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1.
Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evaluated alone and in combination, for their potential to reduce soilborne diseases and increase tuber yield over three field seasons in Maine. Both biocontrol organisms reduced multiple soilborne diseases, stem and stolon canker by 20–38 %, black scurf by 30–58 %, and common scab by 10–34 % relative to the nontreated control treatment, and the combination treatment of both biocontrol organisms together provided nominally better control than individual treatments. However, biocontrol treatments had no direct effect on tuber yield. Compost amendments from different sources all increased total and marketable tuber yield substantially (11–37 % and 17–51 %, respectively) relative to nontreated controls. However, except for some reduction of Rhizoctonia canker, compost amendments did not reduce soilborne diseases (black scurf and commons scab) in any year, and resulted in increased levels of common scab in some years (20–45 % increase). The combination compost-biocontrol treatment, although did not perform significantly better than individual component treatments, still provided indications of combined beneficial effects from both component treatments. This research demonstrated the usefulness of these approaches and combinations as additional options for reduction of soilborne diseases and increased tuber yield and can be implemented for enhanced sustainability and productivity in potato production systems.  相似文献   

2.
Common scab, black scurf and silver scurf belong to serious diseases of cultivated potato that especially impair tuber quality. Tuber infection in 44 potato (Solanum tuberosum ssp. tuberosum L.) varieties was evaluated using two measures – severity and incidence of infected tubers. Both measures were highly correlated. An important result derived from this study supports fungicide application against potato late blight secondarily acts on reducing tuber infection by all evaluated pathogens. Therefore, the conventional potato growing seems to be more effective compared to ecological growing. The pedigree analysis of 44 varieties indicated the presence of Solanum demissum genotypes in the variety genome may negatively affect variety response to Helminthosporium solani presence.  相似文献   

3.
Stem canker on germinating potato sprouts is often caused by seed-borne inoculum of the fungus Rhizoctonia solani. However, high amounts of free-living plant-parasitic nematodes have been found in field patches of potato plants with stem canker. Fungicide treatment of the seed tubers can be used to avoid stem canker caused by seed-borne inoculum but it is unknown if nematodes can affect this. To investigate whether free-living plant-parasitic nematodes, the root-lesion nematode Pratylenchus penetrans or a combination of several plant-parasitic nematode genera in a full nematode community, may have a negative effect on the fungicide seed treatment, a pot experiment with seed tubers inoculated with R. solani, half of which were treated with fungicides, was performed. The seed-borne inoculum caused severe damage to the plants, while no fungal damages were observed on the fungicide treated plants. This shows that the nematodes did not affect the fungicide treatment. The probability of black scurf decreased in treatments with a full nematode community, which may be due to the action of fungal-feeding nematodes.  相似文献   

4.
Summary Seed tubers, cv. Désirée, derived from stocks treated annually with thiabendazole were infected with thiabendazole-resistant strains ofHelminthosporium solani andPolyscytalum pustulans. Samples of seed tubers were either untreated or immersed for 5 min in fungicide suspensions of thiabendazole, imazalil or thiabendazole plus imazalil and planted on four farms in 1988 and 1989. After harvest, tuber samples from each treatment were treated with thiabendazole and stored for 6 months. Applying imazalil or thiabendazole plus imazalil to seed tubers decreased the severity of silver scurf and skin spot on stored progeny tubers. Thiabendazole applied to seed tubers or to progeny tubers after harvest did not affect the severity of either disease, but post-harvest treatment decreased the incidence of black scurf after storage.  相似文献   

