Figure 3.

Effects of grafting with infected material and arrival of infectious vectors on disease progress. (a–c) show the curves representing exposed trees ($E_T$, blue), symptomatic infectious trees ($I_T$, red), asymptomatic infectious trees ($A_T$, green), removed trees ($R_T$, yellow), and the total number of infectious trees ($I_T+A_T$, light blue), for four scenarios: (a) infection is only produced by inserting 1% of infected grafts out of $5\%$ of grafts made initially ($t_i=0$); (b,c) infection is only produced by the initial arrival of a percentage of infected vectors ($I_v\left(0\right)$) and no grafting with infected material occurs (${\mathrm{\Delta }}_T=0$). Initial conditions were taken: in (a) $S_T\left(0\right)=1$, $E_T\left(0\right)=I_T\left(0\right)=A_T\left(0\right)=R_T\left(0\right)=0$; $S_v\left(0\right)=1$, $I_v\left(0\right)=0$, $P\left(0\right)=P^{\ast }$; in (b) $S_v\left(0\right)=0.99$, $I_v\left(0\right)=0.01$ and the remaining as in (a); in (c) $S_v\left(0\right)=0.95$, $I_v\left(0\right)=0.05$ and the remaining as in (a). (d) shows the total number of infectious trees ($I_T+A_T$) for different initial numbers of infectious vectors ($I_v\left(0\right)$), under the same conditions as in (b,c). All other parameters used in the simulations are as in Table 2.