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.
Viable propagules ofVerticillium albo-atrum andV. dahliae were recovered from potato stems before and after burial in the field during 1968–1971. Of 14 cultivars tested: Red Pontiac and Superior ranked highest in numbers of propagules ofV. albo-atrum. Russet Burbank, Kennebec, and Irish Cobbler ranked highest withV. dahliae, respectively. Survival ofV. albo-atrum in infected stems was evident (5 ? 34 × 103 ppg) even after burial in field soil for 17 months. In general, survival ofV. albo-atrum (47–69%) was higher thanV. dahliae (23 – 61%) following field burial of infected stems for 7 months.  相似文献   

2.
Effect of nitrogen and phosphorus fertilization rates on the incidence of Verticillium wilt caused byVerticillium albo-atrum orV. dahliae and tuber yield in potato cv Yukon Gold was evaluated in field plots. In three years of study,V. albo-atrum caused a higher incidence of wilt symptoms (74%–100%) thanV. dahliae (5%–81%) resulting in lower marketable tuber yield. In plots infested withV. albo-atrum, tuber yield ranged from 12.3-22.8 T ha1 compared to 18.1– 31.5 T ha-1 in plots infested withV. dahliae. Application of nitrogen above (280 kg ha-1) or below (70 kg ha-1) the recommended rate of 140 kg ha-1 at planting did not suppress foliar symptoms or protect against yield loss caused by eitherV. albo-atrum orV. dahliae. Similarly, phosphorus rate adjustments did not consistently affect disease incidence regardless of the pathogen. Management of nitrogen or phosphorus fertility rates at planting does not appear to be a viable approach for suppressing Verticillium wilt in the determinant, wiltsusceptible cultivar Yukon Gold.  相似文献   

3.
For three years, potato yields, tuber quality, and incidence ofVerticillium dahliae were measured in field plots previously cropped for one year to the following nonhosts: sudan grass, green peas followed by sudan grass (same year), spring wheat, spring wheat followed by sudan grass (same year), sweet corn and field corn. One year rotation to nonhosts did not reduce the population ofV. dahliae propagules in the soil and in only one of the three years wereV. dahliae propagule numbers in potato stems significantly reduced in plots following nonhost crops, compared with plots following potatoes. Verticillium wilt symptoms in potatoes were not reduced by one year rotation to any of these crops and only in one year in three was yield significantly increased. In two of three years, percent U.S. No. 1 tubers was increased following one-year rotation with green peas plus sudan grass, and in one of the two years, specific gravity was increased by rotation. Rotational cropping to nonhosts for two years between potatoes significantly reduced preplant soil populations ofV. dahliae propagules in the soil and in potato stems the following fall. However, soil populations in these two year rotational plots the spring following potato were not reduced compared to plots previously cropped to potatoes two consecutive years. Cropping to nonhosts for two years had no consistent effect on incidence of Verticillium wilt in subsequent potato crops. Two years’ rotation to nonhosts increased plant height and yield compared to continuous cropping to potato but not percent U.S. No. 1 tubers. The various nonhost crops all had about the same non-significant effect on yield. In two out of three years’ trials, fumigation significantly reduced both the incidence of Verticillium wilt and number ofV. dahliae propagules in stems in plots compared to plots non-fumigated. In only one trial, fumigation significantly increased tuber yields and percent U.S. No. 1 tubers.  相似文献   

4.
Soil population levels ofVerticillium dahliae in Ohio were monitored from May–October, 1982–1985, in 15 fields in potato-wheat rotation and two fields in potato monoculture. Population levels in fields in rotation ranged from 0 to 86 microsclerotia/10 g of air-dried soil with average values during each 6-month sampling period of 9.7, 12.9, 9.6 and 19.6 microsclerotia/10 g of soil for 1982, 1983, 1984 and 1985, respectively. In at least 2/3 of the fields sampled each year, soil populations ofV. dahliae peaked in either July or August, regardless of whether fields were under wheat rotation or potato monoculture. Of the 15 fields under potato-wheat rotation, 13 showed a general pattern of increased populations ofV. dahliae in one or both years following cropping to potato. Among those 13, significantly higher populations (P < 0.05) were observed in one wheat field in 1983 and in eight fields in 1985. In the two fields in potato monoculture, one consistently had population levels ofV. dahliae 3–4 times higher than any other field sampled in this study. Factors that may contribute to periodic changes inV. dahliae populations, implications of these changes in interpreting soil population data, and usefulness of a potato-wheat rotation in managingV. dahliae populations in Ohio are discussed.  相似文献   