5.
Thiabendazole insensitive strains ofHelminthosporium solani, the causal agent of silver scurf, make controlling the disease with seed treatment difficult. Potato tuber seed treatments and environmental storage management practices were investigated as means to minimize silver scurf. Fungicide seed treatments were evaluated for control ofH. solani; disease was evaluated during the growing season, at harvest, and after 5 months of storage. Silver scurf was observed on progeny tubers eleven weeks after planting. Fungicides that reduced silver scurf incidence and severity on the seed resulted in reduced incidence and severity of the disease in the progeny tubers at harvest and significantly lower disease ratings after storage. Only small increases in disease incidence (0-8%) were seen after storage. Thiophanate-methyl with mancozeb, Captan with mancozeb, and fludioxonil were among the most effective in reducing the incidence and severity of silver scurf on seed and in progeny tubers (Incidence on progeny tubers at harvest for these three treatments were 3%, 9%, and 8% respectively). Thiophanatemethyl alone was not effective for control of silver scurf (48% incidence compared to 43% incidence for the untreated control). Environmental conditions in storage affected disease development. Reduced humidity (85%) during the curing period (0–3 weeks after harvest) significantly reduced (11%) the surface area of tubers infected with silver scurf. Free moisture on the tuber surfaces during storage significantly increased (15%) tuber surface area infection.H. solani was shown to survive in soil and on some potato storage building materials for up to 9 months. The silver scurf disease of potatoes can be suppressed using effective seed treatment and storage management.  相似文献   

6.
Black scurf on seed tubers did not result in seed decay or stem cankers and did not affect the tuber yield in two field experiments at Ottawa and Fredericton. Seed pieces were classified into three disease categories: 0 to 1%, 1.1 to 5%, 5.1 to 15%, according to the percentage surface area covered by sclerotia ofRhizoctonia solani. The difference between disease categories, in the amount of black scurf on the seed, was perpetuated on the progeny tubers although the actual amount decreased.  相似文献   

7.
A randomized complete block field trial was conducted over 2 years to evaluate the herbicidal efficacy of glyphosate isopropylamine salt (Roundup®) applied singly at 1.41 kg a.e. ha−1 or in combination with ammonium sulphate (AMS) as surfactant at 0.5, 1.0, 1.5, and 2.0% (wt/v) in a 5-year old oil palm plantation of the Federal University of Technology, Akure located in the rainforest vegetation zone of Nigeria. Assessment of herbicidal efficacy based on the Henderson-Tilton formula indicated that glyphosate applied singly or in combination with varying concentrations of AMS proved highly effective in controlling most of the grasses and broadleaved weeds prevalent in the experimental plots. Herbicidal efficacy on total weed density, weed fresh weight as well as on weed dry weight was found to increase in the order of increasing concentration of AMS. Regressing percentage herbicidal efficacy (Y) against increasing concentration levels of AMS (X) indicated significant (P0.001) positive relationships with an average correlation coefficient (r) of +0.95 in both years. These results confirm the potential of AMS as an effective surfactant that can be exploited in glyphosate-based weed management schemes in the sub-humid tropical environment.  相似文献   

8.
河北省一季作区马铃薯主要病虫害有晚疫病、早疫病、黑痣病和二十八星瓢虫,此外,病毒引起的品种退化比较普遍,造成不同程度的损失。本文根据河北省一季作区马铃薯病虫害发生特点总结出一套综合防控技术体系,包括将马铃薯与玉米、大白菜等非茄科作物轮作3年减轻黑痣病危害;采用脱毒薯克服病毒引起的品种退化问题;种薯和(或)土壤消毒控制黑痣病和晚疫病;待马铃薯生长至封垄后,遇到适宜晚疫病发生的天气,喷施1～3次保护性杀菌剂预防晚疫病和早疫病;一旦监测到晚疫病中心病株后即拔除并装入塑料袋带出田外,并交替喷施有治疗效果、能兼治早疫病且作用机制不同的内吸性杀菌剂及混剂;田间出现马铃薯二十八星瓢虫成虫,在杀菌剂中混入高效氯氰菊酯或高效氯氟氰菊酯等高效杀虫剂防虫;马铃薯成熟前1～2周将地上部分割掉并运出田外后收获块茎。  相似文献   

9.
Silver scurf, caused by Helminthosporium solani, and black dot, caused by Colletotrichum coccodes, cause tuber blemishes on potato (Solanum tuberosum L.) which affect processing and fresh market trade. Tubers from ten cultivars were collected at harvest from three organic farms in Wisconsin and categorized as symptomatic or asymptomatic based on visual symptoms of silver scurf and black dot and/or signs of H. solani and C. coccodes. Tuber incubation and PCR assays were performed on asymptomatic tubers to detect H. solani and C. coccodes. Tuber incubation and PCR assays were in slight to fair agreement (kappa coefficient <0.4) for detecting both pathogens. Most asymptomatic tubers tested were positive by one or both assays for H. solani (75 %) or C. coccodes (94 %). Minituber inoculation assays were also performed to screen potato lines for resistance to silver scurf. Of the 14 lines tested, a diploid interspecific hybrid, C287, had consistently low sporulation, suggesting it has partial resistance to silver scurf. Since the majority of tubers harvested are already infected with one or both pathogens further research should focus on organically acceptable management practices that may inhibit disease development in field and in storage.  相似文献   

