Effects of soil amendment with poultry manure on carnation Fusarium wilt in greenhouses in southwest Spain

In a search for alternatives to methyl bromide for controlling carnation vascular wilt caused by Fusarium oxysporum f. sp. dianthi (Fod), poultry manure plus soil solarization was studied in soil under greenhouse conditions in four 2-year experiments. These were conducted in naturally infested soil to compare the effects of this treatment with soil solarization alone and methyl bromide. Soil treatments were performed during June 2000 for Experiment 1, from July to mid-August 2002 for Experiment 2, from late July to late August 2006 for Experiment 3 and from late May to late June 2008 for Experiment 4. Additionally, a treatment with commercial poultry manure pellet plus soil solarization was included in the two latter experiments. Poultry manure caused reductions of Fod viability in soil samples at depths of 15 and 30 cm, ranging respectively from 93 to 100% and 89 to 100% for Experiments 1, 2 and 3. Carnations planted in plots treated either with poultry manure, methyl bromide or soil solarization had lower final disease incidences, smaller areas under their disease progress curves and higher yields in comparison with untreated plots in Experiments 2, 3 and 4. In Experiment 1, soil solarization was performed under suboptimal conditions, and it provided disease levels and yields similar to those of the untreated control plots. Nevertheless, under the same conditions, previous amendment of Fod-infested soil with poultry manure increased disease control over soil solarization alone, improved carnation yield and quality and also increased plant vigor, thus providing a satisfactory alternative to methyl bromide. The application of organic amendment to the same plot before every crop cycle is recommended to ensure continuous disease control, but the rates of application could be reduced to half for the third and fourth crop cycles, thereby reducing undesirable environmental effects.

► This manuscript generates new knowledge on the control of Fusarium wilt of carnation obtained from field experiments (4 along a total of 8 years) conducted in naturally infested soil, thereby confirming the suitability of soil amendments with poultry manure combined with soil solarization under different environmental conditions.
► This intends a non-chemical alternative to chemical fumigants that have been omitted from the list of chemicals allowed for disease and pest control.
► Details on two formulations of the amendment and on their iterative applications every two years, although with the possible reduction of rates of application, are studied.
► The results obtained seem to offer a technique prone to be integrated in IPM programs to be used by growers to get good and consistent (?) control of the disease.