玉米田杂草生态经济防除阈值及竞争临界期研究

通过田间小区试验表明 ,玉米的产量损失与田间杂草密度呈极显著正相关r=0 .9988 。关系式为y =-0 .9752 0 .0 785x ,(x为每 1m2 杂草数量 )。玉米田杂草的生态经济防除阈值为 80～ 90株 /m2 。玉米田杂草与玉米的竞争临界期为播后 3 2～ 3 5d ,其中以播后 1 5d前除草增产效果最明显     

玉米田杂草经济防除阈值和竞争临界期研究

研究表明杂草密度与玉米的产量损失二者呈极显著的正相关．当玉米田杂草密度超过30－34株/m^2时,必须用药进行防除,以控制杂草的危害;玉米播后13～15d为玉米杂草竞争临界期,只有在玉米与杂草竞争临界期之前进行杂草防除,才能使杂草的危害损失控制在经济允许水平之下。     

杂草对冬小麦的危害损失及经济防除阈值

1997—1999年在山东省桓台县的田间试验表明，荠菜 播娘蒿杂草群落有两个萌发出苗高峰期，除草临界期为小麦苗后的125-175天。杂草发生密度(株／m^2)与冬小麦产量(kg／hm^2)、有效穗数(万穗／hm^2)及秸秆生物量(kg/hm^2)的最佳模型均为直线函数关系，方程分别为Y3=-5．4545X 5995．5，Y4=-0．0293X 31．098和Y5=-8．329X 6987．1。使用巨星除草的经济防除阈值为20株／m^2，人工除草的经济防除阈值为70株／m^2。考虑到杂草群落的生长动态，本区秋季用巨星防除的最低密度为12株／m^2，并认为可以用步测法来粗略测定田间杂草防除密度。     

陕西夏玉米田杂草发生及防治策略

在陕西省重点夏玉米生产县(市)选择有代表性的110块玉米田进行杂草调查,已鉴定出夏玉米田杂草29种,隶属15科。其中优势种群为马唐、狗尾草、铁苋菜,个别地方莎草相当严重,已成为玉米田内难以根除的恶性杂草。玉米播种后10～15d为出草高峰期,播后苗前施药是进行化学防除的关键时期。     

10%烟嘧磺隆防除春玉米田杂草试验

引进10%烟嘧磺隆可分散油悬浮剂,用40%烟嘧磺隆可分散油悬浮剂作为对照药剂进行试验。结果表明,每667 m2用10%烟嘧磺隆可分散油悬浮剂25 g、30 g、35 g、60 g,药后15 d,对玉米田阔叶杂草的防除效果分别为70.5%、79.7%、82.4%和87.4%,对玉米田单子叶杂草防除效果分别为71.2%、80.6%、83%和89%,防除效果与对照药剂差异不显著。施药后15 d,每667 m2用40%烟嘧磺隆可分散油悬浮剂90 g,对玉米田阔叶杂草防除效果78%,对玉米田单子叶(禾本科)杂草防除效果80.2%,与每667 m2用10%烟嘧磺隆可分散油悬浮剂30~35 g的防除效果差异不显著。10%烟嘧磺隆可分散油悬浮剂杀草谱为稗草、狗尾草、画眉草等一年生禾本科杂草和藜、蓼、苍耳等一年生阔叶杂草。     

菵草与油菜的竞争及防除阈值

采用添加系列试验研究了菵草与移栽油菜间的竞争关系.结果表明,菵草与油菜竞争光能,田间光照强度随菵草密度的增加而降低.移栽油菜在菵草的竞争干扰下,单株分枝数、角果数、千粒重及产量均随菵草密度增加而逐渐降低,油菜减产主要与菵草密度增大引起单株角果数减少有关.油菜产量损失与菵草密度之间的关系可用y = -0.0003x2 0.2269x 4.7638的数学模型来模拟,油菜田菵草的经济危害允许水平为3.24%,其防除阈值为8株/m2.     

