西安市夏玉米田常见杂草种类及优势种群调查研究

根据2007~2009年对西安市夏玉米田杂草的系统调查和分析结果,明确了西安市夏玉米田的18科43种常见杂草及不同生态条件下的杂草群落结构,并通过各种杂草的田间均度、田间密度、频率、相对多度等量化参数,确定了反枝苋等9种杂草为西安市夏玉米田杂草优势种群,为制定科学合理的夏玉米田杂草综合治理技术方案,最大限度地控制杂草危害提供科学依据。     

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。     

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。     

夏玉米不同种植模式化学除草技术

夏玉米播种季节(山东一般为5月20至6月15日)正逢高温、多雨季节,杂草生长迅速,加上夏收劳动力紧张,人工作业不便,极易形成草荒,因而玉米田化学除草显得尤为重要。邹平县玉米田化学除草剂的应用始于20世纪80年代中、后期,最初只用莠去津(商品名阿特拉津),到目前已经有十余种除草剂可供选择使用。笔者经过十几年的研究,在摸清夏玉米田杂草生长规律的基础上,掌握了夏玉米不同种植模式(或不同种植时间)下的化学防除方法,现介绍如下:1夏玉米田杂草主要种类和生长规律1.1杂草主要种类本县玉米田杂草种类较多,其中危害较重的有马唐犤Digitariasang…     

夏玉米田杂草发生和为害损失调查研究

根据有代表性的２ 县１０５ 块夏玉米田调查,菏泽地区夏玉米田杂草种类共１７ 科３５ 种,分析探明优势种类１２ 种。试验表明不同杂草混合种群密度与夏玉米产量损失率相关极显著,相关式为ｙ＝４ ．７２３ ６ ＋ ０ ．１８７ ４ｘ 。提出其化学除治指标为每平方米有杂草２０ 株。     

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。     

“SL—950”夏玉米田除草试验总结

东辛农场位于徐淮农业区沿海粘质盐片,土壤肥力中等。由于夏玉米播种时正值夏收夏种期间,农事忙,劳力紧。而过去夏玉米田化除一直使用土壤处理剂,往往因人力、机械紧,而错过播后苗前化除时期,因此,杂草危害对夏玉米生产的发展和单、总产的提高成为一个限制性因素。所以研究和试验夏玉米田杂草的茎叶处理,错开夏收夏种的农忙时期,解决夏玉米田杂草的危害,对加快淮北地区夏玉米生产的发展,有着十分重要的意义。现就“SL-950”玉米田专用的苗后茎叶处理剂试验结果总结如下:     

陕西省夏玉米田杂草发生及防治策略

选择有代表性的110余块玉米田，进行杂草调查，结果表明陕西省夏玉米田杂草有30余种，隶属15科，其中禾本科8种，菊科5种，大戟科，旋花科，藜科各2种，莎草科，马齿苋科，锦葵科，苋科，蒺藜科，茄科，木贼科，唇形科，酢浆草科，蓼科各1种，夏玉米田杂草优势种为马唐，狗尾草，铁苋菜，个别地方莎草相当严重，已成为玉米田内以难以根除的恶性杂草，玉米田杂草播的10－15d是出草高峰期，也是进行化学除草的关键时期，应采取以农业防除为基础，以化学防除为主导的防除策略。     

莠·乙·烟47%悬浮刹防除夏玉米田杂草药效与安全性评价

结果表明,在夏玉米出苗后3～5叶期、杂草2～5叶期,大多数杂草出齐时施用莠·乙·烟47%悬浮剂150～200g/667m2(1 057.7～1 410g.a.i/hm2),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.     

莠·乙·烟47%悬浮剂防除夏玉米田杂草药效与安全性评价

结果表明,在夏玉米出苗后3～5叶期、杂草2～5叶期,大多数杂草出齐时施用莠·乙·烟47%悬浮剂150～200g/667m2(1057.7～1410g.a.i/hm2),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。     

Application of reverse-phase h.p.l.c. for the determination of partition coefficients

Reverse-phase high performance liquid chromatography (h.p.l.c.), using a C₁₈ analytical column, has been applied to the determination of partition coefficients for a range of agrochemicals and industrial chemicals. Using a correlation plot of the logarithm of the capacity factor (k) with the logarithm of the n-octanol/water partition coefficient (P_ow), partition coefficients were predicted with a 95% tolerance interval of ± log 0.80 of the literature ‘shake flask’ value for compounds of random structure over the log P_ow range 0–6. Individual regression lines were fitted for compounds of comparable size and functional grouping, which reduced any bias and thereby enabled more accurate predictions to be made. The reverse-phase h.p.l.c. method has a number of advantages over the traditional ‘shake-flask’ method. Quantitative methods are not required or do not have to be developed and only the determination of the retention time is necessary. Quick and precise determinations of retention times are facilitated by h.p.l.c. and further improvement can be obtained by automation of solvent mixing, solute injection and data processing. H.p.l.c. was used to generate partition coefficient data for highly hydrophobic materials and, because of its resolving power, data for mixtures and solvent fractions. Dual detection, using u.v. and r.i. in series, was necessary for some compounds, particularly unknown mixtures and impure compounds. Calculations of log P_ow based on the fragment-addition method using the structural data file, MACCS, was of considerable value in confirming experimentally derived values. In certain cases, calculated log P_ow values were considered more trustworthy than experimental values.     

