Wheeler T A, Porter D O, Archer D, Mullinix B G
Texas AgriLife Research, Lubbock, TX 79403, Texas Agrilife Extension and Texas AgriLife Research, Lubbock, TX 79403.
J Nematol. 2008 Sep;40(3):210-6.
Plots naturally infested with Rotylenchulus reniformis were sampled in the spring of 2006 and 2007 at depths of 15 and 30 cm in the bed, furrow over the drip tape, and "dry" furrow, and at approximately 40 to 45 cm depth in the bed and dry furrow. Then, 1,3-dichloropropene (Telone EC) was injected into the subsurface drip irrigation at 46 kg a.i./ha, and 3 to 4 weeks later the plots were resampled and assayed for nematodes. The transformed values for nematode population density (IvLRr) before fumigation were higher at 30 and 40 cm depths than at a 15 cm depth. IvLRr before fumigation was higher in the soil over the drip lines than in the bed or dry furrow and was higher in the bed than the dry furrow. IvLRr was higher in the plots to be fumigated than the plots that were not to be fumigated for all depths and locations except at a 15 cm depth over the drip lines, where the values were similar. However, after fumigation, IvLRr was lower over the drip lines at a 30 cm depth in plots that were fumigated compared to samples in a similar location and depth that were not fumigated. There were no other location/depth combinations where the fumigation reduced IvLRr below that in the nonfumigated plots. Yield in 2006, which was a very hot and dry year, was predicted adequately (R(2) = 0.67) by a linear model based on the preplant population density of R. reniformis, with a very steep slope (-2.8 kg lint/ha per R. reniformis/100 cm(3) soil). However, no relationship between nematode density and yield was seen in 2007, which had cooler weather for most of the season. Yield was not significantly improved by fumigation through the drip irrigation system in either year compared to plots treated only with aldicarb (0.84 kg a.i./ha), indicating that the level of control with fumigation did not kill enough R. reniformis to be successful.
2006年春季和2007年春季，对自然感染肾形肾状线虫的地块进行了采样，采样深度为床层15厘米和30厘米处、滴灌带上方的沟以及“干”沟，床层和干沟中约40至45厘米深处也进行了采样。然后，以46千克有效成分/公顷的用量将1,3 - 二氯丙烯（威百亩乳油）注入地下滴灌系统，3至4周后对地块重新采样并检测线虫。熏蒸前线虫种群密度的转换值（IvLRr）在30厘米和40厘米深度处高于15厘米深度处。熏蒸前，滴灌线以上土壤中的IvLRr高于床层或干沟，床层中的IvLRr高于干沟。除了滴灌线以上15厘米深度处的值相似外，在所有深度和位置，待熏蒸地块的IvLRr均高于未熏蒸地块。然而，熏蒸后，与未熏蒸的类似位置和深度的样本相比，熏蒸地块在30厘米深度处滴灌线以上的IvLRr较低。没有其他位置/深度组合的熏蒸能使IvLRr降至未熏蒸地块以下。2006年是非常炎热干燥的一年，基于种植前肾形肾状线虫的种群密度，通过线性模型能较好地预测产量（R² = 0.67），斜率非常陡（每100立方厘米土壤中每只肾形肾状线虫 - 2.8千克皮棉/公顷）。然而，2007年大部分季节天气较凉爽，未发现线虫密度与产量之间的关系。与仅用涕灭威（0.84千克有效成分/公顷）处理的地块相比，这两年通过滴灌系统进行熏蒸均未显著提高产量，这表明熏蒸的防治水平未能杀死足够数量的肾形肾状线虫以取得成功。