5.
Summary Samples of a sandy soil and a marine clay soil sterilized by steam were put in 55-1 containers insulated with polystyrene and placed outdoors on a brick pavement. Sandy soil was infested singly or in all possible combinations with root-knot nematodes (Meloidogyne spp.) and the fungiRhizoctonia solani andVerticillium dahliae, and the marine clay soil was infested with the root-lesion nematodePratylenchus neglectus and the same fungi to evaluate the effects of these organisms on the yield of potato. The experiments were carried out from 1983 to 1986. Tuber yield was reduced by single infestations of theMeloidogyne spp. andV. dahliae but not significantly byR. solani orP. neglectus. A three-factor interaction: nematode ×R. solani × V. dahliae was found in both experiments.R. solani andV. dahliae showed significant synergistic effects when soil was infested with theMeloidogyne spp. orP. neglectus.  相似文献   

6.
A quantitative PCR assay based on the competitive PCR technique was compared to the classical soil dilution (SD) method for its ability to estimateV. dahliae propagules directly in soils collected from fields under potato production. A strong correlation (r = 0.97) was observed betweenV. dahliae propagules estimated using the quantitative PCR assay and those using the SD method. Coamplification ofV. dahliae DNA with competitor DNA provided accurate quantification in the range of 102 to 107 spores and 1 to 100 microsclerotia/g of soil. The number ofV. dahliae propagules detected in PEI soils ranged from 4.9 to 15.6 and 0.06 to 0.5 microsclerotia/g of soil for PCR assay and SD method, respectively. The strong correlation between PCR assay and SD method and the non significant differences between replications of PCR estimates ofV. dahliae propagules in soils (P< 0.05) show that the PCR assay is reliable and reproducible, and comparable to the SD method. This method is fast, does not depend on the subjectiveness of the traditional plating method, and offers an improvement in speed and precision over currently used methods. In addition, it can be extended to estimateV. dahliae propagules in other pathosystems and finds immediate and practical use in epidemiological studies to determine the effects of various crop management strategies on the dynamics and level of fungal propagules in the soil in order to establish threshold levels for assessing disease risks and develop disease prediction systems.  相似文献   

