Aphids are tiny, soft-bodied insects that feed on the sap of plants. They are small, oval-shaped insects that range in colour from green, yellow and black. Sorghum aphids are a serious pest that affects sorghum crop by sucking the sap from the plants. They are often referred to as “plant lice” because of their feeding habits, which can cause stunted growth, distorted leaves and even death of the affected plants. Warm and humid conditions favor the growth and development of sorghum aphids.
Types of Infestation
Sorghum aphids are known to infest the sorghum crop in two ways: direct infestation and indirect infestation. Direct infestation occurs when the aphids feed on the sap of the plant, causing a reduction in the plant’s growth and yield. Indirect infestation occurs when the aphids secrete a honeydew substance, which attracts other pests such as ants and flies. These pests feed on the honeydew, and their feeding activity can also damage the plant.
Scientific Name: Rhopalosiphum maidis, Melanaphis sacchari.
Most Affected States
In India, Sorghum aphids are commonly found in the states of Andhra Pradesh, Karnataka, Maharashtra, Tamil Nadu, Telangana and Gujarat.
Symptoms of Sorghum Aphids
Sorghum aphid infestations can cause significant damage to the crop, resulting in stunted growth and reduced yield. Some of the common symptoms of Sorghum aphid infestations are:
- The presence of aphids can be seen in the central leaf whorl, stems and panicles of the sorghum crop.
- They suck the sap from the plant leading to yellowing of leaves.
- Yellowish mottling of leaves, marginal leaf necrosis and stunted growth are the most common symptoms caused by sorghum aphids.
- Sorghum aphids secrete a honeydew substance, which attracts other pests and can lead to the growth of sooty mould on the plant.
- Transmits maize dwarf mosaic virus.
A combination of different control measures is often required to effectively manage aphid infestations in sorghum crops. The following are some common IPM practices used to control aphids.
- Removal of plant debris and weeds can reduce the population of sorghum aphids.
- Avoid applying excessive doses of nitrogenous fertilizers.
- Maintaining healthy plant growth, providing proper irrigation and adequate nutrients can also help to reduce the impact of aphids on sorghum crops.
- Planting trap crops can be an effective way to manage aphids. Example, planting nasturtiums near the sorghum field can attract aphids away from sorghum.
- Solar Light Trap can be installed in sorghum field to trap and kill the adult aphids. For an acre install one light trap for effective trapping.
- Collect and destroy the heavily infested plant parts.
- Tapas Yellow Sticky Traps @ 6-8 traps per acre can be used for the effective control of aphids in sorghum plants.
- Release natural predators like ladybugs, lacewings and parasitic wasps to control aphid populations.
- Katyayani Activated Neem Oil Biopesticide contains activated azadirachtin which when used at the rate of 5 ml per liter water with a 12 days interval between each spray can effectively control aphids in sorghum crops.
- Amruth Alestra Liquid (Bio Insecticide) contains strains of naturally occurring entomopathogenic fungus Verticillium lecanii which comes in contact with the cuticle of the aphids and colonizes them. The recommended dosage is 2 ml per liter of water.
Commercial chemicals that are used to control sorghum aphids includes,
|Imidacloprid 17.8% SL
|0.75 – 1 ml/lit water
|Thiamethoxam 25 % WG
|0.5 gm/lit water
|Anshul Ikon Insecticide
|Acetamiprid 20% S.P.
|0.5 gm/lit water
|Dimethoate 30% EC
|1.5 – 2.5 ml/lit water
|Acephate 75% SP
|1 – 1.5 gm/lit water