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Locate and characterise the symptoms

After having determined the agro-cultural and parasitic contexts and carefully selected the most representative plants of your pest problem, it is now appropriate to clarify the exact location of symptoms (especially on vegetation - figure 1)  and their characteristics on plants (see tables). We will not describe here the procedure adopted for nursery seedlings and after planting because they are quite similar to that used for mature plants and also to that used for the diseases occurring in the curing barn.

figure 1

Tobacco is a rather aerial plant in which the major organs can be easily distinguished and different disease symptoms can be observed. We have chosen three main organs on which you should focus your observations in order to determine the exact nature of symptoms and signs.

  • Leaves
Abnormal leaf shape

- Stunted plants
- Deformed leaves
- Perforated leaves
 Abnormal leaf colour

- Leaf mosaic
- Leaf chlorosis
- Totally or partly bleached leaves
 Leaf spots

- Small, often necrotic spots
- Brown to black spots
- Yellow, beige, greyish spots
- Powdery, velvety spots
- Beige to brown spots

 Wilted and dry leaves



Last change : 09/17/13
  • Author :
  • D Blancard (INRA)