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1.
In Brazil, the selection and planting of eucalyptus clones resistant to Ceratocystis fimbriata is the pre‐eminent control strategy for the wilt pathogen. However, little is known about host defence responses associated with resistance of eucalyptus to C. fimbriata infection. In this work, enzymatic activity, sugars, lignin, total phenols and phenolic compounds involved in the defence response of eucalyptus clones resistant (RC) and susceptible (SC) to the Ceratocystis wilt were evaluated. Changes were detected in the sugars produced by RC clones, with higher concentrations occurring compared with SC. A similar response occurred with lignin content at 28 days after inoculation (dai) in RC plants. SC plants had an increase in polyphenol oxidase and peroxidase activities at 7 dai. In contrast, RC plants demonstrated high activity of the same enzymes at 2 and 4 dai, decreasing afterwards. There was no difference in phenylalanine ammonia‐lyase activity between resistant and susceptible clones. Hydroxycinnamic acid concentration was higher in RC than in SC; however, there was no difference between RC and SC in flavonoid concentrations. RC had high concentrations catechin, chlorogenic acid and caffeic acid. Histochemical tests demonstrated the presence of phenolic compounds and lignin, at higher intensities, in xylem of RC plants. Inoculation with C. fimbriata induced defence responses in both resistant and susceptible eucalyptus clones, but both the intensity and speed of the responses were higher in RC. Alterations in the concentrations of sugars and lignin, as well as certain enzymes and phenolic compounds, could be used to predict the relative susceptibilities to Ceratocystis wilt of different phenotypes of eucalyptus clones.  相似文献   

2.
The Eucalyptus pathogen Quambalaria eucalypti has been reported from several subtropical and tropical countries of the Southern Hemisphere. During the course of a nationwide monitoring programme aimed at the detection of pathogens in commercial eucalypt plantations in Portugal, Q. eucalypti was found affecting Eucalyptus globulus. The identity of the pathogen was confirmed by sequence analyses of the internal transcribed spacer (ITS) region of the rDNA operon, as well as morphological characteristics. Quambalaria eucalypti is widespread throughout the eucalypt‐producing areas of Portugal. Pathogenicity studies revealed that different host genotypes showed various degrees of susceptibility to the pathogen. To our knowledge, this is the first report of Q. eucalypti on Eucalyptus spp. in Portugal and in the Northern Hemisphere.  相似文献   

3.
A new disease of unknown bacterial aetiology has been observed in eucalyptus stands since 2009. It is characterized by die‐back, wilting and lesions on the branches, petiole and midrib in association with macroscopic and microscopic bacterial ooze. To date, this disease has been observed in stands of clonal Eucalyptus saligna, E. grandis and E. urophylla x E. grandis hybrids and in E. dunnii seedling plantations in the states of São Paulo, Rio Grande do Sul and Mato Grosso do Sul. Considering the economic importance of eucalyptus plantations and the potential losses caused by this disease, this study aimed to identify and characterize the causal agent. Thirty‐four strains were obtained from infected plants, which were collected in the field from four locations. The inoculation of detached leaves and intact rooted cuttings supported pathogenicity in eucalyptus. The phylogenetic analysis of four housekeeping genes (16S rDNA, gapA, recA and rpoB) as well as biochemical tests confirmed the identity of strains belonging to the species Erwinia psidii. This is the first report of E. psidii as the cause of wilt and die‐back in Eucalyptus spp. in Brazil.  相似文献   

4.
The aim of this study was to evaluate the effectiveness of a plant extract obtained from the leaves of coffee plants infected by Hemileia vastatrix (NEFID), different formulations of phosphites and the combination of the extract and phosphites in controlling powdery mildew in eucalyptus mini‐stumps, as well as to study the effects on the production of mini‐cuttings and their rooting percentage. The experiments were conducted on two eucalyptus hybrids (‘urocam’ and ‘urograndis’) in a clonal garden and greenhouse. First, the NEFID plant extract and phosphites of copper, zinc, potassium and potassium/manganese were evaluated to determine their effectiveness in controlling powdery mildew and their toxic effect on the fungus' morphology. Subsequently, we analysed the direct fungitoxicity, curative efficiency and anti‐sporulating action of the NEFID extract and various combinations of phosphites with or without the extract, and we also evaluated their effects on shoot production and rooting in eucalyptus mini‐cuttings. The NEFID plant extract and phosphites of Cu, Zn and K/Mn were more effective than the fungicide pyraclostrobin + epoxiconazole in the control of powdery mildew. Potassium phosphite was not effective in controlling the pathogen. Among the tested mixtures, the combination of 50% NEFID plant extract and 50% copper phosphite was the most effective because it exhibited direct toxicity on powdery mildew, a high curative efficiency, anti‐sporulating action and no adverse effects on the production of shoots or rooting in eucalyptus mini‐cuttings.  相似文献   

