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  • Solanum tuberosum L.  (17)
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  • 1
    ISSN: 1871-4528
    Keywords: reducing sugars ; processing quality ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Reducing sugar and sucrose contents of potato tubers (Solanum tuberosum L.) from six cultivars were monitored both during the growing season and after a four months storage period at 10°C. Significant correlations were found between tuber sugar contents (sucrose, reducing and total) measured at harvest and the reducing sugar content after storage. Similarly, in five of the six cultivars, the sucrose loss and the corresponding reducing sugar gain during storage were significantly correlated.
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  • 2
    ISSN: 1871-4528
    Keywords: cultivar differences ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationships between the number of initial sprouts, the number of main stems, stolons and tubers per plant are depicted in 4-quadrant figures. The number of sprouts per seed tuber varied because of different pre-sprouting conditions and/or because of the use of different cultivars. Good linear relationships are shown between the numbers of sprouts and stems, stolons and tubers, and sprouts and tubers, but especially between stolons and tubers within each trial with the one cultivar. When comparing different experiments with the one cultivar the linear relationship between the numbers of stems and stolons disappeared. When comparing different cultivars, no relation was found between the numbers of sprouts and stems. These two cases also led to a statistically less significant relation between the number of sprouts planted and the number of tubers harvested.
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  • 3
    ISSN: 1871-4528
    Keywords: bacterial wilt ; controlled environment ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato plants, after inoculation with a South African strain of biovar 2 or a strain of biovar 3 ofPseudomonas solanacearum were grown in growth chambers at temperatures ranging from 14/16°C (dark/light) up to 25/30°C. When grown at 14/16°C or higher, plants inoculated with the biovar 2 strain developed wilting symptoms and internal symptoms on progeny tubers and the disease was transmitted by the progeny tubers. When the plants were inoculated with the biovar 3 strain, wilting symptoms developed from 18/20°C, internal symptoms on progeny tubers from 20/22°C and the disease was transmitted by progeny tubers from plants grown at 16/18°C or higher.
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  • 4
    ISSN: 1871-4528
    Keywords: Mediterranean region ; spring ; autumn ; cultivar response ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotypic variation in the adaptation of potatoes of several maturity classes to the specific climatological conditions of the autumn season, to the high summer temperatures and to water deficit, was studied. Late-maturing cultivars exhibited the highest yielding potential both in the spring and autumn seasons but specific compatibility of cultivars to the autumn was detected. The late-maturing cultivars were more susceptible to high temperatures than were the early ones. However, there were significant differences in susceptibility to high temperatures among cultivars of the same maturity class. Susceptibility to water deficit was similar in the various maturity classes, but there were differences in the susceptibility to drought among cultivars of the same maturity class. High yielding potential generally resulted also in acceptable tuber yields under conditions of water deficit. High temperatures in combination with a water deficit aggravated yield losses, especially in the late-maturing cultivars.
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  • 5
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    Potato research 33 (1990), S. 97-108 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; photoperiod ; sucrose ; glucose ; fructose ; reducing sugars ; periderm ; crisp color ; chip color
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Single leaf cuttings with their subtended axillary buds proved to be useful models to study maturation and senescence in potato (Solanum tuberosum L.). Senescence was more rapid if the cultivar was early maturing or if plants were exposed to short days before cuttings were taken. Rooting was decreased by short days before cutting; excision of the buried bud only partially overcame the effects on senescence and rooting. High rates of N to mother plants in the field delayed senescence of cuttings in a way analogous to the delayed senescence of field plants. The tuberization of cuttings from late maturing cultivars was decreased by high rates of N. The color of crisps made from bud tubers was positively correlated with the color of crisps made from ordinary tubers of the same cultivars. Sugar concentrations in bud tubers decreased as cuttings became more senescent and increased after cold storage. Bud tubers harvested while ‘immature’ had greater concentrations of reducing sugars after 90 d at 10°C than did ‘mature’ bud tubers.
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  • 6
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    Potato research 33 (1990), S. 131-133 
    ISSN: 1871-4528
    Keywords: disease screening ; Phoma exigua var.foveata ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tubers were obtained from 80 glasshouse-grown seedlings of each of twelve progenies, inoculated withPhoma foveata Foister, and the mean percentage of infected tubers recorded. There was a good correlation (r=0.798) between this assessment and that made previously on field-grown tubers of eleven of the progenies. A gangrene test on glasshouse-grown tubers is suggested as a more rapid means of identifying progenies with useful levels of resistance.
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  • 7
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    Potato research 33 (1990), S. 487-495 
    ISSN: 1871-4528
    Keywords: PVS ; ELISA ; cDNA ; cloning ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two complementary DNA (cDNA) clones (0.9 kb and 1.6 kb) reacting to the ordinary strain of potato virus S (PVS) were compared with single-stranded randomly primed cDNA (prepared to total genomic RNA) as probes for various strains of PVS, using the technique of nucleic acid spot hybridization (NASH). The cDNA clones detected 11 PVS isolates well, including both Andean and ordinary strains, while one of each strain was detected weakly. As little as 5 femtograms of PVS RNA could be detected. A low cross hybridization was observed with cDNA probes to PVS with potato virus M and carnation latent virus both members of the carlavirus group. No cross homology was detected with seven other potato viruses. NASH was as sensitive and specific as enzyme-linked immunosorbent assay (ELISA), with no pretreatments of crude sap being required before spotting on nitrocellulose filters. Cloned cDNA probes would be suitable for mass screening of PVS.
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  • 8
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    Potato research 33 (1990), S. 433-440 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potatoes were stored in three insulated bins having ventilation rates of 0.0190, 0.0306 and 0.0417 m3/s·t. The results showed that in the climate of northern Italy potatoes can be stored successfully at ventilation rates of not less than 0.0306 m3/s·t resulting in product weight loss of less than 2.0% after 100 days' storage. The incidence of diseases and of sprouting was very low at rates of 0.0306 and 0.0417 m3/s·t, but greater at 0.019 m3/s·t because of the higher tuber temperature. Laboratory tests simulating ambient conditions confirmed the validity of a thermodynamic model simulating air-potato heat exchange.
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  • 9
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    Potato research 33 (1990), S. 417-432 
    ISSN: 1871-4528
    Keywords: stolonization ; tuberization ; tuber bulking ; size grade ; stem number ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tuber-size distribution is regulated by many diverse, interacting mechanisms and is therefore difficult to understand and manipulate. It is determined by plant density, number of stems per plant, number of tubers per stem, and yield. Seed size and plant number per unit area are easy to control, but stem number is affected by less controllable factors. Interactions between stems of different types are important for tuber-size distribution. The hormonal regulation of stolonization and tuberization is still unknown, but under the conditions of north-west Europe the process of tuber set (which is also poorly understood) makes a greater contribution to the final number of tubers than tuberization. The total yield is also relevant, because it affects both the average tuber size and its variation. Tubers on the same stem differ in timing, rate and duration of growth. The resulting hierarchy in sink strength is not consistent over time. Several mechanisms are suggested for this hierarchy.
