Papuana beetle & legumes

July 2001. In Vanuatu, there are reports from VARTC, Santo, of good control of Papuana beetle using the cover crop Glycine wightii. Land is left fallow for 1-2 years following taro or any other root crop. However, a trial in Solomon Islands, many years ago, was inconclusive.

Exact details of the Vanuatu trial were requested: It was not clear what the trial has achieved. Is it that after a fallow period of 2 years growing only the legume cover crop allows you to plant taro again with no damage.
How do you determine that the field is “clean” and what do you mean by “clean”? And, importantly, what is the land that had had the legume being compared to.