首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
JIA Hao 《干旱区科学》2020,12(5):819-836
To combat the problem of residual film pollution and ensure the sustainable development of agriculture in oasis areas, a field experiment was carried out in 2019 at the Wuyi Farm Corps Irrigation Center Test Station in Urumqi, Northwest China. Four types of biodegradable mulches, traditional plastic mulchs and a control group (bare land; referred to as CK) were compared, including a total of six different treatments. Effects of mulching on soil water and heat conditions as well as the yield and quality of processing tomatoes under drip irrigation were examined. In addition, a comparative analysis of economic benefits of biodegradable mulches was performed. Principal component analysis and gray correlation analysis were used to evaluate suitable mulching varieties for planting processing tomatoes under drip irrigation. Our results show that, compared with CK, biodegradable mulches and traditional plastic mulch have a similar effect on retaining soil moisture at the seedling stage but significantly increase soil moisture by 0.5%-1.5% and 1.5%-3.0% in the middle and late growth periods (P<0.050), respectively. The difference in the thermal insulation effect between biodegradable mulch and plastic mulch gradually reduces as the crop grows. Compared with plastic mulch, the average soil temperature at 5-20 cm depth under biodegradable mulches is significantly lowered by 2.04°C-3.52°C and 0.52°C-0.88°C (P<0.050) at the seedling stage and the full growth period, respectively, and the water use efficiency, average fruit yield, and production-investment ratio under biodegradable mulches were reduced by 0.89%-6.63%, 3.39%-8.69%, and 0.51%-6.33% (P<0.050), respectively. The comprehensive evaluation analysis suggests that the black oxidized biological double-degradation ecological mulch made from eco-benign plastic is the optimal film type under the study condition. Therefore, from the perspective of sustainable development, biodegradable mulch is a competitive alternative to plastic mulch for large-scale tomato production under drip irrigation in the oasis.  相似文献   

2.
ABSTRACT Four mechanisms of dispersal of propagules of Phytophthora capsici were investigated through modifications in cultural practices and fungicide applications in field plots of bell pepper (Capsicum annuum). Dispersal of soil inoculum was suppressed, and final incidence of disease was 2.5 to 43% when stubble from a fall-sown, no-till, wheat cover crop was present. Final disease incidence was 71 to 72% and pathogen spread occurred within and across rows when all dispersal mechanisms were operative in plots of pepper planted into bare soil. Final disease incidence was 42 to 78% with black plastic mulch when a sporulating pepper fruit placed on the surface served as the source of initial inoculum. The fungicide metalaxyl applied in the irrigation system did not suppress within-row spread of surface inoculum from a sporulating fruit on plastic, but did limit across-row spread; final disease incidence in metalaxyl-treated plots was 11.5 to 14%. Pathogen dispersal mechanisms were modified most dramatically by the no-till cropping system. Thus, simple changes in cultural practices can have dramatic effects on the development of Phytophthora epidemics. Ecologically based disease management strategies have the potential to reduce our reliance on agrichemicals in this and similar pathosystems.  相似文献   

3.
Six inoculation techniques were compared for their ability to evaluate resistance toColletotrichum acutatum of five strawberry cultivars. Inoculation by dipping the whole cold stored plants in a suspension of conidia adjusted to 2.106 conidia ml–1 made it possible to screen cultivars resistant to crown rot at 28 days after inoculation. Using the dipping technique, 44 strawberry cultivars were evaluated for their resistance to one strain ofC. acutatum, 1267b. Twelve of them did not show wilt symptoms and could be classified as resistant. When another strain ofC. acutatum, 494a, was inoculated to seven cultivars, all of them including Dover, resistant to 1267b, showed wilt symptoms. This result showed the importance of investigations on genotype × isolate interactions to conduct an efficient breeding programme for screening resistance toC. acutatum.  相似文献   

