Chemical control of foliar diseases of perennial ryegrass (Lolium perenne L.) and their effects on yield and quality of the crop

The effects of Drechslera spp. (causing a leaf-spotting disease) and ryegrass mosaic virus (RMV) on the dry-matter herbage yield of Lolium perenne (cv. S24) were assessed from 1977 to 1979 in a field experiment. The effect of Drechslera spp. on quality, i.e. water-soluble carbohydrate and nitrogen content and in vitro digestibility, was evaluated in 1977, when their incidence was greatest. Plots were sprayed regularly with chlorothalonil to control Drechslera spp. and endosulfan to control the eriophyid mite vector of RMV. Four harvests were taken each year and diseases were assessed immediately beforehand. Drechslera spp. were also assessed midway between harvests and Puccinia coronata was recorded in autumn 1978 and 1979. Although yield was increased where chlorothalonil and endosulfan had been applied, this increase could not be entirely attributed to the control of foliar diseases. Drechslera spp. did not affect crop quality.     

Fungicide resistance status in French populations of the wheat eyespot fungi Oculimacula acuformis and Oculimacula yallundae

Eyespot, caused by Oculimacula acuformis and Oculimacula yallundae, is the major foot disease of winter wheat in several European countries, including France. It can be controlled by chemical treatment between tillering and the second node stage. The fungicides used include antimicrotubule toxicants (benzimidazoles), inhibitors of sterol 14α‐demethylation (DMIs) or of succinate dehydrogenase (SDHIs), the anilinopyrimidines cyprodinil and the benzophenone metrafenone. Since the early 1980s, a long‐term survey has been set up in France to monitor changes in the sensitivity of eyespot populations to fungicides. Resistance to benzimidazoles has become generalised since the early 1990s, in spite of the withdrawal of this class of fungicides. In the DMI group, resistance to triazoles is generalised, whereas no resistance to the triazolinethione prothioconazole has yet developed. Resistance to the imidazole prochloraz evolved successively in O. acuformis and O. yallundae and is now well established. Specific resistance to cyprodinil has also been detected, but its frequency has generally remained low. Finally, since the early 2000s, a few strains of O. yallundae displaying multidrug resistance (MDR) have been detected. These strains display low levels of resistance to prothioconazole and SDHIs, such as boscalid. Knowledge of the spatiotemporal distribution in France of O. acuformis and O. yallundae field strains resistant to fungicides allows resistance management strategies for eyespot fungi in winter wheat to be proposed.© 2012 Society of Chemical Industry     

Effects of five vegetable oils on the sweetpotato whiteflyBemisia tabaci

The effects of five economically important vegetable (seed) oils, peanut, cottonseed, castor, soybean and sunflower, on adult and immature stages of the sweetpotato whitefly(Bemisia tabaci (Gennadius) [Hemiptera: Aleyrodidae]) were studied in the laboratory. Irrespective of origin, oil residues had similar effects on immature stages and adult mortality, and on settling and oviposition deterrence. Trends for 5-h settling, 24-h oviposition and 24-h survival of adults on treated plants were similar for oils applied at the same concentration range. Settling deterrence was strong enough to cause adult death due to starvation or dehydration under no-choice conditions, and caused greater mortality than direct physical toxicity; similar results were obtained when adult survival on oil residues was compared to survival of starved adults. Adults recovered when transferred from oil-treated to untreated plants. All oils produced similar effects when sprayed on immatures; the egg and fourth instar (pupa) were the most tolerant stages. The oil concentration required for significant effects on whitefly mortality and behavior was relatively high (>0.3%) compared with published efficacy data for synthetic pesticides, and varied to some extent with oil origin. All tested oils were active as direct and residual larvicides. Peanut oil was the most effective for all tested effects, followed by cottonseed oil, which was significantly less effective than peanut and castor oils when applied-directly to eggs. Only by this latter parameter was castor oil more effective than cottonseed oil and similar to peanut oil. As direct sprays to larvae, soybean and sunflower oils resembled castor oils, but their residues were less effective against all stages.     

Laboratory measures of hemostasis and fibrinolysis after intravenous administration of epsilon-aminocaproic acid in clinically normal horses and ponies

OBJECTIVE: To determine whether epsilon-aminocaproic acid (EACA) administered IV affects hemostasis and fibrinolysis in clinically normal horses and ponies. ANIMALS: 20 clinically normal adult horses and ponies. PROCEDURES: Blood samples were collected 24 hours before (baseline) and 1 and 5 hours after i.v. administration of a low dose (30 mg/kg) or high dose (100 mg/kg) of EACA. Platelet count, fibrinogen concentration, prothrombin time, partial thromboplastin time (PTT), D-dimer concentration, alpha2-antiplasmin activity, and thrombin-antithrombin complex concentration were measured. Values at 1 and 5 hours were compared with baseline values. RESULTS: hour after administration of a low dose of EACA, mean fibrinogen concentration was significantly lower than baseline concentration. Mean PTT was significantly shorter than the baseline value 5 hours after administration of a low dose of EACA. One hour after administration of 100 mg of EACA/kg, mean alpha2-antiplasmin activity was significantly higher than baseline activity. Mean fibrinogen concentration was significantly lower than baseline concentration 1 and 5 hours after administration of a high dose of EACA. Mean PTT was significantly shorter than the baseline value 5 hours after administration of a high dose of EACA. CONCLUSIONS AND CLINICAL RELEVANCE: i.v. administration of 30 and 100mg of EACA/kg to clinically normal horses significantly modified some laboratory measures of hemostasis, consistent with its known antifibrinolytic effects. Although enhanced clot maintenance and diminished bleeding were not directly assessed, the clinical use of EACA may benefit some patients.     

pH-dependent interaction of fumonisin B1 with cholesterol: physicochemical and molecular modeling studies at the air-water interface.

Langmuir film balance technology was used to study the interaction between the mycotoxin fumonisin B1 (FB1) and cholesterol. FB1 was added in the aqueous subphase underneath a monomolecular film of cholesterol, and the interaction was measured as an increase in the surface pressure of the film. Above pH 9, a strong inhibition of the reaction was observed. Similar results were obtained with the bile salt sodium taurocholate. The FB1-cholesterol complex was reinforced by NaCl but was destabilized by NaF, a salt known to break hydrogen bonds. These data suggest that the molecular association between FB1 and cholesterol involves both hydrophobic interactions and a hydrogen bond between the NH3(+) group of FB1 and the OH group of cholesterol. Molecular mechanics simulations of the FB1-cholesterol complex were consistent with this hypothesis. These data may shed some light on the mechanisms involved in the intestinal absorption of FB1 and its biliary excretion.