共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
K. Scholte 《Potato Research》1989,32(1):65-73
Summary The effect ofStreptomyces spp. (netted scab) on the growth of potato was investigated in three pot experiments, in two of which the effect ofVerticillium dahliae was also assessed.
The netted scab organisms attacked all underground plant parts of susceptible potato cultivars early in the growing season;
the roots were especially seriously attacked, markedly reducing tuber yield and number but prolonging the duration of the
growing season. The nematicide oxamyl had little effect on the incidence of netted scab. Repeated growing of the susceptible
cv. Bintje greatly increased soil contamination with the netted scab pathogens.
V. dahliae reduced haulm growth before wilt symptoms were evident and it reduced tuber yield but not number. Oxamyl delayed infection
byV. dahliae by controlling parasiticPratylenchus nematodes (mainlyP. thornei). 相似文献
3.
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. 相似文献
4.
Summary The highlands of South America are the probable geographic origin for the potato gangrene fungusPhoma exigua var.foveata (Foister) Boerema which was found parasitizing plants ofChenopodium quinoa in the Altiplano area of Peru. In vitro studies showed no dissimilarities between it and the antibiotic ‘E’ producing virulent
European isolates ofP. exigua var.foveata. It is as pathogenic to potatoes as the virulent European isolates but onC. quinoa andC. album it is more pathogenic than the European isolates. So far the fungus has not been found on potato tubers in South America
and the reasons why gangrene problems have not arisen there are discussed. 相似文献
5.
Effect of haulm treatments on the formation of microsclerotia ofVerticillium dahliae Kleb. on potato
Summary In four pot experiments, potato plants of cv. Element were artificially infected withV. dahliae. At an early and a late harvest haulms were killed chemically, by burning or by various other treatments, including cutting
them into pieces of different lengths and keeping the debris on the soil surface or covering with soil. After 4 weeks the
plant material was air-dried and the number of microsclerotia per mg was determined.
At the early harvest, in two experiments, the chemical treatment yielded more microsclerotia than the cutting treatments.
Covering colonised haulm tissue with non-sterilised soil was effective in inhibiting microsclerotia formation. Shorter haulm
pieces led to fewer microsclerotia at the later harvest if the material was kept on the soil surface. The variation in microsclerotial
yield and in treatment effects among the different experiments was large. 相似文献
6.
Summary Potato plants of cvs Element and Mirka were artificially infected withV. dahliae in two greenhouse experiments. Leaf blade, petiole, aerial stem, subterranean stem, stolon and root mass were separately
harvested both when the canopy was still green and at maturity. After 4 weeks incubation, the plant tissue was air-dried and
the numbers of microsclerotia per mg tissue and per plant were determined.
The highest numbers of microsclerotia were observed in the haulm when harvest took place at maturity. Cultivar Element yielded
significantly more microsclerotia in the haulm than cv. Mirka, whilst there were no cultivar differences in the microsclerotial
production on subterranean parts. The petiole and the aerial stem contributed most to the total microsclerotial production,
whereas roots were much more important for formation of microsclerotia than stolons. 相似文献
7.
Ulla Bång 《Potato Research》1991,34(4):429-441
Summary The incidence ofP. foveata in soil and tuber samples from field experiments often increased significantly as the harvest season progressed and temperatures
fell. Mean levels of tuber and soil infestation were significantly higher in irrigated rows compared with those artificially
sheltered from precipitation, both at normal and late harvest dates.
Soil infestation was most frequently detected within 10 cm of the parent tuber. No pycnidia were visible on the haulm, and
very few latently infected stem segments and leaves were detected using various methods.
In three out of four years, the incidence ofP. foveata in tubers after wounding was reduced by washing them gently in tap water immediately after harvest. 相似文献
8.
Summary Over 2 years, seed tubers or stems were inoculated withFusarium sulphureum Schlecht. (F. sambucinum Fuckel f. 6 Wollenw.) and the incidence of dry rot on daughter tubers assessed by standardised wound tests. The amount of
stem and soil inoculum was also measured in one year.