5.
An outbreak of a new and severe disease was observed in Eucalyptus plantations of Bahia state, Brazil. An Ascomycota fungus has been frequently associated with the main symptoms of the disease namely leaf spot, branch cankers, shoot blight, defoliation, and dieback. Based on morphological characteristics, phylogenetic analysis (ITS and TEF-1α genes), and pathogenicity test on Eucalyptus plants, Pseudoplagiostoma eucalypti was identified as the causal agent of the disease. Although P. eucalytpi has been known from in Brazil since 1998, this is the first report of it causing severe disease and die-back on Eucalyptus spp. and we also record new symptoms associated with the pathogen.  相似文献   

6.
A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g s) and transpiration rate (E) at CO2 concentrations of 360 μmol mol−1 and ambient humidity and temperature. A, E and g s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m−2 s−1) compared to eucalyptus hybrid GC 584 (21.0 μmol m−2 s−1), E. grandis (19.2 μmol m−2 s−1), C. africana (17.7 μmol m−2 s−1) and G. robusta (11.1 μmol m−2 s−1). C. africana exhibited high E values (7.0 mmol m−2 s−1) at optimal soil moisture contents than G. robusta (3.9 mmol m−2 s−1) and eucalyptus (5.3 mmol m−2 s−1) in field experiment and G. robusta (3.2 mmol m−2 s−1) and eucalyptus (4.2 mmol m−2 s−1) in pot-grown trees. At very low soil moisture content, extremely small g s values were recorded in GC 15 and E. grandis (8 mmol m−2 s−1) and G. robusta (14 mmol m−2 s−1) compared to GC 584 (46.9 mmol m−2 s−1) and C. africana (90.0 mmol m−2 s−1) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol−1 and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.  相似文献   

7.
Powders and essential oils were prepared from the aerial parts of Cinnamomum camphora, Ocimum basilicum, Chenopodium ambrosioides, and seeds of Pimpinella anisum. Their adulticidal activities and effects on the F1 progeny of Trogoderma granarium (Everts) and Tribolium castaneum (Herbst) were evaluated. The chemical composition of the plant oils were identified by gas chromatography (GC) and GC/mass spectrometry (MS). All of the tested botanicals showed insecticidal activities against the test insects in a dose-dependent manner with T. granarium was more susceptible to the tested plant products than T. castaneum. At a concentration of 5 g kg−1, many of the plant powders caused 100% mortality of both insects after 14 days of exposure. The powders of C. camphora, O. basilicum, and C. ambrosioides were effective against T. granarium, while that of C. ambrosioides caused 100% adult mortality of T. castaneum under the same assays conditions. A dose of 1.50 ml cm−2 of the oils of C. camphora and O. basilicum completely controlled T. granarium, while 100% mortality of T. castaneum adults was recorded with P. anisum oil. A significant and/or complete reduction (100% inhibition) of the F1 progeny of both insects was obtained as a result of parental exposure to the tested botanicals, especially at the highest doses applied. Botanicals under investigation showed a considerable grain protecting activity against the tested insect species and could be included in integrated pest management (IPM) strategies.  相似文献   

8.
On-farm experiments were conducted in Khammam district of Andhra Pradesh from 2001 to 2006 to evaluate the biomass productivity, intercrop yields and profitability of Eucalyptus tereticornis clonal and Leucaena leucocephala variety K-636 based systems. Trees were planted at a spacing of 3 × 2 m and evaluated at three locations. Height growth was significantly higher in leucaena during the 4 year where as difference in diameter growth was not significant. Biomass partitioning to the bole was high in case of leucaena, ranged from 83% in 2.5–5 cm diameter at breast height (DBH) trees to 89% in 12.5–15 cm DBH trees and in eucalyptus clones the corresponding values were 71% in 2.5–5 cm DBH trees and 83% in 12.5–15 cm DBH trees. Marketable biomass productivity was higher with leucaena (95 Mg ha−1) in comparison to eucalyptus (87 Mg ha−1). Competition effects of trees on intercrops were observed from the 2 year (2002 post-rainy season). Intercrop yields were 45% of the sole crop in eucalyptus system and 36% in leucaena system during the 2 year. Sole eucalyptus and leucaena plantations and intercropping systems recorded higher gross and net returns over arable cropping. Therefore, it can be concluded that leucaena variety K636 and eucalyptus clonal based agroforestry systems are profitable alternatives to arable cropping under rainfed conditions.  相似文献   