4.
Early anthracnose caused by Colletotrichum acutatum has become an increasingly serious disease on green, unripe bell pepper fruit in Florida. This contrasts with earlier reports of anthracnose occurring on bell pepper primarily as a ripe-rot disease of mature, colored pepper fruit caused by Colletotrichum gloeosporioides. Management of anthracnose on green bell pepper fruit using fungicides and a commercial inducer of systemic acquired resistance, acibenzolar-S-methyl (ASM), was evaluated during three seasons. In two of the three trials, all the fungicides tested including azoxystrobin, fludioxonil + cyprodinil, mancozeb, famoxadone + cymoxanil, copper hydroxide, and ASM significantly increased the number of marketable fruit compared with control plants. These trials identified fungicides that could contribute to a successful pest management program on pepper for controlling anthracnose caused by C. acutatum. The cross-infectivity potential of C. acutatum was investigated on tomato and strawberry by in vitro and field inoculation. Anthracnose lesions formed readily on wound-inoculated detached fruits of all hosts in in vitro assays. Under field conditions, after inoculation, anthracnose lesions occurred on pepper fruit but no lesions of anthracnose were found on either ripe or unripe tomato or strawberry fruit in adjacent plots.  相似文献   

5.
Anthracnose, caused by Colletotrichum acutatum (species complex), has become a troublesome problem in strawberry production worldwide. This paper reports (i) an optimized sampling method combined with a real‐time PCR technique to detect the latent presence of C. acutatum in cold‐stored strawberry plants used as planting material in several European countries, and (ii) a study of the spread of C. acutatum following a point inoculation under field conditions. Screening of different parts of planting material suggested that C. acutatum is most likely to be present on runners and old petioles. In addition, in seven out of nine batches of planting material from different nurseries, latent infection by C. acutatum was detected in at least one of five replicate samples. Field experiments in 2009 and 2010 showed extensive latent within‐field spread of the pathogen on strawberry leaves, with a within‐row dispersal distance up to at least 1·75 m in 1 week. A straw ground cover between the rows did not decrease C. acutatum spread, probably because introduced (and/or subsequent) inoculum was confined to the plant bed (within the row) and was not present between the beds. Moreover, the number of C. acutatum spores on the symptomless leaves, as estimated using a real‐time PCR method, was significantly (P < 0·05) correlated with the incidence of fruit rot at harvest and post‐harvest (r = 0·56–0·66). These results illustrate the importance of detecting latent infections in planting material and strawberry leaves in the field.  相似文献   

6.
The effectiveness of solar heating of the soil by means of mulching with transparent polyethylene, against soilborne pathogens of onions, was tested in two field experiments: at Yotvata (hot region) and at Gefen (cooler one). In both experiments, solar heating significantly reduced the incidence and severity of the pink root disease caused byPyrenochaeta terrestris by 73-100% during the 6-7 months of plant growth.Rhizoctonia solani, Fusarium infection, and weed populations (except forMelilotus) were also considerably reduced by this treatment. In addition, stand and plant growth were improved and yields were increased by 109-125% at Yotvata and by 59-62% at Gefen, as compared with the untreated control. Similar results were obtained when soil was moistened by sprinkler irrigation before applying the mulch or by sprinkler irrigation supplemented by drip irrigation under the mulch. Pentachloronitrobenzene did not control pink root disease.  相似文献   

7.
Anthracnose, caused by Colletotrichum acutatum, is an important disease of almond and has caused significant economic losses in California, Israel and Australia. Anthracnose development was monitored for three growing seasons in an almond orchard in South Australia on two almond cultivars, Price and Nonpareil, with up to 80 % of fruit affected in 2004. Lesions, typical of anthracnose, formed on young developing fruit and symptoms continued to appear until the fruit were ca 20 mm long, after which no further lesions developed. Symptoms were observed on leaves, woody tissue showed signs of dieback, but blossom blight was not observed. Maximum disease incidenceperfor, man and Relative Area Under the Disease Progress Curve (RAUDPC) were significantly larger for Price than Nonpareil for each season, but differences in the apparent rates of infection for both cultivars were insignificant for the three growing seasons. The apparent rates of infection were correlated with rainfall and daily temperature for the three years combined but there was no correlation between maximum disease incidence or RAUDPC and these environmental parameters. Considerably more mummified fruit remained on the trees of cv. Price than Nonpareil each year; however, there was no correlation between the number of mummified fruit in one season and maximum disease incidence, RAUDPC or apparent rate of infection, in the following season. C. acutatum was recovered from mummified fruit, peduncles and bark, from both Price and Nonpareil, every month throughout a year-long sampling period. C. acutatum was also recovered from asymptomatic leaves, fruit, bark, buds and blossom, however, less frequently and at lower rates than from mummified fruit and peduncles. Recovery was consistently greater from Price than from Nonpareil for all tissues.  相似文献   