Inoculating stem bases resulted in greater concentrations of spores on the stem bases, greater soil populations at harvest
and more dry rot on tubers than inoculating the seed tuber. Overall, the incidence of dry rot and the amount of stem and soil
inoculum was similar for the three methods of haulm destruction: cutting and removing the stems, applying sulphuric acid or
applying diquat dibromide to the growing plants. 相似文献
9.
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
10.
Summary The resistance to gangrene (caused byPhoma exigua var.foveata) of progenies from two hybridisation schedules involving cultivars resistant, susceptible, or of intermediate reaction to
gangrene was assessed. Two methods of sampling tubers from field-grown single-plant plots of 18 clones representing each progeny
were used: one tuber was taken from each plant, and a bulk sample of 18 tubers was selected at random from the whole progeny.
Gangrene resistance was assessed after incubating tubers which had been rolled in cornmeal-sand inoculum ofP. exigua var.foveata, and was expressed as a percentage of tubers infected. Results from the two methods of sampling correlated closely, and agreed
well with tests in a subsequent year on 10-tuber samples of each individual clone.
It is concluded that an 18-clone sample adequately represented each progeny, and that the mid-parent gangrene score satisfactorily
predicted the resistance of the resulting progeny. There are indications that susceptibility tended to be dominant. The implication
of these findings to breeding for resistance to gangrene is discussed. 相似文献
11.
Résumé
Fusarium culmorum et, dans une moindre mesure,F. avenaceum, F. sambucinum, Colletotrichum coccodes etCylindrocarpon sp. ont été isolés de tubercules entreposés en atmosphère contr?lée (AC) et atteints de pourriture grave. Des expériences
d'inoculation de tubercules avec 10 espèces ou variétés fongiques et conservation en AC à 8 et 10°C ont montré que: 1) les
champignons non pathogènes en atmosphère normale (ex.:Cylindrocarpon sp.) le devenaient en AC, 2) ceux qui étaient faiblement pathogènes en atmosphère normale étaient nettement plus virulents
en AC (ex.:F. culmorum), 3) les espèces ou variétés virulentes en conditions d'air normales (Fusarium sulphureum etPhoma exigua var.foveata) ne provoquaient pas de pourriture plus grave en AC et leur activité pouvait même être légérement freinée.
Summary The extensive rotting of tubers which occurred during storage trials in controlled atmospheres has led to a mycological and pathological study of the rots. The most frequently isolated species wasFusarium culmorum althoughF. avenaceum, F. Sambucinum, Coletotrichum coccodes and aCylindrocarpon sp. were also present. Tubers of cvs Bintje and Ulla were inoculated with 19 isolates of 10 fungal species or varieties associated with rotting of stored tubers (Table 1). The tubers were incubated at 8 or 10°C in normal or controlled (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2) atmospheres and the extent of rotting was determined a month later (Tables 2 and 3 and Fig. 2). Species which were weakly virulent in a normal atmosphere (variousFusarium spp. andPhoma exigua var.exigua) were clearly more aggressive in the controlled atmosphere and this was especially evident in the case ofF. culmorum. Species ot pathogenic in a normal atmosphere under experimental conditions (Colletotrichum coccodes, Cylindrocarpon sp.,Phoma eupyrena) caused rotting in the controlled atmosphere. The two species which were virulent in a normal atmosphere (F. sulphureum andP. exigua var.foveata) were also virulent in the controlled atmosphere and in some cases the extent of rotting was even less. As a general rule, rotting caused by weakly virulent fungi was greater in both cultivars in the controlled than in a normal atmosphere.
