Doane Daily Cotton Commentary

DTN Grains: Opening | Midday | Closing

Tennessee

How late can we plant corn?

Angela Thompson

Corn and Soybean Ext. Specialist

Jackson, Tenn. (May 9, 2008) – Like it or not, we are going to have more May planted corn than we usually have.

Corn planted in May and especially late in May (I consider anything planted after May 15th as truly ‘late corn’) is more likely to experience some yield decrease due to the likelihood of greater heat during pollination, corn borer problems and disease. Timeliness of rain is also more critical for yield.

The later you plant into May the more likely some yield decreases will happen. Depending on the source used, yield decrease is estimated at 1 bushel/day past May 1 in west TN. Kentucky uses an estimate of 1% loss per day for planting dates past May 10th in western KY.

I have no problem telling folks to continue planting corn in bottom fields or fields that are more capable of providing moisture to the crop. Consider switching to soybeans if seed are available or grain sorghum if fields have droughty soils.

 Some things to consider for late planted corn:

• Don't plant an early maturity (108-112 day) hybrid late. Medium to Late maturity hybrids generally have better tolerance to heat. Check seed company information for the drought tolerance of any hybrid in question.

• Plant a Bt hybrid (be mindful of the 50% Bt refuge requirement in cotton counties); May planted corn has the potential to tassel closer to our second generation Southwestern corn borer egg lay timing which can be more damaging.

• Adjust nitrogen rate and seeding rate to prepare for a slightly lower yield potential (particularly when planting after mid May). On dryland fields consider reducing seeding rates by 10%.

• Depending on environmental conditions in late June and early July, consider applying a foliar fungicide after tassel emergence-- especially if corn is following corn.

Grain Sorghum as Alternative to Corn

I still think corn is more profitable when planted in good soils through mid May- even accounting for some yield decrease.

Grain sorghum seems attractive as a potential ‘corn replacement’ when we move into a late May planting window and on non-irrigated fields that tend to be drought prone.

Sorghum is a good option where it is no longer possible to plant corn but where a corn burndown program containing atrazine has already been applied.

Grain sorghum can NOT be planted into fields treated preemergence with Resolve herbicide. Late planted sorghum has some of the same issues as corn-insect problems and some yield decrease due to drier weather. Grain sorghum yields best when planted in May and there is a 1 bushel per day reduction in yield when planting is delayed from May 20th to June 15th. Yield decreases by about 1.5 bushels per day that planting occurs after June 15th