10%甲基磺草酮悬浮剂防除夏玉米田杂草田间药效试验

田间试验结果表明,夏玉米田播后芽前使用10%甲基磺草酮悬浮剂150～200g/667m2,对夏玉米田阔叶杂草和禾本科杂草均有较好的防除效果,并且持效期较长,对夏玉米生长安全。     

烟嘧·甲基磺草酮36%油悬浮剂玉米田间药效试验

田间药效试验结果表明,烟嘧.甲基磺草酮36%油悬浮剂在春玉米田茎叶喷雾施药,防除春玉米田多种一年生单、双子叶杂草除草效果好,杀草谱广,速效性好,持效期长,药后30d,株防效均在90%以上,鲜重防效均在97%以上,80～200mL/667m2对玉米安全,从成本考虑,建推荐剂量为100～120mL/667m2。     

烟嘧·氯氟吡氧乙酸·莠去津30%油悬浮剂玉米田间药效试验

田间药效试验结果表明,烟嘧.氯氟吡氧乙酸.莠去津30%油悬浮剂在春玉米田茎叶喷雾施药,防除春玉米田多种一年生单、双子叶杂草除草效果好,杀草谱广,速效性好,持效期长,药后30d,株防效均在90%以上,鲜重防效均在97%以上,80~200mL/667m2对玉米安全,从成本考虑,建推荐剂量为100~120mL/667m2。     

2,4-滴异辛酯·莠去津51%悬浮剂防除夏玉米田杂草药效与安全性评价

田间试验结果表明,夏玉米田播后芽前使用2,4-滴异辛酯·莠去津51%悬浮剂50～70g/667m2,对夏玉米田阔叶杂草和禾本科杂草均有较好的防除效果,并且有较长的持效期,对夏玉米生长安全.     

Activity of mesotrione on resistant weeds in maize

Mesotrione is a new callistemone herbicide that inhibits the HPPD enzyme (p-hydroxyphenylpyruvate dioxygenase) and introduces a new naturally selective tool into weed-management programmes for use in maize. Mesotrione provides control of the major broad-leaved weeds, and it can be used in integrated weed-management programmes depending on the grower's preferred weed-control strategy. At post-emergence rates of 150 g AI ha-1 or less, mesotrione provides naturally selective control of key species that may show triazine resistance (TR), e.g. Chenopodium album L, Amaranthus species, Solanum nigrum L, as well as species of weed that show resistance to acetolactase synthase (ALS) inhibitors e.g. Xanthium strumarium L, Amaranthus spp and Sonchus spp. The data presented show that resistant and susceptible biotypes of these species with resistance to triazine herbicides, such as atrazine, simazine, terbutylazine and metribuzin, or ALS-inhibitor herbicides, such as imazethepyr, remain susceptible to mesotrione. These results confirm that there is no cross-resistance in biotypes with target site resistance to triazine or ALS-inhibiting herbicides. It is important that herbicide choice and rotation becomes an integral part of planning weed management, so as to minimise the risks of crop losses from weed competition, build-up of weed seed in the soil and the further development of weed resistance across a range of herbicide modes of action.     

夏玉米田杂草的发生及防除技术

淮北地区夏玉米的生育期在6～9月份,由于这一时期高温多雨,极利于田间杂草的生长,一旦错过防除适期,则很难有效控制杂草危害。为此,我们进行了淮北地区夏玉米田杂草发生及防除技术研究。     

夏玉米田除草剂筛选试验报告

近年来，除草剂的使用面积逐渐扩大，并广泛应用于各种作物田，以其省工省时、简单高效快速而深受欢迎。但在实际应用中也存在一些问题，比如一些除草剂杀草谱窄，残留量高。为确保河南洛阳地区夏玉米田除草剂的安全使用，我们进行了夏玉米田不同除草剂筛选试验。     

Image‐based thresholds for weeds in maize fields

Recent development of site‐specific weed management strategies suggests patch application of herbicides to avoid their excessive use in crops. The estimation of infestation of weeds and control thresholds are important components for taking spray decisions. If weed pressure is below a certain level in some parts of the field and if late germinating weeds do not affect yield, it may not be necessary the spray such places from an economic point of view. Consequently, it makes sense to develop weed control thresholds for patch spraying, based on weed cover early in the growing season. In Danish maize field experiments conducted from 2010 to 2012, we estimated competitive ability parameters and control thresholds of naturally established weed populations in the context of decision‐making for patch spraying. The most frequent weed was Chenopodium album, accompanied by Capsella bursa‐pastoris, Cirsium arvense, Lamium amplexicaule, Tripleurospermum inodorum, Poa annua, Polygonum aviculare, Polygonum persicaria, Stellaria media and Veronica persica. Relative leaf cover of weeds was estimated using an image analysis method. The relation between relative weed leaf cover and yield loss was analysed by nonlinear regression models. The competitive ability parameters and economic thresholds were estimated from the regression models. The competitive ability of weed mixtures was influenced by the increasing proportion of large size weeds in the mixtures. There was no significant effect of weeds which survived or established after the first herbicide application, indicating that early image analysis was robust for use under these conditions.     

