Detalle de: Assessment of vegetative compatibility of Acremonium cucurbitacearum and Plectosphaerella cucumerina isolates from diseased melon plants*

One of the most important disease complexes of melon in Spain has been referred to as collapse, sudden wilt or vine decline. Acremonium cucurbitaceaum and Plectosphaerella cucumerina (anamorph Plectosporium tabacinum ) are two of the fungi implicated in this disease complex. Genetic diversity among populations of these two plant pathogens has been approached by the assessment of vegetative compatibility using nitrate non‐utilizing auxotrophs. In A. cucurbitacearum , with a host range limited to Cucurbitaceae and found in Spain and USA (California and Texas), 10 vegetative compatibility groups have been identified. Plectosphaerella cucumerina has worldwide distribution and wide plant‐host range. From a collection of P. cucumerina isolates with different plant and geographical origins, only four pairs have developed complementary heterokaryons when pairings of phenotypically distinct nit mutants ( nit × NitM) were conducted. Each of the four vegetative compatibility groups consists of two members with close geographical origin and all the isolates were from diseased melon plants. Of the remaining P. cucumerina isolates, two did not produce nit mutants, two were self‐incompatible and the others were vegetatively incompatible among themselves, suggesting that this fungal species may have wide genetic diversity in nature.