Short- and long-term economic implications of controlling crenate broomrape ( Orobanche crenata Forsk.) in broad bean ( Vicia faba L.) under various management strategies

Abstract

An economic model is described and used to investigate the short- and long-term implications of controlling crenate broomrape ( Orobanche crenata Forsk.) infestations in broad bean ( Vicia faba L.) under different management strategies. These include no use of herbicide, applying herbicide once after an infection severity ( IS: number of emerged broomrape m 2) ≥ 0.1, and applying herbicide every year. Crenate broomrape population evolution was affected by initial IS ( IS 0) at the time of implementing the strategy, regardless of the management strategy adopted. Non-application of herbicide was satisfactory when initial infection was very low ( IS ≤ 0.1) resulting in average annualized benefits ( AB) of about 600 and 505 US $ ha −1, after 3 and 9 years for early sowing dates, respectively. Applying herbicide once did not control parasite populations adequately and could only represent an acceptable low-cost alternative in the long term when ( IS ≤ 1) giving an AB of about 653 and 630 US $ ha −1 after 3 and 9 years for early sowing dates, respectively. Annual application of herbicide was the best strategy against broomrape at any IS 0 to minimize crenate broomrape populations and obtain maximum net benefits per year regardless of broad bean cropping frequency. A sensitivity analysis was performed to determine the effect of changing the values of the main economic parameters (efficacy of the herbicide, expected yield, fixed and herbicide costs). In general, sensitivity coefficients were between 0.5 and 1, herbicide cost being the parameter which exerted the least effect on AB in all management strategies. Generally, an ( IS ≤ 1) requires broomrape herbicide treatments in all subsequent broad bean crops in order to ensure economic benefits.