8.
Anthracnose fruit rot, caused by Colletotrichum acutatum, is among the most important diseases of blueberries. Most cultivars are susceptible but ‘Elliott’ is resistant. Our objective was to identify possible antifungal compounds that play a role in the resistance response. Chemical fractions from freeze-dried, ripe fruit of ‘Elliott’ and a susceptible cultivar (Jersey) were extracted with methanol and ethyl acetate. Extracts were screened on solid media for suppression of microconidiation of C. acutatum. The methanolic extract was fractionated and the soluble methanolic fraction from ‘Elliott’ was the most biologically active. This fraction was dried, dissolved in water, and screened in vivo by pre-treating ripe ‘Jersey’ fruit with 0.5, 1, 2, and 4% solutions (w/v) and subsequently inoculating the fruit with C. acutatum. An 88% reduction in infection incidence was observed after 12 days with the 4% solution. Anthocyanins and other flavonoids were then quantified in fruit of the two cultivars using HPLC-MS. ‘Elliott’ fruit contained more anthocyanins (4.87 mg/g of freeze-dried tissue) than ‘Jersey’ (3.27 mg/g of freeze-dried tissue); however, the same compounds were found in both cultivars. ‘Elliott’ fruit also contained more non-anthocyanin flavonoids (0.18 mg/g of freeze-dried tissue) than ‘Jersey’ (0.12 mg/g of freeze-dried tissue), including two distinctive compounds in ‘Elliott’. The non-anthocyanin flavonoid fractions of both ‘Elliott’ and ‘Jersey’ significantly decreased the growth of C. acutatum in a liquid bioassay but the effect was more pronounced in the ‘Elliott’ fraction. The two distinctive compounds in ‘Elliott’ were further characterized by MS/MS and were identified as quercetin 3-O-rhamnoside and, putatively, syringetin rhamnoside. Additionally, we evaluated ‘Elliott’ and ‘Jersey’ methanolic extracts for their ability to inhibit lipid peroxidation, and the extract obtained from ‘Elliott’ was almost twice as active at inhibiting peroxidation. These results provide new insights into the role of antifungal compounds in the resistance response of ripe ‘Elliott’ blueberries to infection by C. acutatum.  相似文献   

9.
A two-year study was conducted to determine the effect of six sanitation treatments on leaf litter density (LLD), relative ascospore production of Venturia inaequalis and scab incidence on spur-leaf clusters, leaves and harvested fruits, on two cultivars with low and high scab susceptibilities, in Hungarian integrated and organic apple orchards. The following sanitation treatments were used: sprays of lime sulphur in autumn, collecting fallen leaves in autumn, straw mulch cover in late winter, sprays of lime sulphur followed by mulch cover, collecting fallen leaves followed by mulch cover, collecting fallen leaves followed by covering the orchard floor with plastic foil, and non-sanitized control. LLD decreased continuously in all treatment plots by 0–23% by mid-May in both orchards and years; however, LLD reduction was 1.4–4.2 times higher in the organic orchard compared to the integrated one. All treatments, except for the lime sulphur treatment, resulted in significant (P < 0.05) reduction of LLD and ascospore production in both the integrated and organic apple orchards compared to non-sanitized plots. The most efficient treatment was leaf collection combined with plastic foil cover, followed by leaf collection combined with mulch cover, leaf collection alone, mulch cover alone, and lime sulphur spray combined with mulch cover, with a reduction in the ascospore production of >95, 72–92, 56–79, 24–38, and 27–46%, respectively, in the mean of both orchards and years. However, only treatments of leaf collection applied alone, or in combination with mulch or with plastic foil cover reduced significantly (P < 0.05) leaf and/or fruit scab incidence by 18–57% compared to non-sanitized plots. These three leaf collection treatments are recommended in both integrated and organic orchards and the possibilities of successfully incorporating these methods into orchard management practices are interpreted.  相似文献   

