A dire drought that has plagued Texas and parts of Oklahoma expanded across the key farming state of Kansas over the last week, adding to struggles of wheat farmers already dealing with weather-ravaged fields.

Harvest in Kansas, the top U.S. wheat-growing state, is set to begin within weeks. But a report issued Thursday by a consortium of climatologists said the three most severe levels of drought spread across the state over the last week, with the most dire conditions concentrated in the key wheat-growing south-central and southwest parts.

“It is pretty bad,” said Kansas state climatologist Mary Knapp. “For a lot of these areas… the last significant rainfall was in July of last year.”

Kansas now has 50 percent of the state suffering severe levels of drought or worse, up from 41 percent last week, according to the Drought Monitor report. Just three months ago, less than 4 percent of Kansas was suffering severe drought or worse.

The drought is eroding production potential at a time when every bushel counts.