Management of crown and root rot disease complex of greenhouse tomatoes with green manure cereal crops

Tzenko Vatchev

Abstract: The ability of green manure cereal crops to reduce crown and root rot disease complex of tomatoes (Lycopersicon esculentum Mill.) was tested in container experiments with greenhouse soil and in on-site experiments in commercial greenhouse plots. All experiments were carried out with greenhouse soil heavily infested with Colletotrichum coccodes (Wallr.) Hughes, Fusarium oxysporum Schlechtend.: Fr. f. sp. radicis-lycopersici Jarvis & Shoemaker (FORL), Fusarium spp., Phytophthora nicotianae Breda de Haan var. nicotianae Waterhouse, А2 compatibility type, Phytophthora spp., Pyrenochaeta lycopersici Schnider & Gerlach, Pythium aphanidermatum (Edson) Fitzp., Pythium spp.and Rhizoctonia solani Kühn. AG-4, all associated with crown and root rot disease complex of greenhouse tomatoes. Green manure crops, including wheat (Triticum aestivum L., cv. Todora), barley (Hordeum vulgare L., cv. Obzor), cereal rye (Secale cereale L., cv. Millennium) and oat (Avena sativa L., cv. Jubilee) were planted at seeding rates three times higher than recommended: 25 g and 22 g m-2 for wheat and barley, respectively, and 15 g m-2 for rye and oat. Plants were cultivated for a period of 60 days mowed and incorporated into the soil. Amended soils were incubated for another 30-day period before planting. Crown and root damage on tomato plants caused by the complex was significantly less (P ≤ 0.001) in all treatments that received green manures. As compared to the untreated controls (clean followed soil) disease severity was reduces by 32.07 – 46.41% in the container experiments and by 26.63 – 40.24% in the commercial greenhouse plots. The highest disease reduction was observed in treatments with rye fallowed by those with oats in both experimental systems. The resulting levels of control obtained under production conditions refers to as some useful disease reduction which is unlikely to be economically efficient if green manuring is used as a single control measure. Results of this study suggest that green manure cereal crops grown off-season can be used as a component of integrated disease management of greenhouse tomatoes.

Keywords: green manure; greenhouse tomato; non-chemical disease control; soilborne plant pathogens; suppressive soils

Date published: 2017-07-06