Modeling the emergence of North African Knapweed (Centaurea diluta), an increasingly troublesome weed in Spain

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Sousa Ortega, Carlos
Royo-Esnal, AritzRoyo-Esnal, Aritz - ORCID ID
DiTommaso, Antonio
Izquierdo i Figarola, Jordi
Loureiro, Iñigo
Marí, Ana Isabel
Cordero, Fernando
Vargas, Manuel
Saavedra, Milagros
Paramio, José Antonio
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North African knapweed (Centaurea diluta Aiton) is an annual weed that is widespread in southern Spain and is of increasing concern in dryland cropping systems. Despite its expanding range in Spain, there is limited information on the emergence timing and pattern of this species, which is critical for developing more timely and effective management strategies. Therefore, there is a need to develop simple and reliable models to predict the timing and emergence of this annual weed under dryland conditions. A multi-location field experiment was established across Spain in 2016-2017 to assess the emergence of C. diluta. At each of 11 locations, seeds were sown in the fall, and emergence was recorded. Overall emergence averaged 39% in the first year across all sites and 11% in the second year. In both years, the main emergence flush occurred at beginning of the growing season. The three-parameter Weibull function best described seedling emergence of C. diluta. Emergence models were developed based on thermal time (TT) and hydrothermal time (HTT) and showed high predictability, as evidenced by root mean square error prediction (RMSEP) values of 10.8 and 10.7, respectively. The three cardinal points were established for TT and HHT at 0.5 ºC, 10 ºC and 35 ºC for base, optimal and ceiling temperature, while base water potential was estimated at -0.5MPa.
Journal or Serie
Weed Science, 2020, vol. 68, núm. 3, p. 268-277