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Tomato plants are subject to attacks from
an array of pests that cause massive damage
to the crop and losses to the farmers. One of
the biggest difficulties of the supply chain is
tokeep thewhiteflies under control. They are
insects of the Aleyrodidae family. As they do
not make any distinction between different
foods and have a high degree of polyphagia,
they attack a variety of agricultural crops, but
it is in the tomato fields that the reflections
of their voracity is witnessed more intensely.
These insects suck the sap and transmit the
virus that jeopardizes the development of the
plants and, consequently, their productivity.
They also inject toxins that cause the fruits to
mature in a non-uniform manner, resulting
into fruit isoporization.
Agronomist Alice Nagata, from Embrapa
Vegetables, explains that whiteflies could in-
fect tomato fields with two strains of viruses:
the geminivirus and the crinivirus. Gemini-
virus infections result into stunted growth,
yellow mosaic symptoms, leaf curl, flower-
ing problems and the production of a small-
er number of fruits. In the case of early infec-
tions, losses could amount to 100%. “One of
the weapons available is the use of resistant
cultivars, but fully resistant hybrids do not
exist”, she says. The phytopathologist main-
tains that the problems caused by geminivi-
rus are more serious in determined growth
tomatoes, where resistant cultivars, even at a
moderate level, are rare.
The crinivirus is also transmitted by the
whitefly and directly affects the fields. In
infected tomato plants, this type of virus
causes chlorosis, the midrib and the later-
al veins turn yellow, reflecting nutrient de-
ficiency – the leaves curl and turn papery.
In general, according to the specialist, the
symptoms appear later than in the case of
geminivirus infections, which normally sur-
face in about 40 days. “In case infections are
caused by viruses, there is no treatment. Pre-
ventive management is the solution”, she
says. “Once the plants have been infected,
there is nothing to do. Either the farmers
put up with the problem and do their best
to maximize their crop under these condi-
tions, or destroy it and start a new one”.
According to the researcher, Embrapa
Beelike fly
Consideredtobeanextremelyvoraciouspest, thewhitefly isone
ofthemostdreadedinsectsbymostBraziliantomatofarmers
