Comparison of the surface magnetic field evolution of our 1.5 M_⊙ models and observational results for 2−3 M_⊙ Ap stars analysed by Landstreet et al. (2007, 2008). Our models with B_p, ini = 10 kG, 1 kG, and 100 G are shown by red, blue, and green lines, respectively (see legend). Similar as in Fig. 8, solid, dashed, dotted, and dash-dotted lines indicate initial periods of P_rot, ini of 1, 10, 100, and 1000 d, respectively. Dots with error bars correspond to observed stars, where black filled symbols show stars for which a field is detected, while gray open symbols are probable magnetic stars. Numbers associated with several stars denote V sin i in units of km s⁻¹. The threshold magnetic field of B_th ∼ 300 G, below which essentially no Ap/Bp stars are found (Aurière et al. 2007), is shown by the black dashed line. A numerical factor of 3.3 is multiplied to the field strengths reported in the literature to convert B_rms into B_p.