Sugarcane
Sugarcane White Grub
Lepidiota stigma
Insect
In a Nutshell
- Root feeding damage leading to reduced nutrient and water supply.
- Over time, leaves turn brown and the maturing stalks deteriorate.
- Plants may lodge during bad weather.
- Larvae may tunnel into the cane stalks.
Sugarcane
Symptoms
Larvae feed on and damage the roots, decreasing the water and nutrient supply to the plant. The symptoms are similar in appearance to drought damage, with an initial yellowing and wilting of leaves. Over time, leaves turn brown and the maturing stalks deteriorate. In extreme cases, the grubs eat up the roots and canes may lodge in case of adverse weather, or simply by its own weight. Grubs may also be found tunneling into the cane stalks. In case of severe infestations and at early stages of cane growth, replanting may be necessary.
Recommendations
Organic Control
Trap trees can be used to lure the beetles and easily destroy them is very effective to reduce infestations of white grubs in nearby sugarcane fields. Jayanti (Sesbania sesban), turi (Sesbania grandiflora), Acacia tomentosa, asam (Tamarindus indica), jengkol (Pithecellobium jiringa), and cashew (Anacardium occidentale) can be used. Cashew is ideal, as it can grow in poor soils and produces nuts. Try biopesticides containing Beauveria spp. to control the infestation.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Chemical control is usually done using soil insecticides. Products containing the slow-realease soil insecticides chlorpyrifos or chlorpyrifos-methyl are effective against these grubs if applied to the root zone before planting. However, the application is not possible in ratoon fields.
What caused it?
Damage may be caused by the grubs of several types of beetles, the most important of which is Lepidiota stigma. Other species may be found, such as Phyllophaga helleri, Pachnessa nicobarica, Leucopholis spp. and Psilopholis spp. The grubs are characterized by a a creamy white and C-shaped body. They become more and more voracious as they grow old, causing severe damage if left unchecked. The amount of damage will depend on their number, their age, the variety of sugarcane and its growth stage when it is attacked. Attacks on old cane lead to yield reduction.
Preventive Measures
- Grow more tolerant varieties, if available.
- Regularly monitor the field for signs of white grubs and beetles.
- Use traps to assess numbers or simply mass-catch adults.
- Or simply collect beetles or grubs by hand.
- Alternatively, shake plants and collect them on a piece of clothe.
- Use trap trees to attract adults and pick them up by hand.
- Avoid cultivating sugarcane on clay soils.
- Ensure soil fertility with right fertilizer balance.
- Do not use broad-spectrum insecticides that kills beneficial insects.
- Carry out a deep plow to dig debris, favor their decomposition and expose grubs to predators.
- Alternatively, remove residues and stubble after harvest and burn them.
- Rotate with non-host crops such as legumes.
- Leave the field fallow some weeks after harvest to break the life cycle of the grubs.
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