0000000000342486
AUTHOR
David E. L. Cooke
Root and Foot Rot of Lantana Caused by Phytophthora cryptogea
Lantana (Lantana camara L.) is an evergreen shrub in the Verbenaceae. In some countries, this plant has been declared a noxious weed. However, a number of sterile or near-sterile forms are cultivated as attractive flowered potted and garden plants. In early spring 2004, ≈4,000 potted, small trees of lantana grown in a screenhouse in a commercial nursery of ornamentals near Giarre, Sicily, showed symptoms of chlorosis, defoliation, and sudden collapse of the entire plant. These aboveground symptoms were associated with a reduced root system, rot of feeder roots, and brown discoloration of the base of the stem. A Phytophthora sp. was isolated consistently from roots and basal stems of sympto…
A molecular method to assess Phytophthora diversity in environmental samples
Current molecular detection methods for the genus Phytophthora are specific to a few key species rather than the whole genus and this is a recognized weakness of protocols for ecological studies and international plant health legislation. In the present study a molecular approach was developed to detect Phytophthora species in soil and water samples using novel sets of genus-specific primers designed against the internal transcribed spacer (ITS) regions. Two different rDNA primer sets were tested: one assay amplified a long product including the ITS1, 5.8S and ITS2 regions (LP) and the other a shorter product including the ITS1 only (SP). Both assays specifically amplified products from Phy…
Wilt and Collapse of Cuphea ignea Caused by Phytophthora tropicalis in Italy.
The genus Cuphea (Lythraceae) includes approximately 250 species of annual, evergreen perennials and short shrubs native to Central and South America. During the springs of 2003 and 2004, 10% of the nursery stock of approximately 12,000 potted cigar-flowers (C. ignea A. DC) grown in a screenhouse at a commercial ornamental nursery near Piedimonte Etneo, Sicily, had symptoms of wilt, defoliation, and rapid collapse of the entire plant. These foliar symptoms were associated with a reduced root system, browning of the collar, and dark brown discolored roots. A Phytophthora species was consistently recovered by plating small pieces of rotted roots of symptomatic plants onto selective medium (3…
Molecular analysis ofPhytophthoradiversity in nursery-grown ornamental and fruit plants
The genetic diversity of Phytophthora spp. was investigated in potted ornamental and fruit tree species. A metabarcoding approach was used, based on a semi-nested PCR with Phytophthora genus-specific primers targeting the ITS1 region of the rDNA. More than 50 ITS1 sequence types representing at least 15 distinct Phytophthora taxa were detected. Nine had ITS sequences that grouped them in defined taxonomic groups (P. nicotianae, P. citrophthora, P. meadii, P. taxon Pgchlamydo, P. cinnamomi, P. parvispora, P. cambivora, P. niederhauserii and P. lateralis) whereas three phylotypes were associated to two or more taxa (P. citricola taxon E or III; P. pseudosyringae, P. ilicis or P. nemorosa; and…
First report of brown rot and wilt of fennel caused by Phytophthora megasperma in Italy
Fennel (Foeniculum vulgare Mill. var. azoricum (Mill.) Thell.) in the Apiaceae family is native to southern Europe and southwestern Asia. It is an economically important crop in Italy that produces approximately 85% of all fennel worldwide. The main producing regions are Apulia, Campania, Latium, and Calabria. During the late winter of 2004 in the Crotone Province of the Calabria Region, following heavy rains, patches of fennel plants with symptoms of brown, soft rot of the bulb-like structure formed by the thickened leaf bases, development of yellow leaves, stunting, and wilting of the entire plant were observed in fields. A homothallic Phytophthora sp. was isolated consistently from the …
A new Phytophthora sp causing a basal canker on beech in Italy.
In autumn 2001, bleeding cankers were observed on the basal portion of the trunk of a declining tree in a forest stand of European beech (Fagus sylvatica L.) in Latium (central Italy). A Phytophthora sp. was isolated consistently from infected trunk bark using whole apples as bait. Isolations were made from brown lesions that developed in the apple pulp around the inserted bark pieces. Pure cultures were obtained by using hyphal tip transfers. Colonies were stellate on V8 juice agar (V8A), uniform to slightly radiate on cornmeal agar, and cottony, without a distinct growth pattern on potato dextrose agar (PDA). On V8A, radial growth rates were 2.1, 4.8, and 4.5 mm/day at 10, 15, and 20°C, …