7.
Management practices for the suppression of Verticillium wilt of Russet Burbank potato include sanitation, use of optimum sprinkler-irrigation practices, soil solarization, and an adequate soil fertility program. Among all cultural factors considered, nitrogen (N) deficiency in potato tissue was most commonly associated with the severity of Verticiilium wilt in Russet Burbank potato. Field studies have shown that increased N availability suppresses Verticiilium incidence on cv Russet Burbank while having no effect on cv Norgold Russet. Studies from both greenhouse and field show that the colonization ofV dahliae in potato stem tissue is suppressed in cv Russet Burbank when the availability of Phosphorous (P) is increased to the optimum. Following one season of cropping with Russet Burbank potato, the treatment providing the optimal N availability also suppressed the increases ofV dahliae populations in the soil during the following year of consecutive cropping. Similarly, after two seasons of continuous potato cropping, treatments with optimal P had lower soil populations ofV. dahliae in soil. Results show the suppression of Verticiilium wilt with optimal fertility. Verticiilium wilt [caused by eitherVerticiilium dahliae Kleb, (microsclerotial form) orVerticiilium albo- atrum Reinke and Berthold (dark mycelial form)] is one of the most severe diseases of potato in the United States. Potato yields, tuber size, and specific gravity may be substantially reduced by this disease, depending on severity, time of occurrence, and growing season. In Idaho and other arid growing regions of the United States, Verticiilium wilt is caused byVerticillium dahliae Kleb. Idaho field studies involving cropping practices, soil fumigation treatments, solarization, and Verticillium-resistant potato clones all support the importance ofV dahliae upon potato yield. Data from these studies show that yield losses due toV. dahliae commonly approximate 5 to 12 metric T/ha (5, 6). Table 1 illustrates the effect of several cropping practices upon relativeV dahliae populations in soil with the effects upon both disease severity and potato yield. With continuous cropping of Russet Burbank,V dahliae populations in soil increased, and yields were reduced by 18 to 19 metric Tlha when compared to locations that had been allowed to remain either weed-free and fallow or where corn had been previously cropped. It was estimated thatV dahliae was influencing yield by about 10 to 12 metric Tlha based on a regression analysis of yield as a function ofV dahliae populations in soil. Similarly, whenV dahliae was suppressed by fumigation treatments involving mixtures of dichloropropene and picfume, yields more significantly increased by 6.5 to 12 metric T/ha (5). Although many factors may influence yields, clones with higher Verticillium resistance than Russet Burbank generally out-yield Russet Burbank. Figure 1 demonstrates the effect of solarization (a technique involving the laying of clear plastic on soil for the purpose of elevating soil temperatures to killV dahliae). When Verticillium was controlled in this manner (lo), there was no significant yield difference between the Russet Burbank potato and the highly resistant A68113-4 clone. The A68113-4 clone grown in non-solarized soil out-yielded the Russet Burbank in non-solarized soil by 31 percent while the solarization treatment significantly increased yield for the Russet Burbank and A68113-4 clones by 46 and 18 percent, respectively. These yield responses were observed in a field where inoculum levels ofV dahliae were relatively low (2.10 cfulgrn of soil). With these losses, the need to develop control procedures is great and to achieve this control the need also exists to accurately evaluate the effect of treatments uponV dahliae. Our Idaho studies have routinely utilized such a procedure (9) in combination with comparisons of both disease severity and yield.  相似文献   

8.
Viable propagules ofVerticillium albo-atrum were recovered from roots and stems of naturally infected weeds and sunflower cultivars before or after burial in the field and from stems and roots of certain non-infested crops after burial in the field for seven months.Verticillium dahliae was recovered less frequently, then only from the roots ofSolanum nigrum (black nightshade). Survival of these pathogens after burial for 7 months varied considerably, ranging from 38 to 58% in sunflower stems and from 19 to 235% in roots of weeds. In stems of weeds and crops which did not contain propagules ofV. albo-atrum before burial, the fungus was recovered consistently after burial, indicating that saphophytic colonization probably occurred during interment.  相似文献   

9.
Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is one of the most important diseases of potato in North America. Soil incorporation of alfalfa residues prior to planting potato could be a nonchemical Verticillium wilt management tactic by reducing the number of viable microsclerotia in field soil. Verticillium dahliae microsclerotia were quantified in field soils where organic material from alfalfa was incorporated, and numbers of microsclerotia were compared to fields where alfalfa residue was not incorporated. In addition, bacterial metagenomics was utilized to characterize soils where organic material from alfalfa was or was not incorporated to determine if alfalfa residue incorporation facilitates the formation of soils that suppress or kill V. dahliae microsclerotia. The number of V. dahliae microsclerotia in soil was greater (P = 0.0003) in fields where crop residue was incorporated than fields without incorporation when chloropicrin was used as a fumigant. Conversely, the number of V. dahliae microsclerotia observed in potato plants did not differ (P = 0.4020) between fields where residues were or were not incorporated if chloropicrin was used. Alfalfa residue incorporation did not significantly alter the soil bacterial metagenome compared to fields not subject to residue incorporation in both years of study. Despite these conclusions, the method can be employed to analyze the effect of grower practices with the intent of linking a field practice to increasing soil bacterial diversity and decreasing Verticillium wilt severity on potato.  相似文献   

