Abstract

Stem and bulb nematode (Ditylenchus dipsaci) is a plant parasite that can cause severe damage to garlic crops in Ontario, Canada, and other garlic growing regions. Accurate soil sampling is important to determine the risk of nematode damage before planting garlic in a field. However, it is not clear where the nematode is most concentrated in the soil profile or how the nematode is best extracted. A field survey and laboratory experiments were conducted in the autumn of 2015 and 2018 to determine the distribution of stem and bulb nematode in the soil profile and to determine the most effective extraction method. The soil in 20 garlic fields throughout southern Ontario was sampled and the top 5 cm and the bottom 5–20 cm of soil were collected in a single core and then separated. Nematodes were extracted from all soil samples using both the Baermann pan and sugar centrifugal flotation methods. Significantly more stem and bulb nematodes were extracted from the top 5 cm of soil and using the sugar centrifugal flotation method. An additional extraction efficacy experiment was conducted using a known quantity of stem and bulb nematodes in soil to compare various extraction methods, and the sugar centrifugal flotation method continued to be the more effective method. These results demonstrate that only the top 5 cm of soil should be collected and assessed for populations of stem and bulb nematode in fields intended for garlic production, and the sugar centrifugal flotation method should be the extraction method of choice.

摘要

茎球线虫（Ditylenchus dipsaci）) 是一种植物寄生虫，可对加拿大安大略省和其他大蒜种植区的大蒜作物造成严重损害。在田间种植大蒜之前，准确的土壤取样对于确定线虫危害的风险很重要。然而，目前尚不清楚线虫在土壤剖面中最集中的位置或如何最好地提取线虫。2015 年和 2018 年秋季进行了实地调查和实验室试验，以确定土壤剖面中茎和球茎线虫的分布，并确定最有效的提取方法。对整个安大略省南部 20 个大蒜田的土壤进行采样，将顶部 5 厘米和底部 5-20 厘米的土壤收集在一个核心中，然后分离。使用 Baermann pan 和糖离心浮选方法从所有土壤样品中提取线虫。使用糖离心浮选法从土壤的顶部 5 厘米中提取了明显更多的茎和球茎线虫。使用土壤中已知数量的茎和球茎线虫进行了额外的提取功效实验，以比较各种提取方法，糖离心浮选法仍然是更有效的方法。这些结果表明，对于拟用于大蒜生产的田地中的茎和球茎线虫种群，仅应收集和评估土壤表层 5 厘米，糖离心浮选法应该是首选的提取方法。使用土壤中已知数量的茎和球茎线虫进行了额外的提取功效实验，以比较各种提取方法，糖离心浮选法仍然是更有效的方法。这些结果表明，对于拟用于大蒜生产的田地中的茎和球茎线虫种群，仅应收集和评估土壤表层 5 厘米，糖离心浮选法应该是首选的提取方法。使用土壤中已知数量的茎和球茎线虫进行了额外的提取功效实验，以比较各种提取方法，糖离心浮选法仍然是更有效的方法。这些结果表明，对于拟用于大蒜生产的田地中的茎和球茎线虫种群，仅应收集和评估土壤表层 5 厘米，糖离心浮选法应该是首选的提取方法。