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1.
Woodchips from several pine species, infested with the pine wood nematode, Bursaphelenchus xylophilus , were treated in transit using phosphine fumigant. Using aluminum phosphide tablets producing 4 g m−3 phosphine, the percentage of infested samples was reduced from 79 to 6% during the voyage from the USA to Sweden. Temperatures in the periphery of the cargo were lower than in the center, and the fumigation was less effective in the periphery. Phosphine concentration had declined to nearly zero before arrival of the chips in Sweden and posed no safety threat to workers or the ship's crew. 相似文献
2.
A flowing solution culture technique was used to study the effects of N nutrition on banana root infestation by the burrowing nematode Radopholus similis . Paired groups of banana plants were grown in separate compartments containing coarse sand (2–5 mm diameter). Input nutrient solutions had fixed compositions and identical total N concentrations. The two compartments differed in their NH4 + /total N concentrations, one receiving 0% NH4 + /total N (100% NO3 − /total N) and the other 60% NH4 + /total N (40% NO3 − /total N). The compartments were connected by a inverted T-shaped tube containing fine sand (200–250 μ m diameter) through which nematodes were inoculated. The pH and N concentrations of the output solution were determined at regular intervals. The pH of the output solution differed markedly between the two compartments, with values of 6.8 and 3.6 in the 0% and 60% NH4 + compartments, respectively. In the compartment receiving 0% NH4 + , the number of nematodes in the roots and the growth of banana plants was significantly higher than in the compartment receiving 60% NH4 + . Even though they were more infested by nematodes, banana plants receiving 100% NO3 − developed better than the less infested plants grown in the medium containing 40% NO3 − . 相似文献
3.
Pitch canker, caused by the fungus Fusarium circinatum , is a disease affecting many pine tree species. In California, Pinus radiata (Monterey pine) is the principal pine host affected by pitch canker. This investigation into factors affecting infection frequency by F. circinatum of P. radiata examined the influence of: (i) wound size; (ii) relative humidity; (iii) time of inoculation; (iv) inoculum density; and (v) wound age. Wounded branches sustained significantly more infections when large-diameter (1·6 mm) rather than small-diameter (0·5 mm) wounds were made. Infection frequencies tended to be higher at 100% RH than at ambient humidity, although these differences were not statistically significant. Infection frequencies were significantly higher on branches inoculated after 17·00 h than on branches inoculated before noon. Infection frequencies were significantly higher for wounded branches spray-inoculated with 5 × 107 rather than 1 × 107 spores mL−1 . Infection frequencies of pruning wounds declined as wounds aged. 相似文献
4.
Single and combined effects of smoke pollution and the root-knot nematode, Meloidogyne incognita race 1, were studied on eggplant in 1988 and 1989 at two sites (K1 and K2) 1 and 2 km respectively away from a coal-fired thermal power plant, and a control site at the Department of Botany, Aligarh Muslim University (AMU). Mean concentrations of SO2 , NO2 and suspended particulate matter (SPM) were respectively 172, 95 and 626 μg/m3 in 1988 and 144, 97 and 556 μg/m3 in 1989 at K1; and 258, 150 and 344 μg/m3 in 1988 and 226, 113 and 293 μg/m3 in 1989 at K2. Peak levels of the gases and SPM were recorded in the early (12.00–15.00) and late (15.00–18.00) afternoon respectively. Concentrations of the pollutants at a control site were very low. Marginal browning appeared on the leaves of eggplants grown at site K2 whether or not they were infected by the nematodes. The galling caused by nematodes was severe at both polluted sites but egg mass production was inhibited at K2. Egg laying was significantly reduced at both polluted sites. M. incognita significantly reduced plant growth, yield and leaf pigment production of eggplant at the control and polluted sites. Most non-infected plants also showed significant reductions in these plant varieties i.e. from the effects of pollution at K2. Foliar concentrations of sulphur were significantly increased at both polluted sites, being greater in infected plants. The interaction of smoke pollution and M. incognita infection led to greater suppressions at the polluted sites, which were mostly significant at K1. At the polluted sites, leaves had more and longer trichomes; also the number and size of stomata were decreased but their openings were wider especially in infected plants at the two polluted sites. 相似文献
5.
