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Nematodes occurrences bounce in Brazilian cotton crops‏

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Survey shows incidences of nematodes in Goiás state, Brazil‏

The increase of nematode occurrences on cotton crops in Brazil has left producers on alert. Nearly 23% of the areas researched in the state of Mato Grosso by Embrapa Algodão are affected by the root-knot nematode (Meloidogyne incognita), a very aggressive and quick spreading nematode.

The most affected regions in the country currently are Mato Grosso and western parts of Bahia, with estimated losses of up to 40% of production. "The worm reduces growth and the number of flowers and fruits stemming from root parasitism," said Nelson Suassuna, a researcher at Embrapa.

According to him, other two species are also issues of worry: "even though they are less harmful, Rotylenchulus reniformis and Pratylenchus brachyurus are present in the Cerrado and deserve attention". According to data from seasons of 2011/2012 and 2012/2013, the species with higher occurrence and space distribution was P. brachyurus, detected in over 9% of the samples homogeneously all over the state of Mato Grosso.

Meloidogyne incognita was present in 23% of the samples, with higher concentration in the east-center, north-center, and north. And a smaller incidence was seen mostly in the Northwest. The specie Rotylenchulus reniformis was detected in 10% of the samples, with higher occurrences in the southern region and intermediary occurrences in the center and north regions.

The specie Heterodera glycines (soybean cyst nematode) was observed in nearly 15% of the samples, mostly in the center-north and northwestern kernels. It was detected in just one soil sample, mostly in cotton areas planted after soybeans because this nematode is not pathogenic to cotton crops.