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1.
Summary Seed tubers were immersed in suspensions of thiabendazole (Storite) or thiabendazole plus imazalil (Extratect) at different
concentrations and planted in a field experiment. During the following 2 years samples of the produce were planted after treatment
with the same fungicide formulation used on the seed.
Silver scurf on daughter tubers decreased as concentrations of fungicide increased and Extratect gave better disease control
than Storite applied at the same thiabendazole concentration. Isolates ofH. solani resistant to thiabendazole were found on seed tubers 6 weeks after treatment with Storite, and also on daughter tubers after
the first application of the higher rates of Storite; their incidence increased with further annual treatments. In 3 years
no thiabendazole-resistant isolates were found after treatment with Extratect. Chlamydospores ofH. solani developed when sensitive isolates were subcultured onto agar containing thiabendazole. Isolates sensitive to thiabendazole
were slightly more sensitive to imazalil than resistant ones. 相似文献
2.
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
3.
The occurrence, pathogenicity (1997 isolates only) and fungicide sensitivity of pathogens causing dry tuber rots in Scottish
seed potatoes was investigated over three storage seasons between 1997 and 2000 in relation to region of production, cultivar,
class and generation of seed potatoes, type of temperature control in store and earthiness of tubers. A total of 156 samples,
each comprising up to ten rotted tubers, was received over the three seasons. The relative importance of each pathogen in
causing rots was summarised by calculating a mean rot index that combined the prevalence of a pathogen in the samples with
the incidence of tubers affected by the pathogen within those samples. Phoma foveata (gangrene) had the highest rot index, which was five times greater than for P. exigua and ten times greater than for P. eupyrena. This relationship was mirrored by the relative pathogenicities of P. foveata and P. eupyrena, as measured by size of rots developing at inoculated wounds in test tubers. Fusarium avenaceum appeared to be the greatest cause of Fusarium dry rots, having a rot index at least twice as great as that for F. solani var. coeruleum. Infection by F. sulphureum was relatively uncommon. In the pathogenicity test, F. avenaceum, F. solani var. coeruleum and F. sulphureum produced rots of similar depths and widths and larger than those of F. culmorum. The mean rot index for Cylindrocarpon spp. was slightly more than that for F. avenaceum, whereas C. destructans produced smaller rots in the tuber pathogenicity test. Region of production affected the prevalence of P. foveata and F. avenaceum, but only the occurrence of P. foveata was affected by class and generation of seed potatoes. Isolate sensitivity to thiabendazole and imazalil was examined in
vitro over 2 years. Six out of seven isolates of F. sulphureum were resistant to thiabendazole, with the remaining isolate being partially resistant. The growth of two out of 34 isolates
of F. avenaceum was inhibited by more than 50% only at 100 mg thiabendazole l−1. All isolates, except those of F. avenaceum,, were inhibited in their growth by more than 50% at either 1 or 10 mg imazalil l−1. However, the growth of 40% of isolates of F. avenaceum was inhibited only at 100 mg l−1. The various changes in pathogen prevalence and isolate sensitivity to fungicides recorded in this study highlight the need
for regular monitoring programmes to be conducted in order that disease-control strategies can remain effective. 相似文献
4.
G. A. Hide 《Potato Research》1994,37(3):287-290
Summary Silver scurf on daughter tubers at harvest was decreased by treating seed tubers with imazalil or thiabendazole in March but
significantly increased when the treated tubers were wounded the day before planting in May. The disease was also increased
by wounding seed tubers not treated with fungicide. Black dot was decreased by seed treatment with imazalil but was not affected
by wounding. 相似文献
5.
Summary Potato tubers inoculated withPhoma exigua var.foveata were dipped or sprayed with fungicide immediately after wounding or after holding them at 5 or 15°C for up to 14 days. Thiabendazole
and 2-aminobutane, either separately or combined, controlled gangrene when applied soon after wounding: on tubers with little
inoculum, application in 2 litres t1 was better than in 400 ml t−1. When treatment was delayed, 2-aminobutane or the mixture was more effective than thiabendazole alone. Adsorption of thiabendazole
onto soil increased with decreasing soil pH and the fungicide gave better control of disease on tubers carrying neutral than
acid soil. Treating tubers with dichlorophen increased gangrene. 相似文献
6.
Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive.
Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated
seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk.
Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than
in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d. 相似文献
7.