10.
Greenhouse and field plot experiments along with surveys of commercial potato fields were conducted to determine the etiology of potato early dying in Delaware and its impact on yield ofSolanum tuberosum cultivar Superior.Verticillium dahliae was the primary pathogen causing early dying, and no increase in disease severity or yield loss was observed when plants were inoculated with bothV. dahliae andColletotrichum coccodes. The field survey showed thatV. dahliae was the predominant pathogen in symptomatic plants, and nematodes were not essential in association withVerticillium to cause early dying. Disease severity was the same in the presence of a low population or absence of nematodes.  相似文献   

11.
Ohio field studies in microplots in the past 6 years have demonstrated a synergistic interaction of the lesion nematodePratylenchus penetrans withVerticillium dahliae in potato early dying. Tests with various populations ofP. penetrans andV. dahliae, alone and in combinations, have shown that disease occurs when both pathogens are present at populations which individually have little or no effect. Yield loss is not necessarily associated with foliar symptom development, but occurs with the addition of high temperature stress during tuberization. Comparative studies with two other species ofPratylenchus commonly found in Ohio potato soils have shown thatP. crenatus does not interact withV. dahliae and thatP. scribneri interacts only slightly. Since all three species feed and reproduce well on potato,Verticillium interactions probably are not due to wounding. The involvement ofPratylenchus withV. dahliae in potato early dying is an important factor that must be considered in the development of future crop-loss predictive systems.  相似文献   

12.
Premature death of potato vines is widespread in irrigated potato fields of the Pacific Northwest.Verticillium dahliae is a major cause of early dying in fields with a history of potato production, but in fields new to potato production, or those that have been fumigated and have a lowV. dahliae population in the soil, premature death of vines can also occur.Erwinia carotovora pv.carotovora (Ecc) andE. carotovora pv.atroseptica (Eca) have been implicated in the early dying disease syndrome in these fields. Both bacterial pathogens are associated with symptoms similar to those caused byV. dahliae; i.e., a progressive chlorosis and necrosis of the foliage and vascular discoloration that may extend a short distance up the stem. Greenhouse pathogenicity studies on cv. Russet Burbank cuttings in which symptom development was identical to that produced byV. dahliae have verified thatEcc andEca can cause potato early dying.  相似文献   

13.
A study was conducted from October 1987 to November 1988 to accumulate data on the distribution of plant-parasitic nematodes, to examine rotation schemes and time of sampling in relation to nematode populations, and to assess the occurrence ofVerticillium spp.-Pratylenchus spp. in potato growing areas of the state of Maine.Pratylenchus penetrans andP. crenatus were encountered most frequently, with detection being 19% higher in early season (May–June) than late season (September–November). All rotation schemes supportedPratylenchus spp.Meloidogyne hapla was encountered in 14% of the early samples and 19% of the late samples. Oats-potato, potato-potato, and clover-potato supported the highestM. hapla population levels. Other nematodes detected in fewer samples and in lower numbers than the two above genera wereParatylenchus spp.,Criconemella spp.,Helicotylenchus spp. andTylenchorhynchus sp. Two plants from each of 27 fields were examined for nematode-fungus associations. Samples from 7 fields were positive forV. dahliae andP. penetrans only,V. alboatrum andP. penetrans were found in 1 field,V. alboatrum alone was detected in 1 field andP. penetrans,V. dahliae andV. alboatrum were found together in 2 fields. The detection of these nematode-fungus associations suggests that the potato early dying complex defined elsewhere in the United States may be occurring in Maine.  相似文献   

