New disease hits Georgia's Vidalia onion crop

07/18/2014 06:53:00 AM
Vicky Boyd

click image to zoomyellow budCourtesy University of GeorgiaAn onion plant infected with yellow budA new disease is hitting Georgia's Vidalia onion crop, leaving a bitter taste in growers' mouths.

Yellow bud, a bacterial disease, turns onion leaves yellow, according to a news release.

The plant either dies or the leaves eventually greens back up. Even in the latter case, the damage has been done and growers see the results with significantly reduced yields.

The disease was first found in Tattnall County in 2007 and has now spread throughout most of the state's onion growing region.

The Psudomonas synringae pathogen is active during the winter growing season and can be spread through the air and by blowing or splashing rain.

It feeds on leaf nutrients and produces a toxin that causes the chlorophyll to turn yellow.

Spray timing is critical, and growers need to apply a protectant fixed copper spray before infection.

Once the pathogen is established on the leaf surface, it can colonize the hollow center of onion leaves and escape treatment.

Although New Mexico, Texas and a few other states produce onions over the winter, University of Georgia pathologist Ronald Gitaitis says he believes Georgia conditions are slightly different and that's why others haven't seen the disease.

Then again, it could be because the bacterium has not yet been found in those other areas.



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