Colletotrichum spp. causing anthracnose on ornamental plants in northern Italy

Species of Colletotrichum are considered among the most important plant pathogens, saprobes and endophytes on a wide range of ornamentals, fruits and vegetables. Several Colletotrichum species have been reported in nurseries and public or private gardens in northern Italy. In this study, the occurrence, diversity and pathogenicity of Colletotrichum spp. associated with several ornamental hosts was explored. Survey were carried out during the 2013–2019 period in Piedmont, Italy. A total of 22 Colletotrichum isolates were collected from symptomatic leaves and stems of two Campanula spp., Ceanothus thyrsiflorus, Coreopsis lanceolata, Cyclamen persicum, Hydrangea paniculata, Liquidambar styraciflua, Mahonia aquifolium and Rhyncospermum jasminoides. A multi-locus phylogeny was established based on the basis of three genomic loci (gapdh, act and tub2). The pathogenicity of selected, representative isolates was tested. Colletotrichum isolates were identified as members of four important species complexes: Acutatum, Gloeosporioides, Dematium and Destructivum. Colletotrichum fioriniae, C. nymphaeae and C. fuscum were found in association with leaf lesions of Mahonia aquifolium, Campanula rapunculoides and Coreopsis lanceolata, respectively. Colletotrichum lineola, C. grossum and C. cigarro were isolated from Campanula trachelium, Rhyncospermum jasminoides and Liquidambar styraciflua, respectively. Colletotrichum fructicola was found to be responsible of anthracnose of Ceanothus thyrsiflorus, Hydrangea paniculata, Cyclamen persicum and Liquidambar styraciflua. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in private gardens and nurseries. The present study improves our understanding of Colletotrichum spp. associated with different ornamental hosts and provides useful information for an effective disease management programme.

Evaluation of Growth, Flowering, and Cold Hardiness of Ceanothus in Western Oregon

Thirty-eight species, cultivars, and hybrid selections of ceanothus (Ceanothus spp.) were evaluated for growth, flowering, and cold hardiness in a landscape trial in Silverton, OR, from 2001 to 2005. Plants were only irrigated for establishment in Summer 2001 and were not pruned or fertilized throughout the trial. Several cultivars showed dieback and leaf damage after 22 °F cold events in late October and early Nov. 2002 and 2003, the most severely affected of which were Ceanothus thyrsiflorus var. griseus, C. thyrsiflorus var. griseus ‘Yankee Point’, Ceanothus hearstiorum, and C. thyrsiflorus ‘Snowflurry’. Among the cultivars evaluated, those recommended for early bloom are ‘Ray Hartman’ and ‘Blue Jeans’. Several cultivars are effective drought-tolerant groundcovers, including ‘Wheeler Canyon’, ‘Joyce Coulter’, and ‘Joan Mirov’. Among the smaller-growing plants, Ceanothus cuneatus var. rigidus ‘Snowball’ and Ceanothus gloriosus ‘Heart's Desire’ made effective groundcovers only 0.6 and 0.2 m tall, respectively.

THE LIFE HISTORY AND HABITS OF A CEANOTHUS LEAF MINER, TISCHERIA IMMACULATA (LEPIDOPTERA: TISCHERIIDAE)

Plantings of Ceanothus griseus L. (also Ceanothus thyrsiflorus var. griseus L.) were invaded by a rare leaf miner, Tischeria immaculata (Braun). Adults appeared at the beginning of May and most flew between 1750 and 2400 h. Mating and egg laying started immediately and females laid an average of 35 eggs (range: 15–48). Eggs measured 0.12 mm by 0.08 mm, were translucent, and hatched to minute larvae which did not feed until 24 h after hatch. Larvae reared at different temperatures and moisture regimes performed best at 21 °C and 70% relative humidity. Frass was ejected through the oval trap door constructed at the initiation of the larval mine. Pupation took place anywhere within the mine but the adult emerged through a crescentic exit hole at the end of the mine.The principal enemy was a eulophid, Pnigalio flavipes Ashmead. Various species of spiders and a bird, Junco hyemalis L., preyed on adults. Emerging adults were also trapped and killed in spittle-bug froth.