Sooty mold

• Symptoms  :
  • progressive appearance of one to several molds on the aerial organs of vegetables and food plants which present variable colors, but often blackish.
  • this sooty mold is harmful because it more or less disturbs the photosynthesis of plants and therefore their development, but it sometimes makes them unmarketable.

• Cause(s) :

  • several insects, including aphids , whiteflies , scale insects , etc. which during their parasitism take large quantities of sap in order to satisfy their food needs, and in particular in proteins. This forces them to reject large amounts of excess sugar in the form of honeydew. This then soils the surface of the organs colonized by these insects;

  • this sweet honeydew is a real godsend for several fungi in the phylloplane of many plants and vegetables that use them for food, and which are the source of sooty mold. Their development on this sugary substrate leads to the gradual appearance of one to several molds on the leaf blade (figure 1), the stem (figure 2) and even the fruits (figure 2) which have variable colors depending on the fungal species. colonizers: Alternaria spp., Cladosporium spp., Capnodium sp., Penicillium sp., etc.

• Diagnostic clues :
  • in the presence of sooty mold, observe the plants more closely in order to detect which insect is parasitizing them, then consult its specific sheet: whiteflies , aphids , scale insects , etc.

• Possible confusion :

• Remedies :
  • only the control of pest populations can remedy this.