Corn barriers in an integrated management strategy to control epidemics of papaya ring spot virus (PRSV-P)
The epidemics caused by papaya ring spot virus (PRSV-P) (Carica papaya L.) have been delayed by an integral management system (MIP), although the individual effectiveness of some components has not been measured. The establishment of corn (Zea mays L.) barriers was evaluated in the control of PRSV-P in Veracruz, Mexico. The MIP included the protection of the nursery with polypropylene mesh, 2743 plants ha-1, eradication of diseased plants, mineral fertilization and weed control. Treatments were: integral management with corn barriers (MIP), integral management without barriers (MIZ) and regional management (MR, 1600 plants ha-1, using insecticides, without barriers and elimination of diseased plants). The logistic model adequately explained the incidence in MIP, MIZ and MR, and severity (R2=0.92 to 0.97) in MIZ; the exponential and Gompertz models explained severity (R2= 0.92 and 0.98) in MIP and MR. The highest epidemic rate was observed in MR (0.054), while MIP reduced it by 42 % (0.031). Barriers induced lower incidence and mean severity (Yp –MIP = 18.4 and 7.1 %; Yp–MIZ = 23.4 and 11.7 %) and final (Yf–MIP = 81.0 and 35.7 %; Yf–MIZ = 94.11 and 43.0 %). Maximum severity at 238 d after transplant (dat) was observed in MR (69.0 %) and the lowest in MIP (35.7 %). The absence of barriers increased the epidemics; in MR the maximum incidence (100 %) and severity (60 %) occurred 175 dat, while in MIP, 238 dat (incidence 80 %, severity 35 %). Barriers improved papaya health under MIP by 14 % (Yf-MIP =81.0 % < Yf-MIZ) and reduced severity by 47.7 % (MIPaudpc=1621.1 < MIZaudpc=2734.7). The MIP, with and without barriers, increased yield from 76.3 to 94.4 % with respect to MR.