10.
Aluminum foil and plastic mulch, covering 57-83% of the ground in peppers from emergence, effectively protected the crop against aphid-borne cucumber mosaic and potato virus Y by repelling winged aphids. Aluminum foil and grey plastic sheets gave the best results, followed closely by white plastic on black. The mulches were most efficient during the first 3 weeks in the field, after which they lost some of their reflectance. Trappings of winged aphids from the aluminum-covered plots during the first 3 weeks were only 2 and 5% of the control, and those in the grey-plastic-covered plots were between 6 and 12%.Myzus persicae was especially sensitive to reflection, and trappings in the aluminum and grey plastic plots during the first 3 weeks were less than 0.6 and 2% of the control, respectively. Repellence of winged aphids was correlated with virus incidence, especially during years with high natural virus spread; infection rates in the mulched plots at harvest time reached only 4.5-6% compared with 45% in the controls. As a result, yields were markedly higher except in the aluminum-mulched plot where in one season growth of plants was retarded, perhaps due to lower soil temperature.  相似文献   

11.
Strawberry, Fragaria × ananassa, and leatherleaf fern, Rumohra adiantiformis, are two important crops in Costa Rica. One of the most severe diseases affecting these crops is anthracnose, caused by members of the fungal genus, Colletotrichum (teleomorph; Glomerella). Eighty single-spore isolates from strawberry and leatherleaf fern were identified as Colletotrichum acutatum by species-specific PCR, and were further characterised by Universally Primed PCR (UP-PCR) fingerprinting analysis, and sequence analysis of the ribosomal internal transcribed spacer (ITS) region. Morphological differences, genotypic variation revealed by UP-PCR fingerprinting analysis, and a single sequence polymorphism within the ITS2 region were found between the isolates from strawberry and leatherleaf fern, respectively. The UPGMA cluster analysis of the fingerprints clearly separated the isolates derived from strawberry and leatherleaf fern into two different clusters. Pathogenicity assays on detached strawberry fruits confirmed the apparent difference between the two groups of isolates. It is therefore suggested that the pathogens responsible for strawberry anthracnose fruit rot and leatherleaf fern anthracnose in Costa Rica, belong to two distinct subpopulations of C. acutatum.  相似文献   

12.
Microscopic investigations were conducted into the interaction of Colletotrichum acutatum on white and red strawberry (Fragaria ×ananassa) fruit surfaces. The results showed that, whilst the early interaction events were similar in both white and red fruits, after 24 h fungal colonization dramatically varied: in white fruits C. acutatum became quiescent as melanized appressoria, but on red fruits it displayed subcuticular necrotrophic invasion. A microarray analysis of white and red strawberries after 24 h of interaction with C. acutatum was performed, in order to reveal differences in gene expression possibly related to the different susceptibility of unripe and ripe fruits. Epi/catechin‐related genes and fatty acid metabolism genes, involved in the production of quiescence‐related molecules such as flavan‐3‐ols, proanthocyanidins and antifungal dienes, were found to be regulated during strawberry ripening, supporting a role for these molecules as preformed defence mechanisms. Besides several genes commonly regulated upon pathogen interaction, different genes were specifically transcribed only in white or red challenged fruits; a number of these, such as those coding for lectin and polyphenol oxidase, possibly account for specific pathogen‐induced responses. The putative biological role of these genes in the different susceptibility of fruits to C. acutatum is discussed.  相似文献   