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  • 10
    ISSN: 1871-4528
    Keywords: DNA probe ; nick-translation ; diagnosis ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary To assess the reliability of dot-spot hybridization assay for the Potato Spindle Tuber Viroid, more than 1000 potato samples were cross-tested by biological and hybridization methods. Both methods gave similar results with a range of cultivars. The dot-spot hybridization test was reproducible with formaldehyde-denaturated cell-sap samples stored at room temperature for over 6 months. This finding means that samples can be transported from field stations to a diagnostic laboratory and allows for cross-checking of results between laboratories. The data suggest that dot-spot hybridization is suitable for breeding and quarantine purposes.
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  • 11
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    Potato research 33 (1990), S. 125-130 
    ISSN: 1871-4528
    Keywords: dehydroascorbic acid ; HPLC ; Dutch Food Composition Table ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Loss of vitamin C (L-ascorbic acid) from Dutch table potatoes during storage at 5–6°C over 8 months from November to July, was studied in two seasons. L-Ascorbic and dehydroascorbic acid were analysed by HPLC. The amount of dehydroascorbic acid was negligible. Total loss of L-ascorbic acid varied between 21 and 60%. Some potato lots lost L-ascorbic acid rapidly in the first four months, others more gradually over the whole storage period. The L-ascorbic acid levels detected were 75–150% higher in the period March–June, but 35% lower in the period December–February than those indicated by the step-wise decreases in the Dutch Food Composition Table.
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  • 12
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    Potato research 33 (1990), S. 235-239 
    ISSN: 1871-4528
    Keywords: processing quality ; glucose ; fructose ; sucrose ; storage ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Reducing sugar and sucrose content of potato tubers (cv. Record) grown in Tayside (northern United Kingdom (UK)) and Lincolnshire (southern UK) were monitored during the 1984 growing season and after two months storage at 10°C. Neither latitude nor agronomic factors were shown to affect sugar content. Significant correlations were found between the post storage reducing sugar content and the sugar contents measured at harvest. Regression analyses indicated that in immature tubers sucrose breakdown was responsible for reducing sugar accumulation during storage.
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  • 13
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    Potato research 33 (1990), S. 335-340 
    ISSN: 1871-4528
    Keywords: water saturation ; tuber injury ; lenticel perforation ; tuber maturity ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The intercellular volume within tuber tissue increases with tuber maturation. At the same time, both tuber injury after mechanical load and lentical perforation after water uptake by tubers in wet peat decreases. The degree of tuber injury is correlated with intercellular space (r=−0.667,n=16) and with water saturation of tissue (r=0.697,n=16). The tubers lose water during storage. In wet soil wilted tubers take up significantly higher amounts of water than turgid tubers, and lenticel perforation is much more frequent. Tuber maturation in autumn and low water loss during storage enhance the cushioning effect of the intercellular gas volume of tuber tissue against outside mechanical load and internal tension after water uptake.
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  • 14
    ISSN: 1573-5036
    Keywords: cell sap ; chloride ; fertilizer ; potassium ; potato ; Solanum tuberosum L. ; solute potential ; source: sink ; sulphate ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In pot experiments with Solanum tuberosum L. (cv Saturna) the application of KCl as compared to K2SO4 delayed tuber development. The solute composition of leaves of the KCl treated plants was significantly lower in K+ and NO3 -, but higher in Mg2+, Ca2+ and Cl-. Since the solute potential in the KCl treated plants was more negative and associated with a higher water content, a higher turgor pressure can be assumed. This could explain the enhanced shoot growth observed with KCl. Application of K2SO4, on the other hand, accelerated the development of tubers. This might result from a less competitive shoot sink in K2SO4 treated plants and a stimulated phloem loading and translocation of assimilates by higher concentrations of leaf-K.
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  • 15
    ISSN: 1573-5036
    Keywords: enzyme activity ; potassium nutrition ; potato ; Solanum tuberosum L. ; starch synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Starch synthesis in potato tubers grown at varied K nutrition 0.1 (K1), 0.25 (K2) and 1.0 mmol K L- nutrient solution (K3) was investigated with particular regard to the activity of selected enzymes (sucrose synthase, UDP-D-glucose pyrophosphatase, starch phosphorylase, amylases) in dependence on tuber K content. Allocation of K to the tubers was nearly the same in all treatments. The activity of enzymes related to tuber K content did not differ significantly. Starch and K content of tubers increased with progressing age, whereas a decrease was observed in growth rate, starch synthesis per day and K uptake per day. Positive correlations between the rates of K uptake, starch production and growth indicate that the dynamic phase of K supply to the tubers is of greater importance for starch synthesizing processes than the influence of total K content.
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  • 16
    ISSN: 1573-5036
    Keywords: chemical compounds ; field and pot trials ; mathematical optimization model ; mineral nutrients ; potato ; Solanum tuberosum L. ; threshold values ; tuber yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data of yield characteristics and the main chemical compounds of potato tubers, received from special NPK-fertilized pot and field trials, were individually evaluated by multiple regression analysis. The best suited mathematical functions, including linear, quadratic and interactive terms of N-, P- and K-concentrations in tuber dry matter, were integrated as independent variables into the models and the SUMT-method was applied for the nonlinear programming. Particular nutrient requirements could be derived from different NPK-ratios which were obtained by optimization. These ratios led to maximum tuber yield (=objective function) while at the same time observing special threshold values (e.g. nitrate) or limiting indices (=constraints) of tuber quality. By means of simulation it was possible to demonstrate characteristic differences between the effect of N-fertilization and varied N-concentrations on tuber yield and composition. Calculation of dependent variables by fixed NPK-ratios of the tubers resulted in excellent correspondence of the values for several parameters with the predictions made by both models, which were based on pot or field experiments.
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  • 17
    ISSN: 1573-8469
    Keywords: Canopy enclosure ; stomatal conductance ; light response curve ; light use efficiency ; photosynthesis ; Solanum tuberosum L. ; transpiration ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Aardappelplanten (Solanum tuberosum L.) cv.Saturna werden onderworpen aan stress als gevolg vanVerticillium dahliae en droogte. In vroege stadia van de groei werden stomataire geleiding, transpiratie en netto fotosynthese bij lichtverzadiging (PAR〉300 W m−2) gemeten aan individuele bladeren en met een mobiel instrumentarium met behulp van gewaskappen. Er werden geen significante verschillen gevonden in de waarden van de stomataire geleiding en de gasuitwisslingskarakteristieken als gevolg vanV. dahliae-besmetting tot een maand na opkomst. Daarna leidde infectie metV. dahliae tot een afname van de stomataire geleiding, transpiratie en netto fotosynthese, speciaal bij oudere bladeren en bij planten die meer aan zonlicht waren blootgesteld. Soms vertoondeV. dahliae interactie met droogte en bleken beide effecten minder dan optelbaar. De hoge waarden van de variatiecoëfficiënten maakten een groot aantal metingen per behandeling noodzakelijk; dit was vooral het geval bij metV. dahliae geïnfecteerde planten hetgeen aantoont datV. dahliae vooral in het begin van de groei niet alle bladeren in gelijke mate aantast. Door de matigende invloed van de integratie van alle bladlagen en mogelijk doordat de bovenste bladeren werden gestimuleerd, werd de totale gewasfotosynthese in mindere mate beïnvloed doorV. dahliae dan de individuele bladfotosynthese. De bovenste niet geïnfecteerde bladeren bleken verantwoordelijk voor het grootste gedeelte van de gewas-fotosynthese. De resultaten tonen aan, dat volgend op een infectie metV. dahliae, de fotosynthese reeds in een vroeg stadium van de groei wordt verminderd als een gevolg van droogtestress in de bladeren.
