Effects of growth stage, leaf position and temperature on adult-plant resistance of wheat infected by Puccinia recondita f.sp. tritici   总被引：2，自引：0，他引：2  

Z. A. PRETORIUS  F. H. J. RIJKENBERG  R. D. WILCOXSON 《Plant pathology》1988,37(1):36-44

Growth stage, leaf position and temperature effects on components of resistance to Puccinia recondita f.sp. tritici in wheat ( Triticum aestivum ) were studied. Inoculation of Era, Glenlea, Sinton and RL6044 plants at five growth stages showed that latent period increased and uredinium numbers decreased as each adult-plant-resistant wheat matured. Growth stage had little effect on latent period in the susceptible cultivar Morocco. No significant differences in latent period determined on the flag, flag -1 and flag -2 leaves of the same plant were observed for Era, Glenlea and RL6044. However, leaf age should be considered in assessing adult-plant resistance because the latent period of P. recondita f.sp. tritici in flag leaves of Sinton was shorter than that determined for the flag-1 and flag -2 leaves. Fewer uredinia developed on the flag -2 leaf of Glenlea than on the flag leaf. The latent period of leaf rust in Era, Glenlea, RL6044 and Morocco was significantly longer at 15°C than at 21°C, but temperature did not affect Sinton to the same degree. Uredinium size was a sensitive criterion of adult-plant resistance. Uredinium development in line RL6044 was significantly restricted at 15°C, but uredinia on Era, Glenlea and Sinton at 15°C were as large as those at 21°C. On the susceptible Morocco uredinia were larger at 15°C than at 21°C.  相似文献   

Effect of MBC fungicide tolerance on the fitness of Ophiostoma ulmi     

JOAN F. WEBBER 《Plant pathology》1988,37(2):217-224

Isolates of Ophiostoma ulmi with mutations conferring high or low levels of tolerance to MBC-generating fungicides were selected in the laboratory. Comparisons between these tolerant forms and their wild type equivalents indicated that the acquisition of a mutation in the tol locus was associated with decreased growth on agar medium. Pathogenicity and bark-colonizing ability were also found to be significantly reduced, indicating that the fitness of tolerant individuals was impaired.  相似文献   

Relative importance of root rots of subterranean clover caused by Aphanomyces euteiches and Phytophthora clandestina     

F. C. GREENHALGH  P. R MERRIMAN  P. J. KEANE 《Plant pathology》1988,37(3):344-350

In a growth-cabinet experiment, Aphanomyces euteiches caused more severe root disease and greater reductions in root and shoot weights of subterranean clover cv. Mount Barker than Phytophthora clandestina in pasteurized sandy loam flooded with water for a 24-h period each week. A. euteiches also reduced plant growth more than P. clandestina in untreated sandy loam. In a similar experiment, both fungi caused the same amount of disease and reduction in growth of cv. Yarloop in pasteurized clay loam flooded for 24 h each week, and P. clandestina caused more disease and a greater decrease in plant growth than A. euteiches when the soil was flooded for 4 h each week. The pathogens did not interact positively in either soil. In an irrigated pasture, soil drenches with the fungicides metalaxyl and fenaminosulf together reduced both root rots to low levels and increased subterranean clover dry matter by 1 96, 0.50 and 1 20 t/ha in the autumn, winter and spring of 1985, respectively, and by 0.59 t/ha in the autumn of 1986. Results suggest that P. clandestina caused most of these losses in yield.  相似文献   

Polygalacturonase isoenzymes and oxalic acid produced by Sclerotinia sclerotiorum in soybean hypocotyls as elicitors of glyceollin     

F. Favaron  P. Alghisi  P. Marciano  P. Magro 《Physiological and Molecular Plant Pathology》1988,33(3)

The polygalacturonases (PG) and oxalic acid produced by Sclerotinia sclerotiorum in infected soybean hypocotyls were investigated as elicitors of the phytoalexin glyceollin I.Purification to homogeneity through isoelectrofocusing and ion-exchange fast protein liquid chromatography revealed three endo-PG isoenzymes (PG-I, PG-II and PG-IV) and one exo-PG (PG-III) in 6-day-old etiolated soybean hypocotyls infected with the B-24 isolate of S. sclerotiorum.PG-I and PG-III, in the range of concentrations tested (0·15–1·2 reducing units ml⁻¹), did not act as elicitors of glyceollin I synthesis. Some elicitor activity was shown by PG-II at 0·6–1·2 reducing units ml⁻¹. PG-IV, at lower doses (0·038–0·30 reducing units ml⁻¹), was even more effective in inducing phytoalexin synthesis. However higher concentrations of PG-IV induced tissue softening and decreased phytoalexin accumulation.PG-II and PG-IV released heat-stable elicitors from purified soybean cell walls supporting the evidence that uronides are intermediate inducers in elicitation by endo-PGs. Oxalic acid was an active elicitor of glyceollin I over the range of concentrations tested (0·31–20 m ) with the maximum at a concentration of 5 m . The inability of oxalic acid to release uronides from purified cell walls makes it unlikely that uronide intermediate elicitors are involved in elicitation by oxalic acid.  相似文献   

