After the leaves infected with the disease, it will cripple and do not seems to grow further.
Besides spraying the affected parts with pesticides, those affected leaves need to cut off to allow new leaves to grow in 1-2 weeks time.
This is the sabah snake grass 优遁草infected by common plant disease, Beardsley灰粉蚧(Dysmicoccus neobrevipes). It normally appears at the bottom of the SSG leaves and the stems. Please inspect the leaves regularly for this disease. The leaves can be eaten at least after 3 weeks of spraying pesticide.