Mother Nature has struck Vidalia onion growers a heavy blow for the second straight year, just as their harvest season is beginning, threatening to significantly reduce the 2013 crop.

Unusual amounts of rain at the wrong times in February and March and unseasonably cold temperatures in late March and early April are taking their toll. Onion growth slowed just as growers were preparing to begin harvesting the first week of April, which meant a very slow start to the season, according to a news release April 19 from the Vidalia Onion Committee.

Growers started reporting an additional problem April 15, which was the official shipping start date set by the Georgia Department of Agriculture. Many onion fields began showing abnormally high amounts of seed stems, also known as bolters or flower stalks.

Vidalia growers predict significant crop losses“Monday morning (April 15) e-mails and phone calls began pouring in about widespread, high percentages of seed stems that were noticed late last week and through the weekend across the production area,” the onion committee release said.

Multiple stress factors, including the excessive rain and cool temperatures, can impact growing onions and lead to seed stems. When the plants “bolt” and shoot up the stalks with flowers that later generate seeds, the onion core is sucked dry and becomes hollow.

However, retailers and consumers should not worry about the quality of Vidalia onions that are shipped this season, the release said, because the seed stem onions are easily recognized during the harvesting and sorting processes and are discarded.

The onion committee did not provide an estimate of how much of this year’s crop is lost to seed stems.

For the 2012 season, about a third of the total Vidalia crop was lost to a late-season outbreak of downy mildew. The disease didn’t show up until just before harvest last year and caught many growers by surprise.