January 2012. Members were asked by a grower in Cambodia why the leaves of the cassava were yellow.

More details were requested about this condition. Is the condition limited to one plant, or many; what is the weather situation: has it been dry recently; how old are the plants; has the land been intensely cropped (and with what?), or is this the first crop after a fallow; are there several varieties affected, is the condition seen on one only or many plants; has any fertilizer been applied, and, if so, what?

It was said to have spread t many plants in the field, slome are close together, others not. Tfhe plants arre now 5 months old. Before the land was planted to Jatropha. After 1 month fertiliazer was applied (15-15-15 NPK) at 330 kg per ha.

The symptoms were not of virus.

A comment from Jane O’Sullivan, at UQ, Brisbane (Associate)

That’s a rather spectacular example of vein-clearing. It looks from the photos as if surrounding plants are not similarly affected. I don’t think it’s nutritional.

It looks like it may have been transient in appearance – only middle leaves are affected (but younger leaves may yet develop it). Is it possible that a normally benign virus became a problem in particular weather conditions? I’m just speculating – it’s not my area!