Drought's upside: Scrawny ragweed plants

Early October is usually the peak of the ragweed allergy season. But pollen levels have been extremely low since the first grains were detected at the beginning of September.

“I think they were a fatality of the drought,” said Dr. Paul Ratner, a San Antonio allergist who measures pollen counts for the San Antonio Express-News.

“I went out about a month ago and looked at the plants, and they were really pathetic-looking,” Ratner said. “They were probably a half to a third of the height they would normally be at that time. They had very little pollen on them, and the pollen they had was pretty shriveled up.”

The recent rains were too little, too late to reinvigorate the plants and produce more pollen, he said.

In most parts of the country, ragweed is the No. 1 allergen. But around here, mountain cedar is much more prolific — producing pollen counts many times higher when the trees let loose in the winter. Still, ragweed remains a distant second.

Not this year. Only low or trace amounts of ragweed pollen have been recorded each day for the past month — with the exception of Thursday when a count of 160 grains per cubic meter of air nudged it into the moderate category.

“There are pockets here and there near drainage ditches and at creek sides,” said David Rodriguez, the Bexar County extension agent for horticulture. “You do see some, but not as much as we have in normal years.”

Giant ragweed, or Ambrosia trifida, is the most common type of ragweed in San Antonio. Often found in low-lying areas such as ditches and creeks, it grows 6 to 10 feet tall.

Ragweed pollen season often extends into the first part of November. But Ratner doesn't expect much change in counts.

“They're very much like a corn plant, and if they didn't get that water during the summer, they didn't survive. We've seen some but it's really been a very weak season.”

However, for those hoping the dreaded mountain cedar trees might be similarly wilted, Ratner said the timing of the recent rains could bring a healthy — or unhealthy, depending on your perspective — crop of cedar pollen this year.