    Notes: Abstract Potato (Solanum tuberosum L.) plants cv.Saturna were subjected to infection withVerticillium dahliae and drought stress. At the early stages of growth, stomatal conductance, transpiration and net photosynthesis were measured at light saturation (PAR〉300 m−2) on individual leaves and with mobile field equipment with the aid of field enclosures. No significant changes in stomatal conductance and gas exchange characteristics occurred as a result ofV. dahliae instomatal conductance, transpiration and and photosynthetic rates, especially on older leaves and on plants exposed to direct sunlight for a longer period of time. In combination with drought,V. dahliae only occasionally showed interaction; their effects being less than additive. High values of coefficients of variatoon necessitated a high number of measurements per treatment; the more so in the inoculated plants which shows thatV. dahliae seems to affect certain leaves while not affecting others early in growth. Crop photosynthesis was less reduced byV. dahliae than individual leaf photosynthesis due to the levelling effect of integration over the whole canopy and possibly through a stimulation of the top leaves. The upper non-affected leaves are responsible for the bulk of photosynthetic crop activity. The results indicate that following an infection withV. dahliae photosynthesis is reduced early in growth as a result of drought stress in the leaves.
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  • 18
    ISSN: 1573-5036
    Keywords: biological control ; cucumber ; Cucumis sativus ; Pythium damping-off ; Pythium nunn ; Pythium ultimum ; Trichoderma harzianum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two biological control agents, Pythium nunn and Trichoderma harzianum isolate T-95, were combined to reduce Pythium damping-off of cucumber in greenhouse experiments lasting 3–4 weeks. T. harzianum T-95, a rhizosphere competent mutant, was applied to seeds and P. nunn was applied to pasteurized and raw soils naturally and artificially infested with Pythium ultimum. Some treatments were also amended with bean leaves to enhance the activity of P. nunn. The biological control of Pythium damping-off was evaluated in a Colorado soil (Nunn sandy loam) and an Oregon soil mix, which were replanted twice after 2 and 3 months. Interactions between P. nunn and T-95 were detected in the Colorado but not the Oregon soil. No consistent evidence of antagonism between P. nunn and T. harzianum was seen, and significant interactions were detected in the Colorado, but not the Oregon soil. In the first planting of some treatments, the combination of P. nunn and T. harzianum gave greater control of damping-off than either applied alone. P. nunn was most effective in soils that were pasteurized or amended with bean leaves. T. harzianum controlled Pythium damping-off in the Colorado, but not the Oregon soil. In both soils, disease declined over time in treatments amended with bean leaves but without P. nunn or T. harzianum added. This suppression was greater in the Colorado soil, which contained an indigenous population of P. nunn. This work demonstrates that two compatible biological control agents can be combined to give additional control of a soil-borne plant pathogen.
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  • 19
    ISSN: 1573-5036
    Keywords: biological control ; Gaeumannomyces graminis var.tritici ; take-all ; Trichoderma harzianum ; T. koningii ; T. hamatum ; pyrones ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Antagonism tests on agar-plates and glasshouse screening indicated that three isolates ofTrichoderma harzianum varied in their ability to antagonize the take-all fungus (Gaeumannomyces graminis var.tritici). Isolate 71 which was the most effective in suppressing take-all of wheat, produced two pyrones and other undetermined analogues. Isolates ofT. koningii andT. hamatum shown to suppress take-all, produced a simple pyrone compound. AlthoughT. harzianum isolates 70 and 73 did not produce any pyrones, they reduced the disease albeit to a much lesser extent than isolate 71; with isolate 73 showing distinct host growth promotion effects. It is proposed that the success of isolate 71 ofT. harzianum was related to the pyrones it produces and that the ability of isolates 70 and 73 to reduce take-all may be related to mechanisms other than those involving antibiotics.
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  • 20
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    Plant and soil 125 (1990), S. 233-238 
    ISSN: 1573-5036
    Keywords: biological control ; bioluminescence ; Enterobacter cloacae ; lettuce ; Pythium ultimum ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plasmid pUCD607 was mobilized into the biocontrol agent Enterobacter cloacae strain E6 by conjugation and the resultant strain, E6(pUCD607), was bioluminescent. Biocontrol of Pythium ultimum by E6(pUCD607) was similar to that of the parent strain, E6. The location of E6(pUCD607) in the soil and in the rhizosphere of lettuce was readily determined by pressing agar medium against plant roots in a root box, allowing the bacteria to grow overnight on the medium, and detecting the presence of bioluminescence by autophotography. There was a positive, linear correlation between population sizes determined by dilution plating and the quantity of light emitted due to bioluminescence. However, both the intercept and slope of this line varied among experiments possibly due to the differing physiological states of cells recovered from soils. The amount of light emitted by the bioluminescent strain E6(pUCD607) was not quantitative. This technique is useful for qualitative determinations of populations and for photographically locating bacteria.
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  • 21
    ISSN: 1573-5036
    Keywords: antibiosis ; bacterization ; biological control ; bacterial wilt ; Bacillus spp. ; Pseudomonas fluorescens ; Pseudomonas solanacearum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract From among 125 strains of fluorescent and 52 strains of nonfluorescent bacteria initially screened in the laboratory for their antibiosis towards the bacterial wilt pathogen, Pseudomonas solanacearum, strain Pfcp of Pseudomonas fluorescens and strains B33 and B36 of Bacillus spp., were chosen and evaluated further in greenhouse and field tests. Pfcp treated banana (Musa balbisiana), eggplant and tomato plants were protected from wilt upto 50, 61 and 95% in greenhouse and upto 50, 49 and 36% respectively in field. Protection afforded by the Bacillus strains was lower. In bacteria-treated plants which were subsequently inoculated with P. solanacearum plant height and biomass values increased and were close to those of nontreated and noninoculated control plants.
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  • 22
    ISSN: 1573-5036
    Keywords: biological control ; Gaeumannomyces graminis var. tritici ; take-all ; Trichoderma harzianum ; T. koningii ; T. hamatum ; pyrones ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Antagonism tests on agar-plates and glasshouse screening indicated that three isolates of Trichoderma harzianum varied in their ability to antagonize the take-all fungus (Gaeumannomyces graminis var. tritici). Isolate 71 which was the most effective in suppressing take-all of wheat, produced two pyrones and other undetermined analogues. Isolates of T. koningii and T. hamatum shown to suppress take-all, produced a simple pyrone compound. Although T. harzianum isolates 70 and 73 did not produce any pyrones, they reduced the disease albeit to a much lesser extent than isolate 71; with isolate 73 showing distinct host growth promotion effects. It is proposed that the success of isolate 71 of T. harzianum was related to the pyrones it produces and that the ability of isolates 70 and 73 to reduce take-all may be related to mechanisms other than those involving antibiotics.
