Glass J R, Johnson K B, Powelson M L
Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331-2902.
Plant Dis. 2001 May;85(5):521-528. doi: 10.1094/PDIS.2001.85.5.521.
Experiments were conducted in an irrigated, sandy loam soil to evaluate mulches and hill sizes as barriers to prevent the development of potato tuber blight caused by Phytophthora infestans. In mulching experiments, five treatments were applied to field plots of cv. Red LaSoda: 1, no mulch; 2, polyurethane spray foam in an 8-cm-diameter area immediately surrounding the plant stem; 3, black polyethylene film over the entire hill except near the stem; 4, a combination of treatments 2 and 3; and 5, a water-permeable, agricultural textile treated with copper hydroxide applied over the same hill area as in treatment 3. In 1998, the incidence of tuber blight in plots mulched with black film (treatments 3 and 4) averaged 32% compared with 56% in plots without this mulch (treatments 1 and 2). In 1999, incidence of tuber blight in plots with and without black film averaged 9 and 20%, respectively. Mulching the stem area with spray foam (treatments 2 and 3) did not reduce the incidence of blighted tubers when compared with the appropriate control. The copper-treated textile mulch (treatment 5) provided reductions in the incidence of tuber blight similar to those observed with the use of black polyethylene film. In a hill size experiment conducted once in 1998 and twice in 1999, three hill size treatments were established on cvs. Red LaSoda, Shepody, and Russet Burbank. Red LaSoda was the most susceptible and Russet Burbank the least susceptible to tuber blight. Comparison of blight incidence in tubers classified by depth in the hill revealed few differences among the hill size treatments, although over all treatments, tubers covered with more than 15 cm of soil had a lower incidence of blight (1 to 14%) than tubers with less soil cover (13 to 59%). Most tuber infections were apparently initiated in eyes and were not concentrated on a portion of the tuber such as the stolon (proximal) or distal end. The fact that black film and textile mulches reduced tuber infection indicates that inoculum of P. infestans can move from foliage to tubers through soil and that inoculum movement is not limited to large channels in the hill such as those created by the potato stems. The mulch treatments, however, provided only partial protection of tubers, limiting the practicality of such treatments to commercial producers. Hill size treatments had little effect on tuber blight incidence, indicating that adequate suppression of tuber infection in an environment conducive to late blight may be inseparably linked to adequate suppression of the foliar phase.
实验在灌溉良好的砂壤土中进行，以评估覆盖物和土堆大小作为防止马铃薯晚疫病（由致病疫霉引起）发生的屏障。在覆盖物实验中，对“红拉索达”品种的田间小区采用了五种处理方式：1. 不覆盖；2. 在植株茎干周围直径8厘米的区域喷施聚氨酯泡沫；3. 除茎干附近外，整个土堆覆盖黑色聚乙烯薄膜；4. 处理方式2和3的组合；5. 在与处理方式3相同的土堆区域覆盖经氢氧化铜处理的透水性农用织物。1998年，覆盖黑色薄膜的小区（处理方式3和4）晚疫病发病率平均为32%，而未覆盖的小区（处理方式1和2）为56%。1999年，有黑色薄膜和无黑色薄膜小区的晚疫病发病率分别平均为9%和20%。与相应对照相比，用泡沫覆盖茎干区域（处理方式2和3）并未降低晚疫病块茎的发病率。经铜处理的织物覆盖物（处理方式5）使晚疫病发病率降低程度与使用黑色聚乙烯薄膜相近。在1998年进行了一次、1999年进行了两次的土堆大小实验中，对“红拉索达”“谢泼迪”和“褐皮伯班克”品种设置了三种土堆大小处理。“红拉索达”对晚疫病最敏感，“褐皮伯班克”最不敏感。按土堆中深度对块茎晚疫病发病率进行比较，结果显示土堆大小处理间差异不大，不过在所有处理中，被超过15厘米厚土壤覆盖的块茎晚疫病发病率（1%至14%）低于土壤覆盖较少的块茎（13%至59%）。大多数块茎感染显然始于芽眼，并非集中在块茎的某一部分，如匍匐茎（近端）或远端。黑色薄膜和织物覆盖物降低了块茎感染这一事实表明，致病疫霉的接种体可通过土壤从叶片传播至块茎，且接种体传播不限于土堆中的大通道，如马铃薯茎干形成的通道。然而，覆盖物处理仅对块茎提供了部分保护，限制了此类处理方式对商业生产者的实用性。土堆大小处理对块茎晚疫病发病率影响不大，这表明在有利于晚疫病发生的环境中，要充分抑制块茎感染可能与充分抑制叶部发病密切相关。