13.
Colonization of red raspberry flowers and fruit by Botrytis cinerea was determined during 2017–2018 growing seasons under commercial fungicide application programmes used for grey mould management in northwestern Washington, USA. Colonization of flowers and fruit was assessed qualitatively (incidence, %) and quantitatively (abundance, number of colonies) by recovering B. cinerea from surface-disinfested samples. Both incidence and abundance of flower colonization were significantly lower than fruit colonization in both untreated and fungicide-treated plots. Incidence of flower colonization did not differ significantly between untreated and fungicide-treated plots (43% vs. 45%, respectively). In contrast, significantly greater colonization incidence was detected at green fruit stage in untreated compared to fungicide-treated plots (96% vs. 77%, respectively). Ripe fruit had the greatest colonization incidence among the three stages sampled and colonization was not significantly different between untreated and fungicide-treated plots (100% vs. 92%, respectively). Similarly, colonization abundance of flowers did not differ significantly between untreated and fungicide-treated plots (1.0 colonies per colonized flower in both treatments), but colonization abundance of green and ripe fruit was decreased 2.3- and 2.1-fold, respectively, in fungicide-treated plots. DNA fingerprinting analysis of the pathogen revealed that different multilocus genotypes colonized flowers and fruit within the same inflorescence and that genotypic diversity increased through time, suggesting independent infection events. Overall, our results demonstrate that under current environmental conditions, raspberry flowers may not be the exclusive or major route of infection for grey mould of red raspberry in northwestern Washington. Implications of current findings for management and further research are discussed.  相似文献   

14.

Development of late blight of potatoes caused by Phytophthora infestans (US 8 fungal genotype, A2 mating type) was monitored in two Russet Norkotah commercial fields at Fort Fairfield in 1996 and Duncan Farm in 1997. Experimental plots representing various disease treatments (low, moderate, high and random late blight severity levels) were established in two fields in 1996. In 1997, only low and high disease treatments were established. The application of fungicides for late blight control was conducted in both years. Late blight incidence and severity were assessed in each plot of each treatment. Components of late blight disease development, tuber blight incidence and tuber yields were determined from each plot. Progress of late blight disease was rapid in 1996 but not in 1997. During the 1996 cropping season, mean disease incidence and severity in the random disease treatment plots were 84 and 21% respectively within 10 days of disease detection. In 1997, low levels of late blight severity were detected in the field plots. Average numbers of late blight leaf and stem lesions on infected plant and fungal sporangia on the diseased leaf were not significantly affected by disease treatment. Late blight foliar severity significantly affected potato tuber yields. Lowest tuber yield was obtained in plots with high disease levels and highest yields were recorded in plots with low late blight severity in 1996. Late blight severity was significantly correlated with tuber yield but not with per cent tuber blight.  相似文献   

15.
Anthracnose, caused by Colletotrichum spp., is a major disease of cultivated strawberry, Fragaria × ananassa. This study identifies the Colletotrichum spp. which causes strawberry anthracnose in the southwest of Spain. A survey of the region was carried out, and the strains isolated were identified as C. acutatum by using the polymerase chain reaction (PCR) with genus and species-specific primers, demonstrating that this species is currently the causal agent of strawberry anthracnose in the studied region. The pathogenicity of C. acutatum and C. gloeosporioides strains was evaluated on two principal strawberry cultivars (cvs Camarosa and Ventana) under field conditions, the latter being more pathogenic than the former.  相似文献   

16.
The effect of irrigation regimes on disease expression in melon plants infected with Monosporascus cannonballuswas studied during two summer growing seasons (1998 and 1999) in the Arava region of southern Israel. Less frequent and reduced irrigation postponed the onset of plant collapse and lowered disease incidence. Delaying disease development in infested fields by reducing irrigation frequency allowed crop harvest before plant collapse. However, reduced irrigation regimes reduced yields, as shown in methyl bromide fumigated plots. Fruits from melon plants grown under reduced irrigation in the infested plots were also of lower quality due to water shortage. The delay in plant collapse under the reduced irrigation treatments was attributed to a combined effect of reduced fruit load and the development of a deeper root system, which could support the increased water demand of the mature, fruiting plant.  相似文献   

17.
Tracing Latent Infection of Colletotrichum acutatum on Strawberry by PCR   总被引：1，自引：0，他引：1  
Colletotrichum acutatum, a quarantine organism on strawberries in the EU, was found in Finland for the first time in 2000. Concern about rapid, unnoticeable spread of this pathogen has necessitated studies to find methods with which the quiescent fungus infection can be detected in imported, cold-stored strawberry plant material. Successful detection of C. acutatum in strawberry tissues by polymerase chain reaction (PCR) is dependent on the method of DNA extraction used. Good-quality nucleic acid, free of PCR inhibitors, was successfully prepared by slightly modifying the DNA extraction method of a commercially available kit. Species-specific primers, previously described in the literature, were successfully used in the PCR reaction. C. acutatum was detected by PCR both on symptomatic and asymptomatic plant parts and in artificially and naturally infected strawberry tissues. Positive PCR results were obtained from ripe and unripe berries, runners, petioles and different parts of crowns. The data demonstrate that the PCR technique can be used to detect C. acutatum in strawberry tissue even in plant parts that do not show visible symptoms.  相似文献   