9.
Essential oils from Hyptis suaveolens (L.) Poiteau (Lamiaceae) and Hyptis spicigera Lamarck (Lamiaceae) were first analysed by gas chromatography and by gas chromatography/electron impact mass spectroscopy and then evaluated for toxicity and repellent activity against Sitophilus granarius (L.) (Coleoptera: Dryophthoridae), one of the most serious worldwide stored grain pests. Fifty-six compounds have been identified in the essential oil of H. suaveolens: monoterpene hydrocarbons were the most represented volatiles (64.1%), followed by sesquiterpene hydrocarbons (24.0%), oxygenated monoterpenes (8.1%) and oxygenated sesquiterpenes (2.4%). Diterpenes and non-terpene derivatives were scarcely represented. Sixty compounds have been identified in the essential oil of H. spicigera: monoterpene hydrocarbons were the most represented class of volatiles (70.4%), followed by sesquiterpene hydrocarbons (22.6%). Results from topical applications on insects showed that both essential oils had an effective insecticidal activity. The complete kill of S. granarius was observed 24 h after treatment at a minimum effective dose of 0.4 and 0.6 μl per insect with H. suaveolens and H. spicigera oil, respectively. Results from repellency tests showed that the two essential oils had a repellent activity on S. granarius adults: at the lowest dose (2 × 10−4 μl oil per cm2), H. spicigera essential oil exhibited a higher repellent effect in comparison to H. suaveolens. No significant differences were observed for the repellent effect between the two essential oils at the highest dose (2 × 10−2 μl oil per cm2).  相似文献   

10.
The Eucalyptus plantation industry in Indonesia has expanded rapidly during the last few decades. During routine nursery disease surveys, symptoms of a leaf and shoot blight disease were detected on Eucalyptus mother plants. Isolates were obtained from symptomatic tissues and identified using DNA sequence analyses. Phylogenetic analyses showed that the isolates were those of Quambalaria eucalypti. Pathogenicity tests were conducted with isolates of Q. eucalypti on clones of E. pellita and E. grandis × E. pellita hybrids. These resulted in symptoms similar to those observed on naturally infected plants. Eucalyptus genotypes tested showed variation in their susceptibility, highlighting the potential to select and breed for resistance and thus to manage future outbreaks of the disease. This is the first report of the pathogen in Indonesia as well as in Southeast Asia.  相似文献   

11.
Fumigant activity of essential oil vapors distilled from Carum copticum C. B. Clarke and Vitex pseudo-negundo Hand I. MZT. was tested against eggs, larvae and adults of Callosobruchus maculatus (F.). Fumigant toxicity was assessed at 27 ± 1°C and 60 ± 5% RH, in dark condition. The influence of different concentrations of the essential oil vapors on egg hatchability, larval and adult mortality was significant. Data probit analysis showed that lethal concentration of the essential oil to kill 50% of the population (LC50) for egg, larvae and adult were found to be 1.01, 2.50 and 0.90 μl/l air of C. copticum oil, followed by 2.20, 8.42 and 9.39 μl/l air essential oil of V. pseudo-negundo, respectively. Between these essential oils, C. copticum was almost more toxic than V. pseudo-negundo on all growth stages of C. maculatus. The present study suggests that essential oils from these medicinal plants may be potential grain protectants as botanical alternative fumigants and could be used in the management of various life stages of C. maculatus.  相似文献   

12.
13.
Thirty-four plant essential oils were screened for their acaricidal and oviposition deterrent activities against two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), in the laboratory using a leaf-dip bioassay. From initial trials, sandalwood and common thyme oils were observed to be the most effective against TSSM adult females. Subsequent trials confirmed that only sandalwood oil was significantly active (87.2 ± 2.9% mortality) against TSSM adult females. Sandalwood oil also demonstrated oviposition deterring effects based on a 89.3% reduction of the total number of eggs on leaf disks treated with the oil. GC–MS analysis revealed that the main components of the sandalwood oil were α-santalol (45.8%), β-santalol (20.6%), β-sinensal (9.4%), and epi-β-santalol (3.3%). A mixture of α- and β-santalol (51.0:22.9, respectively) produced significantly higher mortality (85.5 ± 2.9%) and oviposition deterrent effects (94.7% reduction in the number of eggs) than the control. Phytotoxicity was not shown on rose shoots to which a 0.1% solution of sandalwood oil was applied.  相似文献   

