LAUSR

Soybean, the most important agricultural product in Brazil, is widely cultivated all over the country. The occurrence of green stem and foliar retention (GSFR) has been reported since the beginning of the soybean cultivation in Brazil and its potential causes were attributed to severe attack of stinkbugs or plant nutritional disorders. About two decades ago, a new type of GSFR was reported in Brazilian tropical regions of soybean production, also of an unknown cause. Several possible causes were investigated, but the presence of the nematode Aphelenchoides sp. in symptomatic plants was frequently observed. Koch’s postulates were conducted to check whether this nematode could be the cause of the syndrome. Specimens of Aphelenchoides sp. were isolated from soybean plants and multiplied in colonies of the fungus Fusarium sp. in PDA culture medium. Nematode suspensions were inoculated onto healthy soybean plants and the typical GSFR symptoms were observed. The nematode was recovered from the inoculated plants. Based on both morphological and molecular data, we suggest that Aphelenchoides besseyi is the causal agent of GSFR of soybeans in Brazil, a syndrome popularly known as “Soja Louca II”.