Change in weed control studies of rice paddy fields in Korea

This paper was reviewed on the research status of weed control according to cultivating patterns of rice in Korea. Weed control study in a nursery bed was chiefly carried out to control the species of barnyardgrass at the times of machine transplanting. Propanil and nitrofen were applied successfully in wet-nursery beds, and chlornitrofen and pyrazolate/butachlor were also successfully applied in protected semi-irrigated rice nursery beds in the 1970s. Sequential application of herbicides in the mid-1980s has resulted in the end of hand weeding. In machine transplanting, basic research such as the selection of herbicides was conducted in the early 1970s, and its related research including crop injury, seedling age, and reaction of cultivars were done in the late 1970s to early 1980s. Effects of the continuous application of herbicides and its methods of labor saving for rice cultivation were studied in the mid to late 1980s. When the rice planting methods were newly established, such as transplanting when seedlings were 10-days-old and direct seeding from the early 1990s, weed control research relating to herbicides was carried out (e.g. herbicide registration, crop injury, water management, appropriate application time, and neighboring application with insecticide). Weed control for the dill seeding of fields in wetted and reclaimed saline land have been experimented with, particularly in terms of the physio-ecological characteristics and the control of problematic weeds, and the resistance of weeds to herbicides was also investigated systematically.     

Biological Control of Lantana

Abstract

Experiments conducted at the International Rice Research Institute (IRRI) in the Philippines, showed that all commonly marketed formulations and derivatives of 2,4-D and MCPA were equally effective in controlling barnyard grass [Echinochloa crusgalli (L.) Beauv.] and other annual weeds in transplanted rice (Oryza sativa L). In the Philippines, these phenoxy acid herbicides cost US$2.50/ha as liquid formulations and US$5.50/ha as granular formulations. These low-cost herbicides provide excellent alternatives to hand weeding in transplanted tropical rice. Other herbicides which can control weeds before or after the weeds emerge are more expensive than 2,4-D or MCPA. Some of these selective herbicides, such as butachlor and TCE-styrene + 2,4-D, are in the Philippine market. Their prices vary from US$8 to US$12/ha.

For direct-seeded flooded rice, granular formulations of several new herbicides, such as butachlor, benthio-carb and C-288 (chemistry not yet disclosed), were highly selective in controlling barnyardgrass and other annual weeds under tropical conditions. C-288 controls algae in addition to annual weeds in direct-seeded flooded rice. Of these three promising herbicides, only butachlor is marketed in the Philippines at US$8/ha. For upland rice, the chemicals which look promising are butachlor, benthiocarb and fluorodifen. Butachlor liquid is available to rice farmers in Asia at about US$16/ha. These herbicides provide an excellent alternative to hand weeding. Generally a complete job of weed control in upland rice requires more than one hand weeding.     

SELECTIVITY OF SOME NEW HERBICIDES FOR DIRECT-SEEDED FLOODED RICE IN THE TROPICS

Summary. Granular formulations of several new herbicides were tested for control of weeds in direct-seeded tropical rice. S -(4-chlorobenzyl)- N N -diethylthiolcarbamate (benthiocarb) and N -(butoxymethyl)-2-chloro-2',6'-diethylacetanilide (CP 53619) showed a high degree of selectivity between rice and weed seedlings. Applied 6 days after seeding, when grass weeds were at the 1-2-leaf stage, both herbicides gave excellent control of Echinochloa crus-galli and other weeds, and caused little or no damage to rice cv. IR22.     

Chemical weed control in rainfed upland rice in Nigeria

Abstract

Two field experiments on chemical weed control in Faro 41 upland rice (Oryza sativa L.) variety were conducted at a rainforest site near the National Cereals Research Institute, Amakama Substation in 1989 and 1990. The herbicides tested were a coformulated mixture of pretilachlor and dimethametryne at 1.5, 2.0 and 2.5 kg a.i./ha, a co‐formulated mixture of piperophos and propanil applied at 3.16 and 3.95 kg a.i./ha, and Oxadiazon at 1.0 kg a.i./ha. Two hand weedings and a ‘no weeding’ treatment were included. The herbicides were applied 5 days after planting. All were safely selective to the crop. Most provided adequate weed control through 8–12 weeks after planting. Weeds controlled included Cynodon dactylon, Commelina benghalensis, Dlgitaria horizontalis, Eleusine indica, Panicum maximum and Pennisetum purpureum as grass weeds. The broadleaf weeds were Emilia sonchifolia, Ageratum conyzoides, Portulaca oleraceae, Richardia brasiliensis and Ipomoea Involuncrata. The sedges Mariscus alternifolius and Cyperus esculentus were encountered in the plots. Pretilachlordimethametryne at 2.5 kg a.i./ha had the best weeding score. Twoyear average grain yields of 1.7–2.6 t/ha were obtained from the herbicide treatments. With only 0.4 t/ha from the unweeded treatment, yield losses of more than 80% were recorded.     