Black dot is an important disease of potato that affects all plant parts. The causal agent,Colletotrichum coccodes, is commonly found on potato tubers used for seed. Our objective was to determine thein vitro sensitivity ofC. coccodes to the fungicides maneb, thiabendazole, imazalil and CGA 173506, a phenylpyrrole. These fungicides are currently used, or are being tested for use, as potato seed treatments in the United States. All four fungicides reduced radial growth, sclerotial germination and spore germination ofC. coccodes at 10 μg/ml and higher. The fungicide concentrations that inhibited radial growth by 50% were 2 μg/ml, 5 μg/ml, 35 μg/ml, and 40 μg/ml for imazalil, CGA 173506, maneb and thiabendazole, respectively. TBZ was less inhibitory than the other three fungicides and stimulated sclerotial productionin vitro. Isolates ofC. coccodes differed in their sensitivity to maneb, thiabendazole and imazalil in radial growth, but not spore and sclerotial germination, assays. On CGA 173506, radial growth of fourC. coccodes isolates was inhibited, but these isolates produced sectors which grew normally. Germination of most sclerotia from these isolates was inhibited, but some germinated and produced normal colonies in the presence of CGA 173506. OneC. coccodes isolate was resistant to this fungicide in all assays. 相似文献
8.
Summary Survival of the pathogen causing silver scurf of potato (Helminthosporium solani) in Alberta soils was studied by evaluatingH. solani infection in the progeny ofH. solani-free nuclear seed potato tubers planted in fields where potatoes had never been grown or were grown 1, 2, 3, or 4 years previously.
Daughter tubers from all the fields developed silver scurf lesions, andH. solani was isolated from infected tubers. This is the first report of survival ofH. solani in Alberta soils. Soil-borne inoculum appears to have a role in the epidemiology of the disease and in the introduction of
the pathogen into silver scurf-free potato seed stock. Of 31 plant species tested, only potato was found to be a host ofH. solani. Most of theH. solani isolates from north central Alberta were more sensitive to thiabendazole than those from southern Alberta, where thiabendazole
is much more commonly used. 相似文献
9.
Summary The effect of fungicides and the antagonistic fungusTrichoderma harzianum (Th) on the potato leak pathogenPythium aphanidermatum (Pa) was investigated in vitro. Rot was reduced by 73% to 89% when tubers inoculated withPa were treated by immersion in solutions (0.5% w/v) of the fungicides Ridomil MZ58. Dithane M45. Manebe 80 and Tachigaren 360.
Complete protection was achieved by dusting inoculated tubers with Ridomil MZ58 diluted in kaolin at a final concentration
of 0.1% (w/w). The biological treatments of dipping inoculated tubers in a conidial water suspension ofTh at 108 conidia/ml or of dusting with a mixture of a barley culture ofTh and kaolin to a final concentration of 2×109 conidia/g were as effective as the chemical treatments. Control was still effective when inoculated tubers were treated with
Ridomil MZ58. Tachigaren 360 or the conidial suspension ofTh after 24h incubation at 25°C. 相似文献
10.
S. H. De Boer J. D. Janse D. E. Stead J. Van Vaerenbergh A. R. McKenzie 《Potato Research》1992,35(2):207-216
Summary An indirect sandwich enzyme-linked immunosorbent assay (ELISA) was used to monitor potato stems of three cultivars for the
presence of the ring rot pathogen,Clavibacter michiganensis subsp.sepedonicus, during the growing season and in progeny tubers after harvest. The highest ELISA values were obtained with the highest concentration
of bacteria used to inoculate seed pieces in all cultivars tested. Low ELISA values were obtained for stems and progeny tubers
selected from plants grown from seed inoculated at lower bacterial concentrations. Estimates of bacterial densities in stems
and progeny tubers by immunofluorescence indicated that low ELISA values were most probably caused by low bacterial numbers.
It is suggested that the sensitivity of ELISA for detecting the ring rot pathogen in potato stems and progeny tubers is a
function of the concentration of bacteria in individual seed pieces. 相似文献
11.
Summary
Polyscytalum pustulans spread from infected buds of seed tubers on the nodal scale leaves of elongating stems and stolons. More eyes were infected
at the apical end of developing tubers than at the stolon end.