乙·扑防除玉米田杂草试验报告

通过对40%乙(乙草胺).扑(扑草净)可湿性粉剂进行玉米田间小区试验,明确了该药剂防除玉米田杂草具有效果好,药效期长,杀草谱广,施药期宽等优点。安全适宜的用法在玉米播后苗前或移栽前进行土壤处理,用药量长江以南为150 g/667m2,对水不少于45 kg/667m2。     

嗪草酸甲酯及其混剂防除玉米田杂草的效果

嗪草酸甲酯(阔少)20 g a.i./hm2防除玉米田苘麻、藜、红蓼等阔叶杂草的效果可达到90%,对鸭跖草等阔叶杂草的防效只有50%,对禾本科杂草没有防除作用。嗪草酸甲酯与烟嘧磺隆(玉农乐)、莠去津三者的混剂80%嗪.玉.莠WP 560~800 g a.i./hm2,在玉米2~6叶期,杂草2~5叶期施用,可有效防除田间杂草,对各种杂草的防效都在90%左右,而且对作物安全性好,是个比较理想的混剂配方。     

阔草清与乙草胺混用防除大豆、玉米田杂草药效试验

为了明确阔草清与乙草胺混用的剂量、配伍量、防除效果、安全性及残留对后茬作物的影响，特安排本试验，现将试验结果报告如下：     

烟嘧磺隆·莠去津防除玉米田杂草的效果

85%烟嘧磺隆·莠去津可湿性粉剂对玉米田马唐、狗尾草、马齿苋、反枝苋等一年生杂草具有良好的防除效果,382.5~573.75 ga.i./hm2药后30 d鲜重总防效达到90%左右,对玉米安全。     

九种除草剂对玉米田杂草的防除效果及其安全性评价

为明确9种常用除草剂对玉米田杂草的防除效果及其安全性。在福建省甜玉米制种田,采用茎叶喷雾法开展了9种除草剂在推荐剂量下的田间药效试验,并测定了除草剂对甜玉米及其后茬花椰菜和萝卜的安全性。结果表明,施药后25 d,9种除草剂的杂草株防效和鲜重防效均在92%以上;施药后50 d,27%烟 ? 硝 ? 莠去津可分散油悬浮剂[有效成分(下同) 810 g/hm2 ] 和25%硝磺 ? 莠去津可分散油悬浮剂 (750 g/hm2 ) 处理的杂草防除效果最好,以20%氯氟吡氧乙酸乳油 (180 g/hm2 ) 处理的杂草防除效果最差,杂草覆盖表现为重度。供试的9种除草剂对甜玉米生长安全,无明显药害症状,且部分药剂有明显的增产效果,其中以25%硝磺 ? 莠去津可分散油悬浮剂、20%烟嘧 ? 辛酰溴苯腈可分散油悬浮剂 (300 g/hm2 )、80%莠去津可湿性粉剂 (1 440 g/hm2 ) 和27%烟 ? 硝 ? 莠去津可分散油悬浮剂处理的玉米产量较高,与对照相比,增产率分别为21.03%、19.26%、18.74%和16.84%。10%硝磺草酮悬浮剂 (150 g/hm2 )、27%烟 ? 硝 ? 莠去津可分散油悬浮剂、33.5%硝磺 ? 异丙草胺 ? 莠去津悬浮剂 (1 005 g/hm2 ) 和30%苯唑草酮悬浮剂 (27 g/hm2 ) 处理对后茬花椰菜和萝卜均有较好的增产效果,增产率分别为18.05%和13.68%、3.37%和12.67%、15.45%和11.06%、8.21%和11.67%,但40 g/L烟嘧磺隆可分散油悬浮剂 (60 g/hm2 ) 对后茬花椰菜和萝卜的生长有抑制作用,与清水对照相比,分别减产9.74%和3.57%。研究结果可为甜玉米田杂草防除有效药剂的合理选择和应用提供科学依据。     

喷雾助剂对苯唑草酮防除玉米田杂草的减量增效作用

为了评价不同喷雾助剂对苯唑草酮减量施用下的增效作用,采用仪器分析和田间试验的方法研究了7种助剂对30%苯唑草酮悬浮剂的药液特性和杂草防效的影响。结果表明,7种助剂均能显著降低药液的表面张力、接触角和干燥时间,增加药液铺展直径。其中,杰效利对表面张力和接触角的影响最大,迈丝和渗透者对干燥时间的影响最小。田间试验结果表明,添加迈丝和渗透者对苯唑草酮的增效作用好于其他助剂,苯唑草酮的田间用量可以减少30%以上。