3种除草剂对水稻旱直播阔叶杂草防效及安全性研究

为明确不同除草剂茎叶处理对旱直播水稻田旱生阔叶杂草防除及安全性的影响,采用随机区组试验设计,选用30% 2,4-滴丁酸钠盐AS、84%氯酯磺草胺WG、480 g/L灭草松AS 3种除草剂在水稻4叶期、5叶期施用,施药后每间隔7 d测定杂草株防效、鲜重防效和水稻目测药害,同步测定水稻生长指标和抗逆酶活性。结果表明:30% 2,4-滴丁酸钠盐AS 900.0 g/hm2在水稻4叶期的杂草防效最佳,第28天杂草株防效及鲜重防效仍可达93.55%和96.42%,且对大龄鸭跖草防效显著,施药后水稻生长与人工除草相比无显著差异。叶片SOD、POD活性和MDA含量均先升后降,至施药后28 d恢复正常。30% 2,4-滴丁酸钠盐AS 900.0 g/hm2可高效防除阔叶杂草,该药剂在水稻4叶期和5叶期施用对旱直播水稻安全。     

Prevalence of herbicide‐resistant weed species in Malaysian rice fields: A review

The management of weeds in Malaysian rice fields is very much herbicide‐based. The heavy reliance on herbicide for weed control by many rice‐growers arguably eventually has led to the development and evolution of herbicide‐resistant biotypes in Malaysian rice fields over the years. The continuous use of synthetic auxin (phenoxy group) herbicides and acetohydroxyacid synthase‐inhibiting herbicides to control rice weeds was consequential in leading to the emergence and prevalence of resistant weed biotypes. This review discusses the history and confirmed cases and incidence of herbicide‐resistant weeds in Malaysian rice fields. It also reviews the Clearfield Production System and its impact on the evolution of herbicide resistance among rice weed species and biotypes. This review also emphasizes the strategies and management options for herbicide‐resistant rice field weeds within the framework of herbicide‐based integrated weed management. These include the use of optimum tillage practices, certified clean seeds, increased crop competition through high seeding rates, crop rotation, the application of multiple modes of action of herbicides in annual rotations, tank mixtures and sequential applications to enable a broad spectrum of weed control, increase the selective control of noxious weed species in a field and help to delay the resistance evolution by reducing the selection pressure that is forced on those weed populations by a specific herbicidal mode of action.     

CHEMICAL WEED CONTROL IN BROADCAST-SEEDED FLOODED TROPICAL RICE

Summary. Several new herbicides were tested for control of weeds in broadcast-seeded flooded tropical rice. Among the new herbicides, S-(2-methyl-l-piperidylcarbonyl-methyl)- O,O -di- n -propyl dithiophosphate (C-19490), S-(2-methyl-l-piperidylcarbonyl-methyl)- O,O -di- n -propyl dithiophosphate combined with 2-(1',2'-dimethylpropylamino)-4-ethylamino-6-methylmercapto- s -triazine [C-19490/C-18898 (C-288)], and N -secondary-butyl-4-tertiary-butyl-2,6-dinitroaniline (A-820) were highly selective in controlling Echinochloa crus-galli (barnyard grass) and other annual weeds under tropical conditions. S-(4-chlorobenzyl)- N,N -diethylthiol carbamate (benthiocarb) and N -(butoxymethyl)-2-chloro-2',6'-diethylacetanilide (butachlor) continued to look promising in our experiments. Only butachlor is widely used in Asia.
Désherbage chimique des cultures tropicales de riz inorndé, seméà la volée     

苗期水分管理对水稻分蘖及除草剂控草效应的影响

稻田除草剂大量及高频使用对农作物安全、土壤及水体环境构成了严重威胁,使得除草剂减量使用刻不容缓。水稻机插田药后长时间保水可显著抑制杂草,以此可减少除草剂用量,但长时间保水会导致水稻发育受限。盆栽试验表明,无论是否喷施除草剂30%苄嘧·丙草胺乳油,杂草发生随保水时长增加而减少,且喷施除草剂对杂草防除具显著效果。田间试验表明,稻田施用30%苄嘧·丙草胺乳油100 mL/667m~2后,药后保水7 d时的水稻分蘖及抑草的综合效应达到最佳。     

