Effect of Farming Techniques on Sorghum Midge Infestation and Damage of Sorghum, and the Existence of its Natural Enemies

Sorghum, Sorghum bicolour (L.) Moench, ranks second as Africa’s major and significant cereal food crop, and third for Uganda. About one third of the population in Tanzania, Kenya and Uganda depend on sorghum for their livelihoods. However, sorghum yields have persistently kept lower than average due to several production factors. Rural subsistence farmers engage farming practices that enhance and sustain some sorghum pests that cause damage and substantial crop losses. A study to establish the impact of farming techniques on infestation and damage by the midge Stenodiplosis sorghicola Coquillett, and its existing natural enemies was conducted. Farming practices (mixed cropping of sorghum with maize as a barrier to interfere with sorghum midge flight, resistant sorghum varieties, and sole sorghum or intercrop with cowpea against the sorghum midge). Results showed that use of resistant sorghum variety significantly (P < 0.05) reduced sorghum yield loss, while the interaction between sorghum–cowpea intercrop and maize barriers around the sorghum crop (P < 0.05) significantly reduced sorghum yield loss. Having no barrier around sorghum crop significantly (P < 0.05) increased sorghum midge numbers per panicle. Sole sorghum interaction with sorghum-cowpea intercrop without a barrier condition significantly (P < 0.05) increased sorghum midge infestation. Similarly, the interaction between sorghum sole crop and sorghum-cowpea intercrop with susceptible sorghum crop significantly (P < 0.01) increased the sorghum midge infestation compared to the resistant sorghum variety. Results indicate that use of resistant sorghum varieties intercropped with cowpea, having tall maize plants around the sorghum fields reduced sorghum yield loss caused by the sorghum midge pest. Having no crop barrier around the sorghum field increased the abundance and severity of damage by the sorghum midge to grain sorghum.