Dispersal of Formulations of Fusarium oxysporum f. sp. erythroxyli and F. oxysporum f. sp. melonis by Ants

ABSTRACT A natural epidemic of Fusarium wilt on coca (Erythroxylum coca) in Peru prompted the suggestion of possibly using the pathogen Fusarium oxysporum f. sp. erythroxyli as a mycoherbicide against this narcotic plant. During field trials conducted in Kauai, HI, to test the pathogenicity of the coca wilt pathogen, ants were observed removing formulations from test plots. While removal of formulations by ants was considered detrimental with respect to conducting field tests, ant removal was considered potentially beneficial in disseminating the mycoherbicide. Thus, research was initiated to assess the ability of formulation additives to alter the preference of ants for the formulated mycoherbicide. In Hawaii, preference of indigenous ants for removing formulations was tested using three different food bases (rice, rice plus canola oil, and wheat flour [gluten]). Similar tests were conducted at Beltsville, MD, using F. oxysporum f. sp. melonis, in which the formulation based on wheat flour was replaced by a formulation based on canola meal. Formulations based on wheat were preferred by ants in both locations; up to 90% of the wheat plus rice flour granules (C-6) and the wheat gluten plus kaolin granules (pesta) were removed within 24 h, while only 20% of those containing rice without oils were taken. However, when either canola, sunflower (Maryland only), or olive oil was added to the rice formulation, up to 90% of the granules were taken. The formulation based on canola meal was less attractive to ants, as only 65% of the granules were removed within a period of 24 h. Ants showed no preference with respect to presence or absence of fungal biomass. To alter the attractiveness of the C-6 formulation to ants, C-6 was amended with three natural products. Canna and tansy leaves were added to C-6 at a ratio of 1:5 (wt/wt), while chili powder was added at 1:25 or 1:2.5 (wt/wt). Canna, tansy, and the higher rate of chili powder significantly reduced the number of C-6 granules removed by ants. Canna and tansy leaves affected neither germination nor sporulation of the mycoherbicide, while the high concentration of chili powder reduced viability of propagules in the formulation. More F. oxysporum f. sp. erythroxyli-type colonies were recovered from inside ant nests (9 cm depth) than from nest surfaces, indicating that ants may distribute the mycoherbicide in the soil profile. Ants passively carried propagules of F. oxysporum f. sp. erythroxyli outside their bodies, as well as either very closely adhering to the outside or within their bodies.     

PCR-based differentiation of Fusarium oxysporum ff. sp. lycopersici and radicis-lycopersici and races of F. oxysporum f. sp. lycopersici

The pathogenic type (form and race) of Fusarium oxysporum, which generates wilt symptoms on tomato, was rapidly identified with a polymerase chain reaction (PCR)-based technique. We compared the partial nucleotide sequences of endo polygalacturonase (pg1) and exo polygalacturonase (pgx4) genes from isolates of F. oxysporum ff. sp. lycopersici (FOL) and radicis-lycopersici (FORL) from Japan and designed specific primer sets (uni, sp13, sp23, and sprl) based on the nucleotide differences that appeared among the pathogenic types. PCR with the uni primer set amplified a 670∼672-bp fragment from all isolates of FOL and FORL. With the sp13 primer set, an amplicon of 445 bp was obtained only from isolates of FOL race 1 and 3. With the sp23 primer set, a 518-bp fragment was obtained from isolates of FOL race 2 and 3. The sprl primer set yielded a 947-bp fragment from isolates of FORL, but not from FOL. A combination of amplifications with these primer sets effectively differentiated the pathogenic types of F. oxysporum in tomato.     

Attempted somatic hybridization of Puccinia striiformis f. sp. tritici and P. striiformis f. sp. hordei

Attempts were made to produce somatic hybrids between isolates of Puccinia striiformis f. sp. tritici and f. sp. hordei. A mixed infection was produced on a common susceptible barley host, Fong Tien, using white-spored isolates of P. striiformis f. sp. tritici and yellow-spored isolates off. sp. hordei. Selection was made for non-parental spore colour on selective wheat and barley hosts, and variants thus isolated were analysed for virulence markers, and for isozyme and double-stranded RNA (dsRNA) markers, all of which clearly differentiated the parental isolates. Two white-spored (non-parental) isolates were found on the selective barley host which otherwise resembled the parental f. sp. hordei isolate in virulence, isozyme and dsRNA markers. The most likely explanation of the origin of these isolates is mutation to white spore colour in the f. sp. hordei isolate.     

醉蝶白粉病的发生规律与防治

研究明确醉蝶白粉病菌以闭囊壳、分生孢子和菌丝在病残体上或土壤中越冬。醉蝶开花至盛花期为发生高峰期 ,高温干燥的气候条件发病严重。发生程度与土壤肥力、田间种植密度等关系密切。加强管理 ,清洁田园和30%特富灵、6%乐必耕、75%百菌清、25%粉锈宁可湿性粉剂等在定植后、开花前后喷药 ,每隔10d1次 ,连续5～6次 ,可基本控制该病发生。