10.
The influence of tuber-borne pathogenicStreptomyces on potato common scab incidence in daughter tubers was examined under micro-plot conditions. Visually healthy tubers, surface-disinfested healthy tubers, and tubers with 25% scab coverage were planted in pasteurized soil. At 30, 57, and 93 days after planting, soil and belowground plant parts were sampled from various zones around the mother tuber. The total population of actinomyctes was determined by plating on a semiselective medium, and colonies of pathogenicStreptomyces were identified using polymerase chain reaction (PCR) targeting thetxtA gene. At day 30, pathogenicStreptomyces populations were below detectable levels, whereas by day 93, measurable levels were present on the belowground plant parts and in soil adjacent to scabby mother tubers at 104 to 105 CFU g?1 soil. Incidence of scab in the progeny tubers was 89% at harvest. Progeny tubers produced by visually healthy seed tubers had an incidence of 60% scab and substantial populations of pathogenicStreptomyces were present in the zone near the mother tuber (104 CFU g?1 soil). Plots planted with surface disinfested seed tubers had a very lowStreptomyces population in the tuber zone and yielded 100% marketable tubers. A perfect correlation (r = 1.00) was found between the population densities of pathogenicStreptomyces in the root zone and daughter tuber disease incidence indicating that measurement of such populations in the field can serve as an excellent predictor of scab disease. After harvest, populations of pathogenicStreptomyces (106 to 107 CFU g?1 lesion tissue) remained high on the mother tubers.  相似文献   

11.
Summary An isolate ofRhizoctonia solani AG8 from a barley plant affected with barley stunt was incorporated into soil and caused severe stunting of cv. Désirée potatoes grown in pots. Fresh weight of foliage, stem bases, roots and tubers were greatly decreased. Most main roots were pruned off and a large number of lateral roots developed, resulting in an unusually fibrous root system; many of these lateral roots were also pruned off. Infected plants did not have stem canker or stolon infection nor was black scurf found on progeny tubers.  相似文献   

12.
Silver scurf, caused byHelminthosporium solani, and black dot, caused byColletotrichum atramentarium, are pathogens of tuber periderm whose presence in Colorado was only recently reported. A field survey conducted in September 1977 revealed thatC. atramentarium was more prevalent (21.8% tuber infection) and had a wider distribution thanH. solani (5.4% tuber infection). A greater incidence of both pathogens was observed on thin skinned tubers of chipping cultivars (49.0% infection) than on thicker skinned tubers of table stock cultivars (9.1% infection). Conidial development ofH. solani is tretic, pleurogenous, and requires 17–21 hours per conidium. Conidial septations appear while conidial elongate, and require 3–5 hours per septum. Light microscopy revealed that at least 11 conidia per conidiophore are produced in culture in 54 hours at 20–25 C (68–77 F) and humidity >90%. Scanning electron microscopy showed that fructifications ofH. solani (conidiophores-conidia) arise from beneath infected tuber periderm. Histological studies indicate some peridermal loosening and sloughing. Heavy deposition of unidentified compounds was observed in infected periderm, and hyphae were restricted to periderm cells. Fresh weight loss of tubers naturally infected withC. atramentarium was significantly greater than fresh weight loss of nearly noninfected (< 1% surface area infected) control tubers. Periderm infected with eitherH. solani orC. atramentarium appeared similar, i.e. shriveled, suggesting infections from either pathogen may result in increased fresh weight loss through alteration of the periderm.  相似文献   

