1.1. Striga sp
Striga is a root parasitic weed which is a major constraint to sorghum production, particularly in semi-arid regions of sub-Saharan Africa, where it can cause up to 100% yield loss in farmers’ fields.. Striga ssp attack its host by attaching its roots in sorghum roots and therefore Striga cause damage to sorghum in two ways. The first negative effect on sorghum growth is the competition for water and nutrients while the second one is the disruption of the sorghum hormonal balance. The control of Striga is very difficult because the parasite causes damage to sorghum before emerging above the ground. Despite this, many control options against Striga have been studied ranging from cultural and mechanical control methods such as hand weeding, crop rotation, nitrogen fertilizer and Striga resistance/tolerant varieties. The figure below shows sorghum crops damaged by Striga hermonthica and striga asiatica respectively .
1.2. Sorghum shoot fly
Sorghum shoot fly is caused by Atherigona soccata and is one of the most damaging insect pests of sorghum. To damage sorghum plants, larvae cut the growing point, and the central leaf dies, resulting in the typical dead heart symptoms. The dead leaf can be pulled from the plant and, at the base, emits an odor. The young, whitish-yellow maggot feeds on decaying plant tissue. Most damage occurs one week to one month after plant emergence. Effective control practices are early planting; high seeding rate and use of shoot fly resistant sorghum varieties.
1.3. Sorghum stem borer
Sorghum stem borer is caused by Busseola fusca. It is a key insect of sorghum. As symptoms and damage, young larvae eat leaves and mature larvae bore into stalks and produce dead hearts. Large larvae tunnel in stalks causing reduced grain fill and increased stalk lodging. Stalk borer damage also may make plants more susceptible to stalk rot diseases. Boring by larvae often causes the peduncle to break and panicle to fall. To control this insect, it is advised to destroy or to burn dry stalks and the use of resistant varieties.
1.4. Sorghum ergot
Sorghum ergot is caused by a fungus called Claviceps africanae. The disease symptoms begin after flowering and the fungus infects unfertilized flowers and as a result, it produces sugary exudates on the infected flowers. After maturity, the infected seed produces an elongated black horn resembling ergot of rye but which are much larger. Control of the disease is possible by rotation and by planting resistant cultivars.
1.5. Sorghum midge
Sorghum midge is caused by Contarinia sorghicola. It is the most widely distributed of all sorghum insect pests and it occurs in almost all regions of the world where sorghum is grown. As symptoms, eggs are laid inside the glumes of the flower; and larvae feed on the development seeds, producing empty spikelets that give the appearance of failure to set seeds. Early and uniform planting of sorghum is the most effective cultural management method. Also cultural practices that promote uniform panicle exertion and flowering in a field are important in midge control. A deep plowing sorghum residue kills some overwintering larvae, reducing sorghum midge abundance next year. Resistant varieties can be also very effective.
1.6. Sorghum grain weevil
Weevils are the primary and most destructive insect pests worldwide of stored sorghum grain, especially in warm, humid countries. Weevils infest grain in the field and in storage. The adult weevil bores a hole into a sorghum grain, deposits an egg, and covers it with a gelatinous substance. As methods of management, stored grain insect pests can be managed by sanitation, well constructed and maintained bins, and residual insecticides like Skana Super has to be applied to the bin and grains.
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