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Tomato chlorosis virus  (ToCV)

 

General 

  • Crinivirus transmitted by several species of whiteflies according to the semi-persistent mode, essentially subservient to the phloem of plants.
  • ToCV is not widespread in DROM-COM
  • Virus rather specialized in Solanaceae
  • Observed mainly, sometimes under shelter.

 

  • Susceptible botanical family(s)
Solanaceae

 

  • Production areas affected :
Mayotte Reunion Guyana

 

  • Organs attacked
Leaves

 


Symptoms 

  • Symptoms :
    • Chlorotic mottling, yellowing in interveinal spots on lower and middle leaves of plants randomly distributed in the crop (Figures 1-4).
    • Small reddish to brown necrotic alterations sometimes visible on the lamina (figures 5 and 6).
    • Fairly sustained interveinal yellowing generalized to many leaves, the veins of the leaflets remaining dark green and contrasting with the rest of the leaf blade.
    • Old leaves thick, curled and becoming brittle, and drying out (Figure 7).
    • Less vigorous plants, fruits with delayed growth and maturation.
  • Possible confusion : food disorders (magnesium, potassium, nitrogen, etc.), tomato yellow leaf curl virus (TYLCV), tomato infectious chlorosis virus (TICV), ( Pepino mosaic virus - PepMV )
  • Signs : no visible signs, confirm the possible presence of whiteflies.

 


Biology

 

  • Conservation : on a range of natural plants restricted to about thirty cultivated or wild hosts serving as virus reservoirs: potato, pepper, Datura stramonium, Solanum nigrum, S. nigrescens, Physalis peruviana, P. ixocarpa, etc.).

  • Transmission : by several species of whiteflies according to the circulating semi-persistent mode*: Trialeurodes vaporariorum (Westwood), Bemisia tabaci (Gennadius, the most efficient vector) biotypes A, B (= Bemisia argentifolii Bellows & Perring) and Q, and Trialeurodes abutilonea (Haldeman). Certainly spread by seedlings in production regions where viruliferous whiteflies abound in nurseries.


*Its virus acquisition time by the insect is 48 hours, sometimes less, and it remains viruliferous for approximately 3 days. Once "injected", the virus remains limited to the vessels of the phloem, in which it multiplies. It does not seem that virus transmission to the insect's offspring is possible.

 


Protection

 

  • Protect nurseries and young plants in the field with veils (Agryl P17 type) or mesh fabrics (Filbio type), etc.
  • Check the quality of the seedlings and check that they have been protected, including during transport and storage before planting, for example using agro-textiles.
  • Under shelter, quickly make it insect-proof by blocking the openings with nets  insect-proof .
  • Avoid setting up a new culture near old cultures that may already be contaminated
  • weed the plots and their surroundings in order to eliminate sources of viruses and/or vectors.
  • Place sticky yellow signs in shelters and to monitor potential whitefly infestation pressure.
  • Control whitefly populations ( biological control , insecticide protection ).
  • Quickly eliminate the first infected plants if there are few of them.
  • Rapidly eliminate plants at the end of cultivation so that vector whiteflies do not multiply there and do not represent a danger for nurseries or future crops.
  • Carry out a crawl space for a few weeks under shelter. If you do not have this time, the uprooting of the tomatoes will be preceded by an insecticide treatment in order to reduce pest populations.
Last change : 07/07/22
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Figure 6
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Figure 7