Visit fields regularly during the bloom period, when the plant starts to pollinate. Inspect plants in the mid-morning to coincide with midge activity. Start along field borders because if few midge adults are present in these areas, there is no need to scout the entire field. Sorghum midge adults are poor flyers. Select 100 seed heads randomly, if midge population is high. Visual inspection of the whole seed head is the best sampling method. The threshold level is 1 adult midge per head, after 20 to 30% of the heads begin to bloom (Boyd; Bailey, 2000).
Management and cultural practices
- Plant sorghum in the field as uniformly as possible. Sorghum planted on a staggered basis is more susceptible to sorghum midge
attack. Staggered planting or uneven emergence is an ideal situation for insect reproduction. A significant yield loss occurs where blooming is not uniformed. Sow seeds together with the other farmers in the area (Teetes; Pendleton, 1999).
- Plant midge-resistant sorghum varieties (Teetes; Pendleton, 1999). Ask for assistance from the local agriculture office or from agricultural technicians.
- Clear in and around the field of Johnsongrasses (Sorghum halepense). These grasses are alternate hosts of the sorghum midge. Destroying alternate host plants eliminates sources of insect pests that infest sorghum (Teetes; Pendleton, 1999).
- Practice proper field sanitation. Cut and plow-under crop residues. This method helps reduce the
populations of over-wintering larvae. Destroying the crop soon after harvest and eliminating the volunteer sorghum plants suppresses the insect pest abundance the following year (Teetes; Pendleton, 1999).
- Practice crop rotation. Sorghum benefits most when rotated with a broadleaf or taprooted crop such as cotton or soybean. Growing sorghum in a field planted with a different, non-host crop the previous year significantly reduces the abundance of some insect pests, as well as some diseases and weeds (Teetes; Pendleton, 1999).