Raspberry Root Rot Research Articles

Methods for assessing the resistance of raspberry genotypes to Phytophthora root rot

Zoospores and agar discs of the fungus causing raspberry root rot (Phytophthora fragariae) were used as inoculum to assess the resistance of raspberry genotypes in pot experiments. High zoospore concentrations resulted in more severe symptoms than low concentrations. There was a strong correlation between the results obtained with zoospores and with colonized agar discs as inocula. although disease was generally more severe with the former. The severity of root rot was correlated with a number of other symptoms, in particular growth reductions, stem lesions and leaf wilting, and some of these symptoms could possibly be used as measures of resistance. There was no evidence of physiological specialization with the range of isolates and raspberry genotypes used. Pot tests in general gave results which matched reported resistances in the field, and could be used to assess the resistance of breeding lines and selections.

Phytophthora species attacking strawberry and raspberry1

Phytophthora frugariae causes red core root rot of strawberries. Although the disease is probably most acute in northern Europe, serious outbreaks have been reported from a number of Mediterranean countries, especially France and Italy. Leather rot of fruit and crown rot, which are caused by P. cuctorum, can also be severe problems in warmer climates. Both fungi survive in soil for long periods, but the most common form of spread is in diseased planting material. Sensitive tests have been developed to detect red core in planting material, and been used to effect in certification schemes. Root rot of raspberry has gained prominence in the last 10 years in Europe as raspberry growing has expanded, but the disease has been known for many years in France. Nine species of Phyfophthora have been recovered from affected plants, but two of these, one with affinities with P. megasperma, and P. cumbiuora, are responsible for most major outbreaks. The other species are only troublesome where drainage is poor. Again, spread is mainly in infected material. Few raspberries are resistant to root rot, but some wild RubuP spp., blackberries and raspberry x blackberry hybrids are resistant and may be useful in breeding programmes.

Identity, Virulence, and Isolation Frequency of SevenPhytophthoraspp. Causing Root Rot of Raspberry in New York

Identity, Virulence, and Isolation Frequency of Seven<i>Phytophthora</i>spp. Causing Root Rot of Raspberry in New York

Phytophthora cryptogea as a cause of root rot of raspberry in Australia; resistance of raspberry cultivars and control by fungicides

Phytophthora cryptogea was isolated from field plantings of the red raspberry cultivars Glen Clova, Canby and Willamette which showed wilting, dieback, stem lesions and root rotting. Pathogenicity of P. cryptogea to raspberry was demonstrated in glasshouse experiments. Twelve cultivars of raspberry were screened for resistance to the disease by growing them in artificially infested soil. Glen Clova and Canby were highly susceptible whilst Chilcotin, Nootka, Haida and Puyallup were resistant. Soil treatments with either metalaxyl, phosphorous acid or fosetyl aluminium controlled the disease. This is the first record of a phytophthora root rot of raspberry in Australia, and the first demonstrating the pathogenicity of P. cryptogea to raspberry.

White root rot of raspberry in Victoria is caused by a Vararia species

Microscopic studies and pathogenicity tests on a fungus consistently associated with diseased roots and canes of raspberry ( Rubus idaeus ) have shown that a species of Vararia causes white root rot of raspberry in Victoria.

Phytophthora erythroseptica . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora erythroseptica . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Potato, asparagus, cineraria, tomato, pea, raspberry, tulip, Zantedeschia , sugarcane, vetch. DISEASE: Pink rot of potato; shanking of tulip; rhizome rot and leaf blight of Zantedeschia ; sugarcane seed-piece rot; raspberry root rot; tomato buckeye rot. GEOGRAPHICAL DISTRIBUTION: Europe (UK, Irish Republic, Belgium, Bulgaria, France, Greece, Italy, Netherlands, Poland, Switzerland, USSR, Yugoslavia); Asia (India, Indonesia, Iran); Africa (Egypt); N. America (Canada, USA); Central America (Cuba); S. America (Venezuela, Peru); Australia; New Zealand. (CMI Map 83, ed. 4, 1973). TRANSMISSION: Soil-borne, oospores disseminated from diseased potato stems and roots persisting for many years. In the field tubers are generally infected through the stolon, but direct infection through eyes may occur in field and storage under moist conditions (13, 180; 19, 40). Transmission during storage, and survival of inoculum in apparently healthy tubers, was shown to be possible (57, 758). Tulip bulbs were invaded from the soil through the roots to the basal plate and flowering stem (18, 183).

ROOT ROTS OF THE RASPBERRY

The investigations reported here are concerned with isolations from diseased raspberry roots, preliminary inoculations with isolates, and microscopic examination of naturally and artificially infected roots.The following fungi were isolated from naturally infected roots: Coniothyrium Fuckelii, Cylindrocarpon radicicola, Fusarium sp., possibly F. orthoceras, Cylindrocladium sp., Pythium spp., Rhizoctonia Solani, Rhizoctonia sp. (orchid type), and in preliminary inoculation experiments each fungus was found to be capable of producing necrotic lesions on healthy roots. Microscopic examinations of roots artificially inoculated with pure cultures of the above fungi, showed in the roots the presence of the fungus used for inoculation. In addition the "phycomycetous mycorrhizal" fungus already associated with root rot of strawberries and tobacco was observed to be almost always present in roots of affected raspberry plants, and, to a lesser extent, in apparently healthy roots from apparently normal plants. Nematodes, especially Anguillulina pratensis, the meadow nematode, were present in and on roots from certain soils, while they were absent from roots from other soils. Strawberry and raspberry seeds were sown in sterilized and non-sterilized affected soil with the result that the roots in sterilized soil appeared to be healthy, while those in the non-sterilized soil became affected with necrotic lesions.Evidence is given which shows not only that certain symptoms of raspberry root rot are similar to the symptoms of strawberry root rot, which is considered to be a major factor in the degeneration of strawberries in both Europe and America, but also that many of the fungi and nematodes generally conceded to be associated with root rots of strawberry are likewise associated with root rots of raspberry. In the Fraser Valley, British Columbia, where certain raspberry plantations appear to be heavily infected with root rots, the possibility that these root rots may play an important role in connection with the un-thriftiness of such plantations should not be overlooked.