Aphid transmission of severe-mosaic virus of annual stock

Abstract does not appear. First page follows.

Introduction

In the canyons of the Montara Mountains and the slopes along the Pacific Ocean, the mild-mosaic virus of annual stock (Matthiola incana var. annua) induces a conspicuous breaking in the color of the flower petals in all but white and yellow flowering types. The breaking renders these affected varieties unmarketable as cut flowers. A severe mosaic disease of annual stock with a striking color-breaking and conspicuous mottling and malformation of the leaves occurs in home gardens and in a nursery at San Pablo, Contra Costa County.

The turnip or false cabbage aphid, Rhopalosiphum pseudobrassicae (Davis), breeds on annual stock under natural conditions; the cabbage aphid, Brevicoryne brassicae L., and green peach aphid, Myzus persicae (Sulzer), do not.

Review of Literature

A review of the literature on virus diseases of annual stock has been published by (Tompkins (1934), (1939)4 and (Severin and Tompkins (1948)).

A paper by (Oliveira and Borges (1944)) appeared and was not reviewed in our last contribution. A number of cultivated and wild crucifers, tobacco and Nicotiana glutinosa were tested, by juice inoculation, with nine isolates of an annual-stock virus from Lisbon gardens. The symptoms induced by each of the isolates on the differential hosts were mosaic, rugosity, stunting, chlorosis, necrosis, blistering, and streak.

Materials and Methods

The virus causing severe mosaic of annual stock was obtained at San Pablo, Contra Costa County. Plants of the Fiery Blood Red variety of annual stock and the February variety of cauliflower grown from seeds were used in all experiments reported in this paper. All inoculated annual stock plants were held for observation after the flowering stage.