Delays in the development of the 2008 corn crop across the Western Corn Belt increase the odds that stalk and root rots will be a problem this fall.

That's according to veteran corn breeder Dr. Tom Hoegemeyer, chief technology officer for Hoegemeyer Hybrids of Hooper, Nebraska. "We are set up for the perfect storm of having dead or dying stalks and roots this fall," said Dr. Hoegemeyer.

In many corn fields, peak grain filling stage occurred a week or more later than usual this year. Dr. Hoegemeyer said that when grain filling happens later in the season-with days getting shorter-it can impact the photosynthetic balance of the plant and lead to more root and stalk rots. "This year, we really need a sunny August and good leaf disease control to keep photosynthesis going at maximum rates," he said.

During grain filling, Dr. Hoegemeyer explained, corn plants will attempt to fill all the kernels that were pollinated. "The plant will search for sugar to fill the yield potential that has already been set up in the ears, even if it means starving stalks and roots to death. Under more extreme filling stress, the plant will even cannibalize stalk and root tissue, remobilize the starches and sugars, and move it to the ears."

Once that happens, Dr. Hoegemeyer said, the door is open to the fungi that cause root and stalk rots. "These fungi are not good pathogens-that is, they are not very good at attacking live, healthy tissue," he continued. "However, they are very good saprophytes, which means they are very efficient in attacking dead or dying tissue. In fact, the organisms that break down last year's crop residue are the very ones that cause stalk and root rots in this year's crop."

Dr. Hoegemeyer speculates that corn yields could be off as much as 15 percent from recent crops. "I don't forecast corn yields or football scores," Dr. Hoegemeyer said. "However, I suspect that yields will be off five to fifteen percent from what we seen the last few years. Most fields seemed to have some issues, and while the best fields will be excellent, I think there are some significant holes in this year's crop particularly in areas that flooded or suffered from excessive moisture early. Combine that with a slower start from cool weather and later grain filling, and I believe we will be short of the last couple years' yield on average."