The 2010 corn harvest has begun in far western parts of the state, and producers are finding several issues in their fields as a result of extreme heat and dry weather. Producers who haven't started harvesting in this area, and those farther east, need to scout for problems, so they'll know which fields to harvest first, said Chad Lee, grain crops specialist with the University of Kentucky College of Agriculture.

While far western Kentucky counties have experienced the most extreme heat and driest conditions this summer, the whole state has had above normal temperatures. Western Kentucky also has been abnormally dry, and other areas of the state have sections that are dry.

One of the biggest concerns with these conditions is weakened cornstalks. Dry weather caused crops to stop taking in nutrients during seed development. With no other source of nutrients, the seeds might have pulled nutrients from the stalks in order to complete their development.

To check for stalk deterioration, farmers need to grab a plant at chest height, pull it toward them until it is at an angle and let go. If the stalk snaps back and stands up, it is strong. It's weak if it falls over. If farmers find weak stalks in their fields, they may want to go ahead and harvest those fields first. If the state were to get heavy rain or strong winds before these fields are harvested, lodging could occur. This would make harvest difficult and possibly cause crop loss.

The earlier start may require producers to harvest at a higher moisture content and dry the crop. In areas where harvest is already under way, some producers are reporting grain with 25 percent moisture content or higher. Growers can determine whether the costs of drying grain would be offset by the costs of anticipated harvest losses on the UK grain storage systems extension website http://www.bae.uky.edu/ext/Grain_Storage/calculators.htm.

Another concern is ears falling off the plant, which could complicate harvest and create yield losses. In most cases, these are heavier ears. In areas that have been abnormally dry, like Graves County, kernels are falling off the ears in corn with low moisture levels, said Kenny Perry the county's agriculture and natural resources extension agent. These issues are both due to the hot, dry weather that caused the corn to rapidly mature and dry down.

"Corn normally goes through seed set and seed fill for about 60 days in Kentucky," Lee said. "This year, much of that corn reached maturity two or even three weeks early, dramatically reducing the time needed for seed set and seed fill."

UK agriculture and natural resources extension agents in far western Kentucky are reporting significant yield losses in the portion of the crop that has already been harvested. Tom Miller, Ballard County's agent, said his county's yields are ranging from 100 to 140 bushels per acre with average yields around 130. The National Agricultural Statistics Service estimated the county's 2009 average yield at 167 bushels per acre.

Perry said yields vary widely across fields in his county depending on an area's soil type and moisture holding capacity. He reported yields between 30 and 180 bushels per acre and 90 and 210 bushels per acre in the same fields. He estimated the county's 2010 average yield will be around 120 bushels per acre. The county's 2009 average yield estimate was 154 bushels per acre.

Yields also vary across fields in Fulton County, said Cam Kenimer, county agriculture and natural resources extension agent. With about 35 percent of the county's corn harvested, average yields are around 125 bushels per acre. This is below the county's 2009 estimated average yield of 174 bushels per acre, but he added that 2009 was the county's best yielding year on record.