Management Practices to Control Multiple Herbicide Resistant Phalaris minor in Wheat

Phalaris minor is a major winter season grass weed particularly in wheat crop. It is a highly competitive weed and causes significant yield losses, even up to the extent of complete crop failure. In India, it has evolved multiple herbicide resistance (against PS‐II [photosystem‐II site‐A], acetyl‐CoA carboxylase [ACCase], and acetolactate synthase [ALS/AHAS] inhibitors). The various factors attributing to increased selection pressure for herbicide resistance evolution are mono‐cropping (rice‐wheat system), use of herbicides with similar mode of action, faulty spray techniques (over and under dosing, delayed spray), rice residue burning, intensive tillage and delayed sowing of wheat. Further, inbuilt attributes of P. minor such as higher tendency to tolerate anaerobic conditions in rice, morphological similarity to wheat until flowering stage, seed shedding before wheat harvest, frequent emergence in flushes favor its proliferation in rice‐wheat system. Use of alternative herbicides of different modes of action in rotation or in mixture is of prime importance in resistance management. Alternate herbicides such as pyroxasulfone, aclonifen, pendimethalin, trifluralin, flufenacet, flumioxazine, bixlozone, and cinmethylin can be utilized for control of multiple herbicide‐resistant populations of P. minor . Additionally, developing herbicide‐tolerant wheat cultivars against glyphosate and glufosinate will further increase the available alternative herbicide options. However, for sustainable management, alternate herbicides should be used in rotation, sequence or mixture along with integration of various non‐chemical tactics such as crop rotation, competitive cultivars, higher seed rate, narrow row spacing (15–17.5 cm), stale seed bed, advance sowing, conservation tillage, and weed seed free crop seed.