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Yacon diseases and pests and their control strategies

The yacón plant gets infected by different species such as nematodes, bacteria, fungi, viruses and insects.

The root-knot nematode (Meloidogyne incognit) leads to crop loss due to the various symptoms as poor growth and roots with characteristic galls (Dropkin, 1989; Mogor & Mogor, 2003). Following, disease free propagation material is necessary to intensify the yacon production. A safe procedure is to take shoot axillary buds as ideal explants and a disinfection treatment with a sodium hypo- chlorite aqueous solution (Mogor & Mogor, 2003).

Rhizoctonia sp. can lead to rot in the root and crown of the yacón plant. If 50% of the roots are infected, the plants become unmarketable and inedible. The rot and discoloration occur not only the tubers but also on other plant parts, especially the offsets (“seeds”) and rootstock. Therefore, the use of clean and healthy yacón offsets and rootstocks for propagation are important to reduce disease spreading (Fenillea R. C. et al., 2005).

Also, insects like the sunflower caterpillar (C. lacinia saundersii) can cause damage by feeding on yacón leaves. The presence of natural enemies and trap plants are control strategies to reduce herbivore damage in yacón cultivation (Silva D. et al., 2015). Trap plants as for example sunflowers can be planted between yacón plants. As they are more attractive to insects, less insects will feed on the yacón plants.

Furthermore, different Badnaviruses infect the yacón plant. The Yacon necrotic mottle virus infects yacón (Smallanthus sonchifolius) and causes necrosis, chlorosis, stunting and malformation of leaves. Yucca bacilliform virus leads to damage as chlorotic lesions on the leaves. The lesions disperse along the leave veins and increase in intensity towards the tips whereby the lesions gradually turn necrotic (Alangar I. et al., 2016)