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  • 23
    ISSN: 1573-5036
    Keywords: biological control ; cucumber ; Cucumis sativus ; Pythium damping-off ; Pythium nunn ; Pythium ultimum ; Trichoderma harzianum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two biological control agents,Pythium nunn andTrichoderma harzianum isolate T-95, were combined to reduce Pythium damping-off of cucumber in greenhouse experiments lasting 3–4 weeks.T. harzianum T-95, a rhizosphere competent mutant, was applied to seeds andP. nunn was applied to pasteurized and raw soils naturally and artificially infested withPythium ultimum. Some treatments were also amended with bean leaves to enhance the activity ofP. nunn. The biological control of Pythium damping-off was evaluated in a Colorado soil (Nunn sandy loam) and an Oregon soil mix, which were replanted twice after 2 and 3 months. Interactions betweenP. nunn and T-95 were detected in the Colorado but not the Oregon soil. No consistent evidence of antagonism betweenP. nunn andT. harzianum was seen, and significant interactions were detected in the Colorado, but not the Oregon soil. In the first planting of some treatments, the combination ofP. nunn andT. harzianum gave greater control of damping-off than either applied alone.P. nunn was most effective in soils that were pasteurized or amended with bean leaves.T. harzianum controlled Pythium damping-off in the Colorado, but not the Oregon soil. In both soils, disease declined over time in treatments amended with bean leaves but withoutP. nunn orT. harzianum added. This suppression was greater in the Colorado soil, which contained an indigenous population ofP. nunn. This work demonstrates that two compatible biological control agents can be combined to give additional control of a soil-borne plant pathogen.
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  • 24
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    Plant and soil 129 (1990), S. 85-92 
    ISSN: 1573-5036
    Keywords: biological control ; chitinase ; cloning ; parasitism ; antibiosis ; competition ; rhizosphere ; Serratia marcescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacterial antagonism, responsible for biological control, may operate by antiobiosis, competition or parasitism. Parasitism relies on lytic enzymes for the degradation of cell walls of pathogenic fungi. Serratia marcescens was found to be an efficient biocontrol agent of Sclerotium rolfsii and Rhizoctonia solani under greenhouse conditions. Populations of 105 or 106 colony forming units g-1 soil were the most effective. Drench and drip application of S. marcescens suspension were more effective in controlling S. rolfsii than spraying, mixing in soil or seed coating. The highest population density of the bacteria in the rhizosphere was found on the proximal portion of the root, decreasing significantly until the tips, where it increased again. The isolated Serratia, found to possess chitinolytic activity, was able to release N-acetyl D-glucosamine from cell walls of S. rolfsii. The gene coding for chitinase was cloned into Escherichia coli and the enzyme was uniquely excreted from the bacterium into its growth medium. When S. rolfsii was sprayed by partially purified chitinase produced by the cloned gene, rapid and extensive bursting of the hyphal tips was observed. This chitinase preparation was effective in reducing disease incidence caused by S. rolfsii in beans and R. solani in cotton, under greenhouse conditions. A similar effect was obtained when a viable E. coli cell, containing the plasmid with the chitinase gene (pLCHIA), was applied. It appears that genetic engineering of the lytic enzymes, such as chitinase which play an important role in plant disease control, may improve the efficacy of biocontrol agents.
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plant pathology 96 (1990), S. 119-132 
    ISSN: 1573-8469
    Keywords: biological control ; carnation ; iron ; pseudomonads ; rockwool ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Verwelkingsziekte in anjers op steenwol, veroorzaakt doorFusarium oxysporum f. sp.dianthi (Fod), werd gereduceerd indien het ijzer-chelaat Fe-EDDHA in plaats van Fe-DTPA werd toegevoegd aan de nutriëntenvloeistof. Bacterisatie metPseudomonas sp. stam WCS417r had een additioneel effect bij de matig resistence cultivar Pallas maar niet bij de vatbare cultivar Lena. Toevoeging van Fe-EDDHA in plaats van Fe-DTPA aan planten als ijzerbron resulteerde op de wortels in hogere aantallen en percentages fluorescerende pseudomonaden, diein vitro antagonistisch waren ten opzichte vanFod. De verschillen waren echter alleen significant 56 dagen na planten voor de cultivar Lena en 14 en 28 dagen na planten voor de cultivar Pallas. Beide chelaten vertoonden bij verschillende concentraties geen effect op de kolonisatie van de wortel door beide microorganismen. Echter, wanneer beide micro-organismen gezamelijk werden toegevoegd nam de wortelkolonisatie doorFod stam WCS816 af bij concentraties lager dan 10−5 M Fe-EDDHA. Er werd meer van het siderofoor fusarine doorFod stam WCS816 geproduceerd bij concentraties lager dan 10−4 M Fe indien Fe-EDDHA in plaats van Fe-DTPA als ijzerbron aan het cultuurmedium was toegevoegd. Er werd geen effect van beide chelaten gevonden op de siderofoorproduktie door WCS417r. Indien een overmaat van het gezuiverde siderofoor van WCS417r werd toegevoegd aan Fe-EDDHA werden een sterkere afname van de kiembuislengte gevonden dan toevoeging aan Fe-DTPA. De reductie van de kiembuislengte bleek niet volledig verklaard te kunnen worden door een afname van de ijzerbeschikbaarheid. Het chelaat EDDHA heeft ook een toxisch effect op conidiën van fusarium. Wij concluderen, dat de waargenomen reductie van de verwelkingziekte door Fe-EDDHA een gevolg is van de afname van de ijzerbeschikbaarheid voorFod. Dit wordt waarschijnlijk versterkt door de ontwikkeling van een antagonistische, fluorescerendePseudomonas-populatie die sterk concurreren om ijzer. Het additioneel effect dat door bacterisatie metPseudomonas sp. WCS417r van de met Fe-EDDHA behandelde matig resistante anjers (‘Pallas’) werd verkregen is voor een deel het gevolg van een directe concurrentie om ijzer tussen de sideroforen vanFod stam WCS816 en vanPseudomonas sp. stam WCS417r.
    Notes: Abstract In carnations grown on rockwool disease incidence of fusarium wilt caused byFusarium oxysporum f.sp.dianthi (Fod) was reduced when Fe-EDDHA instead of Fe-DTPA was used as iron source in the nutrient solution. Addition ofPseudomonas sp. strain WSC417r intensified this reduction in the cultivar Pallas, moderately resistant to Fusarium, but not in the susceptible cultivar Lena. Treatment of plants with Fe-EDDHA instead of Fe-DTPA as iron source resulted in higher numbers and percentages on the roots, ofin vitro antagonistic fluorescent pseudomonads. However, differences were only significant at 56 days after planting for cv. Lena and at 14 and 28 days after planting for cv. Palas. Both chelators, at different concentrations, had no effect on root colonization by eitherPseudomonas sp. strain WCS417r orFod strain WCS816. However, when coinoculated, reduced numbers of propagules ofFusarium were found at concentrations of Fe-EDDHA lower than 10−5 M. Higher concentrations of the siderophore fusarine produced byFod strain WCS816 were demonstrated when Fe-EDDHA instead of Fe-DTPA was used as iron source in culture media. At equal concentrations, no such differences were found in the amount of siderophore produced by WCS417r. Germ tube length ofFod was less with Fe-EDDHA than with Fe-DTPA. The reduction of germ tube length was stronger when the purified siderophore of WCS417r was added in excess to the culture media with Fe-EDDHA than those with Fe-DTPA. Therefore, the observed reduction of germ tube growth can not completely be explained by iron deprivation. It appeared that EDDHA exhibited a toxic effect for conidia ofFod strain WCS816 as well. we conclude that the observed disease reduction by Fe-EDDHA is a consequence of a limitation of iron availability forFod. This limitation is possibly intensified by the increase in number or percentage of antagonistic fluorescent pseudomonads that strongly compete for iron. The additional effect after bacterization withPseudomonas strain WCS417r in Fe-EDDHA treated carnations of cv. Pallas is likely to be due, at least partly, to a direct competition for iron between the siderophores ofFod strain WCS816 and ofPesudomonas sp. strain WCS417r.
