Leaf stripe and stem rot caused by Burkholderia gladioli, a new maize disease in Mexico.
A disease in maize plants, not previously observed, appeared in 2003-2004 in Cosoleacaque, Tlalixcoyan and Paso de Ovejas counties, in the state of Veracruz, Mexico. Initial symptoms on leaves were small white-yellow watery spots, which coalesced into dry necrotic stripes 0.3 wide and up to 8cm long. Reddening sometimes developed on these leaves. Stems developed a rot in the crown. The flag leaf became rot and necrotic at the base, rolled inwards and dried out. Necrosis developed at the base of the corn ears and their growth was inhibited. These symptoms were initially observed in Asgrow-7573 commercial maize plantings. A bacterium characterized by white colonies, gram negative, aerobic, rod-shape, opaque, round colonies with entire margins on casaaminoacid peptone and glucose media was consistently isolated from diseased maize plants. On King's Medium B, the isolates produced yellow, non-mucoid colonies, with the majority of the strains secreting a diffusible yellow pigment into the media. The bacterium identity was confirmed by PCR amplification and sequencing of 16S and 23S genes rDNA fragments. The bacterium was identified as Burkholderia gladioli. Its pathogenicity on maize plants in Mexico is a new record.