Similar to other crops, there are a few insects capable of causing economic damage in sorghum if not managed timely and efficiently. These range from root and seed damaging insects to those that feed on the leaves, the stalk of plant or directly on the sorghum grain. All of these insects, however, can be controlled with sound integrated pest management practices.
Growers and consultants should familiarize themselves with these insects as well as the management practices that should be adopted to minimize their impact. These management practices may include hybrid selection, planting date, management of crop residue, elimination of weedy host plants and timely application of crop protection products when warranted.
As with other crops, weed control is critical in producing good sorghum yields. In order to manage weeds effectively, growers should plan their weed control strategy in advance of planting. Weed control begins with a clean field prior to planting. A pre-emergence herbicide should be applied at or soon after planting, before the crop emerges. The most critical time for weed control is during the first 30 days of the sorghum plant's life. When determining which herbicides to apply, it is crucial to consider crop rotation restrictions.
There are a number of reasons for poor pre-emergence weed control. Pre-emergence can occur if the herbicide does not get activated in the soil. Herbicide must be absorbed and moved throughout the soil by rainfall or irrigation prior to weeds germinating and emerging. Heavy crop residue on the soil surface prevents herbicide from uniformly entering the soil. Too much rain after herbicide application can result in the herbicide leaching further into the soil profile, diluting the herbicide to an effective rate. When applying a herbicide, poor pre-emergence can occur if the herbicide rate is not high enough for the field soil type. Additionally, weed resistance can deter emergence.
It is important to be aware of the ways crop injury can occur. If rain moves herbicide on top of the seed injury can occur. Cool temperatures can slow down emergence, allowing more herbicide to be absorbed by the sorghum seed. Planting seeds too deep can result in a longer emergence time, which allows more herbicide to be absorbed by the seed prior to emergence. If herbicide rate is too high for the soil type and pH, crop injury can occur. Damage can also occur if post emergence applications are made after sorghum is far along in development. Many post emergence herbicides must be applied before the fifth leaf stage.
Like other crops, sorghum is susceptible to a number of economically important diseases. The severity of any given disease is dependent on hybrid susceptibility, presence of the disease and a favorable environment for the disease to proliferate.
Diseases of economic importance in the U.S. include head smut, downy mildew, stalk rots, maize dwarf mosaic, ergot, anthracnose and other foliar diseases.
Many of the diseases sorghum is susceptible to can mimic symptoms caused by environmental stress, insect damage and herbicide injury. Growers and consultants should familiarize themselves with the common diseases in their regions as well as how to identify and manage them in their field.
Below are links to sorghum disease resources:
Alabama Weeds, Disease and Insect Control Guide
Arkansas Recommended Chemicals for Weed and Brush Control
Georgia: Grain Sorghum Pest Management
Kansas Sorghum Insect Management Guide
Kansas Chemical Weed Control
Kansas: Diagnosing Sorghum Production Problems
Louisiana Field Crops Grain Sorghum Diseases
Louisiana Sorghum Insecticide Guide
Louisiana: Grain Sorghum Weed Management
Mississippi Insect Control Guide for Agronomic Crops
Mississippi Weed Control Guidelines
Missouri: Management of Grain Sorghum Diseases
North Carolina Weed Management in Grain Sorghum
Oklahoma Managing Sorghum Insects and Mites
South Dakota Sorghum Weed Control Guide
Tennessee Sorghum Insect Control Guide
Tennessee Weed Control Manual
Texas Sorghum Insects
Texas Grain Sorghum Weed Control & Harvest Desiccation Guide
Weed Control in Sorghum (Video)