Data from surveys of winter wheat fields in the period 1974-1986 and of seed lots in the period 1962-1986 and identifications of diseases on plant samples were compiled to describe the occurrence of snow mould (Monographella nivalis) and Fusarium spp. On average, M. nivalis dominated over Fusarium spp. The complex of Fusarium spp. constituted mainly of E culmorum, followed by E avenaceum and E graminearum. M. nivalis was dominant in May on stem-bases and in July on leaves and leaf sheaths. On seeds M. nivalis predominated only in years with low temperatures in July and August.Average brown footrot infection in the field was 4% tillers in May and 5~ culms in July. Brown footrot intensity in July was high in cropping seasons with high precipitation in October and with low temperatures in October, November and December. In July during the early eighties, an average of 8 % of leaves and 6% of flag leaf sheaths were infected by M. nivalis. Average ear blight incidence was 1.2% glumes infected. Seed contamination by these pathogens averaged 26% in the years 1962-1986. The contamination was high in years with high precipitation in June, July and August. Aspects of cv. resistance and yield loss are illustrated.
Background: Xanthomonas campestris pv. campestris (Xcc) is a seed-transmitted plant pathogenic bacterium that causes black rot of crucifers. Seed lots and plants are screened for contamination with this pathogen using plating or serological assays. These methods, however, are time consuming and not very sensitive, respectively. Therefore, flow cytometry (FCM) was evaluated as a tool for the rapid detection and quantification of Xcc cells labeled with a mixture of specific fluorescein isothicyanate (FITC)-monoclonal antibodies (mAb) in pure culture, in mixed cultures of Xcc with either the common saprophyte Pseudomonas fluorescens (Psf) or a nonpathogenic X. campestris isolate (Xc), and in crude seed extracts.
Time to pod set and seed position on the plant were studied as possible within-plant components contributing to variation in quality of seeds within seed lots of soybean (Glycine max (L.) Merrill) cultivar IAS-5. Plants were grown at 28/22°C (NT = normal temperatures) or 33/27°C from the beginning of pod set onwards (HT = high after normal temperatures), The heaviest seeds were produced on positions in the canopy where also the earliest pods were formed: main stems versus branches and upper versus lower main stem sections. The variation in weight between seeds within a seed lot was mainly determined by position in the canopy, contributing 23 and 30% under NT-and HT-conditions, respectively. Days to pod set contributed 2 and 27% respectively. Position fully accounted for variation resulting from days to pod set under NT-but not under HT-conditions. Seeds from earlier pods had a lower viability. For explaining differences in viability between seeds within a seed lot, days to pod set of individual seeds was more important than seed position. Components of variation between plants were largely additional to within-plant components and at least of equal importance.
Treatment of narcissus bulbs with methoxy ethyl mercury chloride, pimaricin or thiram provided control of basal rot and primary root rot, caused by Fusarium oxysporum f. sp. narcissi and secondary root rot and 'skin disease' caused by F. oxysporum ff. spp. A similar treatment with formalin was only effective against basal rot and root rot. Newly formed roots of bulbs treated with the mercurial, pimaricin or thiram became more heavily colonized by Penicillium and Trichoderma spp. than those of untreated or formalin-treated bulbs. Especially P. janthinellum and T. viride appeared to protect the roots against the pathogens. These fungi were found to be antagonistic to F. oxysporum f. sp. narcissi and F. oxysporum ff. spp., both in experiments in vitro and in vivo. A synergism between P. janthinellum and thiram was observed with respect to inhibition of mycelial growth of F. oxysporum f. sp. narcissi in vitro and to control of root rot and basal rot in vivo. In vitro, similar effects were found for pimaricin and organic mercury. Pimaricin was found to stimulate the production of antibacterial metabolites by Cylindrocarpon destructans in vitro. In the field, a synergistic effect was observed between pimaricin and C. destructans with respect to control of basal rot.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.