The pyrethrins and related compounds. Part XXXIV. Optimisation of insecticidal activity in non-esters     

Ahmet E. Baydar  Michael Elliott  Andrew W. Farnham  Norman F. Janes  Bhupinder P. S. Khambay 《Pest management science》1988,23(3):247-257

Optimisation of activity within the structural constraints defined by the preceding work, by varying the substituents on phenyl in the acid fragment (10 variations), the nature of the group fulfilling the dimethyl function (three variations), the central linking group (four variations) and the presence or absence of a 4-fluoro substituent in the alcohol fragment, has led to achiral compounds as active as bioresmethrin against houseflies and mustard beetles. Statistical analysis of the effects has shown that particular combinations, for instance the cyclopropyl form of dimethyl with a central E-alkene group (but not a central ether group), lead to higher activity than expected. 4-Fluoro substitution enhances activity more strongly against mustard beetles. Difluorocyclopropyl compounds are on average slightly more active than cyclopropyl analogues.  相似文献   

Leaching potential and decomposition of fluroxypyr in Swedish soils under field conditions     

Lars F. Bergstrm  Alec S. McGibbon  Steve R. Day  Marten Snel 《Pest management science》1990,29(4):405-417

The mobility and decomposition of the herbicide fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) was studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile-drained plots (clay). Soil samples to a depth of one metre were also collected in both soils to characterize the temporal depth distribution of fluroxypyr in the profiles. The herbicide was applied as the I-methylheptyl ester of fluroxypyr at two rates, 187.5 and 375.0 g a.e. ha^?1, representing the normal and double the dose of the compound used for spring cereals. Some lysimeters received supplementary watering. Only two leachate samples (one from each soil) had concentrations of fluroxypyr above the detection limit (1 μg litre^?1), i.e. 2 and 5 μg litre^?1. Both samples were collected within two months after application, when less than 2 mm of drainage had been collected. The methylheptyl ester of fluroxypyr was not found in any of the samples. Fluroxypyr levels above the detection limit in soil (5 μg kg^?1 dry soil), were never found below the topsoil (0.2 m) in the clay profile, while, in the sandy profile, levels just above the detection limit were found occasionally in deeper soil layers. Concentrations were reduced to undetectable or very low levels within three months after spraying.  相似文献   

Synopsis of type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. III. Nematoda     

F Moravec 《Folia parasitologica》1990,37(4):367-383

The paper comprises a list of the nematode type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. These materials include a total of 110 species and subspecies.  相似文献   

First record of the nematode Syncuaria squamata (Linstow, 1883) from common cormorants (Phalacrocorax carbo (L.)) in Czechoslovakia     

F Moravec 《Folia parasitologica》1990,37(4):365-366

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Achievements of ichthyoparasitological research in the Institute of Parasitology of the Czechoslovak Academy of Sciences     

F Moravec  J Lom 《Folia parasitologica》1990,37(4):289-294

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Additional records of nematode parasites from Papua New Guinea amphibians with a list of recorded endohelminths by amphibian hosts   总被引：1，自引：0，他引：1  

F Moravec 《Folia parasitologica》1990,37(1):43-58

An examination of a small sample of four species of frogs (Cophixalus riparius, Phrynomantis humicola, Ph. stictogaster, Ph. wilhelmana) from Papua New Guinea yielded altogether 5 species of nematodes, 2 of them being new to science. These include: Cosmocercella phrynomantisi sp. n. (type host Ph. humicola), Spinicaudinae gen. sp., Parathelandros andersoni sp. n. (type host C. riparius), Oswaldocruzia bakeri, and Paracapillaria spratti. C. phrynomantisi sp. n. differs from congeneric species mainly in the length of spicules (0.180 mm) and the character, arrangement and number of caudal papillae in the male, while P. andersoni sp. n. is characterized mainly by the presence of four well developed spines on the male tail. Pseudocapillaria spratti is redescribed in detail and it is transferred to Paracapillaria as P. spratti (Moravec et Sey, 1986) comb. n. Capillaria combesi Chabaud et Knoepffler, 1985 is transferred to Amphibiocapillaria Moravec, 1982 and Capillaria petiti Justine et Bain, 1987 to Pseudocapillaria Freitas, 1959. A survey of the endohelminths (excluding Hirudinea) hitherto reported from New Guinea amphibians is presented.  相似文献