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  • 26
    ISSN: 1573-8248
    Keywords: Orius insidiosus ; Spodoptera frugiperda ; biological control ; predation ; functional response ; Orius insidiosus ; Spodoptera frugiperda ; lutte biologique ; prédation ; réponse fonctionnelle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé On a observé que les adultes d'O. insidiosus mangeaient les œufs et les stades les plus jeunes de la chenille «légionnaire»Spodoptera frugiperda (J. E. Smith). Il y avait significativement plus de larves néonates tuées en 24 h que de larves âgées de 1, 2 ou 3 jours. Les prédateurs mâles et femelles ont montré une réponse fonctionnelle de type II lorsqu'ils se nourrissaient sur des densités variées d'œufs et de larves néonates de la chenille «légionnaire».
    Notes: Abstract Orius insidiosus (Say) was observed to successfully prey on eggs and earlier instar larvae of the fall armyworm (FAW),Spodoptera frugiperda (J. E. Smith). Significantly more neonates of FAW were killed per 24 h than either 1, 2 or 3 d old larvae. Female and male predators exhibited a typical type-II functional response when preying on varying densities of eggs or neonates of FAW.
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  • 27
    ISSN: 1573-8248
    Keywords: Euclasta whalleyi ; Euclasta maceratalis ; Cryptostegia grandiflora ; Gymnanthera nitida ; biological control ; Euclasta whalleyi ; Cryptostegia grandiflora ; Gymnanthera nitida ; Euclasta maceratalis ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé A Madagascar, la pyraleEuclasta whalleyi Popescu-Gorj & Constantinescu, se trouve surCryptostegia grandiflora R. br. et les autres genres de la sous-famille desPeriplocoideae de la famille desAsclepiadaceae. Les études faites sur sa biologie et sa spécificité ont montré qu'elle était inféodée à cette sous-famille. LeGymnanthera nitida R. Br. originaire d'Australie, fait aussi partie de cette sous-famille, et est l'hôte d'une espèce d'Euclasta originaire d'Australie,E. maceratalis Lederer. Malgré la possibilité d'attaquerG. nitida, et de rivaliser avecE. maceratalis, E. whalleyi a été approuvé pour être lâché en Australie en octobre 1987. Durant l'année 1988 plus de 22 000 larves ont été lâchées dans la nature, mais leur établissement n'y a pas encore été prouvé.
    Notes: Abstract In Madagascar, the leaf feeding Pyralid,Euclasta whalleyi Popescu-Gorj & Constantinescu, occurs onCryptostegia grandiflora R. Br. and other genera in the subfamilyPeriplocoideae of the familyAsclepiadaceae. Studies on its biology and host plant specificity have shown it is restricted to this subfamily. The Australian native,Gymnanthera nitida R. Br., also belongs to this sub-family and is host to an Australian native moth,Euclasta maceratalis Lederer. Despite the likelihood ofE. whalleyi feeding onG. nitida and competing withE. maceratalis, the moth was approved for release in Australia in October 1987. During 1988 over 22,000 larvae were released; field establishment is not yet proven.
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  • 28
    ISSN: 1573-8248
    Keywords: Heteroptera ; Miridae ; Macrolophus caliginosus ; predation ; functional response ; feeding preference ; biological control ; Myzus persicae ; Tetranychus urticae ; Heteroptera ; Miridae ; Macrolophus caliginosus ; prédation ; réponse fonctionnelle ; préférence alimentaire ; lutte biologique ; Myzus persicae ; Tetranychus urticae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'étude en laboratoire des réponses fonctionnelles des femelles adultes deMacrolophus caliginosus Wagner vis-à-vis des deux proiesMyzus persicae Sulzer etTetranychus urticae Koch montre dans les 2 cas une réponse de type II deHolling (1959). L'estimation du temps de manipulation (Th) et du taux d'attaque instantané (a) pour l'aphide (Th=.055 jour; a=1.035) et pour l'acarien (Th=.025 jour; a=.947) permet d'établir un modèle mathématique décrivant la prédation sur les 2 proies présentes simultanément et de préciser ainsi, au regard des résultats expérimentaux, l'existence d'une préférence du miride pour le puceronM. persicae.
    Notes: Abstract Functional response studies of females ofMacrolophus caliginosus Wagner for 2 prey speciesMyzus persicae Sulzer andTetranychus urticae Koch showedHolling's type II response (1959). Estimations of handling time (Th) and attack rate (a) obtained for the aphid (Th=.055 day; a=1.035) and for the mite (Th=.025 day; a=.947) enabled the development of a mathematical model which describes the predation rate on the 2 prey simultaneously. This mirid shows a sharp preference for aphids over mites.
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  • 29
    ISSN: 1573-8248
    Keywords: Diaeretiella rapae ; cabbage aphid ; biological control ; allelochemic ; synomone ; Diaeretiella rapae ; puceron du chou ; lutte biologique ; allélochimique ; synomone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Une interaction transmise apparemment par synomones entreDiaeretiella rapae, parasitoïde primaire et le puceron du Chou,Brevicoryne brassicae a été étudiée dans les conditions naturelles. L'application directe d'une émulsion d'allylisothiocyanate à la dose de 0,25 ml par plant de Chou donnait des taux de parasitisme et/ou un nombre d'hyménoptères plus élevés que ceux observés sur plants traités avec 0,25 ml d'eau ou avec 0,25 ml d'extrait de moutard sauvage. Ces résultats suggèrent l'existence d'une interaction transmise par synomone entre les espèces impliquées indiquant des chemins potentiels pour accroître les taux de parasitisme naturels par la manipulation de l'environnement chimique des cultures de Colza.
    Notes: Abstract An interaction apparently mediated by synomones (Nordlund et al., 1981) betweenDiaeretiella rapae (M'Intosh), a primary parasitoid and the cabbage aphid,Brevicoryne brassicae (L.), was investigated under field conditions. Direct application of an allylisothiocyanate emulsion at a rate of 0.25 ml per broccoli plant consistently gave higher aphid parasitization rates and/or number of wasps per plant than those observed on plants treated with 0.25 ml of water or with 0.25 ml of wild mustard extract. These results suggest the existence of a synomonemediated interaction between the species involved, indicating potential avenues to enhance field parasitization rates through manipulation of the chemical environment of cole cropping systems.
