Management of Papaya ring spot virus (PRSV-P) of papaya under Pune conditions.

Incidence of Papaya ring spot virus (PRSV-P) causes heavy economic losses to the papaya growers throughout the world. The boost in fruit crop cultivation under the aegis of National Horticultural Mission has witnessed wide spread raising of the plantations of papaya in the Maharashtra state, India, but simultaneously the papaya growers of this region have also started experiencing disastrous effects of disease caused by PRSV. The quick spread of the disease in the field leave little scope for adopting any control measures against the malady and necessitates the integrated management strategy. The present studies carried out at IARI Regional Station experimental farm at Pune, Maharashtra, India during 2007-08 dealt with finding off season hosts of PRSV in the field, suitable planting date to avoid the disease infection, varietal screening to have resistant/tolerant source as well as identification and seasonal colonization of aphid species on papaya under Pune climate. The biological indexing and electron microscopy studies revealed Cucumis melo L., Alternanthera sessilis (L.) R. Br. Ex DC., Datura metel L., Xanthium indicum Koern., Cassia tora Linn. and Physalis minima L. as important off season weed hosts of PRSV. The planting done in July exhibited lowest PRSV incidence (28.33%) followed by planting done in April (35.0%) at hundred percent flowering stage. Screening of eight commercial papaya cultivars showed the lowest disease incidence (13.2%) at hundred percent flowering stage in the cultivar 'Madhubala' followed by cultivars 'CO2' (39.8%) and 'Pusa Nanha' (44.8%) when compared with the widely grown 'Red Lady' (86.0%). The observations on aphid colonization on papaya plants in the field showed maximum aphid population (10.47/plant) as well as its biological control agents in the month of December on the plants transplanted in the month of October. The aphids were identified as species of Myzus persicae Sulz., Ceratovacuna lanigera Zehn., Macrosyphum sp. and Toxoptera aurantii (B.d.F.).