Michele Negre

Effectiveness of control strategies against Botrytis cinerea in vineyard and evaluation of the residual fungicide concentrations.

This investigation was undertaken to test different control strategies against Botrytis cinerea vineyards. Two commercial vineyards, “Barbera” and “Moscato,” located in Piedmont (Northern Italy) were divided into seven plots and treated with different combinations of fungicides including fenhexamid, pyrimethanil, fludioxonil + cyprodinil, iprodione, and boscalid, a new carboxamide compound. An integrated strategy including a chemical (pyrimethanil) and a biocontrol agent (Trichoderma spp. t2/4ph1) was also included. At harvest, the percentage of bunches and berries attacked by B. cinerea and the concentration of the chemical fungicides were determined. All the pesticide residues at harvest were below the maximum residue level (MRL), except when two applications of pyrimethanil per season were applied. Boscalid was the most effective active ingredient against B. cinerea among the tested chemicals. When boscalid application was followed by a treatment with pyrimethanil, its efficacy was similar to that shown by two treatments of pyrimethanil. However, this second strategy was not feasible due to the risks of resistance development in the pathogen and to the residue accumulation as indicated by the analysis.

Conventional and microwave assisted hydrolysis of urban biowastes to added value lignin-like products

The hydrolysis of five fermented water insoluble urban wastes is shown to convert the insoluble recalcitrant organic lignin-like fraction to added value soluble lignin-like products in high yields. The hydrolysate products are a mixture of complex polymeric molecules which maintain the memory of the proximates of the pristine materials. For a composted biowaste, taken as the case study, a process feasibility study comparing the microwave (MW) assisted versus the conventional (CON) reaction is reported. Product yields and quality are investigated as a function of four process parameters: i.e. pH (8–13), temperature (60–200 °C), and liquid–solid w/w ratio (4 and 10) and contact time (1 min–4 h). Microwave heating allows obtaining the same products, and in the same yields, as conventional heating in 1–2 orders of magnitude lower time. It is possible to achieve 50–60% yields of soluble lignin-like products at relatively low temperatures ≤100 °C. The obtained yield vs. temperature trend indicates that even higher yields may be obtained at higher temperatures. The potential scalability of MW assisted versus CON hydrolysis to the industrial level is discussed in relation to the reaction rate and reactor cost. The results offer worthwhile research scope to compare MW and CON heating for the hydrolysis of other fermented and non-fermented material as collected biowastes.

Moniliformin analysis in maize samples from North-West Italy using multifunctional clean-up columns and the LC-MS/MS detection method.

A fast clean-up method has been developed to purify maize extracts and to detect moniliformin (MON) in maize samples from North-West Italy over a four-year period (2008–2011). The method is based on the use of MycoSep® 240 Mon clean-up columns (Romer Labs®). Samples were extracted using acetonitrile/water (84:16, v/v), and the extracts were purified with previously described clean-up columns. The liquid chromatography–tandem mass spectrography (LC-MS/MS) analysis has been carried out by means of hydrophilic interaction chromatography (HILIC), combined with negative electrospray mass spectrometry. The method has a recovery of 76–91% (relative standard deviation, RSD%: 6–14%), a limit of detection (LOD) of 1 µg kg–1 and a limit of quantification (LOQ) of 4 µg kg−1. Naturally contaminated maize (108 samples) was analysed for MON content. The average percentages of positive samples was 93% with the following ranges (µg kg−1): 33–2606 (2008);

Changes in chemical and biological parameters during co-composting of anaerobically digested sewage sludges with lignocellulosic material

This study reports a pilot experiment of composting of anaerobically digested sewage sludges deriving from the production of biogas in a wastewater treatment plant. Two composting piles (about 15 m3 each) were prepared by mixing 50% and 30% (v/v) sludges with lignocellulosic material. The composting process was monitored through determination of the main physicochemical properties. The stability of the composts was assessed by determination of the respiration index and dehydrogenase activity. The collected data indicated that, at both sludges concentrations, the process produced a compost suitable for agricultural applications as far as the physicochemical properties were concerned. On the other hand, in the pile containing 50% sludges, the maximum temperature of the thermophilic phase was lower than the temperature required (55°C) to ensure the sanitization of the compost. The germination and growth indexes of Lepidium sativum indicated the lack of phytotoxicity of the final materials. The suitability of the composts as field improvers and horticultural substrates has been attested through plant bioassays conducted on maize and chrysanthemum.

Refuse derived soluble bio-organics enhancing tomato plant growth and productivity

Municipal bio-refuse (CVD), containing kitchen wastes, home gardening residues and public park trimmings, was treated with alkali to yield a soluble bio-organic fraction (SBO) and an insoluble residue. These materials were characterized using elemental analysis, potentiometric titration, and 13C NMR spectroscopy, and then applied as organic fertilizers to soil for tomato greenhouse cultivation. Their performance was compared with a commercial product obtained from animal residues. Plant growth, fruit yield and quality, and soil and leaf chemical composition were the selected performance indicators. The SBO exhibited the best performance by enhancing leaf chlorophyll content, improving plant growth and fruit ripening rate and yield. No product performance-chemical composition relationship could be assessed. Solubility could be one reason for the superior performance of SBO as a tomato growth promoter. The enhancement of leaf chlorophyll content is discussed to identify a possible link with the SBO photosensitizing properties that have been demonstrated in other work, and thus with photosynthetic performance.