Zusammenfassung Eine starke F?ulnis von in Kontrotrollierter Atmosph?re gelagerten Kartoffelknollen veranlasste eine mykologische und pathologische Untersuchung. Der am h?ufigsten isolierte Pilz warFusarium culmorum. F. avenaceum, F. sambucinum, Colletotrichum coccodes undCylindrocarpon sp. wurden ebenfalls bestimmt. Neunzehn St?mme von 10 Pilzsorten oder-Arten welche bei Lagerf?ulnis vorkommen (Tab. 1) wurden auf Knollen der Sorten Bintje und Ulla inokuliert. Die Lagerung wurde bei 8 oder 10°C under Normalbedingungen oder kontrollierter Atmosph?re durchgeführt (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2). Der F?ulnisgrad (Abb. 1) wurde nach einem Monat bonitiert. Die Ergebnisse sind in den Tabellen 2 und 3 dargestellt und in der Abb. 2 illustriert. Unter in Normalbedingungen nur schwach virulente Arten (verschiedeneFusarien undPhoma exigua var. exigua) waren deutlich aktiver in kontrollierter Atmosph?re. Dies was besonders der Fall fürF. culmorum. Pilze, die im Versuch unter Normalbedingungen nicht pathogen waren (Colletotrichum coccodes, Cylindrocarpon sp., Phoma eupyrena), haben unter kontrollierter Atmosph?re Sch?den verursacht. Hingegen werden die beiden unter Normalbedingungen sehr pathogenen Arten (F. sulphureum undP., exigua var.foveata), durch kontrollierte Atmosph?re wenig beeinflusst. Es wurde sogar in einigen F?llen eine gewisse Verringerung des F?ulnisbefalls beobachtet. Ganz allgemein haben die getesteten kontrollierten Bedingungen die Entwicklung der Pilzf?ulnis an beiden Kartoffelsorten gef?rdert, speziell durch Pilzarten, welche unter Normal-bedingungen wenig Sch?den verursachen.相似文献
12.
Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut
surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average
tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150
Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day−1 (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from
−0.2 ARI day−1 (at 7°C) in all cultivars to a maximum of −0.8 ARI day−1 (10°C). 相似文献
13.
K. Scholte 《Potato Research》1989,32(3):367-376
Summary The effects of soil-borneRhizoctonia solani on yield and quality of potato were studied by an extensive individual plant sampling procedure. From 1983 to 1986, stem
canker and stolon pruning were examined in 10 768 plants growing on a sandy soil. Tuber yield and quality and haulm yield
per plant were also recorded.
The degree of attack byR. solani depended on the cropping frequency of potato. Severe and very severe stem and stolon attacks decreased fresh yield, dry matter
yield and dry matter content of tubers and increased the number of deformed and small tubers, whereas the effect on haulm
yield and stem number was small.
Potato cultivars differed in susceptibility toR. solani, but yield response did not differ significantly between cultivars at the same levels of stem and stolon infection. 相似文献
14.
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
15.
Kerstin Olsson 《Potato Research》1988,31(3):423-429
Summary The levels of incorporation of Mg and Ca into tuber cell walls and middle lamellae were compared with the intensity of attack
byPhoma exigua var.foveata (P.e.f.) (gangrene) andFusarium solani var.coeruleum (F.s.c.) (dry rot) in six genotypes varying in their levels of resistance. The Mg:Ca ratio was higher in those genotypes more resistant
toP.e.f., while the cation effect on attack byF.s.c was variable. Although genotype resistance may be improved by extra Mg bridges in the pectin structure the genotypic differences
in susceptibilty to gangrene could not be explained by differences in Mg content assessed from alcohol-insoluble solids. Analyses
of breeders' selections showed no general relationship between Mg or Ca contents and disease incidence. Therefore, genotypic
differences in incorporation of these cations could not be used for screening for improved resistance. 相似文献
16.
P. Kastelein A. Bouman A. Mulder L. J. Turkensteen J. W. L. van Vuurde 《Potato Research》1996,39(1):31-42
Summary In the Netherlands seed potato crops are harvested when still green, the haulm being destroyed before harvest. We compared
the effect on the contamination of seed potatoes byErwinia carotovora subsp.atroseptica (Eca) andE. chrysanthemi (Ech) of the common method of haulm destruction by flailing and chemically destroying remaining stems, with the recently
developed green crop lifting method.