Chemical and biological agents were evaluated for their ability to suppress root rot, caused by Phytophthora cactorum , in field-grown radiata pine seedlings in New Zealand. Trials were conducted over two seasons in an area of a forest nursery with a natural infestation of P. cactorum , and a history of root rot. In each season, symptoms of root rot developed during April, one month after root pruning, when seedlings were approximately six months old. In trial one, root rot incidence by mid July 2007 was 9·1% in untreated plots and 8·4% in plots that had been treated with metalaxyl-M/mancozeb (14 kg ha−1 ) at seedling emergence. Disease incidence was lowest (2·1%) in plots that received seven monthly applications of phosphorous acid (6·5 L ha−1 ). Other treatments, including seed coating with thiram or Trichoderma spp., and foliar applications of methyl jasmonate, did not control disease. In trial two, effects of treatment timing relative to root pruning were investigated. By late June 2008, three months after root pruning, root rot incidence was 22·2% in the untreated plots. Phosphorous acid was the most effective treatment and almost completely suppressed disease (0·1% incidence) when applied fortnightly from February until May (seven applications). Metalaxyl-M/mancozeb (15 kg ha−1 ) was not effective (21·4% incidence) when applied five months before root pruning. However, disease incidence was reduced when the chemical was applied one week after root pruning (14·9% incidence) and greater control was achieved (8·2% incidence) when the application rate was increased to 50 kg ha−1 . 相似文献
6.
The production of ascochitine by seven isolates of Ascochyta fabae accounted for the toxicity of culture filtrates of the fungus to cells isolated from leaves of Vicia faba. The LD50 value for cells from cultivars that were susceptible, tolerant or resistant to the fungus was similar i.e. 3·0 × 10−5 m , 3·8 × 10−5 m and 2·9 × 10−5 M, respectively. Ascochitine affected neither the germination of seeds nor the growth of mature plants at 5·17 × 10−4 m but caused necrosis and wilting of plant cuttings at 2·5 × 10−4 m and 5·10−4 m . There was no association between virulence of 16 isolates of A. fabae for three cultivars of V.faba and the production of ascochitine in vitro. One isolate produced no ascochitine in vitro and yet was the most virulent for two of three cultivars. The toxin could not be extracted from infected plants. 相似文献
7.
溴甲烷对松木片中松材线虫的熏蒸作用 总被引：2，自引：0，他引：2
采用二次正交旋转组合设计,在室内条件下研究了溴甲烷剂量、熏蒸处理时间和处理温度对松木片中松材线虫熏蒸效果的影响。结果表明,溴甲烷剂量是影响熏蒸效果的最主要因子;14、18 ℃和22 ℃条件下处理24 h,松材线虫死亡率达99.9%时的溴甲烷浓度分别为17.92、16.07、14.87 g/m3; 14、18、22 ℃条件下,松材线虫死亡率达99.9%时,溴甲烷浓度和时间乘积,即CT（99.9）分别为192.52、174.705、166.229 g•h/m3。溴甲烷可用于口岸松木片中松材线虫的除害处理。 相似文献
8.
The susceptible rose cv. Madelon and the partially resistant cv. Sonia both responded with reduced development of rose powdery mildew when they were treated with the synthetic inducer 2,6-dichloroisonicotinic acid (INA). The EC50 for number of colonies cm−2 was approximately 0.4 mg L−1 in both cultivars when treated 4 days prior to inoculation. However, conspicuous differences were observed with respect to number of spores per cm2 . For sporulation, the EC50 was 0.37 mg L−1 in cv. Madelon and only 0.08 mg L−1 in cv. Sonia. A comparison with the pathosystems cucumber/ Sphaerotheca fuliginea and red cabbage/ Peronospora parasitica is made and the importance of the observed phenomenon for the selection of parents in a breeding programme for (partial) resistance is discussed. 相似文献
9.
The fungitoxicity of allyl-isothiocyanate (AITC) vapour against Penicillium expansum , the causal agent of blue mould on pears (cvs Conference and Kaiser), was evaluated. The best control of blue mould was obtained by exposing fruits for 24 h in a 5 mg L−1 AITC-enriched atmosphere, the extent of control depending on the inoculum density. Lesion diameter was inversely related to AITC concentration. In treated fruits the percentage of infected wounds increased with conidial concentration, with fewer than 20% affected at 1 × 103 conidia mL−1 to almost 80% at 1 × 106 conidia mL−1 . In comparison, >98% of wounds were infected in untreated fruits irrespective of conidial concentration. AITC treatments were effective up to 24 h after inoculation for Conference and 48 h for Kaiser. AITC treatments also controlled a thiabendazole-resistant strain of P. expansum , reducing the incidence of blue mould by 90% in both cultivars. The use of AITC produced from pure sinigrin or from Brassica juncea defatted meal may be an economically viable alternative to synthetic fungicides against P. expansum . 相似文献
10.