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  • 30
    ISSN: 1573-8248
    Keywords: biological control ; egg parasitoids ; orchard pests ; false codling moth ; Lutte biologique ; parasitoödes oophages ; ravageurs de vergers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Dans la partie ouest de la province du Cap, en Afrique du Sud, des lâchers inondatifs du parasitoïde oophageTrichogrammatoidea cryptophlebiae Nagaraja ont été réalisés contreCryptophlebia leucotreta (Meyrick), dans 5 exploitations de citrus, sur une période de 2 saisons consécutives. Un lâcher de 80 000 parasitoïdes par hectare et par semaine a été réalisé durant 29 et 33 semaines respectivement pour les 2 saisons. A la fin de chaque saison le nombre total de parasitoïdes atteint fut de 2.3 et 3.8 million d'individus par hectare respectivement. Comparée avec les zones non-traitées, sur les mêmes vergers, la population larvaire des zones de lâchers fut réduite de 54% lors de la 1re saison et de 60% lors de la 2c. Le pourcentage de perte de récolte a été réduit de 49.4±12.4 et de 61.1±8.3% respectivement. Ce résultat est à relier à l'augmentation du taux de parasitisme constaté sur la population des œufs. L'efficacité de ce traitement est semblable à celle obtenue avec l'application des inhibiteurs “de synthèse de la chitine”, mais le prix de la production des parasitoïdes n'est que de 30% par rapport à celui du prix de l'insecticide. Le travail manuel trop intensif, demande que des essais soient réalisés pour vérifier si des lâchers inoculatifs, à un taux plus élevé par semaine et sur une période plus courte seraient efficaces.
    Notes: Abstract Inundative releases of the egg parasitoidTrichogrammatoidea cryptophlebiae Nagaraja were made againstCryptophlebia leucotreta (Meyrick) on 5 commercial citrus farms in the western Cape Province, South Africa, over 2 successive seasons. A target release volume of 80 000 parasitoids ha−1 week−1 was established for releases over 29 and 33 weeks during the 2 seasons. Total seasonal volumes reached an equivalent of 2.3 and 3.8 million parasitoids ha−1 respectively. Compared with check treatments on each farm, larval population size was reduced in the release areas by 54% in the 1st and by almost 60% in the 2nd season. Percentage crop loss was reduced by 49.4±12.4 and 61.1±8.3% respectively. Treatment effects were clearly related to increases in rate of parasitism measured in both artificially-placed and in nativeC. leucotreta egg populations. Treatment efficacy is similar to that obtained with applications of chitin synthesis inhibitors but parasitoid production costs are 30% of insecticide costs. Manual distribution of parasitoids is labour intensive, however, and further studies should investigate whether inoculative releases at higher rates per week over a shorter period, are effective.
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  • 31
    ISSN: 1573-8248
    Keywords: Steatococcus ; Cryptostegia grandiflora ; biological control ; Steatococcus ; Cryptostegia grandiflora ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La nouvelle espèce de cochenilleSteatococcus sp.nov., se trouve surCryptostegia grandiflora R. Br. à Madagascar. L'étude de sa biologie et de sa spécificité a montré qu'elle peut survivre jusqu'à 6 mois sur quelques genres de la famille desApocynaceae et indéfiniment sur plusieurs genres de la famille desAsclepiadaceae. L'espèce a été, pour cette raison, refusée comme agent de lutte biologique pourC. grandiflora, importante mauvaise herbe dans le Nord de l'Etat du Queensland en Australie.
    Notes: Abstract The soft scale,Steatococcus new species, occurs onCryptostegia grandiflora R. Br. in Madagascar. Studies on its biology and host plant range showed colonies could survive for up to 6 months on some genera in theApocynaceae and indefinitely on many genera in the familyAsclepiadaceae. The species was therefore rejected as a biological control agent forC. grandiflora, a serious weed in northern Queensland, Australia.
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  • 32
    ISSN: 1573-8248
    Keywords: Phenacoccus manihoti ; Epidinocarsis lopezi ; Nigeria ; cassava ; biological control ; density dependence ; Phenacoccus manihoti ; Epidinocarsis lopezi ; manioc ; Nigéria ; lutte biologique ; dépendance de la densité
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Suite à l'introduction d'Epidinocarsis lopezi (De Santis) en vue d'une lutte biologique contre la cochenille du manioc (CM)Phenacoccus manihoti Mat.-Ferr. dans le sud-ouest du Nigéria en 1981 et 1982, 11 groupes de champs situés dans 2 régions ont été échantillonnés toutes les 2 semaines jusqu'en 1988, afin d'estimer l'impact de cet auxiliaire. Les populations du ravageur sont restées au-dessous de 10 CM par pousse la plupart du temps, malgré la présence d'hyperparasitoïdes indigènes, prouvant ainsi le succès continu de la lutte biologique parE. lopezi dans la région. Les coccinelles indigènes et polyphages n'ont été présentes que pendant les sommets de population de la CM, tandis que le parasitoïde spécifique était commun toute l'année. Pendant certaines périodes la courbe du parasitisme suggère une dépendance de la densité retardée. Comme 89% de toutes les pousses sont exemptes de la cochenille et comme le parasitoïde est très mobile, les taux de parasitisme ont été calculés sur la base des pousses individuelles. Malgré la grande variance des données couvrant 4 878 pousses infestées, une légére augmentation du parasitisme et, par conséquent, une dépendance positive de la densité sont constatées sur toutes les pousses ayant entre 1 et 10 CM du 3e et 4e stade. De telles pousses représentent 64% de toutes les pousses infestées. Aux densités d'hôte plus élevées le degré de parasitisme diminue rapidement. Les résultats sont discutés à la lumière des différentes théories sur la régulation des populations par les ennemies naturels.
    Notes: Abstract Following the successful introduction ofEpidinocarsis lopezi (De Santis) for biological control of the cassava mealybug (CM)Phenacoccus manihoti Mat.-Ferr. in southwestern Nigeria in 1981 and 1982, 11 groups of cassava fields were sampled every 2 weeks up to 1988 for impact assessment. After 1984, CM populations remained mostly below 10 per tip despite the presence of native hyperparasitoids, demonstrating the long-term success of biological control byE. lopezi in the region. Indigenous polyphagous coccinellids were found only during peak host densities, whereas the specificE. lopezi was common throughout the year. During some periods, percentage parasitism indicated delayed density dependence. Since 89% of all sampled cassava tips had no CM at all and the parasitisme is very mobile, parasitization rates were also calculated for individual infested tips (N=4,878). Parasitism increased slightly with host density on tips having between 1 and 10 CM of the 3rd and 4th instars, indicating positive density dependence. Such tips comprised 64% of all infested tips. At higher host densities, parasitism rates fell rapidly. The results are discussed in view of different theories on population regulation by biological control agents.
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  • 33
    ISSN: 1573-8248
    Keywords: insecta ; Xanthogaleruca luteola ; Erynniopsis antennata ; Tetrastichus brevistigma ; Tetrastichus erynniae ; biological control ; Insect ; Xanthogaleruca luteola ; Erynniopsis antennata ; Tetrastichus brevistigma ; Tetrastichus erynniae ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Erynniopsis antennata (Rondani), parasitoïde larvaire introduit de la galéruque de l'orme,Xanthogaleruca luteola (Müller), a été trouvé dans 11 des 12 villes de Californie du nord où des échantillonnages surUlmus procera Salisbury etUlmus pumilla L. ont été effectués en 1986 et/ou 1987. Le parasitisme apparent maximum fut supérieur à 40 % dans 4 des localités, mais le parasitisme moyen pour l'ensemble des sites fut de 4.5 %. Un parasitoïde des nymphes, également introduit,Tetrastichus brevistigma Gahan, a été trouvé dans 7 villes seulement, avec un taux de parasitisme apparent moyen et maximum de 1.2 et 22 % respectivement.E. antennata peut être utile pour la gestion des populations de galéruques de l'orme, mais une connaissance approfondie de sa biologie et de meilleures méthodes d'échantillonnage sont nécessaires.