After chenical haulm destruction the levels of contamination with both Eca and Ech surviving cold storage were found not to
differ significantly from those after green crop lifting. Losses due to watery wound rot (Pythium ultimum) were considerable in the warm and humid conditions during 1991, especially after green crop lifting. 相似文献
17.
Summary A two year field experiment was conducted twice to assess effects of chemical soil disinfection at planting and methods of
harvesting potatoes on stem infection withRhizoctonia solani in the subsequent year. In the first year of the experiments seven methods. including one with soil disinfection at planting,
were applied in August. In the following year,R. solani stem and stolon infection (disease severity) on potato plants were assessed in June. Soil treatment at planting with pencycuron
resulted in lowest disease severity in the following year. Compared with chemical haulm killing and haulm pulling. immature-crop-harvesting
also resulted in a lower disease severity, but only when black scurf was scarce on tubers at harvest in the preceding year. 相似文献
18.
Soile Prokkola 《Potato Research》1994,37(2):103-111
Summary Seed potatoes of cvs Record and Bintje were grown with 30, 80 or 130 kg N/ha. In the subsequent growing season the seed tubers,
which were inoculated or not with two concentrations ofErwinia carotovora subsp.atroseptica (Eca), were subjected to the same fertilization treatment. The incidence of blackleg and the level of seed tuber decay increased
from the uninoculated treatment to the higher inoculum level, but the degree varied considerably from one year to another.
Cv. Bintje was more susceptible to blackleg and yield loss caused by Eca than cv. Record. In 1990, when disease incidence
was high, the proportion of blackleg stems increased with increasing doses of nitrogen fertilizer which had been applied to
the seed crop, but was not significantly affected in 1988 and 1992. Seed tuber decay was retarded by the lowest nitrogen dose.
The yield of the subsequent crop was not affected by the nitrogen dose applied to the seed crop. 相似文献
19.
Summary The kinetics of accumulation of phytoalexins, glycoalkaloids and phenolics was studied in two potato cultivars differing in
their degrees of field resistance when infected withPhytophthora infestans. Tuber slices and leaves of cvs Pampeana INTA (high degree of field resistance, free of R genes) and Bintje (susceptible)
were infected with race C (complex race 1, 3, 5, 7, 11) ofPhytophthora infestans. Phytoalexins and phenolics accumulated in tuber and leaf tissues which had been inoculated. The levels of these compounds
in the susceptible cv. Bintje were relatively low and similar to those found before inoculation. Leaves of cv. Pampeana INTA
had a very high glycoalkaloid content, suggesting that glycoalkaloids may play a role in protection of leaves against the
fungus. However, we could find no correlation between resistance and glycoalkaloid content of tubers. Our results suggest
a major role of phytoalexins, phenolics and glycoalkaloids in the complex mechanisms of field resistance. 相似文献
20.
Summary The incidence of infection withSpongospora subterranea was studied in the non tuber-bearingSolanum brevidens andS. etuberosum and the tuber-bearingS. acaule, S. sucrense andS. tuberosum cvs Olympia and Pito. Shoot cuttings were grown in soil naturally infested withS. subterranea, or the roots were inoculated with a zoospore suspension. Logit models were used to analyse the data. The incidence ofS. subterranea was higher in plants inoculated with zoospore suspension than in those grown in infested soil (odds ratio (OR) 10.65). Ageing
the inoculum reduced the incidence of infection in the plants (OR 0.30) without altering the interspecific differences. The
ORs of infection (compared to cv. Olympia) were 0.07, 0.29, 0.60 and 2.88 forS. acaule, S. sucrense, S. brevidens andS. etuberosum. OnlyS. acaule was significantly more resistant to infection than cv. Olympia. No infection was detected in cv. Pito. 相似文献