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These Diseases Threaten Basil – symptoms and control

These Diseases Threaten Basil - symptoms and control

Is your basil affected by mottle or deformed leaves? The following lines explain which diseases are behind the symptoms and how to combat them.

Septoria fungal infections

They are expressed in brownish necrosis on the leaves, which gradually spread. The spores of the sac fungus genus Septoria strike primarily in warm, humid weather in June, July, and August.

In the final stages of the disease, the foliage dries up and falls off. Although effective fungicides have so far been lacking, with a little luck you can stop further spread in this way:

  • At the first symptoms, cut back affected branches to a pair of leaves
  • Isolate the basil from other plants in the pot
  • discard if plant does not recover
  • Burn clippings or dispose of with household waste

As a preventative measure, it is recommended not to fertilize with a high nitrogen content and to always water the basil from below. The choice of location also plays a key role. Choose a sunny, warm spot that is protected from rain.

Lucerne Mosaic Virus

This widespread viral infection is transmitted in different ways. Infected tools are often the cause, or aphids brought the bacteria with them. After an incubation period of 2 weeks, the first symptoms appear in the form of lightening of the leaf veins and mosaic-like patterns on the foliage. As a result, deformations develop and the plant dies.

Combating the virus directly is neither chemically nor biologically possible. Infected basil plants should be destroyed immediately. To prevent the disease from spreading further in the garden, you should take vigorous action against the aphids. How to prevent lucerne mosaic virus:

  • Only use certified seed from specialist retailers
  • disinfect all tools meticulously before and after maintenance work
  • Do not leave any plant remains on the ground as possible wintering quarters for the virus

Suspected thrips

As part of current research, thrips were suspected of also transmitting the virus. Prudent hobby gardeners therefore also include the control of these pests in the preventive measures.


Do not fight aphids on basil with one of the common liquid home remedies, such as the classic soft soap solution. The herbal plant does not want to be sprinkled with water or sprayed with other liquids.

In this case, you can get rid of the annoying pests with pure charcoal ash or rock dust. Simply spread with a powder tip.

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