14.
Brassicaceous plants rich in glucosinolates have been used as biofumigants for the management of soilborne pathogens. Efficacy of Brassica plant tissue has mainly been attributed to toxic isothiocyanates released upon the hydrolysis of glucosinolates. Management of Phytophthora cinnamomi, the causal agent of oak root rot in rangeland ecosystems using biofumigation, is promising, but requires further validation. The biofumigation activity of 14 brassicaceous plants was evaluated under experimental conditions. All evaluated plants rich in sinigrin suppressed (100%) the mycelial growth of P. cinnamomi, while plants rich in aromatic or other aliphatic glucosinolates had little or no suppressive effect. Simulating soil amendment in field conditions, the effects on natural soil artificially infested with P. cinnamomi chlamydospores were examined with Brassica juncea, Eruca vesicaria and Lepidium sativum, three species with different glucosinolate profiles. Only B. juncea decreased the viability of chlamydospores significantly in comparison with untreated soil only 1 day after biofumigation, whereas E. vesicaria needed 8 days to reach significance and L. sativum had no effect at all. Despite the decreases in soil inoculum, biofumigation with B. juncea did not prevent the root infections in a highly susceptible host (Lupinus luteus). However, biofumigation with plants rich in sinigrin, such as B. juncea, decreased P. cinnamomi soil inoculum under the experimental minimum threshold for oak disease expression. Although biofumigation should be considered as an effective measure to be incorporated in integrated control of the oak disease, biofumigation by itself would not be effective enough for the substantial suppression of P. cinnamomi inoculum.  相似文献   

15.
The black vine weevil Otiorhynchus sulcatus (Coleoptera: Curculionidae) is a well-known insect pest causing damages and economic losses on various horticultural plants. In recent times, numerous other weevils like O. rugosostriatus, O. raucus, O. ovatus or O. salicicola are becoming increasingly important in horticulture. We applied mark-release-recapture studies to estimate population size, survival rates, aggregation patterns and dispersal capabilities of adult O. raucus and O. rugosostriatus in a commercial plantation of perennial ornamental plants. Knowledge of these characteristics is important for the correct timing and design of efficient control strategies. Of 191 individually coded O. raucus and 340 O. rugosostriatus, 30 and 24%, respectively, were recaptured at least once over a period of 96 days. The majority of weevils were recaptured within 2–3 m away from their release point and thus both species can be regarded as being quite sedentary. In accordance, patchiness of weevil distribution was clearly evident in the study area. Population sizes reached maximum values after the peak of adult emergence from pupae in spring (for O. raucus) and late summer (for O. rugosostriatus), with high survival rates being evident in particular for O. raucus. This study provides for the first time data on population ecology of two weevil species, whose abundance and importance as putative insect pests in horticulture has increased over the last years.  相似文献   

16.
Pine plantations in the southeastern United States are often created using site preparation treatments to alleviate site conditions that may limit survival or growth of planted seedlings. However, little is understood about how site preparations affect longleaf pine (Pinus palustris P. Miller) seedlings planted on wet sites. In a 2-year study (2004 and 2005) on poorly drained, sandy soils of Onslow County, North Carolina, we examined the effects of common site preparation treatments on microsite conditions and quantified relationships between microsite conditions and longleaf pine seedling survival and growth. Treatments used in the study included site preparations designed to control competing vegetation (chopping and herbicide) combined with those that alter soil conditions (mounding and bedding). During both years, mounding and bedding treatments reduced the amount of moisture within the top 6 cm of soil and increased soil temperatures when compared to flat planting (p < 0.001). Soil moisture was inversely related to seedling mortality in 2004 (r2 = 0.405) and inversely related to root collar diameter in 2005 (r2 = 0.334), while light was positively related to root collar diameter in 2005 (r2 = 0.262). Light availability at the seedling level was highest on treatments that effectively reduced surrounding vegetation. Herbicides were more effective than chopping at controlling vegetation in 2004 (p < 0.001) and 2005 (p = 0.036). Controlling competing vegetation, especially shrubs, was critical for increasing early longleaf pine seedling growth.  相似文献   