    Notes: Abstract Erynniopsis antennata (Rondani), an introduced larval and larval-adult parasitoid of the elm leaf beetle (ELB),Xanthogaleruca luteola (Müller), was found in 11 of 12 northern California cities whereUlmus procera Salisbury andUlmus pumila L. were sampled in 1986 and/or 1987. Maximum apparent parasitism was over 40% in 4 of the cities, but mean parasitism for all sites combined was 4.5%. An introduced pupal parasitoid,Tetrastichus brevistigma Gahan, was found in only 7 cities, with mean and maximum apparent parasitism of 1.2 and 22%, respectively.E. antennata may be of value in managing ELB populations, but more knowledge of its biology and improved sampling methods are required.
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  • 34
    ISSN: 1573-8248
    Keywords: Microthrix inconspicuella ; Emex australis ; biological control ; apple orchards ; Microthrix inconspicuella ; Emex australis ; lutte biologique ; vergers de pommiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Les tests de spécificité conduits au laboratoire en Australie en 1977, montraient queMicrothrix inconspicuella pouvait se développer sur le jeunes feuilles de pommiers (Harley et al., 1979). Les études conduites en vergers de pommiers en Afrique du Sud montraient la possibilité d'une faible alimentation, mais moins de 40% des derniers stades larvaires atteignaient le stade adulte quand ils étaient confinés dans des manchons sur des branches de pommiers. Il n'y avait ni alimentation, ni survie dans de grandes cages ou en plein air. Les adultes issus de larves nourries sur pomme étaient plus petits, déformés, s'accouplaient occasionnellement et pondaient des œufs fertiles, mais leur descendance ni se nourrissait, ni se développait sur fruit ou feuille de pommier. En conclusion, les larves deM. inconspicuella ne se développaient pas sur pomme ou sur feuilles de pommier en plein air, les dommages étaient principalement limités aux pommes déjà blessées et l'alimentation sur feuilles était minimale. Dans les conditions normales de la lutte contre les ravageurs, les populations deM. inconspicuella ne pouvaient survivre sur une partie quelconque du pommier ou surE. australis croissant sous les arbres.
    Notes: Abstract Host specificity tests carried out in the laboratory in Australia during 1977, showed thatMicrothrix inconspicuella Ragonot could develop on young apple leaves (Harley et al., 1979). Field studies in unsprayed apple orchards in South Africa showed that some feeding occurred, but fewer than 40% of late instar larvae developed to adults when confined in sleeves on apple tree branches. No feeding or survival occurred in large field cages or in the open. Adults which developed from apple fed larvae were smaller, deformed, occasionally mated and laid fertile eggs but their progeny did not feed or develop on apple fruit or leaves. In conclusion,M. inconspicuella larvae did not develop on apple fruit or leaves in the field, damage was mainly limited to apples already injured and feeding on leaves was minimal. Under normal pest control practicesM. inconspicuella populations did not survive on any part of the apple tree or onE. australis growing under the trees.
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  • 35
    ISSN: 1573-8248
    Keywords: Phytomyza orobanchia ; Orobanche crenata ; Vicia faba ; biological control ; geographical distribution ; Syria ; Phytomyza orobanchia ; Orobanche crenata ; Vicia faba ; lutte biologique ; distribution géographique ; Syrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé On a conduit une étude en 1988 pour déterminer la fréquence et la distribution dePhytomyza orobanchia Kaltenbach dans 21 emplacements du nord-ouest de la Syrie. Des capsules d'orobanche (Orobanche crenata Forska) ont été examinées dans des champs de fève (Vicia faba L.)P. orobanchia était présent dans 95% des emplacements et 55,5% des 630 plantes d'orobanche observées étaient infectées. Sur les 1 890 capsules examinées, 32,5% étaient attaquées. La population deP. orobanchia était plus importante sur la côte, où 79% des plantes étaient endommagées. La production de graines d'orobanche était réduite de 29,4% du fait d'une destruction moyenne de 91,1% des graines dans les capsules infestées.
    Notes: Abstract A survey was carried out in 1988 to determine the occurrence and distribution of the flyPhytomyza orobanchia Kaltenbach [Diptera: Agromyzidae] on broomrape (Orobanche crenata Forskal) at 21 locations in northwestern Syria. Fruit capsules of broomrape were examined in faba bean (Vicia faba L.) fields. The fly was present at 95% of the locations sampled. Of 630 broomrape plants examined over all locations, 55.5% were infested. Of the 1,890 capsules examined, 32.5% were attacked. Fly populations were highest near the coast where 79% of the broomrapes were damaged. The total seed output of broomrape plants was reduced by 29.4% in the surveyed area due to a mean seed destruction of 91.1% per infested broomrape capsule.
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  • 36
    Electronic Resource
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    BioControl 35 (1990), S. 659-660 
    ISSN: 1573-8248
    Keywords: Psylla hyalina ; biological control ; Psylla hyalina ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'inventaire des ennemis naturels associés àPsylla hylina infestantAlbizia lebbeck a révélé la présence de 2 parasitoïdes primaires, d'un hyperparasitoïde, de 5 coccinellides, d'un ligaeide et de 3 champignons pathogènes, tous ces ennemis naturels étant signalés pour la 1re fois deP. hyalina.
    Notes: Abstract A survey of the natural enemies associated withPsylla hyalina infestingAlbizia lebbeck has revealed 2 primary parasitoids, 1 hyperparasitoid, 5 coccinellids, 1 lygaeid and 3 fungal pathogens, all being new records forP. hyalina.
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  • 37
    ISSN: 1573-8248
    Keywords: Bruchidae ; Acanthoscelides quadridentatus ; A. puniceus ; Mimosa pigra ; biology ; host specificity ; biological control ; Bruchidae ; Acanthoscelides quadridentatus ; A. puniceus ; Mimosa pigra ; biologie ; spécificité ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La biologie et la spécificité vis-à-vis de l'hôte des Bruches se nourrissant de graines,Acanthoscelides quadridentatus (Schaeffer) etA. puniceus Johnson, en provenance du Mexique ont été étudiées dans l'unité de quarantaine en Australie. Les caractères distinctifs des génitalia de chacune des espèces sont illustrés. La ponte était observée sur 16 des 73 espèces de plantes testées, mais les larves mouraient sans pénétrer dans les gousses ou les graines, excepté surMimosa invisa K. F. P. Von Martins etM. pigra L. les larves ayant pénétré dans les graines deM. invisa mouraient au 1er stade. Les bruchides étaient spécifiques deM. pigra et furent en conséquence lâchés comme partie d'un programme de lutte biologique contre cette mauvaise herbe dans la partie nord de l'Australie en Avril 1983 et en Thaïlande en juillet 1984.
