Biologically-Effective-Dose of Tolpyralate and Tolpyralate plus Atrazine for Control of Multiple-Herbicide-Resistant Waterhemp [<i>Amaranthus tuberculatus</i>(Moq.) J. D. Sauer] in Corn

The biologically-effective-dose of tolpyralate, a new 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibitor, applied alone or tank-mixed with atrazine, for the control of multiple-herbicide-resistant (MHR) waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] has not been studied in corn. Seven field experiments were conducted during a three-year period (2018, 2019, 2020) in Ontario, Canada with MHR waterhemp to determine: 1) the dose-response of MHR waterhemp to tolpyralate and tolpyralate plus atrazine, and 2) the relative efficacy of tolpyralate and tolpyralate plus atrazine to post-emergence corn herbicides, dicamba/atrazine (500/1000 g·ha−1) and mesotrione + atrazine (100 + 280 g·ha−1). Tolpyralate + atrazine (120 + 4000 g·ha−1) caused 13% corn injury at one site two weeks after application (WAA), which was observed as transient foliar chlorosis and bleaching of new leaves. At 12 WAA, the predicted dose of tolpyralate for 50% control of MHR waterhemp at Cottam and on Walpole Island was 8 and 2 g·ha−1, respectively;the predicted dose of tolpyralate + atrazine for 50% control of MHR waterhemp at Cottam and on Walpole Island was 5 + 160 and 1 + 21 g·ha−1, respectively. The difference in predicted dose at the two sites is likely due to differences in MHR density and resistance profile. Applied at the registered rate, tolpyralate (30 g·ha−1) and tolpyralate + atrazine (30 + 1000 g·ha−1) controlled MHR waterhemp similar to dicamba/atrazine and mesotrione + atrazine across sites. This study demonstrates that tolpyralate + atrazine, applied POST, provides season-long control of MHR waterhemp in corn.

THE IMPACT OF RADIOTHERAPY COURSE LENGTH ON THE TREATMENT RESULTS OF NASOPHARYNGEAL CARCINOMA(NPC)

Analyses made among four radiotherapy schedules for NPC in order to determine whether there is an impact of radiotherapy course length on treatment results.A series of 320 NPC patients were divided into four radiation treatment branches each with a schedule, this clinical trial was non-randomized.Radiotherapy course length factor was considered with a derivative LQ model formula that biological effective dose(BED)=nd[1 +d/(α/β)]-(T-28).The four branches were:1.split-course 103 cases, with an intermediary rest of 3-4 weeks,mean total dose 70Gy/35fx,73d, BED 51.6 Gy; 2.continuous 115 cases, 72Gy/36fx, 61d, BED 62.6 Gy;3.hyperfractionation I 52 cases, 1.5 Gy b.i.d.,time interval(Ti)≥6 hr, 75Gy/49fx,57d,BED 65.5Gy;4. hyperfractionation Ⅱ 50 cases, 1.2 Gy b.i.d., Ti≥6hr,76Gy/60fx,59d,BED 63.0 Gy.Treatment results were compared with 1-, and 3-year loco-regional recurrent rates,and 1-,and 3-year survival rates, and these rates were of a negative interrelation with prolonged course duration, but of a positive one with BED valas.Continuous branch was of a course mean 12 days shorter than the spilt-course one, its treatment results were nearly 10% higher in some subgroups;and hyperfractionation branches were slightly better than continuous one.