14.
In three years (1994, 1995, and 1996), a total of 100 commercial potato fields in southeastern Idaho were surveyed for soil variables, severity of Verticillium wilt, soil inoculum density ofVerticillium dahliae andColletotrichum coccodes, colonization of stems, root, and tubers byV. dahliae andC. coccodes, and tuber yield, size, and quality. As a generalization, factors related to soil integrity (organic matter, organic nitrogen, and increased nutrient availability) were most closely related to wilt suppression and higher tuber yields, whereas factors related to loss of soil integrity (sodium and reduced nutrient availability) were related to increased wilt and lower tuber yields. In a multiple regression analysis, three independent variables, feeder-root infections byV. dahliae, sodium content in soil, and soil organic content, were significant predictors of tuber yield. With these three factors, this model accounted for 49%, 53%, and 62% of the field variability related to total yield in 1994, 1995, and 1996, respectively. Throughout this investigation,V. dahliae root infections had the most direct effect on tuber yield, which emphasizes the importance of quantifying root infections in epidemiological studies of Verticillium wilt. Based on these results, organic matter may be one factor that can be manipulated for suppression of Verticillium wilt without reducing soil populations of the pathogen.  相似文献   

15.
The effect of plowing and deep-rip tillage, in combination with chemigation or shank injection of metam sodium, onVerticillium dahliae populations and disease development was assessed in two fields with differing soil types and potato rotations. Soil samples were collected on a geo-referenced basis at depths of 0 to 10 cm and 10 to 20 cm before tillage, after tillage, after chemical application, and before planting and assayed for the presence of the pathogen. Propagules ofV. dahliae were detected at 140 of 141 sites sampled prior to tillage. Most (74.4% in heavy, sandy loam; 63.1% in light, loamy sand) were concentrated in upper 10 cm of the soil profile. Plowing redistributed inoculum vertically while deep-rip tillage did not. In the non-chemical treated areas of both fields, theVerticillium population reached a maximum between 25 July and 8 August before declining to near pre-tillage levels. Overall, the population generally was lower in the field with heavy soil, higher organic matter content, and a 3-year crop rotation. Metam sodium appeared to be most effective when shank injected, as the levels of inoculum in both fields declined by 60% to 80% following this application method. Chemigation was ineffective in the lighter soil, but the inoculum density in the deep-rip tillage area of the field with the heavier soil declined by nearly 20% in the upper and 60% in the lower strata following this treatment. The number ofV. dahliae propagules at the 10- to 20-cm depth in the plowed area of the same field was reduced by 25% following chemigation, but remained unchanged in the upper strata. Wilt was reduced in both fields by as much as 50% with shank injection of metam sodium with concomitant increases in total yield, marketable yield and gross income. Increases in total yield were significant (P<0.05) for the main effect of chemical, in the plowed area of the field with the heavier soil type following shank injection. These data suggest that growers might benefit from altering their tillage and chemical application practices as part of an integrated approach to managing Verticillium wilt.  相似文献   

16.
Summary The effect ofStreptomyces spp. (netted scab) on the growth of potato was investigated in three pot experiments, in two of which the effect ofVerticillium dahliae was also assessed. The netted scab organisms attacked all underground plant parts of susceptible potato cultivars early in the growing season; the roots were especially seriously attacked, markedly reducing tuber yield and number but prolonging the duration of the growing season. The nematicide oxamyl had little effect on the incidence of netted scab. Repeated growing of the susceptible cv. Bintje greatly increased soil contamination with the netted scab pathogens. V. dahliae reduced haulm growth before wilt symptoms were evident and it reduced tuber yield but not number. Oxamyl delayed infection byV. dahliae by controlling parasiticPratylenchus nematodes (mainlyP. thornei).  相似文献   

