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Powdery, velvety spots

Powdery or velvety spots on tobacco leaves are often due to development of fungi with varying behaviour on this solanaceae crop.
As for the parasitic fungi of foliage, a velvety or felting layer observed on the lamina is  due to their sporulation on the leaves  which is  the final stage of their parasitism: Golovinomyces cichoracearum var. cichoracearum (formerly Erysiphe cichoracearum, agent of powdery mildew of tobacco or "powdery mildew", figure 1), rusts, such as Puccinia substriata and Uredo nicotianae, and Alternaria alternata, Thanatephorus cucumeris ou Peronospora hyoscyami f.sp. tabacina, already described in the sections related  to brown to black, or yellow to beige spots.


Figure 1  Figure 2

Opportunistic fungi may colonise the lamina superficially, in particular during insectfeedings. That is the case for fungi causing sooty mould (figure 2), especially in the presence of aphids or whiteflies. To prevent this type of damage, one should control the development of these pests by using various protection methods. Remember that auxiliary insects (Beneficial insects) help to limit the proliferation of insects damaging tobacco.

Last change : 02/14/13
  • Author :
  • D Blancard (INRA)