Prunus necrotic ringspot and prune dwarf viruses in New Zealand

Abstract

Abstract In New Zealand Prunus necrotic rings pot virus (NRSV) is carried without symptoms on peach, nectarine, apricot, and Japanese plum. Tatter leaf symptoms develop on the rootstock clone F12/1 and some sweet cherry varieties. Prune dwarf virus (PDV) has been found only in mixed infections. NRSV is widespread in some peach varieties, cherries, and plums, but incidence is low in apricots and nectarines. PDV is widespread only in cherries. NRSV was seed transmitted in 0.75% of seed from infected Golden Queen and in 12% of seed from Muir peach. Two of 16 trees pollinated with pollen from infected trees became infected. Spread of NRSV was detected in all three orchards indexed in three successive seasons. NRSV was eliminated by hot-water treatment of budwood for 10 min at 55°c or 20 min at 50°, and PDV was eliminated after 10 min at 55°. Hot-air treatment followed by tip grafting eliminated both NRSV and PDV from most cherry tips after heating for 13 to 24 days. NRSV was eliminated from peach tips after 17 and 24 days' heating, and from plum after 21 days. The NRSV particle was “spherical”, 20 to 25 mμ in diameter. Serological relationship to a Californian almond calico strain of NRSV was demonstrated.