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  • Author or Editor: B.K. Duffy x
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Host nutritional variables were evaluated for their effects on the severity of crown and root rot of tomato caused by Fusarium oxysporum f.sp. radicis-lycopersici. Tomato (Lycopersicon esculentum Mill.) seedlings (cv. Bonnie Best) were grown in a pathogen-infested, soilless rockwool system in the greenhouse and were fertilized with a nutrient solution that was amended with macro- and microelements at various rates. Disease was evaluated after 2 weeks using an index of 0 to 4, and plant fresh weight was measured. Regression analysis indicated that disease severity was significantly increased by ammonium-nitrogen [NH4Cl, (NH4)6Mo7O24, and (NH4)2SO4], NaH2PO4·H2O, Fe-EDDHA, MnSO4, MoO3, and ZnSO4·7H2O. Disease severity was reduced by nitrate-nitrogen [Ca(NO3)2·4H2O] and CuSO4·H2O. Low rates of NH4NO3 (39 to 79 mg·L-1 N) reduced disease, but rates above 100 mg·L-1 N increased it. Disease was not affected by MgSO4·7H2O. In all cases, plant growth was inversely related to disease severity. Mineral fertilizers had no effect on nutrient solution pH. This information sheds new light on environmental factors that influence plant-pathogen interactions, and may be applied to develop a management strategy for Fusarium crown and root rot based on host nutrition.

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In-field (IF) and above-ground (AG) container production of landscape ornamentals are both conventional methods which were compared to a newer production method, pot-in-pot (PIP). Our objective was to determine costs and economic feasibility for each method. Model nurseries were synthesized to represent a 4-ha nursery utilizing 2 ha of production area operating over a three-year period. Finished plant material were grown in 40-L containers for above-ground and pot-in-pot production, and 2 m ball and burlapped material for in-field production. One budget was constructed to reflect costs for Lagerstroemia indica, Cornusflorida, and × Cupressocyparis leylandii under each production method. Capital requirements and annual fixed costs for all three species were lowest for IF and highest for PIP production. Variable costs for all tree species were lowest for IF and highest for AG with PIP intermediate. With better utilization of a given production area, PIP had the lowest total cost of production, followed by AG and IF methods.

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