18.
移栽甜玉米田覆盖控草技术   总被引：1，自引：0，他引：1  
为了明确不同覆盖方式对甜玉米田杂草出苗生长的抑制效果,寻求更安全环保的控制甜玉米田杂草发生危害的方法,本研究采用大田试验,在甜玉米移栽前,将不同厚度的玉米秆、水稻秆及1层黑色地膜均匀覆盖于小区内.结果显示,处理后20、40 d,黑色地膜能完全抑制甜玉米田杂草的生长,且能显著提高甜玉米产量,增产率为45％;不同厚度的稻秆和甜玉米秆覆盖能够控制杂草的发生,且覆盖厚度越厚,控草效果越好,顺序为稻秆20 cm＞甜玉米秆20 cm＞稻秆10 cm＞甜玉米秆10 cm.秸秆覆盖均能显著增加甜玉米的产量,且甜玉米秆20 cm处理的甜玉米产量最高,但彼此间无显著性差异.  相似文献   

19.
Rumple is a serious peel collapse of Primofiori lemons in the southeast of Spain with an unresolved aetiology. Symptoms typically occur on fruits at ripening under wet conditions as dark sunken lesions producing premature fruit drop and damaged fruits unacceptable for fresh commercialization. A total of 16 Colletotrichum spp. isolates established from rumple-affected lemons collected during the autumn of 2007 from two different orchards were characterized by molecular and phenotypic assays and compared with reference isolates. Species-specific PCR reactions using β-tubulin 2 nucleotide sequences showed Colletotrichum gloeosporioides to predominate (81.5%) with limited occurrence of C. acutatum (18.75%). Among the C. gloeosporioides isolates, five (38.5%) showed benomyl resistance and eight (61.5%) were highly sensitive to the fungicide. The limited occurrence of C. acutatum could be related to factors such as the presence of both species on the same fruit, unfavourable meteorological conditions and low disease incidence. This work reveals an association of C. gloeosporioides and C. acutatum isolates with rumple disease of lemons and expands the range of C. acutatum on citrus.  相似文献   

20.
Citrus post-bloom fruit drop (caused by Colletotrichum acutatum) frequently occurs in the southwestern region of São Paulo State, Brazil. A survey of Colletotrichum isolates associated with symptoms of post-bloom fruit drop in São Paulo State showed C. gloeosporioides in addition to C. acutatum. The objectives of this study were to confirm the identification of C. gloeosporioides isolated from symptomatic citrus flowers, to test the pathogenicity of C. gloeosporioides isolates, to compare the development of disease caused by C. gloeosporioides and C. acutatum, and to determine the frequency of C. gloeosporioides in a sample of isolates obtained from symptomatic flowers in different regions of São Paulo State. Through the use of species-specific primers by PCR, 17.3% of 139 isolates were C. gloeosporioides, and the remaining 82.7% were C. acutatum. The pathogenicity tests, carried out in 3-year old potted plants of sweet oranges indicated that both species caused typical symptoms of the disease including blossom blight and persistent calyces. Incubation periods (3.5 and 3.9 days, respectively, for C. acutatum and C. gloeosporioides) and fruit sets (6.7 and 8.5%, respectively for C. acutatum and C. gloeosporioides) were similar for both species. The incidences of blossom blight and persistent calyces were higher on plants inoculated with C. acutatum than in those inoculated with C. gloeosporioides. Conidial germination was similar for both species under different temperatures and wetness periods. Under optimal conditions, appressorium formation and melanisation were higher for C. gloeosporioides than for C. acutatum. These results indicated that Colletotrichum gloeosporioides is a new causal agent of post-bloom fruit drop.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号