高粱田除草剂种类及施药方法筛选试验初报

为了筛选高效的高粱除草剂和适合的施药方式, 我们进行了高粱田间杂草化学防除药剂及施药方法筛选试验, 通过除草效果、产量和收益分析, 初步认为:施药方法上土壤封闭明显优于茎叶处理。土壤封闭剂中, 42%丁·异·莠去津SC、42%异丙草·莠SC除草剂对阔叶杂草和禾本科杂草防除作用优良, 鲜重防效均超过90%, 高粱产量虽低于人工除草, 但差异不显著, 减产幅度在1%以下; 使用这类药剂高粱生产的利润高于人工除草。茎叶处理剂中, 25%辛酰溴苯腈EC等除草剂对高粱生长影响较小, 对藜、反枝苋等阔叶杂草防效高, 高粱产量低于人工除草, 但高粱生产的利润高于人工除草。建议在高粱生产中使用这些除草剂。     

Implications of delayed Echinochloa spp. germination and duration of competition for integrated weed management in water-seeded rice

Summary Co-ordinating herbicide applications with the suppressive ability of the crop has the potential to improve weed control and optimize herbicide use in water-seeded rice. However, the successful integration of herbicide applications and crop development depends on the timing and duration of competition between rice and weeds. The critical period of competition between rice and Echinochloa species was examined in field and glasshouse experiments from 1996 to 2000. In 1999 and 2000, Echinochloa species seeded 30 days after rice in field experiments did not survive and rice yields were not reduced when plots were kept weed-free for 30 days or longer. In a basin experiment conducted in 1998, E. phyllopogon seeded with the crop was unaffected by light competition alone but the relative importance of shading by the crop increased when E. phyllopogon was seeded after rice. Management strategies that delay the germination or growth of Echinochloa species might confer a competitive advantage to rice and reduce the need for herbicide applications. However, yields in the field experiments were reduced by at least 18% after only 30 days of competition in both years, suggesting that it may be difficult to integrate currently available herbicides with crop growth in water-seeded rice.     

20％嗯唑酰草胺·灭草松ME防除水稻直播田一年生杂草及安全性

通过对20％曙唑酰草胺·灭草松ME防除水稻直播田一年生杂草及对水稻安全性的试验,明确了每667111。用20％嗯唑酰草胺·灭草松ME在有效剂量下,与10％韩秋好EC、48％灭草松AS相比较除草效果显著,杀草谱广;在水稻直播田中,当水稻秧苗2叶期后,杂草处于2～4叶期,用剂量为210—240mL／667m2（630—720a．i．g／hm2）时,能有效地防除水稻直播田一年生单双子杂草和异型莎草,证明了在水稻直播田应用吧唑酰草胺·20％灭草松ME对水稻是安全的。     

甲嘧磺隆等3种除草剂对云南黄馨、金钟扦插苗成苗及生长的影响

阔叶杂草是苗圃中重要的危害性杂草,然而控制苗圃阔叶杂草的有效化学方法却很少,主要原因是能防除阔叶草的除草剂往往对苗木不安全或缺少对其安全性研究。选择甲嘧磺隆、乙氧氟草醚和扑草净3种杀草谱较广的除草剂,通过2015年田间小区试验,研究不同用量下这3种除草剂对苗圃常见苗木云南黄馨、金钟扦插苗成苗、发芽、生根、株高等因素的影响。结果显示:用药时雨水、土壤湿度可严重影响植物生长状况,雨水多、湿度大,则发根、出叶少;用药时间影响药剂效应,扦插前用药,药剂影响大于扦插后用药,这可能是扦插前、扦插后苗在遇药时的叶芽状态及水分不同所造成的。研究还发现,药剂对苗木成苗无不良影响,7.5 g a.i./hm~275%甲嘧磺隆WDG处理对苗木出叶、株高无影响;而在生根方面,在药后30 d,只有对照的71.1%,用药后100 d,与对照相当,乙氧氟草醚144、288 g a.i./hm~2,扑草净450、900 g a.i./hm~24个处理的结果与甲嘧磺隆7.5 g a.i./hm~2处理相同;对于甲嘧磺隆15 g a.i./hm~2处理,在前期对苗木出叶、生根都有较大影响,3个月后影响逐渐减少甚至消失;甲嘧磺隆22.5 g a.i./hm~2处理对苗木出叶、生根、株高的抑制可持续3个月以上。     

