Taro pests and diseases

Taro canopy cover

Weed control is necessary until the taro leaf canopy has closed

Taro crops are affected by a number of weeds, insect pests and diseases.

Weeds

Newly planted taro crops are susceptible to competition from weeds, so control weeds after planting. Weeds are generally not a problem once the leaf canopy has closed. Control weeds towards the end of the life cycle as the crop matures, as this is a critical period for starch accumulation.

Plastic mulching can provide a barrier to growing shoots and corms. Take care when spraying around taro plants, as chemical damage to taro plants has resulted from spray drift off adjoining properties. 

Insects

Numerous insect pests have been recorded in the Pacific region, but few have been identified in North Queensland, where taro is still a relatively new crop.

Many chewing insect grubs feed on the rich, starchy corm. Cluster caterpillars can be a major problem as they strip the upper surface of the taro blade. The eggs are laid in clusters and are covered with fine hair-like scales. Mature caterpillars are about 45 mm long and grey with a green underside. They have a pale stripe and a series of dark spots along the sides. Young hawk moth caterpillars can also cause significant damage by making holes in and defoliating the leaves as can grasshoppers.

Although various beetles feed on taro, none have been specifically identified as taro beetles in North Queensland. 

Diseases

Erwinia soft rot is caused by Erwinia atroseptica. The corm becomes mushy and smelly and the affected plants eventually wilt and die. The condition appears to be exacerbated by high organic matter, particularly in areas previously under pasture. Chewing insects - for example, the white cane grubs in North Queensland cane land - also contribute to the problem.

Shot hole leaf disease is a common fungal disease in the wet tropics. It is worse during wet weather and in closely spaced plants. Initially, small, dark spots appear on the leaves, then, as these spots increase in size, the centre of most spots falls out. The leaves become unmarketable and the reduction in photosynthetic area can cause substantial reduction in corm yield.

Other pests

Rats can often be a problem in taro crops. Control is usually through setting baits and traps. Clearing of perimeters and encouraging carnivorous birds (use of owl perches etc.) are other techniques that growers sometimes use. To a lesser extent wild pigs, wallabies and scrub turkeys can cause concern. Fencing is the most effective measure to manage these animals.

Further information

References

  • Carmichael, A. et al (2008) TaroPest - An illustrated guide to pests and diseases of taro in the South Pacific. ACIAR monograph # 132
  • Daniells, J.W., Hughes, M., Traynor, M., Vawdrey, L. and Astridge, D. (2008) Taro Industry Development: The First Step. RIRDC Publication no 09/066.
  • Daniells, J. W., Petiniaud, P. and Salleras, P. (2004) Taro. In 'The new crop industries handbook' eds. S. Salvin, M. Bourke and T. Byrne. RIRDC Publication No 04/125. pp 90-97.
  • Hughes, M.J., Daniells, J.W., Vawdrey, L.L., Astridge, D.A. and Traynor, M. (2008) Australian taro industry: benchmark survey. Queensland DPI&F  PR08-3392. 57pp.
  • Lambert, M (ed.) 1982, 'Taro cultivation in the South Pacific', South Pacific Commission, Noumea, New Caledonia.
  • Purseglove, JW 1972, Tropical crops, 'Monocotyledons 1', Longman Group Limited.

Last updated 07 April 2014