Transmission of radish-mosaic virus by aphids

Abstract does not appear. First page follows.

Introduction

A mosaic disease of the cultivated radish (Raphanus sativus) is common in the vegetable gardens of the San Francisco Bay districts. The disease also occurs on wild radish, which probably serves as a reservoir of the virus.

(Tompkins (1939))4 reviewed the literature on mosaic diseases of Raphanus species. He also published the results of studies on host range and properties of the radish-mosaic virus. The virus was found to be readily transmitted by mechanical inoculation. Numerous unsuccessful attempts were made to transmit the virus by means of the cabbage aphid, Brevicoryne brassicae (L.), turnip or false cabbage aphid, Rhopalosiphum pseudobrassicae (Davis), and the green peach aphid, Myzus persicae (Sulzer).

(Magistad (1938)) listed daikon (Raphanus sp.) mosaic in the Hawaiian Islands.

(Parris (1940)) listed a mosaic on Raphanus sp. in Hawaii.

(Dale (1948)) recorded the occurrence of a mosaic disease on three crucifers in Trinidad, British West Indies, one of which was an eastern variety of radish, known locally as moorei and which he suggested may be Raphanus sativus var. hortensis. He found by inoculation tests that the radish (R. sativus) varieties French Breakfast and Burpee’s Red Giant appear to be immune to the virus described in his paper. The virus was transmitted by Rhopalosiphum pseudobrassicae (Davis).

The following is a report of a study undertaken on aphid transmission of the radish-mosaic virus described by (Tompkins (1939)). Tests were made with aphid species that breed on White Icicle radish under natural conditions and with species that have not been reared on this host plant. A comparison was made between transmission of the virus by unfasted infective aphids, and transmission by previously noninfective fasted aphids after short infection-feeding intervals. Other aspects investigated include a comparison of virus transmission, by lots of varying numbers of aphids, with mechanical inoculation; and the retention of the virus.