For Grain Sorghum Health and Yield the First 40 Days are Critical

Published: April 13, 2010

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. Plants that survive this are often weak and yield less than healthy plants. Severely damaged plants may die, and this results in thin stands and skips in rows, and farmers must occasionally replant entire fields due to death of most or all seedlings.

Farmers can help protect grain sorghum seedlings from this problem 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 2010. 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).