Akihiro Takahashi Shigeo Yamada Hirokazu Yamada Takashi Kawana 《Weed Biology and Management》2001,1(3):182-188
The effects of a novel pyrimidine herbicide, NS-245852 [2-chloro-6-fluorophenyl-4-(trifluoromethyl)thieno[2,3-d]pyrimidine-2-yl-ketone], on mitosis in oat ( Avena sativa L. cv. Zenshin) root tips were investigated by using light and immunofluorescence microscopy. The root growth was strongly inhibited at 10−7 mol L−1 of NS-245852, and swollen root tips were induced at 5 × 10−8 mol L−1 . As observed by the use of light microscopy, the herbicide produced disrupted mitosis and large polynucleate cells in the meristematic root tissue. These symptoms were similar to those of mitotic disrupter herbicides. The immunofluorescence microscopy studies of the root tip cells treated for 30 min revealed that spindle fibers and the preprophase band were reduced, although kinetochore fibers and the phragmoplast were not affected. Kinetochore fibers remained as small fluorescence spots, and the phragmoplast disappeared after a 3 h treatment. No microtubule arrays were observed by a longer treatment (longer than 3 h). Among the microtubule arrays, spindle fibers and the preprophase band were found to be the most sensitive to the herbicide, whereas kinetochore fibers were the most resistant. The phragmoplast was intermediate. Thus, the primary action of NS-245852 is the inhibition of polymerization of tubulin into microtubules. 相似文献
11.
The effects of different levels of inoculum of Aspergillus carbonarius and time of inoculation on berry infection and the development of aspergillus bunch rot on grapevines (cv. Sultana) were studied under field conditions. Inflorescences at full bloom were inoculated with aqueous spore suspensions of A. carbonarius containing 0 or 1 × 106 spores mL−1 in 2004/05 and 0, 1 × 102 or 1 × 105 spores mL−1 in 2005/06. In both years, the incidence of infection in inoculated berries was significantly higher than in uninoculated berries. Incidence of infection in berries from veraison until harvest was higher than at earlier stages of bunch development (berry set to berries that were still hard and green). Inoculation of bunches at veraison did not significantly increase A. carbonarius infection prior to harvest, at harvest, 6 days after harvest or when berries were over-ripe. Bunches inoculated at harvest did not significantly increase infection 6 days after harvest or when berries were over-ripe. Aspergillus carbonarius was isolated more frequently from the pedicel end (53·1%) than from the middle section (37·5%) and distal end (35·0%) of berries that were inoculated with 105 spores mL−1 . 相似文献
12.
促分裂原活化蛋白激酶(Mitogen Activated Protein Kinase)在线虫生长发育过程中具有重要作用。本研究利用RACE方法克隆了松材线虫mapk基因,其基因全长1 744 bp,5'UTR长243 bp,3'UTR长81 bp,含有一个1 098 bp的开放读码框,包括6个外显子和5个内含子,为单拷贝基因,其预测的蛋白序列与其他线虫的序列相似性为77.66%~84.01%。通过体外转录合成341 bp的dsRNA,将松材线虫的幼虫浸泡在1.5 mg·mL-1dsRNA中24 h后,mapk表达量下降约85%,松材线虫的死亡率约为对照的4.2倍,经dsRNA浸泡的成虫,繁殖能力下降约50%,表明mapk基因的沉默可能抑制松材线虫的繁殖能力。 相似文献
13.
Two short sequences, situated in the bacterial 23S rDNA gene, were used as primers for the PCR detection of Erwinia amylovora bacteria. All 34 E. amylovora strains tested, coming from different geographical and host plant origins and of different virulence, produced a 565-bp PCR fragment. The E. amylovora bacteria could be discriminated from all other phytobacteria with which no PCR product was observed. Only Escherichia coli bacteria were cross-recognized by the production of a weaker PCR band of similar size to E. amylovora . In a fast PCR protocol, where two temperatures were cycled, E. amylovora in pure culture could be detected on gel at concentrations as low as 3 × 102 cfu mL–1 . This corresponds to a detection limit of 1.5 bacteria per PCR. However, reliable PCR detection in woody host plant tissue was only obtained with PVP/PVPP-treated sample extracts. Using E. amylovora -spiked plant extracts and extracts of fruit tree shoots artificially infected with E. amylovora , the PCR detection sensitivity was determined to be 6.6 × 102 cfu mL–1 of extract. Starting from the plant samples, the PCR detection results were visualized on gels within 5 h. 相似文献
14.
