Standard non-target tests for risk assessment of plant protection products are unsuitable for entomopathogenic fungi—a proposal for a new protocol

Journal of Soils and Sediments - The successful implementation of a plant protection product depends on its effectiveness against a target species and its safety for the environment. Risk...     

Biological control of fusarium seedling blight disease of wheat and barley

ABSTRACT Fusarium fungi, including F. culmorum, cause seedling blight, foot rot, and head blight diseases of cereals, resulting in yield loss. In a screen for potential disease control organisms and agents, Pseudomonas fluorescens strains MKB 100 and MKB 249, P. frederiksbergensis strain 202, Pseudomonas sp. strain MKB 158, and chitosan all significantly reduced the extent of both wheat coleoptile growth retardation and wheat and barley seedling blight caused by F. culmorum (by 53 to 91%). Trichodiene synthase is a Fusarium enzyme necessary for trichothecene mycotoxin biosynthesis; expression of the gene encoding this enzyme in wheat was 33% lower in stem base tissue coinoculated with Pseudomonas sp. strain MKB 158 and F. culmorum than in wheat treated with bacterial culture medium and F. culmorum. When wheat and barley were grown in soil amended with either chitosan, P. fluorescens strain MKB 249, Pseudomonas sp. strain MKB 158, or culture filtrates of these bacteria, the level of disease symptoms on F. culmorum-inoculated stem base tissue (at 12 days post- F. culmorum inoculation) was >/=31% less than the level on F. culmorum-inoculated plants grown in culture medium-amended soil. It seems likely that at least part of the biocontrol activity of these bacteria and chitosan may be due to the induction of systemic disease resistance in host plants. Also, in coinoculation studies, Pseudomonas sp. strain MKB 158 induced the expression of a wheat class III plant peroxidase gene (a pathogenesis-related gene).     

Performance of the Swedish lucerne variety U 0615 from seed multiplied in Israel

Seed of the Swedish lucerne variety U 0615 harvested in a seed field in Israel for four consecutive seasons was tested in field trials in Sweden. Differences in seed yield between plants were demonstrated in Israel — less winter-dormant plants gave more than four times as much seed as winter-dormant plants. On the average Israel-grown seed yielded less in the first cut than Swedish-grown seed, which indicates a decrease in winter-hardiness. The yield was especially reduced in 1962 when winter damage was severe. It is pointed out that varieties may react differently when seed is produced outside the area of adaptation. In a variety with a high degree of heterogeneity, e.g. U 0615, the mode of increase and the stage to be multiplied at southern latitudes should be tested carefully before it is undertaken commercially.Swedish Seed Association, Uppsala 1, Sweden.The Hebrew University, Faculty of Agriculture, Rehovot, Israel.     

Changes in adaptation in a Swedish and an Italian lucerne variety when grown for seed without isolation

Seed of two lucerne varieties, Tuna from Sweden and Nostrale (common) from Italy, multiplied in isolated stand and in the vicinity of each other, was tested in field trials at Perugia (Italy) and at Uppsala (Sweden). In both places distinct differences between the intercrossed populations Tuna (× Nostrale) and Nostrale (× Tuna) were demonstrated. The decrease in winterhardiness as compared with Tuna was very pronounced in the trial at Uppsala. It is concluded that the influence of volunteer lucerne plants in a field or in the vicinity of a seed field is economically very important when seed of a North European variety is produced outside the area of adaptation.

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Samenvatting Zaad van twee lucernerassen, Tuna uit Zweden en Nostrale uit Italië, afkomstig van geïsoleerde en van naast elkaar gezaaide velden, werd gebruikt voor veldproeven te Perugia (Italië) en te Uppsala (Zweden). Op beide plaatsen konden duidelijke verschillen tussen de populaties Tuna (x Nostrale) en Nostrale (x Tuna) worden vastgesteld.Opvallend was de achteruitgang in winterhardheid van het in Italië, in de nabijheid van het ras Nostrale, vermeerderde Zweedse ras Tuna.Geconcludeerd wordt dat bij de vermeerdering van Noord-Europese lucernerassen in andere landen (buiten het gebied, waaraan zij zijn aangepast) spontane kruisbestuiving met andere rassen of opslag-planten voorkomen dient te worden.

     

Leaf Absorption of Atmospheric Ammonia Emitted from Pig Slurry Applied beneath the Canopy of Winter Wheat

Abstract

Absorption of volatilized ammonia after application of slurry onto the soil surface (sand) between rows of a wheat crop was studied in two experiments. The slurry was labelled with ¹⁵N-NH₄. During seven days the accumulated gaseous N loss from the slurry varied from 6.9 to 11.1 g N m^?2. In April ammonia losses from slurry applied beneath a 5 cm high wheat crop were equal to losses from slurry applied to a fallow, but 2.2% of the lost atmospheric ammonia was taken up by the leaves. In May ammonia loss from slurry applied between the rows of a 43 cm high crop was reduced by 6% compared to the loss from fallow, because of a reduced transfer of ammonia from the slurry to the air. Of the emitted ammonia 3.3% was absorbed by the canopy.     

Influence of soil mineralogy and chemistry on site quality within geological regions in Sweden

The relationship between soil properties and forest site quality was investigated. The site quality functions currently used fail in predicting variations within regions and the purpose of this study was to evaluate if the local accuracy in forest resource assessments could benefit from the use of geological and geochemical data. The investigation was conducted in mid-Sweden within two geological regions. The mineralogy of the parent material (C horizon) was estimated using a method for normative mineralogical assessment and the soil chemistry was determined for five soil horizons. The importance of individual minerals for site quality was different within the two geological regions. Functional relations were established between the properties in different soil horizons and site index. The functions between mineralogy and site index were improved by splitting the data according to the geologically different regions. The mineralogy explained 37–61% of the variation in site index, whereas the properties in the upper soil profile (O–B horizon) related more strongly to site index (18–80%). Stronger relations could be established in the mineralogically rich than in the mineralogically poor area.     

Impact of wheat flour-associated endoxylanases on arabinoxylan in dough after mixing and resting

The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.