MISSISSIPPI STATE -- Mississippi's unpredictable weather is keeping farmers guessing, and recent hail damage is forcing some growers to make their toughest decisions.

County agents and specialists with Mississippi State University's Extension Service have been busy across the state during this year's crop season. A cool, wet spring followed by the hotter and drier than normal months of May and June produced two sets of challenges, but recent hail storms may have dealt the hardest blows yet.

"Hail can have a devastating effect on corn in the tasseling stage, which was about the stage for much of the damaged fields," said Dr. Erick Larson, Extension agronomist at MSU. "Yield losses will depend on the amount of leaf damage."

Larson predicted that plants with 33 percent defoliation (leaf loss or damage) could lose 10 to 15 percent of their yields. Plants with 50 percent defoliation could lose 25 percent of their yield, and with 75 percent damage, yield losses could be as high as 50 percent.

Most of the hail damage occurred from south of Greenville and eastward across the state.

Yazoo County Agent Tim Pepper said Extension is trying to evaluate each crop and field individually before making recommendations to farmers. Damaged corn will not regrow leaves. Growers may have to wait until harvest time to see how much of their crop was hurt.

"If hail breaks the terminals off the soybean plants, growers probably will have to replant. It's late, but not too late," Pepper said. "Some of the cotton has been completely stripped of its leaves, but the root systems could allow the plants to regrow leaves and fruit. These plants will have lost about four to five weeks of maturity if they can recover."

A later maturity date makes moisture a more critical issue. Weather will become increasingly important throughout harvest.

Pepper said late cotton will not face the insect problem in his area that it could have a few years ago. The arrival of the boll weevil eradication program and Bt cotton will make late season insects less of an issue. Still, damaged cotton will require intense management.

"Farmers will apply growth regulators to force cotton back into the fruiting mode," Pepper said. "They will need to monitor the plants' conditions, especially fertility. The good news is we can carry the plant to a later maturing date without the traditional insect pressures."

Dr. Will McCarty, Extension cotton specialist, said wind damage has been worse than in recent years. Blowing sand can strip the outer layers of the stem and leaf surfaces of seedlings. Generally, scar tissue forms and the plants recover rapidly. In some cases disease organisms may enter through these wounds and cause severe problems or even plant death.