Evaluation of the field dissipation of fungicides and insecticides used on fruit bearing trees in northern Italy

The dissipation of the fungicides captan, cyprodinil, fludioxonil, dithianon, and tebuconazole and of the insecticides chlorpyrifos, fenitrothion, and malathion was studied, following a single treatment of different cultivars of pears, apples, and peaches. The study was conducted in northern Italy, over two successive growing seasons (2004 and 2005). The treatments were performed by the farmers involved, in line with their usual practice. At various time intervals from treatment to harvest, representative samples of fruit were collected and analyzed for pesticide residues. In some cases, concentrations lower than the maximum residue levels (MRLs) were found immediately after treatment. In all trials a rapid decline in pesticide concentrations was observed leading to residues at harvest greatly below the MRLs.

Use of model soil colloids to evaluate adsorption of phenanthrene and its mobilization by different solutions

The effects of cyanobacteria aqueous extracts containing Microcystin-LR (MC-LR) on the seed germination and growth of Pisum sativum, Lens esculenta, Zea mays and Triticum durum were investigated. Experiments were carried out on a range of doses of the extract (equivalent to 0, 1.6, 2.9, 5.8, 8.7 and 11.6 mu g MC-LR/mL). The results confirm that these plants were sensitive to cell-free extracts of a toxic Microcystis and that germination inhibition was dose dependent. One-way analysis of variance (ANOVA) showed that P. sativum is the most sensitive tested species with a 97% germination rate reduction and L. esculenta was the most resistant. At the 8th day, the exposure to the microcystins (MC) resulted in a significant decrease of plant epicotyls length, roots length and a net inhibition of lateral root formation. It is concluded that MC could affect also terrestrial plants seedling germination and growth. Therefore, the use of water for irrigation contaminated by MC could exert negative biochemical effects on seed and plant metabolism which might influence the agricultural crops.

BIOAVAILABILITY AND BIODEGRADATION OF PROSULFOCARB IN SOIL

Active microbial degraders of the herbicide prosulfocarb (PSC) were isolated to evaluate their performance in soil with a view to their use for bioremediation. The isolated cultures (a microbial consortium and a Pseudomonas sp. strain) were active when tested in mineral medium with PSC as the only carbon source, but had an adverse effect on the soil indigenous microflora. Biodegradation in the inoculated soils was thus lower than in the uninoculated soil when only the indigenous microflora was present. Further tests showed that the strong affinity of PSC for soil organic matter affected its bioavailability and hence its biodegradation by the inocula. Bioremediation of PSC contaminated soils could thus be undertaken by biostimulation of indigenous microflora.

Microbial metabolism of fluazifop-butyl.

A microbial mixed culture able to grow on fluazifop-butyl and fluazifop was isolated. Fluazifop degradation by this microbial population was studied either when the herbicide was applied as the sole carbon source or in the presence of a second carbon source (sodium acetate or sodium propionate). The degradation rate was enhanced by sodium propionate. The degradation was found to be stereoselective. The S-enantiomer of fluazifop was degraded at a much higher rate than the R-enantiomer. Fluazifop disappearance was accompanied by formation of three metabolites which were identified by UV, IR, MS and NMR analyses. The metabolites were shown to be: 4-(5-trifluoromethyl-2-pyridyl)oxyphenol, 5-trifluoromethyl-2- hydroxypyridine and 2-(5-trifluoro-methyl pyridyl)hydroxy acetate.

Organically modified clays as binders of fumonisins in feedstocks.

This study reports an investigation on the ability of organically modified clays to bind mycotoxins, fumonisins B1 (FB1) and B2 (FB2). Organically modified clays are commercia materials prepared from natural clays, generally montmorillonite, by exchanging the inorganic cation with an ammonium organic cation. A screening experiment conducted on 13 organically modified clays and 3 nonmodified clays, used as controls, has confirmed that the presence of an organic cation in the clay interlayer promoted the adsorption of both fumonisins. On the basis of the results of the screening test, four modified clays and a Na-montmorillonite were selected for the determination of the adsorption kinetics and isotherms. On all the tested materials adsorption took place within one hour of contact with fumonisins solutions. Adsorption isotherms have pointed out that the modified clays exhibited a higher adsorptive capacity than the unmodified clay. It was also demonstrated that, notwithstanding the reduced structural difference between FB1 and FB2, they were differently adsorbed on the modified clays. Addition of 2% modified clays to contaminated maize allowed a reduction of more than 70% and 60% of the amount of FB1and FB2 released in solution. Although in vivo experiments are required to confirm the effectiveness of the organically modified clays, these preliminary results suggest that these materials are promising as fumonisins binders.