Susceptible Host Plants Research Articles

Ornamental flowering plants experimentally infected with curly top

Abstract does not appear. First page follows. Introduction Several investigators have recorded the experimental transmission of virus diseases of plants to a large number of species in different genera of many families. A review of the literature on the host range of certain virus diseases shows an extensive host range as determined by experimental infection, but the reported natural host range is often limited, as illustrated in table 1. The natural infection of ornamental flowering plants with curly top has already been reported in a previous paper.(27)4 A list of the plants experimentally infected, but without details of the experiments or description of the symptoms, was published in the Plant Disease Reporter.(7) The details and results of the experiments performed to experimentally infect ornamental flowering plants with curly top are given in the present paper. No intensive investigations have been conducted to determine which plants are resistant or immune to curly top; only plants experimentally infected with the disease are reported in this paper. The symptoms on the susceptible host plants are briefly described. The longevity of the last living male and female beet leafhopper, Eutettix tenellus (Baker), was ascertained on inoculated plants and a record was kept of all plants on which the leafhopper completed its life cycle.

Statistical Aspect of the Production of Primary Lesions by Plant Viruses

AN analogy has frequently been drawn between the production of bacterial colonies on artificial media and of primary lesions on the leaves of susceptible host plants inoculated with an extract of virus-diseased tissues. In a recent paper, Youden, Beale and Guthrie1 have carried this analogy one step further, and have suggested that the relation between the numbers of lesions and the relative concentrations of virus particles in the inoculum may be described in the same way as the relation between the numbers of bacterial colonies and the concentration of bacteria in the plated suspension. Their equation takes the form: where y is the number of lesions given at any concentration x of the virus, N represents the maximum lesions obtainable, and a is a constant.

The Occurrence of Viable Cotton Root-Rot Sclerotia in Nature

Viable sclerotia of the cotton root-rot fungus, Phymatotrichum omnivorum, have been found under natural conditions in the soil of infested cotton fields in Texas, showing that this fungus is a soil organism not restricted to living roots of susceptible host plants, but having an independent means of over-wintering and dissemination.

THE OCCURRENCE OF VIABLE COTTON ROOT-ROT SCLEROTIA IN NATURE

Viable sclerotia of the cotton root-rot fungus, Phymatotrichum omnivorum, have been found under natural conditions in the soil of infested cotton fields in Texas, showing that this fungus is a soil organism not restricted to living roots of susceptible host plants, but having an independent means of over-wintering and dissemination.