13.
In regions with short growth seasons, it is of great importance to use potato (Solanum tuberosum L.) seed tubers with a high growth vigour and a short growth cycle. Such qualities may be obtained by treatments advancing the physiological age of the seed tubers. In this study, we have exposed tubers from four cultivars to various combinations of temperature and light conditions (green-sprouting) for 3–7 months in controlled climate. Subsequent sprout quality, seed tuber health and performance were studied in laboratory, greenhouse and field trials. Satisfactory short, sturdy and leafy sprouts were produced even after 7 months storage at 15 °C under light exposure. An assay of black scurf (Rhizoctonia solani) on the tuber skin showed that light exposure significantly reduced the occurrence compared with dark-stored tubers, while the average effect of storage temperatures was insignificant. In general, green-sprouting advanced emergence and plant growth by 1–2 weeks, and showed early tuber initiation and growth, compared to untreated material. Yields, 107 days after planting in the field trial, did not deviate significantly from untreated tubers. However, plant development at harvest was in accordance with general responses to physiological ageing of potato seed tubers, i.e. still tall and immature plants from untreated tubers, and short and mature plants from aged tubers. Results demonstrated the possibility of successful long-term storage of potato seed tubers in light at elevated temperatures and a potential for earlier harvests and higher early yields from such treatments.  相似文献   

14.
The potato genotypes (Solanum tuberosum L.) with russet tuber skin are generally resistant to powdery scab (Spongospora subterranea f.sp. subterranea or Sss). Lipoxygenase (LOX; EC 1.13.11.12) and patatin are two key storage proteins that are known to offer resistance to several diseases and insects. The objective of this study was to find out the relationship of these proteins in stored tubers with potato tuber powdery scab resistance, especially in russet skinned potatoes. An evaluation of potato germplasm with different tuber characteristics in a greenhouse environment over several years (2006–’11) suggests that russet skinned tuber genotypes (Mesa Russet, Centennial Russet and Russet Nugget) with negligible tuber disease severity index (DSI) and 100 % marketability were resistant to powdery scab. Higher physiological levels of LOX protein (on a dry weight basis) were negatively correlated with tuber DSI and positively correlated with tuber russet skin. Tuber total protein and patatin-lipase levels did not have a significant relationship with tuber powdery scab resistance. The proposed role of LOX protein in suberin- and/or non-suberin-mediated mechanisms of powdery scab resistance in russet skinned tubers are discussed here. The physiological levels of LOX protein can be considered as a useful marker for powdery scab resistance in potato breeding programs.  相似文献   

15.
Crop damage is associated with infection by plant pathogens but can also arise through abiotic factors. However, the plant pathogens are involved in biotic interactions with other plant pathogens, and these interactions may differ depending of the cultivar of the crop. Here, the interaction between the fungus Rhizoctonia solani (AG3) and free-living plant-parasitic nematodes was investigated in a pot experiment with different potato cultivars. No synergistic interaction between R. solani and plant-parasitic nematodes was found, instead there was an effect of treatment with lower tuber yield when nematodes occurred alone. There were differences among the cultivars regarding incidence of black scurf, dry weight of stems and tubers, and there was interactive effects between treatment and cultivar regarding dry weight of stolons and roots. Therefore, results concerning incidence and damage of R. solani and/or plant-parasitic nematodes found for one cultivar may not be applicable to other cultivars.  相似文献   

16.
TX1523-1Ru/Y, a unique specialty cultivar with deep-yellow flesh color and an attractive russet skin, was released in 2003 by the Texas Agricultural Experiment Station. The smaller, immature tubers are round, but take on an oval shape as they mature. Eyes are shallow and the tuber surface is smooth. Tuber size tends to be medium (113.4–283.5 g; 4–10 oz). Total and marketable yield varies with year and location, but tends to be comparable to ‘Yukon Gold’, with percent marketable yield slightly higher. Vines are semi-prostrate, with medium vigor and size, and relatively early maturity. Specific gravity is about the same or slightly less than Yukon Gold, but generally greater than ‘Russet Norkotah’. TX1523-1Ru/Y has good culinary qualities, with resistance to after-cooking-darkening, and can be chipped, boiled, baked, or microwaved. It has been reported to be excellent to superior as a microwave product. Unlike Yukon Gold, TX1523-1Ru/Y is resistant to hollow heart, brown centers, and internal discoloration. It tends to be less susceptible to tuber infection by late blight (Phytopthora infestans) than Yukon Gold, has greater resistance to common scab (Streptomyces scabies), and is less susceptible to black scurf (Rhizoctonia solani). TX1523-1Ru/Y is believed to be the first yellow-fleshed resset-skin cultivar released in the United States.  相似文献   

