A Survey Investigating the Infection of Fusarium langsethiae and Production of HT‐2 and T‐2 Mycotoxins in UK Oat Fields

Fusarium langsethiae is a toxigenic fungal species that has been reported in European small‐grain cereal crops such as oats, wheat and barley. Although its relative contribution to fusarium head blight (FHB) symptoms is not well understood, it is reported to contaminate these cereals with high levels of HT‐2 and T‐2 trichothecenes mycotoxins that are currently under consideration for legislation by the European Commission. Ten commercial oat fields in Shropshire and Staffordshire (two adjacent counties in the Midlands) in the UK were surveyed in the 2006/2007 growing season. Samples were taken from predetermined field locations at Zadoks growth stages 32/33, 69, 77‐85 and 90‐92 for F. langsethiae biomass and HT‐2 and T‐2 toxins quantification. The results from this study showed that oats can be heavily infected with F. langsethiae and have high concentrations of HT‐2 and T‐2 toxins with no apparent FHB symptoms. The regression of HT‐2 + T‐2 toxins on F. langsethiae DNA concentration was highly significant (P < 0.001, r² = 0.55). The results indicated that although F. langsethiae had no direct effect on crop yield, it may result in indirect economic losses where the grain can be rejected or downgraded as a result of intolerable levels of HT‐2 and T‐2 toxins, which are of human food and animal feed safety concern. The influence of cultural field practices on the infection and HT‐2 and T‐2 toxins accumulation in oats was not clear and warrants further studies to identify the sources of F. langsethiae inoculum and conditions favourable for infection and mycotoxin production.     

Non-target effects of repeated methiocarb slug pellet application on carabid beetle (Coleoptera: Carabidae) activity in winter-sown cereals

The effects of repeated annual application of methiocarb-based slug pellets, broadcast on the soil surface and drilled into the seed bed, on carabid beetle activity were investigated over a four year period on a winter-sown cereal field using pitfall traps in barriered plots. Following applications in late autumn all winter-active carabid populations were severely depressed; total carabid activity falling to less than 5% and 10–15% following broadcast and drilled applications, respectively, compared with untreated plots. Spring and summer-active species, not active at the time of application, were largely unaffected by applications and were responsible for a gradual recovery of total activity from early spring onwards. Activity of all affected winter species remained demonstrably depressed on treated areas for the remainder of their seasonal incidence. However, all except one species, Bembidion obtusum, recovered to normal activity levels in the following season prior to reapplication. Recovery patterns are discussed in terms of the known biology of the species involved. Evidence that a minority of summer-active species were also affected by treatments, sometimes positively and sometimes negatively, were attributed to indirect effects possibly involving prey availability and foraging behaviour. The long-term ecological and short-term agronomic implications of methiocarb effects on carabid populations in winter-sown cereals are discussed.     

Somaclonal variation from Sorghum bicolor (L.) Moench cell culture

Plant Cell, Tissue and Organ Culture (PCTOC) - Sorghum bicolor (L.) Moench, plants were regenerated from 4 to 5 month old callus cultures originally derived from seedling explants. Somaclonal...     

A case of sporotrichosis caused by two genetically differentSporothrix schenckii strains

A survey for the natural occurrence of Fusarium mycotoxins, deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN), in Dutch cereals (totaling 29 samples) harvested in 1984/1985, showed that 90%, 79% and 62% of samples were contaminated with DON, NIV and ZEN, respectively. Average contents (ng/g) in the total of positive samples were 221 (DON), 123 (NIV) and 61 (ZEN). Among the cereals examined, the highest concentrations (ng/g) was 3198 (DON), 1875 (NIV) and 677 (ZEN) in a yellow corn sample for animal feed. The results of this survey show that Dutch cereals were relatively significantly contaminated with Fusarium mycotoxins.     

Relationship between the population of viable sclerotia ofSclerotium rolfsii in soil to cropping sequence in the Nigerian savanna

Populations of viable sclerotia ofSclerotium rolfsii were highest in soil in a field in which tomato was planted for three successive years before sampling and in one in which tomato followed groundnut in the 2 years prior to this study. The lowest sclerotial numbers were recorded in fields in which groundnut followed maize or in which maize or sorghum was the last crop before sampling.     