甲磺隆的应用技术及对后茬作物的安全性研究

在冬小麦 1～ 2叶期施用甲磺隆 1.8～ 2.5 g/hm2 ,可有效防除北京地区麦田常见阔叶杂草 ,优于当前常用除草剂苯磺隆 15g/hm2 春季施用的除草效果 ,安全性与春季施用苯磺隆 15g/hm2 相当。实验室降解结果表明 ,当甲磺隆初始浓度为 6.25μg/kg以下时 ,经过215d后 ,对后茬玉米安全。研究表明 ,向日葵是甲磺隆理想的生物测定试材 ,对甲磺隆的最低检出浓度达到 0.125μg/kg,其根长抑制率与除草剂浓度有高度的相关性 ,最佳的剂量 -反应模型为 y=a+b lnx     

Weed control in summer-sown soybeans with flumioxazin plus acetochlor and flumiclorac-pentyl plus clethodim

Field trials were conducted in Taigu, Shanxi province, China, to evaluate the efficacy of flumioxazin plus acetochlor and flumiclorac-pentyl plus clethodim applied to summer-sown soybeans at pre- and postemergence. It was demonstrated that tank-mixing flumioxazin at 50 g ai ha^-1 and acetochlor at 800 g ai ha^-1 created an effective soil-applied herbicide for weed control in soybean crops. The control efficacy was better than when the herbicides were applied individually, and no injury was caused to the soybeans. Flumiclorac-pentyl at 50 g ai ha^-1 plus clethodim at 70 g ai ha^-1 suppressed both broad-leaved weeds and grass weeds with an increased efficacy of more than 90%. Flumiclorac-pentyl applied alone or tank-mixed caused some injury to soybean seedlings, but the soybeans recovered 2–3 weeks after treatment and there was no reduction in the yield.     

Chemical control of perennial nutsedge (Cyperus rotundus L.) in tropical upland rice

Five herbicides were tested in the dry and in the wet season for their effectiveness in conlrolling perennial nutsedge (Cyperus rotundus L.) in direct-seeded upland rice in the tropics. K-223 [N-(α,α-dimethylbenzyl)-N'-P-tolyl urea] gave the best results. When broadcast sprayed at 8.0 kg a.i./ha in the dry season and 10 kg a.i./ha in the wet season and immediately mixed into the soit just before drilling, K-223 gave excellent perennial nutsedge control with no visible crop damage and increased the grain yield. Bentazone at 2.0 kg a.i./ha applied 7 days after crop emergence was highly selective and gave fair control of nutsedge without being toxic to the crop. MBR 8251 [1.1,1-trifluoro-4′-(phenylsulfonyl) methane-sulfono-o-toluidide] at 2.0 kg a.i./ha, mecoprop (MCPP) at 1.5 kg a.c./ha and fenoprop (silvex) at 1.0 kg a.e./ha applied 7, 14 and 7 days, respectively after crop emergence provided a fair degree of nutsedge control. Fenoprop and MBR 8251 caused slight and mecoprop moderate initial toxicity, but the injury sustained did not significantly affect crop yield.     

常用新型除草剂防除直播晚稻抗药性稗草药效现状及治理对策

[目的]比较常用新型除草剂防除直播晚稻抗药性稗草的效果.[方法]选择常用新型茎叶除草剂及组合用药,在播后苗前实施了封闭控草的直播晚稻田间稻苗3叶期,进行茎叶喷施防除抗药性稗草示范试验.[结果]参试药剂对稗草具有很高的株防效、鲜重防效,但药后田间残存稗草仍能对水稻造成危害:10％口恶唑酰草胺EC 100～130 mL/6...     

嘧草醚对双季稻田杂草的防效及后茬作物的安全性影响

为明确嘧草醚及其相关除草剂混用对移栽田杂草的防效及其对水稻和后茬作物的安全性,于2018年在江西双季稻田进行了田间试验。结果表明:10%嘧草醚WP对稗Echinochloa crus-galli有优异的防除效果,有效剂量45～120 g/hm~2处理药后45 d对早稻和晚稻田稗草的防效均在90%以上,且对水稻和后茬作物油菜、白菜、紫云英、小麦和马铃薯生长安全,但对阔叶类鸭舌草和莎草类异型莎草的防效较差;10%嘧草醚WP分别与10%苄嘧磺隆WP和25 g/L五氟磺草胺OD混用,对早稻和晚稻田稗草、鸭舌草和异型莎草的防效均达91%以上,且对水稻生长安全;而与扑草净混用对杂草的防效略低,且对水稻会产生药害,严重影响产量。因此,对于以稗草为优势种群的水稻田,可选用10%嘧草醚WP 45～60 g/hm~2进行防治;对于禾本科杂草、阔叶杂草和莎草科杂草发生并重的水稻田,可选择10%嘧草醚WP 30～45 g/hm~2与10%苄嘧磺隆WP或25 g/L五氟磺草胺OD 20～30 g/hm~2混用进行治理。     