17.
Verticillium wilt, caused by Verticillium dahliae Kleb., is a primary component of the early dying complex of potato (Solanum tuberosum L.) in the United States. Although genetic resistance to V. dahliae exists and has been incorporated into several potato cultivars, the commercial potato industry is still dominated by cultivars susceptible to the pathogen. As a result, soil fumigation with metam sodium remains an important means by which Verticillium wilt is controlled, despite its expense and potentially negative environmental impact. Recent restrictions on metam sodium use by the Environmental Protection Agency directed at reducing exposure to vapor emissions have increased the need to improve shank injection of the soil fumigant. In studies reported here, the application of metam sodium reduced the severity of Verticillium wilt, however, soil temperature at the time of injection, metam sodium injection depth, and application rate had little overall effect. In 2011, temperature at the time of metam sodium injection did not result in significant differences in any parameter evaluated. However, in 2012, soil populations of V. dahliae, wilt severity and host colonization were significantly reduced when metam sodium was applied at 4 °C compared to 13 or 15 °C. No significant differences were observed between a single or two metam sodium injection depths in any parameter evaluated across the 2 years the study was conducted. While all rates of metam sodium significantly reduced soil populations of V. dahliae compared to the non-treated control, significant differences across rates were rarely observed. Improved control of Verticillium wilt and increased yield can be achieved as a result of these studies. The effective control of Verticillium wilt can be obtained by using metam sodium at a comparatively low rate of 373 l/ha, particularly when applied at a relatively cold soil temperature of 4 °C using a single injection depth of 25 cm. The potential impact of these application modifications of metam sodium in reducing emissions and non-target exposure is discussed.  相似文献   

18.
Talaromyces flavus a fungal antagonist, was isolated from soil samples collected from potato fields in Varamin and Karaj districts, Tehran province, Iran. Antagonistic effects of T. flavus isolates against Verticillium albo-atrum, the causal agent of potato wilt disease were investigated in the laboratory and greenhouse conditions. T. flavus colonies were recovered after three weeks from soil samples cultured on selective medium. Antagonistic effects of volatile and non-volatile extracts of T. flavus isolates on V. albo-atrum growth were investigated in the laboratory and five that caused higher growth inhibition of V. albo-atrum, were selected for greenhouse experiments. Infection index was compared in the greenhouse in a split plot trial with five isolates applied to soil, seed, or both arranged in a randomized complete block design with four replications. The minimum infection index was observed when seed were treated with T. flavus with the most effective isolate being Tf-Po-V-52. On seed, the minimum infection index was observed with Tf-Po-V-50. The most effective T. flavus isolate was also evaluated in a field experiment. Results indicated that infection index in seed treatment contained this isolate was 0.15 whereas that of control was 3.5. The overall results of this study showed that it may be possible to manage potato Verticillium wilt disease effectively by using T. flavus, a biocontrol fungus.  相似文献   

19.
Summary The interaction betweenErwinia carotovora subsp.atroseptica (Eca) andVerticillium dahliae and its effect on symptom development in potato cultivars showing different degrees of resistance to them was examined over two seasons in irrigated fields in a hot, dry climate. Four cultivars were used: Cara, highly resistant to blackleg and tolerant to Verticillium wilt; Pentland Crown also resistant to blackleg but susceptible to Verticillium wilt; Désirée, moderately susceptible to blackleg but tolerant to Verticillium wilt; and Maris Bard, susceptible to both diseases. Seed tubers were inoculated with Eca immediately after harvest in Scotland, to simulate natural infection, and then planted in Israel in soil naturally infested byV. dahliae. In Verticillium tolerant cultivars, Eca infection increased the rate of colonization byV. dahliae and significantly enhanced symptom development, as assessed by suppression of plant height and wilt symptoms. This report is a portion of the Ph.D. thesis of the senior author in Ben-Gurion University of the Negev.  相似文献   

20.
Pratylenchus penetrans andP. crenatus were the dominant plantparasitic nematodes in potato roots and soil in Prince Edward Island. No nematodes were recovered from potato tubers. Forage legumes and grasses grown in rotation with potatoes also harbored large populations of root lesion nematodes. The amount of water moving through the stems of potato plants infected withP. penetrans in the greenhouse generally was less than in nematode-free plants;P. crenatus did not produce this effect. Telone-II, Telone-C-17, and Temik reduced the number of nematodes substantially in field plots. Yields of Superiors, Kennebecs, Sebagos and Netted Gems in nematicide-treated plots were not significantly greater than in untreated plots. There was a small but significant reduction in the specific gravity of tubers in the Telone-treated plots.  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