Samac Deborah A, Schraber Samuel, Barclay Stuart
United States Department of Agriculture-Agricultural Research Service, Plant Science Research Unit, and Department of Plant Pathology, University of Minnesota, St. Paul 55108.
Department of Plant Pathology, University of Minnesota, St. Paul.
Plant Dis. 2015 May;99(5):614-620. doi: 10.1094/PDIS-03-14-0240-RE. Epub 2015 Apr 30.
Most alfalfa seed is treated with the fungicide mefenoxam (Apron XL) for control of soilborne seedling diseases caused by Phytophthora medicaginis and Pythium spp. However, Apron XL is not active against Aphanomyces euteiches, the causal agent of Aphanomyces root rot (ARR), an important component of the alfalfa seedling root rot complex. Moreover, Apron XL-treated seed cannot be used in organic production systems. A seed coating using aluminosilicate (natural zeolite) at a rate of 0.33 g of zeolite per gram of alfalfa seed was tested as an alfalfa seed treatment. Inoculated growth chamber trials were conducted to determine the percentage of seedlings protected from Phytophthora root rot (PRR) and ARR. The mineral seed coating resulted in significantly greater control of PRR, with a mean of 89% healthy seedlings (disease score of 1 or 2 on a 1-to-5 scale) compared with the Apron XL treatment, with a mean of 38% healthy seedlings, or the control treatment, with 15% healthy seedlings. The mineral seed coating also resulted in significantly greater protection against ARR, with 67% healthy seedlings compared with 3 and 2% healthy seedlings with the Apron XL and control treatments, respectively. The coated seed were used for in vitro assays with Pythium ultimum and P. paroecandrum to test for protection from seed rot and damping off. The mineral seed coating resulted in a significantly greater percentage of healthy seedlings compared with the Apron XL and control treatments. In growth chamber assays with naturally infested field soils with a range of disease pressure, the mineral seed coating resulted in a similar or greater percentage of healthy plants than the Apron XL treatment. The mineral coating had no effect on in vitro growth of Sinorhizobium meliloti, and nodule numbers were similar on roots from mineral-coated and untreated seed. These experiments indicate that the zeolite seed coating is a promising means of controlling seedling diseases in alfalfa production systems.
大多数苜蓿种子都用杀菌剂甲霜灵锰锌（Apron XL）处理，以防治由苜蓿疫霉和腐霉菌引起的土传幼苗病害。然而，Apron XL对引起苜蓿根腐病（ARR）的致病疫霉无效，而苜蓿根腐病是苜蓿幼苗根腐病复合体的一个重要组成部分。此外，用Apron XL处理过的种子不能用于有机生产系统。以每克苜蓿种子0.33克硅铝酸盐（天然沸石）的用量进行种子包衣，作为苜蓿种子处理方法进行了测试。进行了接种生长室试验，以确定免受疫霉根腐病（PRR）和苜蓿根腐病侵害的幼苗百分比。矿物种子包衣对疫霉根腐病的防治效果显著提高，健康幼苗的平均比例为89%（在1至5级评分中病害评分为1或2），相比之下，Apron XL处理的健康幼苗平均比例为38%，对照处理的健康幼苗比例为15%。矿物种子包衣对苜蓿根腐病的防护效果也显著提高，健康幼苗比例为67%，而Apron XL处理和对照处理的健康幼苗比例分别为3%和2%。包衣种子用于对终极腐霉和近缘腐霉的体外测定，以测试对种子腐烂和猝倒病的防护效果。与Apron XL处理和对照处理相比，矿物种子包衣使健康幼苗的比例显著提高。在具有一系列病害压力的自然感染田间土壤的生长室试验中，矿物种子包衣产生的健康植株比例与Apron XL处理相似或更高。矿物包衣对苜蓿中华根瘤菌的体外生长没有影响，矿物包衣种子和未处理种子的根上的根瘤数量相似。这些实验表明，沸石种子包衣是控制苜蓿生产系统中幼苗病害的一种有前景的方法。
