The First 40 Days are Critical for Grain Sorghum Health and Yield

Published: March 8, 2011

Grain sorghum was the sixth most valuable field crop grown in Missouri during 2009 following soybeans, corn, wheat, rice, and cotton. The value of this crop was about $30 million, but the value would have been greater if not for reduced yields caused by seedling diseases. Grain sorghum seedling diseases can be caused by several microorganisms that normally live in the soil on organic matter but can attack grain sorghum seedling roots especially when the soil is cold and wet and the soil pH is low. Seedling diseases cause dark red to black rotten areas to develop on grain sorghum roots. The leaves of diseased seedlings may wither or appear pale-green, and diseased plants will be smaller than healthy plants. Most sick plants die, and this causes thin stands, skips in rows, and occasionally entire fields or parts of fields must be replanted. Some sick plants may survive, and these are often weak and yield less than healthy plants. Farmers can help protect grain sorghum seedlings from seedling diseases by following a few simple guidelines.

1. Plant only when the soil temperature 4 inches deep has warmed up to about 65°F by 8:00 a.m. and plant only when at least 7 days of warm and dry weather are predicted immediately after planting.
2. Plant only high-quality seed that has a high germination rate.
3. Plant in fertile soils that have a pH of 6.0 to 6.5. Grain sorghum seedlings growing in soil with a pH less than 5.5 are more likely to be diseased.
4. Plant in well drained fields. Make sure field surface drainage is adequate to quickly eliminate excess water and enhance internal soil drainage by breaking hardpans with a ripper.
5. Have the seed treated with extra fungicides when grain sorghum is planted early in the season, in poorly drained fields, in clay soils, and certainly when planting in fields where seedling diseases have been a problem in previous years.
6. When planting no-till, equip your planter to move trash away from the row, so the sun can warm the soil around the seed faster.

Following these suggested procedures will give Missouri grain sorghum farmers a better chance of producing high yield and profit during 2011. More information is available at your University of Missouri Extension county office and is posted on the University of Missouri Delta Center web page (www.aes.missouri.edu/delta).