In late 2003, nine populations of Sclerotinia homoeocarpa in Ontario Canada (seven of which had been previously sampled in early 1994, prior to the registration of sterol demethylation-inhibiting (DMI) fungicides for turf disease control in Canada) were sampled and tested for sensitivity to propiconazole. Four of the nine populations had not been treated with DMI fungicides during the intervening years, and isolates from these locations were sensitive to propiconazole (geometric mean EC50 values of 0·005–0·012 µ g mL−1 , compared with 0·005–0·008 µ g mL−1 for the original 1994 populations). Among the five populations from 2003 that had been exposed to DMI fungicides, mean EC50 values were significantly greater, ranging from 0·020 to 0·048 µ g mL−1 . A significant correlation of determination was found between estimated number of fungicide applications and log EC50 ( R 2 = 0·832, P = 0·0001), and the equation predicted that 42·3 applications of propiconazole would be needed to bring a sensitive population (EC50 < 0·01 µ g mL−1 ) to a resistant level (EC50 > 0·10 µ g mL−1 ). Fungicide sensitivity vs. duration of fungicide efficacy was also tested, and it was found that isolates with decreased sensitivity were able to more quickly overcome the inhibitory effects of fungicide application, reducing the duration of control from 3 weeks to 2 weeks. 相似文献
15.
JOSEPH S. VITELLI BARBARA A. MADIGAN PETER E. VAN HAAREN STEPHEN SETTER PETER LOGAN 《Weed Biology and Management》2009,9(1):54-62
The liana, hiptage ( Hiptage benghalensis ), is currently invading the wet tropics of northern Queensland and remnant bushland in south-eastern Queensland, Australia. Trials using seven herbicides and three application methods (foliar, basal bark, and cut stump) were undertaken at a site in north Queensland (158 700 hiptage plants ha−1 ). The foliar-applied herbicides were only effective in controlling the hiptage seedlings. Of the foliar herbicides trialed, dicamba, fluroxypyr, and triclopyr/picloram controlled >75% of the treated seedlings. On the larger plants, the cut stump applications were more effective than the basal bark treatments. Kills of >95% were obtained when the plants were cut close to ground level (5 cm) and treated with herbicides that were mixed with diesel (fluroxypyr and triclopyr/picloram), with water (glyphosate), or were applied neat (picloram). The costings for the cut stump treatment of a hiptage infestation (85 000 plants ha−1 ), excluding labor, would be $A14 324 ha−1 using picloram and $A5294 ha−1 and $A2676 ha−1 , respectively, using glyphosate and fluroxypyr. Foliar application using dicamba for seedling control would cost $A1830 ha−1 . The costs range from 2–17 cents per plant depending on the treatment. A lack of hiptage seeds below the soil surface, a high germinability (>98%) of the viable seeds, a low viability (0%) of 2 year old, laboratory-stored fruit, and a seedling density of 0.1 seedlings m−2 12 months after a control program indicate that hiptage might have a short-term seed bank. Protracted recolonization from the seed bank would therefore be unlikely after established seed-producing plants have been controlled. 相似文献
16.
R J Jettner S R Walker J D Churchett F P C Blamey S W Adkins & K Bell 《Weed Research》1999,39(4):287-295
The sensitivity of 22 major crops, pastures and weeds from the north-east grain region of Australia to atrazine and chlorsulfuron residues was determined in a glasshouse using a soil-free bioassay system. A logistic equation was fitted to the seedling fresh weights as a function of the logarithm of herbicide concentration by non-linear regression and used to calculate the doses for 10%, 30% and 50% inhibition of seedling growth (ID10 , ID30 and ID50 ). The ID50 for atrazine ranged from 0.03 to 0.04 mg a.i. L–1 for Salvia reflexa Hornem. and barley to 1.47 mg a.i. L–1 for sorghum. The ID50 for chlorsulfuron ranged from 0.19 to 0.21 μg a.i. L–1 for lucerne and snail medic to 102 μg a.i. L–1 for wheat. Based on ID50 values measured, the predicted responses of each species to a range of concentrations of atrazine and chlorsulfuron were classified into four categories ranging from no damage to severe damage. These sensitivity data will assist in planning cropping sequences in soils previously treated with atrazine or chlorsulfuron. 相似文献
17.