17.
The purpose of this study is to investigate the insecticidal activity of two benzoic acids 2(3)-tert-butyl-4 hydroxyanisole (BHA) and 2,6-di(tert-butyl)-p-cresol (BHT); two phenolic acids 3-phenyl-2-propenoic acid (CA) and trans-4-hydroxy-3-methoxycinnamic acid (FA); and two essential oils of Eugenia caryophyllata (clove tree) and Thymus vulgaris (thyme) against Oryzaephilus surinamensis (L.) vector carrier of aflatoxigenic fungi on stored peanut. The weight loss of peanut, susceptibility of insects, Aspergillus isolation frequency from insects and peanut, and aflatoxin B1 analyses from peanut were determined. BHA, BHT, and BHA/BHT mixture were highly effective against O. surinamensis, these chemical agents give 100% mortality at the doses assayed. Essential oil of thyme at 2,000 and 3,000 ppm were highly effective against O. surinamensis, these concentrations gave 100% mortality. No Aspergillus section Flavi contamination was observed in dead insects collected from peanut treated with BHA/BHT mixture. No differences were observed in the fresh weight of pods peanut among treatments with and without chemical agents. All samples of treated peanut pods showed complete inhibition of this toxin after 120 days of storage. Our results indicate that these substances could be evaluated further for the control of pest vectors of aflatoxigenic fungi of stored peanut.  相似文献   

18.
The pine wilt disease (PWD) is caused by Bursaphelenchus xylophilus and poses great environmental and economic challenges. Thus, the development of sustainable techniques for the control of this epidemic disease is of major importance. This work aimed at evaluating if the application of different molecular weight (MW) chitosans as a soil amendment could be used to control the PWD in maritime pine (Pinus pinaster, very susceptible to the disease) and stone pine (Pinus pinea, less susceptible). At the end of the experimental period (24 days after inoculation), P. pinaster and P. pinea untreated plants presented ca. 3825 ± 100 and 70 ± 47 nematodes, respectively. In P. pinaster, the high‐MW chitosan prompted the most drastic results, inducing a 21.9‐fold reduction in nematodes numbers, whereas in P. pinea, the most effective was the low MW chitosan, which reduced nematodes numbers up to 7‐fold, compared with untreated plants. P. pinea seems to be highly resistant to the disease, presenting nematode numbers up to 54.6‐fold lower than P. pinaster and less severe chlorophyll loss (ca. 2‐fold).  相似文献   

19.
This study demonstrated that disease resistance against anthracnose (caused by Colletotrichum camelliae) in camellia (Camellia pitardii) could be induced by chitosan oligosaccharide (COS) applied to leaves at 50 µg/ml. The induced resistance lasted for 10–15 days, with the optimum induced effect against anthracnose occurring by the third day. Following treatment with C. camelliae alone, COS alone and C. camelliae and COS combined, camellia plants showed different responses, which included the activity of H2O2, the defence‐related enzymes, such as polyphenol oxidase, peroxidase, catalase, phenylalanine ammonialyase, and concentration of soluble proteins. Plants that received COS treatments consistently had higher levels of biochemical activity than plants not treated with COS. Assessment of anthracnose severity on infected plants, as evidenced by reduced lesions on leaves, indicated that COS‐induced camellia plants had significantly lower disease ratings. To our knowledge, we are first to report the inducement by COS on camellia against anthracnose.  相似文献   

20.
Allelopathic effects of eucalyptus are widely reported and are considered the major factor limiting the establishment of native species in eucalyptus forests. However, reports of the allelopathic effects of eucalyptus are mostly based on laboratory bioassay, not on field trials. In the present study, we conducted field trials to determine the allelopathic effects of eucalyptus and to develop strategies for establishment of mixed stands of native species and eucalyptus. In the field, seed germination and seedling survivorship of native species were determined in the presence and absence of eucalyptus leaf litter or living roots. In the seed germination experiment, seed germination rate of Delonix regia was higher than for Elaeocarpus sylvestris and Tsoongiodendron odorum. Seed germination rates of E. sylvestris and T. odorum were low in both the presence and absence of eucalyptus treatments. The germination rate of D. regia was significantly inhibited by all eucalyptus treatments, but only during the early period. In the seedling establishment experiment, seedling survivorship of E. sylvestris and Michelia macclurel was not inhibited by any treatments, but the seedling survivorship of Schima superba was significantly inhibited by eucalyptus litter addition alone. Seedling height of S. superba and M. macclurel was significantly suppressed when eucalyptus roots were present in treatments, but the seedling height of E. sylvestris was only significantly suppressed by the treatment of roots alone. We propose two strategies for establishment of mixed stands of native species and eucalyptus: (1) direct seed-sowing is effective only for those species (e.g. D. regia) with high germination rates in natural conditions; (2) seedling transplants are more efficient approach for establishing species (e.g. E. sylvestris) with low germination rates. We suggest that mixed plantations of eucalyptus and E. sylvestris can be established by transplanting seedlings of E. sylvestris into eucalyptus plantations.  相似文献   

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