Sclerotia, first found within the agar of ageing cultures, appeared to form from thickened hyphal rings within the aerial
hyphae and conidiophores. As infected plants senesced, sclerotia developed within single or groups of host cells in diseased
stem bases and remained viable for seven years in undisturbed soil. Sclerotia were also found after harvest in skin spots
on decayed seed tubers. 相似文献
12.
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
13.
Summary The majority of isolates ofFusarium avenaceum caused dry rot on potato tubers; many were as pathogenic asF. coeruleum. Pathogenicity ofF. avenaceum was not related to the plant species from which the isolates originated. Tubers of potato cv. Cara were more susceptible
than those of cvs Romano or Maris Piper. Temperature (5–15° C) had no effect on lesion depth but lesions tended to be slightly
wider at the lowest temperature. Two isolates (of 61) from wheat and white lupin had a moderate level of resistance to thiabendazole.
The results are discussed in relation to the control of dry rot in stored potato tubers. 相似文献
14.
Summary Tests for systemic induced resistance (SIR) to late blight were performed with different potato cultivars in field trials
and in growth chamber experiments.
The non-pathogenPhytophthora cryptogea (Pc) and salicylic acid (Sa) were used as inducer agents. In the field, plants were naturally infected byPhytophthora infestans while the indoor plants were inoculated. The degree of SIR obtained varied with the cultivar used and also with the type
of inducer. For example in the field the susceptible cv. St. Cecilia had enhanced resistance with Pc whereas Sa caused increased
susceptibility. Inbred resistant cvs acquired increased resistance after treatment with Sa.
In a separate pilot experiment in a growth chamber, Sa at two different concentrations was injected into potato seed tubers
before planting. The higher Sa concentration increased resistance in genetically resistant cultivars while the lower Sa concentration
brought about increased susceptibility. 相似文献
15.
Summary In 1983 and 1984 there were reports in Norway of more severe late blight infection than usual on tubers of cv. Pimpernel,
a cultivar without R-genes known to be somewhat resistant to both haulm and tuber infection. Results from routine tests confirmed
earlier experience that cv. Pimpernel shows stable resistance to tuber late blight, although the ranking of cultivars may
vary between years.
In experiments during three harvest seasons tubers of different cultivars were inoculated with isolates ofP. infestans obtained from stocks of cv. Pimpernel with severe tuber late blight and with other isolates. In these experiments the isolates
from cv. Pimpernel caused more rot on tubers of Pimpernel than did other isolates. 相似文献
16.
Potato stolbur is a phytoplasmal disease that seriously affects yield and tuber quality in South Eastern Europe, Russia and
the Mediterranean areas. In 2007 and 2008, field experiments were carried out to determine stolbur resistance of processing
potato cultivars at Sannicolau Mare (Romania) by determining consistency and concentration of reducing sugars (fructose and
glucose), sucrose and phytoplasmas in potato tubers. In both years, non-symptomatic potato tubers showed sucrose levels in
the range of 3,000 mg kg−1 fresh weight (FW). In contrast, sucrose concentrations were up to 11,820 mg kg−1 FW in 2007 and 19,560 mg kg−1 FW in 2008 in tubers showing severe symptoms. These high values severely affect suitability of tubers for processing as sucrose
serves as substrate for the formation of reducing sugars that are the limiting factor in fried potato production for Maillard-related
discolouration. The cultivars examined differed considerably in susceptibility to stolbur disease. Whereas cvs. ‘Courage’
and ‘Lady Rosetta’ showed high numbers of diseased tubers and high sucrose concentrations, ‘Lady Claire’ had a lower incidence
of symptomatic tubers and lower sucrose concentrations. However, fully resistant cultivars were not observed. Across all cultivars
examined, phytoplasmal concentration was significantly higher in symptomatic tubers than in non-symptomatic ones. 相似文献
17.
Ulla Bång 《Potato Research》1992,35(1):3-15
Summary In each of the five years 1978 to 1982, seed lots of cv. Bintje, variously infested byPhoma foveata Foister andFusarium solani var.coeruleum (Sacc.) Booth, as found by wound and cut tests, respectively, were planted in a series of field experiments at six sites
in Sweden. A statistically significant relationship between seed and progeny infestation was found forP. foveata each year, and in three years forF. solani.
Benomyl and thiabendazole mist treatments of seed tubers at grading in spring controlled the development of gangrene and dry
rot in treated seed tubers, but did not consistently reduce the levels ofP. foveata andF. solani infestation in progeny from treated seed tubers.