红脉穗螟Tirathaba rufivena Walker是槟榔上的重要害虫。本研究采用大蜡螟诱捕法,对海南省主要槟榔产区槟榔园中采集到的土样进行昆虫病原线虫的诱捕,并评估了目标线虫对红脉穗螟的致病力。在采集的150份土样中共有12个土样经检测发现含有昆虫病原线虫,检出率为8%。其中,屯昌、定安和万宁三个市县采集的土样中检出的带线虫比率相对较高,分别为12.90%、11.76%和10.00%,而海口和保亭土样中未检出昆虫病原线虫。在室内以大蜡螟为试虫测试线虫的致病力,结果表明诱捕的12个线虫种群均对大蜡螟幼虫具有一定的致病力,但致病力的大小存在较大差异（120 h校正死亡率21.11%～72.22%）。选取致病力较高的Tc05、Wn01和Wn09样本测试对红脉穗螟3龄幼虫的致病作用,结果显示在600 IJs/mL线虫液处理后24 h,Wn01种群对寄主的校正死亡率达到86.67%,半致死浓度LC50为283.70 IJs/mL;Tc05和Wn09对红脉穗螟的致病力相近,校正死亡率分别为61.67%和65.00%,LC50分别为504.75 IJs/mL和502.70 IJs/mL。研究表明,Wn01,Tc05和Wn09线虫种群对红脉穗螟幼虫具有一定的控制潜力。 相似文献
18.
Summary. Translocation of 3-amino-1,2,4-triazole-5-14 C (14 C-aminotriazole) was compared to that of 14 C-assimilates in couch grass ( Agropyron repens (L.) Beauv.) at three different growth stages.
Assimilates of14 CO2 were translocated from the treated shoot to other shoots and rhizomes at the 2–3-leaf and 3–4-leaf stages of development. Much less labelled material was translocated into untreated shoots at the 5-leaf stage. More 14 C-assimilates were translocated to the roots than to untreated shoots at all developmental stages. The translocation patterns of 14 C-aminotriazole and 14 C-assimilates were similar.
Two metabolites, A and B, were formed from14 C-aminotriazole, which chromatographed identically to previously described metabolites in Cirsium arvense (L.) Scop. A was further metabolized into B. Labelled aminotriazole and its two metabolites were translocated throughout the plants. Metabolite A was phytotoxic when concentrated and re-applied to couch grass, but its properties were not those of Unknown II from Cirsium arvense. They were the same as those of Unknown III. Whether or not metabolite A and Unknown III are identical was not established.
Migration des substances assimilables marquées au14 C, du 3 amino-1,2,4-triazole et de ses métabolites chez Agropyron repens 相似文献
Assimilates of
Two metabolites, A and B, were formed from
Migration des substances assimilables marquées au
19.
Sensitivity of Phytophthora infestans to mandipropamid and the effect of enforced selection pressure in the field 总被引：1，自引：0，他引：1
Sensitivity to the new carboxylic acid amide (CAA) fungicide mandipropamid (MPD) in Phytophthora infestans was measured for isolates collected between 1989 and 2002 in Israel prior to the commercial use of MPD (baseline sensitivity, 44 isolates), and from MPD-treated (25 isolates) and untreated fields (215 isolates) in nine European countries and Israel between 2001 and 2005. All isolates were sensitive to MPD, with EC50 values ranging between 0·02 and 2·98 µ g mL−1 . Plastic-tunnel (UK), shade-house (Israel) and field experiments (Israel) conducted during 2001–05 showed that enforced selection pressure, applied preventively or curatively, imposed by repeated sublethal (5 µ g mL−1 ) or excessive (500–1000 µ g mL−1 ) doses of MPD on mixed isolates of P. infestans produced no isolates resistant to the compound. The results of this study indicate that the probability of a buildup of resistant sub-populations of P. infestans to mandipropamid in the field is low. 相似文献
20.
Factors affecting the production of conidia of Peronosclerospora sorghi , causing sorghum downy mildew (SDM), were investigated during 1993 and 1994 in Zimbabwe. In the field conidia were detected on nights when the minimum temperature was in the range 10–19°C. On 73% of nights when conidia were detected rain had fallen within the previous 72 h and on 64% of nights wind speed was < 2.0 m s−1 . The time period over which conidia were detected was 2–9 h. Using incubated leaf material, conidia were produced in the temperature range 10–26°C. Local lesions and systemically infected leaf material produced 2.4–5.7 × 103 conidia per cm2 . Under controlled conditions conidia were released from conidiophores for 2.5 h after maturation and were shown to be well adapted to wind dispersal, having a settling velocity of 1.5 × 10−4 m s−1 . Conditions that are suitable for conidia production occur in Zimbabwe and other semi-arid regions of southern Africa during the cropping season. 相似文献