The phytate and mineral content of some cereals,cereal products,legumes, legume products,snack bars,and nuts available in New Zealand

Analyses for phytate by an indirect precipitation method and for the minerals calcium (Ca), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) by atomic absorption spectrophotometry were carried out on 100 foods available in New Zealand. Foods with 1% phytate (dry weight basis) included untoasted muesli, rolled oats, wheat germ, wheat bran, soybean, and some soy products. Most breads contained between 0.35 and 0.60% phytate; legumes on average had 0.62% phytate, as did snack bars. There was a wide variation in Ca and Zn contents: There was a tenfold variation in Ca content among the legume products, whereas there was a seventyfold variation in Zn content among the cereals. The phytate: Zn molar ratio, which is presumed to indicate the biovailability of Zn, was above 20∶1 for two-thirds of the cereals and almost all of the snack bars; it was above 15∶1 for one-third of the breads, almost all of the legumes, and half of the legume products. These high phytate: Zn molar ratios, as well as some Ca: phytate molar ratios above 6∶1, indicate that there might be a reduced biovailability of Zn in many of the foods analyzed in this study.     

Somatic embryogenesis and plant regeneration from immature inflorescence segments of Coix lacryma-jobi

Callus was obtained from segments of immature inflorescence of Coix lacryma-jobi cultured on N6 medium containing 1–2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 3–5% sucrose. Plantlets were regenerated when embryogenic calluses were transferred onto MS medium with 0.5 mg/l kinetin and 0.01 mg/l naphthaleneacetic acid (NAA). Regenerated plants had the diploid chromosome number (2n=20).     

The effect of soil compaction on the saprophytic growth of Rhizoctonia solani

The increase in bare patch of cereals associated with minimum tillage practices prompted an investigation of the relationship between soil compaction and saprophytic growth of Rhizoctonia solani. In soils wetter than 10 kPa there was a greater density of hyphae in compacted than in non-compacted soil. In relatively dry soil, however, there was wider exploration by hyphae in non-compacted than in compacted soil. The implications of these findings for disease management are discussed.     

Hydroxamic acids affecting barley yellow dwarf virus transmission by the aphid Rhopalosiphum padi

2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a hydroxamic acid (Hx) occurring in wheat, was shown to deter feeding by the aphid Rhopalosiphum padi (L.), and to reduce BYDV transmission to the plant. Dual choice tests with wheat leaves showed the preferential settlement of aphids on leaves with lower levels of DIMBOA. Electric monitoring of aphid feeding behaviour showed that in seedlings with higher DIMBOA levels fewer aphids reached the phloem and they needed longer times to contact a phloem vessel than in those with lower levels. When aphids carrying BYDV were allowed to feed on wheat cultivars with different DIMBOA levels, fewer plants were infected with BYDV in the higher DIMBOA cultivars than in the lower ones. Preliminary field experiments showed a tendency for wheat cultivars with higher Hx levels to be more tolerant to infection by BYDV than lower Hx level ones.     

Effect of aluminium on the growth of 34 plant species: A summary of results obtained in low ionic strength solution culture

The results from many experiments conducted over 5 years to determine the tolerance of 34 plant species (87 cultivars) to aluminium (Al) are summarised. All experiments were conducted in a temperature-controlled glasshouse using a low-ionic-strength solution culture technique. The activity of Al³⁺ (M) at which top yields were reduced by 50% (Al_RY50) was determined for each cultivar.The species Bromus wildenowii, Cynosurus cristatus, Hordeum vulgare, Triticum aestivum (cvs Warigal, Scout, Sonora-63), Avena byzantina, Arabidopsis thaliana, Lycopersicon esculentum and Nicotiana plumbaginifolia were all very sensitive to Al (Al_RY50<1). The species Poa pratense, Lolium perenne (NZ-derived cultivars), Lotus corniculatus, Avena sativa (cvs West, Carbeen, Camellia and Coolabah), Triticum aestivum (cvs Cardinal and Waalt), Allium cepa and Asparagus officinalis were sensitive to Al (Al_RY50 1–2).The pasture grass species Lolium perenne (Australian and European and derived cultivars), Lolium hybridum and Lolium multiflorum, Dactylis glomerata (Apanui and Kara), Phalaris aquatica, Festuca arundinacea and the pasture legumes species Trifolium pratense, Trifolium repens and Trifolium subterraneum were all moderately sensitive to Al (Al_RY50 2–5). Other species that were also moderately sensitive included Triticum aestivum (cvs Atlas-66, BH146, and Carazinho), Avena sativa (cvs Swan and Blackbutt), Avena Strigosa, Petunia x and Phaseolus vulgaris (cvs Red Kidney, Black Turtle and Haricot).The most tolerant species (Al_RY50>5) were (in order of increasing tolerance) Phaseolus vulgaris (cvs Tendergreen, The Prince and Yatescrop), Cucurbita maxima, Dactylis glomerata (cv Wana), Paspalum dilatatum, Lotus pedunculatus, Ehrharta calycina, Medicago sativa, Holcus lanatus, Festuca rubra, Phaseolus lunatus and Agrostis tenuis. Agrostis tenuis was at least twice as tolerant as the next most tolerant species (Al_RY50>30 compared to 15.6).