The site of cultivation markedly influenced mean levels ofP. foveata infestation, which were found to be related to temperature and rainfall during a 40 day pre-harvest period at the trail sites;
however, mean levels ofF. solani infestation were not so related. 相似文献
18.
S. S. Leach 《American Journal of Potato Research》1985,62(3):129-136
A survey of selected potato soils in Maine was made to determine the species and populations ofFusarium spp. present.Fusarium solani ‘Coeruleum’ was most often isolated butFusarium roseum ‘Sambucinum’ was not recovered from any soil. Crops or cropping sequences in general showed no direct relationship to observed Fusaria populations or tuber dry rot. Field studies were conducted to determine the effect ofFusarium contaminated seed on soil and daughter tuber contamination. Whole and cut seed were inoculated withFusarium roseum ‘Sambucinum’ and half of each lot treated with thiabendazole (1500 ppm) to controlFusarium seed decay. Soil populations ofF. roseum ‘Sambucinum’ were higher near plants produced from non-treated, cut seed tubers. No increase inFusarium populations was found between plants or near plants produced from whole or thiabendazole treated seed. Daughter tuber contamination was greatest from plants produced from non-treated contaminated cut seed, and lowest from whole or treated seed. Whole non-treated seed produced daughter tubers with contamination equal to treated whole seed. This indicates that the use of whole seed could be a method to reduce daughter tuber contamination and reduce reliance on chemical treatments. Cut seed contaminated withFusarium spp. is an important source of daughter tuber contamination which can result in a high amount of tuber dry rot in storage. 相似文献
19.
The effects of (S)-(+)-carvone treatments on seed potato tuber dormancy and sprouting 总被引：1，自引：0，他引：1
Summary Potato seed tubers may suffer from premature sprouting during storage, thus limiting their suitability for cultivation. Commonly
used sprout suppressant treatments negatively affect but viability and therefore a reliable method to inhibit bud development
must still be found for seed tubers. The monoterpene carvone ((S)-(+)-carvone) was tested in small scale experiments. The
vapour of this compound fully inhibited bud growth of tubers cv. Monalisa stored at 23°C without affecting bud viability throughout
6 months of treatment. The most effective range of carvone vapour concentrations was between 0.34 and 1.06 μmol mol−1. With these qualities we can expect carvone to become a suitable sprout suppressant for seed tubers. 相似文献
20.
Summary Suspensions of 12 fungicides were evaluated for controlling skin spot on stored potatoes in two experiments. Tubers produced
from seed tubers inoculated withPolyscytalum pustulans (Experiment 1) or tubers wounded with pin pricks before dipping in mycelial suspensions ofP. pustulans (Experiment 2) were immersed for 5 minutes in suspensions of different fungicides at 10 mg l. 100 mg 1 or 1 g l a.i. After
incubation in sealed plastic bags at 5°C the numbers of skin spots developed at random over the tuber surface (Experiment
1) or at pin pricks (Experiment 2) were recorded after 20 or 24 weeks.
In both experiments carbendazim, thiabendazole and thiophanate methyl and in one experiment thiophamine were most effective
in decreasing incidence of skin spots. Imazalil, prochloraz and sisthane also had highly significant effects at higher concentrations
(100mg l. l g l a. i).
