小麦矮腥黑穗病在无积雪条件下发病的研究

小麦矮腥黑穗病在无积雪条件下发病的研究王圆俞晓霞（农业部植物检疫实验所１０００２９）小麦矮腥黑穗病ＴｉｌｅｔｉａｃｏｎｔｒａｖｅｒｓａＫｕｈｍ（简称ＴＣＫ）是我国进境植物检疫一类危险病害，病菌冬孢子能在土中存活６～７年，甚至长达１０年之久。冬孢子可随...     

小麦矮腥黑穗病检验方法的改进

对小麦矮腥黑穗病Ｔｉｌｌｅｔｉａ ｃｏｎｔｒｏｖｅｒｓａＫｕｈｍ、以下简称（ＴＣＫ）实施麦粒带菌检验时，利用α－淀粉酶处理小麦筛下物的洗涤沉淀，可消除淀粉粒的干扰，提高孢子截获数量。在设定条件（７０℃，２０分钟内）下经淀粉酶处理后的ＴＣＫ冬孢子，其形态、大小、网脊高度和胶鞘厚度与对照均无明显变化。７０℃下，分别以５００、３００、２００、１００和０个酶单位／ｇ沉淀物的剂量处理２０分钟，以３００单位／     

从进口草籽中截获绒毛草腥黑穗菌

本文介绍了小麦矮腥黑穗病菌（ＴＣＫ）的近似种－绒毛草腥黑穗菌（ＴＨＳ）的检验鉴定情况,并详细比较了两种黑粉菌,发现两种冬孢子萌发对温度条件要求不同。     

小麦矮腥黑穗病孢子不同药剂处理发芽试验

小麦矮腥黑穗病孢子不同药剂处理发芽试验魏哲轩（连云港动植物检疫局２２２０４２）小麦矮腥黑穗病ＴｉｌｅｔｉａｃｏｎｔｒａｖｅｒｓａＫüｈｎ（ＴＣＫ）孢子萌发，是学术界在探讨的一个课题，很多学者都在进行研究。试图在温度、湿度、光度及ｐＨ值等方面索求促其萌...     

玉米丝黑穗病原菌冬孢子萌发条件研究

通过不同条件对玉米丝黑穗病菌冬孢子萌发率影响的试验研究表明,甲醛处理对玉米丝黑穗病菌冬孢子萌发有明显促进作用,萌发率达88.89%,冬孢子在麦芽糖和水琼脂培养基上萌发率最高达84.49%。在不同温度和pH条件下冬孢子萌发率差异较大。冬孢子在28℃时最适合萌发,达89.67%,在pH为7时萌发率最高达89.02%。     

制约稻粒黑粉病菌冬孢子萌发的关键因素

在相同条件下，从稻田直接收集的病粒中的稻粒黑粉病菌厚垣孢子不能萌发，而取之于仓库中的孢子能萌发。为探明其制约因素，对该病菌进行了光照和浸水时间试验。研究结果表明：稻粒黑粉病菌冬孢子形成后，必须经光照射后，方可进入休眠期；度过5～6个月休眠期的冬孢子，必须浸水48h以上才开始复苏；复苏后的冬孢子必须在光照条件下才能萌发。未完成后熟作用的冬孢子和完成后熟但尚未复苏的冬孢子即使在光照条件下也不能萌发。即稻粒黑粉病菌冬孢子必须经历后熟、休眠、复苏三个阶段后，在适宜的光照与温湿条件下，方可萌发。光照对其冬孢子具有双重作用，促使后熟进入休眠和刺激萌发。     

小麦矮腥黑穗病菌对温度的敏感性

通过研究小麦矮腥黑穗病菌不同菌株冬孢子萌发对温度的敏感性,进一步明确不同TCK菌株冬孢子萌发对温度的反应,以便深入了解此病害发生和流行的成因.选取采自不同年份的45个TCK菌株,室内控制不同温度条件下对这些菌株的萌发过程及萌发特性进行观察记录,分析所得数据.5℃和10℃不同培养温度下,参试菌株的萌发率和萌发过程存在显著或极显著差异.同一采集年份不同菌株在相同培养温度下,萌发过程和萌发率有明显的差异,随着保存年限的增长,菌株冬孢子的萌发率会逐渐下降,但在常温下放置8年左右的部分菌株仍然具有萌发能力.不同的菌株萌发对温度确实具有不同的敏感性,此结果为防止该病害的传入、定殖、传播以及预测和防治决策提供了重要依据.     

冬孢子网脊高度值和自发荧光显微学在鉴别小麦矮腥和网腥菌瘿中的应用

本试验于１９９６年对来自美国、加拿大和欧洲的１０６个小麦矮腥黑穗病菌（ＴＣＫ）和小麦网腥黑穗病菌（ＴＣＴ）菌瘿进行了冬孢子网脊高度值测量和自发荧光显微学观察。结果表明,网脊高度指数值（ＬＩ－Ｒ）可以准确地鉴别不同来源的ＴＣＫ菌瘿,准确率达９８．６％,而来源于美国和加拿大的ＴＣＴ菌瘿则有不同程度的错判。自发荧光显微学方法可准确地鉴别不同来源的ＴＣＴ菌瘿,准确率达１００％,同时也能较准确地鉴别不同来源的ＴＣＫ菌瘿,但不适合鉴别保存时间过长或已死亡的ＴＣＫ菌瘿。结合这两个特征,将能比较可靠地对菌瘿进行鉴别     

应用计算机视觉技术自动识别TCK冬孢子的研究进展

应用计算机视觉技术自动识别ＴＣＫ冬孢子的研究进展陈克，王圆，吴品珊（农业部植物检疫实验所北京１０００２９）在进口粮检疫中，小麦矮腥黑穗病菌（ＴＣＫ）占有相当重要的地位，但ＴＣＫ与网腥（ＴＣＴ）的鉴别一直是个难题。在１９８９～１９９２年“中美ＴＣＫ鉴定...     

温度对小麦矮腥黑穗病菌冬孢子萌发的影响

温度对小麦矮腥黑穗病菌冬孢子萌发影响的试验结果表明,TCK冬孢子在-2～12℃范围内都可以萌发,5℃为最佳萌发温度。同一分离菌冬孢子在不同温度处理的萌发特性和萌发率有差异;不同分离菌冬孢子在相同温度下的萌发特性和萌发率有很大差异。在5℃下5个分离菌中,冬孢子萌发起始时间最短的为15 d,最长为35 d,培养60 d时分离菌T_t1、T_t2、T_y、T_m和T_u冬孢子的萌发率分别为86.4%、23.9%、23.3%、44.3%和81.0%。根据分离菌T_t2不同温度下培养50 d时的萌发率,建立了萌发率(Y)与温度(X)的模型为Y=0.150 8 exp[-0.02949(X-4.957 6)]2,此结果为TCK的风险评估提供了基础数据。     

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.     

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.     

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.     

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。     

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.