Sorghum, production

Major production constraints include; Striga weed, birds and fungal seed borne diseases such as smuts.

Striga attacks the plant and causes wilting, yellowing and stunting. Control of Striga can be achieved through:

The most important pests include sorghum shoot fly, birds, grasshoppers and sorghum stemborer.

1.11 Birds

Birds are perhaps one of the most important pests of sorghum not only in Africa but also in other parts of the world. They are capable of inflicting heavy losses and causing economic damage. In Africa the most notorious species is Quelea quelea and is found In the Sahel region, right from Senegal in West Africa through to Sudan, Uganda, Kenya, Southern Tanzania, Malawi, Zambia and South Africa.

Birds are mainly controlled by, scaring them away from the sorghum fields and attacking their nesting sites. Sorghum genotypes resistant to bird damage are also effective in decreasing bird damage. These genotypes have characteristics such as tough integuments and awns, goosenecks thus making them less susceptible to bird damage.

1.12 Stemborers

These are important throughout semiarid regions where sorghum is cultivated. The most important species include Chilo partellus, Sesamia calamitis and Buseola sorghida. Chilo partellus is mainly found in the semi areas of East Africa and India while Sesamia calamitis and Buseola sorghida are distributed throughout all sorghum growing areas in Africa.

Control of stemborers can be achieved through;

1. Sanitation (destruction of crop residues, volunteer plants and alternative hosts). Crop residues can be destroyed through burning the stalks and other residue immediately after harvesting (Harris, 1962; Unnithan and Seshu Reddy, 1989). However, burning of crop residues may not be practical in communities where soil fertility is low and no fertilizers are used since crop residue is the only source of organic matter.
2. Use of insecticides, which provides curative control (Warui and Kuria, 1983). However, use of chemical control is rarely justified in low input agricultural systems because of high costs (Ingram, 1958; Marthez, 1972). Also, the boring habit of the larvae protects them against the sprays and hence regular sprays may be required which poor resource farmers cannot afford (Sithole, 1990).
3. Habitat management. This strategy has been developed using the "Push and Pull" method that involves repelling and attracting the pest away from the target crop (Khan et al, 1997b).
4. Intercropping with non-host plants to modify the crop micro environment in such a way that does not favor pest attack (Seshu Reddy, 1990; Pats, 1996; Khan et al 1997b).
5. Biological control. This involves use of natural enemies of the pest (Chilo partellus, Buseola species etc) in order to control the pest. Recent research work on stemborers has been focusing on the introduction exotic parasitoids in countries where Chilo partellus is wide spread.

The most important disease is the seed borne smuts. There are 3 common types sorghum smuts:

1. Covered smuts controlled by seed dressing with relevant organic fungicide.
2. Loose smut also controlled by seed dressing.
3. Head smut controlled by sanitation measures. This involves collecting and destroying all smutted heads.