Technical information on sorghum pests.
Sorghum is a hardy species that is generally not exposed to pests. Although most often the pest pressure remains low and does not justify intervention, some parasitic attacks can occur, especially in high temperature conditions. You will find below the different pests that can be found in vegetation on sorghum:
Borer insects : Sesamia – Sesamia nonagrioides and Corn borer – Ostrinia nubilalis
The most frequent damage is characterized by perforations of leaves linked to the borers. The attacks of sesamias are characterized by the presence of larvae in the lower stems. Attacks by boring insects can cause lodging damage at the end of the cycle.
Blue leafhopper – Zyginidia scutellaris
Symptoms in the form of small white spots are usually located on older leaves. The 3 or 4 newest leaves are more or less free of symptoms. The risk period is the joint stage of sorghum. The risk is usually low to nil.
The damage thresholds for the following types of aphids are as follows:
- Sitobion avenae : 500 aphids per plant on sorghum before the 8-10 leaf stage.
- Metopolophium dirhodum : 5 aphids per plant before the 3-4 leaf stage; 10 aphids per plant between 4-6 leaves; 20-50 aphids per plant between 6-8 leaves.
- Rhopalosiphum padi : half of all panicles colonized during the 3 weeks after heading
Heliothis – Helicoverpa armigera
Heliothis larvae can cause damage to sorghum by consuming reproductive organs and seeds at the beginning of silking. The risk period is between flowering and the dough stage. The damage threshold is one caterpillar per panicle.