Leaf fungi and spots

The following fungi are common leaf fungi. When, due to a less vital soil and weak plant resistance, these fungi occur, one of the products bellow can be used. These products support the natural recovery ability and have a wholesome, nourishing and plant strengthening effect when the soil and the plants are influenced from the outside.

Powdery mildew

This fungus can be recognized by white powdery spots on the leaves which can be wiped off. On the contrary, downy mildew can not be wiped off. Powdery mildew is most common in hot humid weather. Plant saps are extracted from the plant, after which the leaves, shoots and flowers are inhibited in their development and deform. Plants and trees such as roses, Norway maple and oak are susceptible to powdery mildew.

Downy mildew

Downy mildew is a fungus that spreads using spores. This fungus appears on the underside of leaves and affects it from inside. These leaves discolor and prematurely fall off. Downy mildew can not or hardly be wiped off the leaf, as opposed to powdery mildew. This is partly because the fungus is inside the leaf. The spores spread quickly in humid and hot weather. The fungus can spread to other parts of the plant.


Rust is a fungal infection which affects the leaves of trees like poplars. Rust occurs especially in hot and humid weather. The top of the leaf gets small orange spots. A fine, orange powdery substance forms underneath the leaf, which turns brown in autumn. Rust results in leaves falling off prematurely. This is severely growth-inhibiting.



Alternaria is a fungus that can spread rapidly, mainly in tomatoes and potatoes.The aggressive type is Alternaria solani , which can affect healthy plants and tubers. At the same time, the fungus produces a toxin that destroys the leaves. Alternaria alternata has similar symptoms but can only affects plants that have already been weakened by aging, stress or virus infection. This affects only damaged leaf tissue , for example due to mechanical damage, virus infection, magnesium or manganese deficiencies or damage from wind, hail or drought. Alternaria can completely destroy a crop within two to three weeks. The leaves turn brown from the edge or the tip. This discoloration advances to the middle of the leaf as small round-shaped brown lesions with concentric rings. The size of the spots ranges from several millimeters to two centimeters. Furthermore, a black, velvet-like deposit develops on the tissue. Tubers can get infected as well. These can be recognized by dark-colored spots with a slightly raised edge. Alternaria and Verticillium or manganese deficiency look similar. However, the latter do not exhibit the concentric rings.

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