Showing papers on "Rust published in 1980"

Nature of Atmospheric Rust on Iron

Abstract: In order to elucidate the mechanism of self‐protection of weathering steel, the action of atmospheric rust was studied through a discussion of physical, chemical, and electrochemical nature of rust, with special attention to the effect of copper addition. The aggregating state of rust layer is influenced by two factors: the time of exposure and beneficial elements added to steel. Copper addition inhibits the growth of primary colloidal particle. This action of copper has an effect on the properties of rust and serves to increase the protective ability of rust layer.

Screening methods and further sources of resistance to peanut rust

Abstract: creened for resistance to rust at ICRISAT, India. Preliminary field screening was done during the 1977 rainy season when a natural epidemic of rust was in progress. The cultivars or lines which were rated between 2 and 5 on a Spoint scale during this screening were further tested during the 1977/78 dry season employing an infector row system of susceptible cultivars and spreader plants systematically interplanted with the test material. High relative humidity was maintained in the field by operating an overhead sprinkler irrigation system. Percentage leaf area damaged on the test material was estimated at 10 day intervals from approximately 90 days after their emergence until harvest. Each entry was also assessed on a scale proposed by Mazzani and Hinojosa. Two land races, NC.Ac. 17090 and EC. 76446 (292) were more resistant than either PI. 259747 or PI. 298115 which were reported resistant by other workers. In addition, NC.Ac. 17030, NC.Ac. 17132, NC.Ac. 17129, NC. Ac. 17135 and NC.Ac. 17124 were moderately resistant. Four cultivars or lines with different levels of resistance in the field were tested in the greenhouse at three different stages in development. The results indicated that resistance increased as the plants aged.

Parasitism of carnation rust (Uromyces dianthi) by Verticillium lecanii

Abstract: Verticillium lecanii (Zimm) Viegas was found infesting uredinia of Uromyces dianthi (Pers) Niessl, the causal organism of carnation rust in a nursery In the laboratory U dianthi, inoculated on to carnation leaf pieces, caused typical rust symptoms, but in the presence of V lecanii either rust infection was prevented or the formation of urediniospores was arrested, depending on the time of application of V lecanii conidia In a glasshouse, V lecanii applied at the appropriate time reduced rust in carnation plants inoculated with U dianthi

The susceptibility of potato varieties to internal rust spot

Abstract: In tubers of ten potato varieties the incidence of internal rust spot lesions increased and the calcium concentration decreased when the concentration of calcium chloride supplied to the plants fell from 9 to 1 mM. A simple linear model relating the probit transformation of internal rust spot incidence to tuber calcium concentration for each variety showed that there were substantial differences in varietal susceptibility to internal rust spot which were not related to tuber calcium concentration.

Pathogenic variability in Uromyces viciae-fabae.

Abstract: SINGH, S. J., and S. S. SOKHI. 1980. Pathogenic variability in Uromyces viciae-fabae. Plant Disease 64:671-672. Seven isolates of Uromyces viciae-fabae causing rust of pea were differentiated into six pathotypes, based on differential reactions of 15 pea, sweet pea, and lentil hosts.

Tolerance of spring barley cultivars to leaf rust, Puccinia hordei

Abstract: Fifteen spring barley cultivars were evaluated in two years for their tolerance to leaf rust, Puccinia hordei. The consistency between the results obtained in the two experiments was rather poor. The most tolerant cultivars produced low seed yields, the least tolerant ones high seed yields. A strongly negative relationship existed between harves-index and tolerance.

The effects of light and a photosynthetic inhibitor on the expression of the Lr20 gene for resistance to leaf rust in wheat

Abstract: A possible relationship between photosynthetic activity and the occurrence of hypersensitivity was explored. Most of these experiments exploited the temperature-sensitivity of the Lr20 gene which is expressed at 20 °C but not at 30 °C. Colonies of avirulent rust were thereby grown at 30 °C before transfer to 20 °C where necrosis and limitation of fungal growth occurred under normal conditions. Necrosis was largely prevented in leaves held under coloured cellophanes which filtered out photosynthetically active wavelengths of light. Necrosis was also prevented by application of 3-(3,4-dichlorophenyl)-l,l-dimethylurea (DCMU). Despite the prevention of necrosis by DCMU, the avirulent rust grew very litde in the presence of the Lr20 gene. These results suggested that photosynthesis is involved in processes leading to necrosis in this system and showed that necrosis is not essential for expression of resistance to rust growth.

Process for producing iron oxide containing magnetite

Abstract: In a process for producing an iron oxide having magnetite as a main component by heating to reduce a powder of an iron oxide or a hydrated iron oxide in an atmosphere for reduction, an improvement characterized in that said atmosphere for reduction comprises an inert gas, steam and a gas of an organic compound for reducing an iron oxide.

Some effects of rust infection and moisture stress on growth, diffusive resistance and distribution pattern of labelled assimilates in sunflower

Abstract: Greenhouse experiments, where sunflower plants (cv. Peredovic) were inoculated with Puccinia helianthi at the vegetative stage of plant growth, showed that the effect of rust on growth parameters varied according to the moisture stress to which plants were subjected. Rust infection caused a marked reduction in the diffusive resistance of leaves in darkness. However, the diffusive resistance in light of leaves not stressed or subjected to mild moisture stress was unaffected by rust infection. In uninfected plants subjected to moderate moisture stress, the diffusive resistance in light increased markedly, whereas in rust-infected leaves it remained the same as in leaves not stressed or subjected to mild moisture stress. Carbon-14 uptake by the first pair of true leaves of non-stressed plants or those subjected to mild moisture stress was unaffected by a low level of rust infection (9% disease rating). Carbon-14 uptake by uninfected leaves was reduced when they were subjected to moderate moisture stress. Rust infection and moderate moisture stress caused a reduction in the rate of translocation of labelled assimilate from leaves fed with 14CO2 and also altered the distribution pattern of labelled translocate to various sinks.