Before any late-season weed control operations are planned to manage herbicide-resistant weeds, it is essential to evaluate the plants’ maturity and shattering potential. Our goal was to assess the seed-shattering phenology of common ragweed (Ambrosia artemisiifolia L.) using pollination bags as seed traps. A secondary goal was to evaluate the efficiency of these traps. Trials were conducted from 2014 to 2017 at two locations in eastern Canada (Saint-Jean-sur-Richelieu, QC, and Harrow, ON). At each location, three adjacent fields were seeded with spring wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], or corn (Zea mays L.). Each field was divided into four replicate blocks that included two treatment plots with 5 weeds m−2 planted on the same date as the crop or when crop plants had two leaves (early or late emergence). To evaluate shattering in time, the experiment included up to 12 weekly collection dates (subplots). In each subplot, weeds were individually bagged at flowering (using mesh bags) until collection, when the number and viability of shattered and retained seeds per plant was recorded. Weather data as well as crop and weed stages were recorded. The effect of the pollen bags on seed retrieval and viability was evaluated by installing open and closed bags in corn and uncropped (bare) plots at a single location. Ambrosia artemisiifolia seed biomass was equivalent or higher in closed bags, and seed viability was equivalent or slightly reduced. No seeds were produced before harvest in spring wheat, as dispersal started in September. The percentage of seeds retained on the plant decreased linearly (1 site-year) or followed a logistic equation (4 site-years) with day of year or growing degree days. Dispersal in time was similar between early- and late-emerging weeds and similar in both corn and soybean. On average, more than 50% of A. artemisiifolia seeds were dispersed before harvest in corn and soybean.

中文翻译：

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小麦、玉米和大豆中常见的豚草 (Ambrosia artemisiifolia) 种子破碎

在计划任何晚季杂草控制操作来管理抗除草剂杂草之前，必须评估植物的成熟度和破碎潜力。我们的目标是评估普通豚草的落粒物候（青蒿L.) 使用授粉袋作为种子捕集器。第二个目标是评估这些陷阱的效率。2014 年至 2017 年在加拿大东部的两个地点（QC 的 Saint-Jean-sur-Richelieu 和安大略省的 Harrow）进行了试验。在每个位置，三个相邻的田地都播种了春小麦（小麦L.)、大豆 [最大甘氨酸(L.) Merr.]，或玉米 (玉米L.)。每个田地被分成四个重复块，其中包括两个处理地块，杂草 5 平方米-2在与作物相同的日期或作物有两片叶子时种植（早期或晚期）。为了及时评估破碎，该实验包括多达 12 个每周收集日期（子图）。在每个子区中，杂草在开花时被单独装袋（使用网袋），直到收集，此时记录每株植物破碎和保留种子的数量和活力。记录了天气数据以及作物和杂草阶段。花粉袋对种子回收和活力的影响通过在玉米和未种植（裸露）地块的单一位置安装开放和封闭袋来评估。青蒿封闭袋中的种子生物量相当或更高，种子活力相当或略有降低。春小麦在收获前没有产生种子，因为 9 月开始传播。保留在植物上的种子百分比随着一年中的天数或生长期天数呈线性下降（1 个站点年）或遵循逻辑方程（4 个站点年）。早期和晚期杂草的扩散时间相似，玉米和大豆的扩散时间相似。平均而言，超过 50%青蒿种子在收获前分散在玉米和大豆中。