Ask yourself, have herbicides been used on or near the affected crop?
Sugarcane can show a phytotoxic reaction to some herbicides. Leaf symptoms may be the result of herbicide uptake through the roots, leaves, or by leaf burn.
Depending on the dose, soil texture, environmental conditions and variety, symptoms may vary but in general the following foliar symptoms are typically seen in cane:
Phytotoxicity symptoms due to systemic herbicides
- Yellowing of the whole leaf (diuron + hexazinone)
- Yellowing of the leaf margins and/or tips (atrazine)
- Yellowing of the leaf in combination with leaf stunting (imazapic)
- Bleaching (whitening) of the whole leaf (isoxaflutole)
- Leaf scorching and leaf tip dieback (2,4-D, MSMA)
- Slight reddish brown discolouration of the leaves covered by the spray (ametryn)
- Droopy, flaccid and yellow or necrotic leaves and marked growth reduction (glyphosate)
Phytotoxicity symptoms due to contact herbicides
- Leaf scorching and stunting (paraquat, diquat)
Usually phytotoxic symptoms are transitory and cane grows out of the symptoms with or without yield loss. However, cane harmed by glyphosate may continue to deteriorate and die.