Silver Leaf Nightshade

Silverleaf nightshade (Solanum elaeagnifolium) is a serious problem in cultivation paddocks. Once established it is impossible to eradicate. The plant's root system penetrates to a depth of more that 2 metres. Chemical control is generally ineffective on established plants because the chemicals don't reach all of the roots. PLOUGHING INCREASES THE PROBLEM because the broken root parts grow into new plants. The only way control can be achieved is by preventing plants from producing seed. And, because the seeds can remain viable in the ground for 15 years, eradication is a long term project.

The Silverleaf Nightshade Best Management Practice guide (530k pdf) provides further detail.