Gulli danda (Phalaris) not dying even after spray in wheat, what now?

If gulli danda (Phalaris minor) survives a spray that used to work, the most likely reason is herbicide resistance, which is very common in the rice-wheat belt where the same product was used for years. The first thing to do is rotate to a different mode of action. If you have been using clodinafop or isoproturon, switch to pinoxaden or to sulfosulfuron, ideally a product you have not relied on before. Other reasons for poor kill are spraying on a dry field, spraying when the weed is too big past 30 to 35 days, low water volume, or wrong nozzle. Make sure the field is at working moisture, the weed is small, you use the full label water volume with a flat-fan nozzle, and you spray on a calm day. Beyond chemicals, plan for next season: timely sowing, a dense crop stand, a pre-emergence pendimethalin spray right after sowing, and rotating in a non-cereal crop like mustard or berseem on the worst plots to run down the weed seed bank. Use only herbicides recommended for wheat, follow the product label dose and timing, and confirm the choice with your local KVK, because resistance patterns differ field to field and the wrong product can hurt the crop.