This tip was provided by:
Ronnie Schnell, Cropping Systems , College Station, ronschnell@tamu.edu
Statewide
Stalk Rots and Harvest
Stalk rots can occur in sorghum and often go unnoticed until significant lodging occurs. Yield loss can result from severe lodging but also from reduced head size and poor grain fill. Two common stalk rots are charcoal rot and fusarium rot. Each are caused by different fungal pathogens. The fungus invades the plant through the crown roots and then continues to colonize and destroy (shredding) the tissue of the lower nodes. Fusarium rots will cause tan to reddish colored shredding while charcoal rots will cause grayish to black shredding. Often the tissue at the second or third node above the crown roots become so weak the plant will eventually lodge.
Moisture stress is a common contributor to the development of stalk rots although crop nutrition, insect damage and plant populations will contribute as well. Some hybrids are more susceptible than others but no hybrid is immune. Lower plant populations can help in two ways; reduce stress due to interplant competition for resources (water and nutrients) and greater stalk diameter. Larger stalks will stand better than thin stalks, especially when disease is present.
As harvest approaches, the presence of stalk rots should be considered when making decisions about harvest timing and use of harvest aids. Presence of the disease can be easily checked using a pinch test. Simply pinch the stalk between your thumb and index finger at nodes just above the brace roots. If the stalk tissue is soft, stalk rot is likely present. You can split the stalk open to confirm. The degree to which the fungus has destroyed the tissue will affect standability. Shredding across multiple nodes will increase the susceptibility to lodging. Harvest as soon as possible to avoid yield loss due to significant lodging. Additionally, dry down after harvest aids are applied can exacerbate lodging. Severely infected plants will likely fall regardless of application of harvest aids.
For information on grain sorghum or sorghum forages for your area, or for specific questions you have on sorghum, contact your local county agricultural Extension agent, an Extension crop specialist, Dr. Ronnie Schnell (ronschnell@tamu.edu) or Dr. Calvin Trostle, extension agronomist, Lubbock at (806) 746-6101, ctrostle@ag.tamu.edu Your question will be relayed to the appropriate Texas A&M AgriLife staff as needed.
