Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 7624 IREC Farmers' Newsletter No. 195 ­ – Rice R&D 2016 Malcolm Taylor Agropraisals Pty Ltd, Cobram, Vic W ITH DPW, the rice crop is maintained in an aerobic state for prolonged periods prior to the mid- tillering stage of rice development. Flush irrigations and/or rain events encourage successive germinations of barnyard grass that must be controlled to prevent major reductions in rice yield potential. Recommendations for weed management in DPW rice entail: l  field rotations to lower soil weed seed burdens l  clean seedbeds l  minimal disturbance at sowing l  contact herbicides prior to crop emergence (e.g. paraquat or glyphosate) l  timely application (post-flushing, pre- emergence (PFPE) of selective residual herbicides (Stomp® and Magister®). Achieving the recommended timing for herbicide application can be challenging if rainfall events prevent access of ground-rig sprayers to paddocks. Trafficability is assured at the time of sowing, thus a post-sowing timing option (i.e. immediately after seeding, prior to initial flushing) would be advantageous to ensure pre-emergent herbicides are applied before crop and weed emergence. Residual herbicides applied to DPW rice crops will often cease to be effective prior to permanent inundation. In 2015–16 five field trials were conducted to test post-sowing timings of herbicide and also sequential residual herbicide treatments to improve the flexibility and reliability of herbicide programs for barnyard grass control in DPW rice. Plots measured 3 m x 8 m, were replicated four times and treated with a handboom delivering 100 L/ha. All plots were visually rated for crop injury and weed control, and harvested by direct heading with a small plot header. Rice crops established with delayed permanent water (DPW) provide the perfect environment for barnyard grass germination and establishment. QUICK TAKE l  The control of barnyard grass is a particular challenge in fields of direct sown rice with delayed permanent water. l  Residual herbicides for rice such as Magister® (clomazone) and Stomp® (pendimethalin) are best applied post-flush, pre- emergence (PFPE) mixed with a knockdown herbicide. l  Sequencing these herbicides by repeat applications were tolerated by rice, however only minor improvements were demonstrated over the tank mixture applied at the recommended timing (PFPE). l Advancing application timings to post-sowing (i.e. immediately after seeding, prior to initial flushing) reduced treatment efficacy. l In 2015–16 five field trials tested post-sowing and sequential residual herbicide treatments to improve flexibility and reliability for barnyard grass control in DPW rice. IMPROVED CONTROL OF BARNYARD GRASS IN DPW RICE