Elmer Wade H
Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, CT 06504.
Plant Dis. 2009 Feb;93(2):175-179. doi: 10.1094/PDIS-93-2-0175.
Earthworm densities have been regarded as reliable indicators of soil health, but their role in suppression of plant disease has not received much attention. Several greenhouse studies were done to determine if soils infested with soilborne pathogens and augmented with earthworms (Lumbricus terrestris) could reduce disease of susceptible cultivars of asparagus (Asparagus officinalis), eggplant (Solanum melongena), and tomato (Solanum lycopersicum). Soils planted with asparagus were infested with Fusarium oxysporum f. sp. asparagi and F. proliferatum, eggplant with Verticillium dahliae, and tomato with F. oxysporum f. sp. lycopersici Race 1. In each host-disease system, earthworm activity was associated with an increase in plant growth and a decrease in disease. In general, plant weights were increased 60 to 80% and estimates of disease (area under the disease progress curve, percent vascular discoloration, and percent root lesions) were reduced 50 to 70% when soils were augmented with earthworms. Soil dilutions on selective media revealed that densities of fluorescent pseudomonads and filamentous actinomycetes were consistently higher for rhizosphere soils augmented with earthworms. In the studies with Verticillium wilt of eggplant, compared to the controls, the densities of total bacteria and Mn-transforming microbes were reduced in the presence of earthworms while population densities of bacilli and Trichoderma spp. were not affected. Disease suppression may have been mediated through microbiological activity. These studies suggest that strategies to increase earthworm densities in soil should suppress soilborne diseases.
蚯蚓密度一直被视为土壤健康的可靠指标，但其在抑制植物病害方面的作用却未受到太多关注。开展了多项温室研究，以确定接种了土传病原菌并添加蚯蚓（正蚓）的土壤是否能够减轻芦笋（石刁柏）、茄子（茄）和番茄（番茄）易感品种的病害。种植芦笋的土壤接种了尖孢镰刀菌芦笋专化型和层出镰刀菌，茄子接种了大丽轮枝菌，番茄接种了尖孢镰刀菌番茄专化型1号生理小种。在每个寄主 - 病害系统中，蚯蚓活动与植物生长增加和病害减轻相关。总体而言，当土壤添加蚯蚓后，植物重量增加了60%至80%，病害评估指标（病害进展曲线下面积、维管束变色百分比和根损伤百分比）降低了50%至70%。选择性培养基上的土壤稀释液显示，添加蚯蚓的根际土壤中荧光假单胞菌和丝状放线菌的密度始终较高。在茄子黄萎病的研究中，与对照相比蚯蚓存在时总细菌和锰转化微生物的密度降低，而芽孢杆菌和木霉属的种群密度未受影响。病害抑制可能是通过微生物活动介导的。这些研究表明，增加土壤中蚯蚓密度的策略应能抑制土传病害。
