or deformed leaves. The animals rarely damage the plant to the point where it dies, but the feeding sites pose another danger: the sunflower is weakened, making it much easier for fungi to spread.
You can remove caterpillars or individual lice by picking them up with your fingers. You can also use a simple household remedy to combat a small infestation of lice: Put a little washing-up liquid and water in a spray bottle and spray on the affected areas.
Of course you can also kill pests with pesticides and avert further damage to the plant. If your sunflower develops seeds, you must use a special spray that does not damage the seeds or leave behind harmful toxins.
It is better not to eat the sunflower seeds from plants that have been treated with pesticides.
The most common diseases of the sunflower
As already mentioned, sunflowers are particularly frequently attacked by fungi. It is not uncommon for the diseases to occur where the plant has already suffered previous damage from pests or theweather.
In the case of fungal diseases, the root or the stem of the plant is usually attacked:
Pythium
If waterlogging forms in the root area or if the soil is very s alty, this fungus can spread. It causes the roots to die off.
» Control:
The best treatment is to drain the root immediately and reduce the salinity of the soil.
Root rot
The fungus appears at the transition from stem to root. Fungal growth requires high humidity and spreads very quickly.
» Control:
Special commercially available antifungal agents (e.g. this one) can protect the sunflower and reduce the fungal infestation.
Sclerotinia
This fungus affects the root and sprouts. The fungus appears hairy and forms distinct braids.
» Control:
Without antifungal treatment, the plant dies.
Fusarium
This fungus is insidious because it attacks the plant through the roots, but spreads further through the vascular tracts. The sunflower is wilting.
» Control:
There is no remedy for this fungus.
There are also fungi that do not specifically attack the roots but the leaves:
Alternaria
It is characterized by greyish-brown spots on the leaves, covered with a black coating of fungal spores.
» Control:
Antifungal agents combat the fungus very reliably.
Powdery mildew
Infestations of powdery mildew are common between May and August. A white lawn of fungus forms on the leaves.
» Control:
The disease can be treated with an antifungal agent.
Downy mildew
Unlike powdery mildew, which grows white mats on the surface of leaves, this fungus grows on the underside of leaves and is gray or purple in color.
» Control:
Antifungal agents control the fungus.
To combat fungi, it is necessary not only to treat the disease itself, but to eliminate the cause of the infestation. Infestation often occurs due to high humidity or waterlogging. Sunflowers that are very close together or are hemmed in by other plants are prone to fungal diseases. If this is the case for you, consider transplanting the sunflowers.