    Notes: Abstract The biology and host specificity of the seed-feeding bruchids,Acanthoscelides quadridentatus (Schaeffer) andA. puniceus Johnson, from Mexico were studied in quarantine facilities in Australia. Distinguishing characters in the genitalia of each species are illustrated. Oviposition was recorded on 16 of 73 species of plants tested but larvae died without entering pods or seeds, except onMimosa invisa K. F. P. von Martius andM. pigra L. Larvae entering seeds ofM. invisa died in the first instar. The bruchids were clearly specific toM. pigra and were subsequently released as part of a program for biological control of this weed in the Northern Territory, Australia in April 1983 and thailand in July 1984.
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  • 38
    ISSN: 1573-8248
    Keywords: Phthorimaea operculella ; granulosis virus ; Bacillus thuringiensis ; life-table parameters ; biological control ; potato ; Phthorimea operculella ; granulovirus ; Bacillus thuringiensis ; paramètres biologiques ; lutte biologique ; pomme de terre
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Les effets de 3 différentes concentrations d'un granulovirus (GV) et d'une application standard deBacillus thuringiensis Berliner sur les paramètres biologiques de la teigne de la pomme de terrePhthorimaea operculella (Zeller) ont été testés en laboratoire. Le taux de survie le plus faible (0,4%) a été observé lorsque les larves de la teigne avaient été élevées sur des tubercules traités avecB. thuringiensis (200 mg Thuricide/kg de pomme de terre); dans ce cas, la teigne ne s'est pas reproduite. Comparativement au témoin et au traitement à la plus faible concentration de GV (0,002 équivalent larve par kg de pomme de terre (LE)), le taux de survie sur des tubercules traitées avec 2,0 et 0,2 LE a été réduit de manière significative, à savoir: 0,8% et 11,1% par rapport à 32,5% et 34,7% respectivement. Cependant, la durée de la génération n'a pas été affectée par les applications du GV et la fécondité n'a été réduite que par la concentration la plus élevée. Par conséquent, le taux de reproduction net (rm), comparé à celui du témoin (rm=0.00105), a été réduit de manière significative par la concentration de GV la plus élevée (rm=0.0004), modérément par la concentration intermédiaire (rm=0,0071) et n'a pas été affecté par la concentration la plus faible (rm=0,0100). Finalement, les conséquences pour une lutte biologique dans les lieux de stockage traditionnels ont été discutées.
    Notes: Abstract Experiments were conducted to evaluate the effect of 3 different concentrations of a granulosis virus (GV), and a standard application ofBacillus thuringiensis Berliner, on the life table parameters of the potato tubermothPhthorimaea operculella (Zeller) in the laboratory. Survival from egg to adult emergence was lowest (0.4%) and no reproduction occurred when larvae were fed on tubers treated withB. thuringiensis (i.e. 200 mg Thiricide/kg potatoes). Survival was 0.8, and 11.1% on tubers treated with 2.0, and 0.2 larval equivalents/kg potatoes (LE) of the GV, respectively, and was significantly (p〈0.05) reduced compared to that for the lowest GV concentration (0.002 LE), and the control, i.e. 34.7, and 32.5% survival, respectively. However, generation time was not affected by the GV and fecundity was reduced only at the highest concentration. As a result, the intrinsic rate of increase (rm) was significantly reduced at the highest, slightly reduced at the intermediate, and was not different for the lowest GV concentration as compared to the control, i.e. 0.0004, 0.0071, and 0.0100 compared to 0.0105, respectively. The implications for a potential biological control of the potato tubermoth in rustic potato stores are discussed.
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  • 39
    ISSN: 1573-8248
    Keywords: Anaphes diana ; biological control ; natural enemy introduction ; Sitona hispidulus ; egg density ; Anaphes diana ; lutte biologique ; Sitona hispidulus ; densité des œufs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Anaphes diana (Girault) (=Patasson lameerei Debauche), mymaride parasite des œufs deSitona spp., provenant d'Europe, a été libéré aux Etats-Unis à partir de 1976 et il a été retrouvé dans l'Etat du Delaware. Des techniques sont décrites pour l'extraction des œufs deSitona du sol. Après 9 ans de prélèvements dans un champ de luzerne au Delaware (〉19,300 œufs obtenus), la densité moyenne des œufs viables hivernant deSitona hispidulus (F.) a été 14,6 par 100 cm3 du sol (1 cm de profondeur). Bien que le niveau de parasitisme parA. diana ne dépasse pas 0,29%, le fait que cette espèce ait été retrouvée pendant 3 ans, et jusqu'à 7 ans après le dernier lâcher, indique qu'elle s'est probablement établie dans l'Etat du Delaware.
    Notes: Abstract Anaphes diana (Girault) (=Patasson lameerei Debauche), a mymarid egg parasite ofSitona spp., was introduced from Europe beginning in 1976 and is now tentatively established in the United States. Techniques are described for the separation of eggs ofSitona spp. from soil, using a series of fine-mesh sieves, water, and a saturated salt solution. Data from 9 years of sampling in an alfalfa field at Newark, Del. (〉19,300 host eggs extracted), showed that the mean peak density of viable overwintering eggs ofSitona hispidulus (F.) was 14.6 per 100 cm3 of 1 cm deep surface soil. At the study site,Sitona egg densities consistently increased during the fall as a result of oviposition, peaked during January and February and decreased during the spring as a result of egg hatch. Although the incidence of parasitism byA. diana remained surprisingly low (0.29%), the fact that the species was recovered during 3 years and up to 7 years after the last release, indicates that it has colonized at the Delaware release site.
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  • 40
    ISSN: 1573-8248
    Keywords: biological control ; Pistia stratiotes ; Neohydronomus affinis ; water lettuce ; host specificity ; lutte biologique ; Pistia stratiotes ; Neohydronomus affinis ; laitue d'eau ; spécificité vis-à-vis de l'hôte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Neohydronomus affinis a été introduit en Australie comme agent de lutte biologique potentiel contre la laitue d'eau,Pistia stratiotes. Les études en quarantaine ont démontré que ce coléopètre était spécifique deP. stratiotes et il a été libéré dans les champs en 1982. En conséquence, il a été lâché comme agent de lutte contre cette mauvaise herbe dans plusieurs autres pays. En AustralieN. affinis réduit les infestations deP. stratiotes de 40% ou plus en l'espace de 12 à 18 mois. Les résultats sont discutés en fonction de son efficacité dans d'autres parties du monde. Nous concluons queN. affinis contrôle effectivementP. stratiotes dans les régions tropicales (à la latitude 22°), mais dans les régions plus froides son efficacité fluctue avec les conditions saisonnières.
    Notes: Abstract Neohydronomus affinis was imported into Australia as a potential biological control agent for the floating aquatic weedPistia stratiotes. Quarantine studies demonstrated that this weevil was host specific toP. stratiotes and it was released into the field in 1982. Subsequently it was released as a control agent for this weed in several other countries. In AustraliaN. affinis reduced infestations ofP. stratiotes by 40% or more within 12–18 months. The results are discussed in relation to its effectiveness in other parts of the world. We concluded thatN. affinis effectively controlsP. stratiotes in tropical regions (to lat. 22°), but in cooler regions its effectiveness fluctuates with seasonal conditions.
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