Zusammenfassung Es wurden 12 Fungizide auf ihre Wirkung auf das Myzelwachstum vonPolyscytalum pustulans und auf das Auftreten der Tüpfelfleckenkrankheit an gelagerten Kartoffelknollen geprüft. Formulierte Fungizide wurden in Konzentrationen von 0.3 bis 80 mg l in 2%igen, auf pH 7 abgepufferten Malzagar inkorporiert. Der durchmesser der Kolonien wurde nach 4-w?chiger Inkubation bei 15°C gemessen, die meisten Verbindungen ergaben niedrige Hemmkonzentrationen (IC50, Tabelle 1). Die Prüfung der Fungizide erfolgte in 2 Versuchen durch 5-minütige Immersion von Knollen in Suspensionen von 10 mg 1, 100 mg 1 und 1 g l Wirkstoff. In Versuch 1 wurden die Knollen von Saatgut, welches zur Pflanzung mitP. pustulans inokuliert worden war. 5 Tage nach der Rodung behandelt. In Versuch 2 wurden 8 Wochen lang gelagerte Knollen gewaschen und dann mit einem Ger?t, mit 25 Nagelspitzen (1 mm lang, 0,5 mm Durchmesser an der Basis) in 3 mm Abstand in einer Platte (20 mm × 20 mm × 3 mm) mit Handgriff, verletzt (Abb. 1). Das Ger?t wurde an 2 Stellen in die Knollen gedrückt, die verletzten Knollen wurden unmittelbar danach in eine Suspension von 10 Wochen alten mazerierten Kulturen vonP. pustulans von 2%igem Malzagar getaucht. Am n?chsten Tag wurden die Knollen mit den Fungiziden behandelt. In beiden F?llen wurden die Knollen nach Abtropfen luftgetrocknet und bei 5°C in drahtverschlossenen Plastikbeuteln gelagert. Ermittelt wurde die Zahl der Tüpfelflecken (Abb. 1) bei zuf?lligem Auftreten (Versuch 1, 20 Wochen) und nach Verletzung mit Nagelspitzen (Versuch 2, 24 Wochen). Carbendazim, Thiabendazol, Thiophanatmethyl und Thiophamine waren die effektivsten Verbindungen zur Verhinderung von Tüpfelflecken an gelagerten Knollen (Tabellen 2 und 3). Imazalil, Prochloraz und Sisthane hatten bei h?heren Konzentrationen ebenfalls hochsignifikante Wirkung. Die Knollenbesch?digung verursacht neue Verwundungen, an denen sich Tüpfelflecken bilden k?nnen, deshalb sind Fungizidprüfungen offensichtlich auch zu anderen Zeitpunkten als unmittelbar nach der Rodung m?glich, wie dies bei natürlich infizierten Knollen erforderlich ist. Ausserdem war das Auftreten von Tüpfelflecken zwischen Proben besch?digter Knollen weniger variabel als bei Knollen aus inokuliertem Pflanzgut.
Résumé Douze fongicides ont été testés afin d'observer leur action sur la croissance mycélienne dePolyscytalum pustulans et l'incidence de l'oosporiose sur les tubercules en conservation. Des formulations de fongicides ont été incorporées dans la gélose avec 2% d'extrait de malt tamponné à pH 7 à des concentrations variant de 0,3 à 80 mg/l. Le diamètre des colonies a été mesuré à 15°C après 4 semaines d'incubation. La plupart des produits ont donné une inhibition à des concentrations faibles (IC50, tableau 1). Deux expérimentations ont été mises en place pour tester les fongicides après immersion des tubercules pendant 5 minutes dans des suspensions de 10 mg/l, 100 mg/l et 1 g/l de matière active. Dans la première expérimentation, les tubercules provenant de plants inoculés avecP. pustulans à la plantation ont ètè traités 5 jours après l'arrachage. Dans la deuxième expérience, les tubercules ont été conservés pendant 8 semaines, puis la vés et blessés à l'aide d'une plaque (fig. 1) en laiton (20 mm×20 mm×3 mm) munie de 25 pointes (1 mm de long 0,5 mm de large à la base) espacees de 3 mm chacune. Chaque tubercule est blessé de deux endroits et immergé immédiatement dans une suspension contenant une culture deP. pustulans agée de 10 semaines et macérée dans une solution d'extrait de malt à 2%. Les tubercules ont été traités avec les fongicides le jour suivant. Dans les deux expérimentations, les tubercules traités ont été ressuyés puis séchés et mis dans des sacs en plastique. Les sacs sont fermés et stockés à 5°CC. Le nombre de taches sur les tubercules, soit présentes sur toute la surface après 20 semaines dans la première expérimentation, soit aux endroits des blessures après 24 semaines dans la deuxième expérimentation, a été enregistré (fig. 1). Le carbendazime, le thiabendazole, le méthyl thiophanate et la thiophamine ont été les produits les plus efficaces vis à vis de l'oosporiose sur tubercules en conservation (tableaux 2 et 3). L'imazalil, le prochloraz et le sisthane ont eu des effets significatifs aux concentrations les plus élevées. Les tubercules blessés pour l'expérimentation provoquent des conditions favorables au développement de l'oosporiose; il est donc suggéré de tester les fongicides à d'autres dates que celle de l'arrachage où l'on utilise obligatoirement des tubercules infectés naturellement. De plus, en ce qui concerne l'expression des sympt?mes, les échantillons de tubercules blessés présent nt une variabilité moins importante que des tubercules provenant de semences inoculées.相似文献