17.
A survey of the prevalence of skin blemish diseases in potatoes after the growing seasons of 2008 and 2009 was carried out on 247 potato lots representing different cultivars and production regions in Norway. The results showed the presence of silver scurf (Helminthosporium solani) in all lots. Skin spot (Polyscytalum pustulans) and black scurf (Rhizoctonia solani) were found in 80% of the lots, and black dot (Colletotrichum coccodes) and common scab caused by Streptomyces spp. were present in 50–70%. Also, powdery scab (Spongospora subterranea) occurred in 65–80% of the lots, and root-lesion nematodes (Pratylenchus spp.) were detected in 60% of the sub-samples that exhibited symptoms of common scab.  相似文献   

18.
Millennium Russet is a medium-late variety with long tubers having light russet skin and white flesh. It has potential as a fresh market and processing (french fries) variety. The tuber type of Millennium Russet is similar to Russet Burbank, but with better external and internal quality. The marketable yield, tuber set, and specific gravity are higher than Russet Burbank. Tubers show good fry color when processed from cold storage (7.2 C). Millennium Russet has a bland flavor and is less mealy and discolored than Russet Burbank. Chemical maturity of Millennium Russet occurs at approximately the same time as Russet Burbank, but it has lower sucrose levels in the bud and stem end. The glucose levels of Millennium Russet were 50% less than Russet Burbank throughout the first 4 months of storage at 10 C. Low glucose levels in the stem end of Millennium Russet when processed out of storage suggest tolerance to stress and low vulnerability to sugar end. Millennium Russet is resistant to common scab and corky ring spot, moderately resistant to dry rot, pink rot, and black scurf, and moderately susceptible to Verticillium wilt, bacterial wilt and brown rot. Millennium Russet is more sensitive to blackspot bruise than Russet Burbank, but more resistant to shatter bruise. Tuber yield of Millennium Russet was less responsive to nitrogen rates when compared with Russet Burbank, but tuber size distribution was more responsive to increases in in-row spacing.  相似文献   

19.
Control of silver scurf on daughter tubers was obtained by imazalil applied to seed tubers as a pre- or post-storage treatment or as a furrow treatment (at time of planting), in three field experiments. Post-storage and pre- and post-storage combination treatments provided consistent results. The most effective treatment in the first and second experiments was the combined pre- and post-storage application of imazalil. However, separate pre- and post-storage treatment also significantly reduced the incidence compared with the non-treated control. No differences were observed between dosages of 15 and 30 g a.i. of imazalil per ton of seed tubers. Although furrow treatment at planting time (1.5 1/ha) significantly reduced silver scurf incidence on daughter tubers, it was less effective than seed treatments. However, the combined treatment of pre-storage application and furrow treatment significantly reduced the disease and was more effective than the single pre-storage seed treatment. In the third experiment, a reduction of disease incidence and severity index was obtained by post-storage treatments or with the combination of pre- and post-storage applications.  相似文献   

20.
Drycore is an important quality deficiency in Europe especially in organic potato production and after grass clover leys. The drycore symptom is attributed to Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris (Frank) Donk). In the framework of a 3-year survey (2001–2003), data concerning potato quality, crop rotation, management, and site parameters were analysed from 185 potato fields. The hypothesis was tested that injuries on potatoes caused by wireworms facilitate the penetration of R. solani and favour the formation of drycore. Analysis of variance showed a significant influence of wireworm damage, seed quality, and grass clover leys in the crop on the level of drycore damage. On fields which had both a low occurrence of black scurf on the seed tubers and a low occurrence of wireworm damage at harvest, significant drycore damage was never observed. The relative risk for drycore damage on tubers was significantly higher if black scurf or wireworm damage was on the same tuber. In contrast, no higher risk for drycore was observed on tubers with slug damage. Abiotic factors like farm manure application, organic matter content, texture, and pH of the soil also had no significant influence on the level of drycore. Thus, the wounding of potatoes by wireworm could be confirmed as the major variable for drycore. The mode of action has to be clarified under controlled conditions.  相似文献   

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