Herbicide tank-mixing for post-emergence weed control in sugar beets

Tank-mixtures of selective herbicides were evaluated for 2 years on field-grown sugarbeets under two weed flora situations: (a) mixed floras of broad-leaved and grass weeds and (b) weed floras of broadleaves grown beyond their stages of greatest sensitivity to herbicides. In these situations single herbicides usually fail to provide satisfactory post-emergence weed control in sugarbeets. Of several tank-mixtures, which could be devised for use in the first situation, ethofurnesate + Betanal AM 11, diclofop-methyl + Betanal AM 11 and diclofop-methyl + metamitron gave synergistic phytotoxicity to sugarbeet seedlings. Synergism in weed control, becoming apparent by an accelerated appearance of the herbicidal effects, was obtained with the mixture alloxydimeton + Betanal AM 11. This mixture was not phytotoxic and appears to be the most efficient for simultaneous control of broad-leaved and grass weeds. From trials in the second situation it became apparent that the activity of metamitron, which was reduced on older weeds, could be restored by mixing with a non-phytotoxic oil or a low dose of Betanal AM 11. These mixtures should be useful when growth of sugarbeets has been retarded by carried-over herbicides, drought, frost, etc.     

Relative growth and photosynthetic response of water-seeded rice and Echinochloa oryzoides (Ard.) Fritsch to shade

Echinochloa oryzoides is a serious weed of rice worldwide and one of the most important weeds of water-seeded rice in California, USA, where resistance to most available herbicides has been detected. Developing new integrated weed management strategies that include rice suppression of E. oryzoides growth requires understanding their relative responses to resource limitation. The effects of shade on the growth, morphology and CO 2 exchange rates (CER) of E. oryzoides and rice (cv. M-202) were assessed in glasshouse and growth chamber experiments. Plants were grown at 100, 50 or 18% of full sunlight (glasshouse) or at 500 and 250 µmol PPFD m-2s-1 (growth chamber) within a completely randomized design with two factors and four replicates. Shade was imposed at 21 days after seeding (d.a.s.) (glasshouse) and at 14 d.a.s. (growth chamber). Height, leaf area, tillers, and leaf, stem, root and seed dry weights were determined for both species. CER were determined for plants in the growth chamber. Both species increased dry-matter allocation to leaves and maintained CER when subjected to low light. However, in contrast to rice, E. oryzoides maintained or increased leaf area, specific leaf area and leaf area ratio (LAR) in response to shade. E. oryzoides tiller number and seed output were reduced only at 18% sunlight. Rice lacked such adaptive ability and tiller number and seed were reduced at 50% sunlight. Shade alone may not prevent the seed production of E. oryzoides. However, E. oryzoides increased LAR at the expense of allocation to roots. Thus, for substantial E. oryzoides control, early nutrient deprivation by rice roots may be as relevant as improving rice ability to intercept light.     

地膜覆盖和除草剂对夏玉米田杂草及玉米生长发育的影响

研究了地膜覆盖和除草剂对夏玉米田杂草和玉米生长发育的影响.结果表明,在玉米3～5叶期施药,药后33 d,杂草数量降至最低,56％2甲4氯钠可湿性粉剂处理的杂草减退率和相对株防效分别比40 g/L烟嘧磺隆油分散制剂提高了11.71百分点和12.65百分点.揭膜后,白色地膜覆盖下杂草的平均鲜重显著低于对照,比对照减少73.25％,相对鲜重防效分别是黑色地膜覆盖、56％2甲4氯钠可湿性粉剂、40 g/L烟嘧磺隆油分散制剂处理的1.12、1.15、1.73倍.地膜覆盖出苗率高且整齐一致,平均株高和叶数比对照高,对玉米的穗粒重、百粒重及其产量有明显的增效作用,以白色地膜覆盖下玉米产量最高,增产率比黑色地膜覆盖的高1.23百分点,比40g/L烟嘧磺隆油分散制剂处理高16.09百分点;而施用56％2甲4氯钠可湿性粉剂严重影响了玉米产量的形成,其产量比对照降低3.09％.