2 Summary 1Thermal soil disinfestation techniques are effective reducers of weed seedbank and 2 weed emergence. Two experiments (Exp 1 and 2) were conducted to test the effect of 3 brief exposure to varying temperatures on the seed germination of Amaranthus 4 retroflexus, Echinochloa crus-galli, Galinsoga quadriradiata, Portulaca oleracea, 5Setaria viridis, and Solanum nigrum. To this end, species seeds were moistened with 6 loamy-sand soil and placed into test tubes. The tubes were heated rapidly and then 7 cooled by dipping them into a hot water bath until target temperatures were achieved. 8Exp 1 temperatures ranged between 55 and 85°C at 5°C intervals and Exp 2 ranged 9 between 48 and 86°C at 2°C intervals. Thereafter, the tubes were dipped into a cooling 10 (1°C) water bath. Exposure to target temperatures ranged between 2 and 5 s. Soil 11 temperatures were monitored using embedded thermocouples. A log-logistic dose-12 response model described the effect of heating on seed germinability; temperatures 13 required for 99% reductions were calculated. Based on the predictive model equation 14 used, weed species' germination sensitivity to high temperature exposure can be ranked 15

Weed control is one of the most important practices for a satisfying crop performance. In organic farming, weeds are mainly controlled by using mechanical methods, which may result in incomplete crop selectivity. Maize is one of the crops for which mechanical weed control is commonly applied. To assess weed control efficacy and the possible crop injuries caused by mechanical interventions (harrowing, hoeing and ridging), a field experiment was carried out in 2013–2014 on traditional flint Italian varieties of maize (Marano, Ottofile, Pignoletto, Nostrano and the hybrid Maranello) suited for organic food production. The study included the following treatments: weed control with a spring tine harrow + hoeing and ridging (STH), manual weed removal all season long (MWR), spring tine harrowing + manual weed removal (STH + MWR) and an untreated check (CHK). In the 2 years, the experiment was carried out in two similar fields in which 60 plots (6 × 10 m) were arranged in a RCBD with three replications. Weed control efficacy was assessed by determining weed density, weed species composition and weed cover after each mechanical intervention in the STH and CHK plots. Weed diversity indices were also calculated at the final assessment. The possible crop injuries caused by mechanical means were assessed by determining maize plant height, number of leaves, and plant density after each mechanical intervention. At maturity, maize yield and other yield-related traits (1000-seed weight, hectolitre weight, and grain moisture) were determined. The results showed that the mechanical treatments lowered the weed infestation, without changing weed species dominance and slightly lowering species richness; even though they were not able to completely control the weeds. In both years, the final weed density in STH plots was of about 50 plants m−2. Better weed control was obtained when weeds were at early growth stages and with a repeated number of harrowing. Mechanical weeding did not cause significant injury in terms of plant height nor density; however, for Marano and Maranello, a delay in the crop cycle was observed as shown by the lower number of leaves in STH compared with MWR. Yield ranged from 0.3 t ha−1 for Marano CHK to 10.4 t ha−1 for the hybrid Maranello in MWR + STH. Yield and yield-related traits were not affected by mechanical weeding.

SUMMARYThe current study focuses on the dissipation pattern of imazamox in a soil-water environment under the two most adopted rice management systems in Europe, conventional water seeding and dry-seeding. Changes in imazamox concentrations were studied over time in topsoil, field water, irrigation water, outlet water and ground water. The study was performed from 2010 to 2011 in one of the most important rice growing areas of Europe (Vercelli, northwest Italy).Imazamox dissipated rapidly in both the water and soil environments. In soil, imazamox halflife ranged from 2.2 to 3.3 days in 2010 and from 2.2 to 3.1 days in 2011. In paddy water, imazamox dissipated rapidly and no important differences among the management systems were found. In addition, the study showed that despite the short half-life of imazamox, the herbicide might be transported from treated fields in outlet waters by means of floodgates.The highest concentrations in outlet waters were found in the conventional water-seeded system, at the sampling site close to herbicide spraying. Imazamox residues were even found in inlet waters, suggesting discharge of the herbicide from paddies located upstream or drift during spraying. Imazamox residues in ground waters were always below the quantification limit. Overall, the low imazamox persistence observed during the 2-year study did not allow 2 important differences between the two systems to be revealed. To reduce imazamox discharge from treated fields in the first days after spraying, a useful practice might be to keep water inside the fields for at least a week after spraying.

Ambrosia artemisiifolia (common ragweed) is an annual weed known to infest crops and disturbed areas, and cause human pollinosis. To examine the effect of different thermal regimens on seed germination, during seed after-ripening, a study was conducted for two years. In 2012 (year 1) and 2013 (year 2), ragweed seeds collected from a single wheat stubble field were divided and stored under one of the five temperature regimens: constant-20°C, +5°C, room temperature (18°C), +25°C, and field conditions. Germination tests were performed every 15 days of storage from day 17 to day 213. Storage conditions showed a strong influence on ragweed seed germination duration. At constant low temperatures (-20°C), seed behaved in an opposite manner depending on the year; in year 1 germination was inhibited while it was stimulated in year 2. At higher temperatures, seed dormancy was unbroken due to a lack of exposure to low temperatures. Under field conditions, seeds reached a high level of germination after a few days of storage due to temperature fluctuations. The different behaviours of ragweed seeds shown at constant temperatures revealed different dormancy depths in the two years that might be due to population variability and maternal environment differences during seed maturation.

17 18The influence of buffer strips and soil texture on runoff of flufenacet and isoxaflutole was studied 19 for two years in Northern Italy. The efficacy of buffer strips was evaluated on six plots 20 characterized by different soil textures; two plots had Riva soil (18.6% sand, 63.1% silt, 18.3% 21 clay) while the remaining four plots had Tetto Frati (TF) soil (37.1% sand, 57% silt, 5.9% clay). 22Additionally, the width of the buffer strips, constituted of spontaneous vegetation grown after crop 23 sowing, was also compared for their ability to abate runoff waters. Chemical residues in water 24 following runoff events were investigated, as well as their dissipation in the soil. After the first 25 runoff events, concentrations of herbicides in water samples collected from Riva plots were as 26 much as four times lower in waters from TF plots. On average of two growing season, the field 27 half-life of flufenacet in the upper soil layer (5 cm) ranged between 8.1 and 12.8 days in Riva soil, 28 8.5 and 9.3 days in TF soil. Isoxaflutole field half-life was less than 1 day. Buffer strip was very 29 affective by the uniformity of the vegetative cover, particularly, at the beginning of the season. In 30 TF plots, concentration differences were generally due to the presence or absence of the buffer strip, 31 regardless of its width. 32 33