Elsinoe Veneta Research Articles

Control of Insect Pests and Diseases in an Ohio Fruit Farm with a Laser-guided Intelligent Sprayer

Laser-guided variable-rate intelligent spray technology is designed to significantly reduce pesticide use with a positive impact on the environment. However, there have been no reports on applying this technology to commercial fruit farms. Comparative experiments of intelligent variable-rate and conventional constant-rate spray applications for pesticide use and pest control were conducted at a fruit farm in Ohio during two consecutive growing seasons. Apple (Malus pumila), peach (Prunus persica), blueberry (Vaccinium section Cyanococcus), and black raspberry (Rubus occidentalis) were used for the tests. Pest severity of codling moth (Cydia pomonella), oriental fruit moth (Grapholitha molesta), scab (Venturia inaequalis), and powdery mildew (Podosphaera leucotricha) in apple; oriental fruit moth, brown rot (Monilinia fructicola), and powdery mildew (Podosphaera pannosa) in peach; spotted wing drosophila (Drosophila suzukii), mummy berry (Monilinia vaccinii-corymbosi), and phomopsis (Phomopsis vaccinii) in blueberry; and anthracnose (Elsinoe veneta) in black raspberry were assessed. There was equal severity of pests between intelligent and conventional spray applications, whereas the intelligent spray reduced pesticide use by 58.7%, 30.6%, 47.9%, and 52.5% on average for apple, peach, blueberry, and black raspberry, respectively. These results illustrate that intelligent spray technology is more environmentally friendly than conventional standard spray technology and equally or more effective for control of insect and disease pests in fruit production.

High Tunnel and Open Field Production of Floricane- and Primocane-fruiting Raspberry Cultivars

Identical trials were conducted in a multibay high tunnel and an adjacent open field in southwestern Michigan to compare primocane-fruiting cultivars (Autumn Britten, Caroline, Chinook, Heritage) and floricane-fruiting cultivars (Canby, Encore, Heritage, Nova) of red raspberry (Rubus idaeus). Floricane-fruiting plots of ‘Heritage’ were pruned to produce fruit on floricanes and primocanes (double cropping). The most productive cultivars in both environments were ‘Nova’ and ‘Canby’ (floricane) and ‘Caroline’ and ‘Heritage’ (primocane). These cultivars produced annual yields of 5.5 kg·m−1 row in the tunnel and 2.5 kg·m−1 row in the field. The order of primocane harvest (earliest to latest) was the same in the tunnel and field: ‘Autumn Britten’, ‘Caroline’, ‘Chinook’, and ‘Heritage’. Cultivars with the greatest average berry weight in the tunnel and field were Encore and Nova (floricane) and Autumn Britten and Caroline (primocane). ‘Chinook’ and ‘Autumn Britten’ tended to have the highest incidence of gray mold (Botrytis cinerea) of primocane-fruiting cultivars, but incidence was similar in floricane cultivars. Overall mold incidence was 1% in the tunnel and 13% in the field. Leaf spot (Sphaerulina rubi), cane anthracnose (Elsinoe veneta), spur blight (Didymella applanata), and botrytis cane blight (B. cinerea) were common in the field but absent in tunnel. Phytonutritional analyses of primocane fruit indicated that genotype differences were not consistent across the two environments. Relative cultivar characteristics (harvest season, yield, berry quality) were similar in the field and tunnels, but the tunnel environment tended to increase plant vigor, yield, and fruit quality and suppress several diseases.

Functional Markers for Red Raspberry

Primers to 43 genes, including those involved in the phenylpropanoid and volatile pathways, cell wall, ethylene and polyamine metabolism, and from Prunus linkage group (LG) 6 were tested in red raspberry (Rubus idaeus) cultivars Latham and Glen Moy, and 40 were polymorphic. Thirty-seven genes were subsequently mapped in the ‘Latham’ × ‘Glen Moy’ population and were placed across all seven Rubus LG. This brings to 97 the total number of genic markers mapped in this Rubus mapping population. Fifteen genes are associated with existing quantitative trait loci for ripening, cane diseases, including yellow rust (Phragmidium rubi-idaei), cane botrytis (Botrytis cinerea), spur blight (Didymella applanata), and cane spot (Elsinoe veneta) or fruit color in R. idaeus and can be used for identifying bacterial artificial chromosome clones for physical mapping studies. A cluster of four genes from Prunus LG6 mapped together to Rubus LG3, suggesting that there may be sufficient synteny between these Rosaceae over small genomic regions that can be exploited in future studies.

Fungi in leaves, twigs and stem bark of Populus tremula from northern Spain

SummaryFungal species were recorded from Populus tremula leaves, twigs and bark (trunk) at eight sites in the northern region of Spain, with the aim of evaluating the effect of sampling site, sampling tissue and isolation method on the frequency and species distribution of the fungi recovered from necrotic and healthy tissues. Two different isolation methods were used: the first consisted of finding fruitbodies on plant tissues after incubating them in wet and warm conditions, and the second included growing mycelia from plant fragments plated on potato dextrose agar (PDA). A total of 48 fungal species were isolated from 960 plant fragments. Cytospora chrysosperma, previously reported to be a pathogen of poplar, was recovered very frequently and was recorded as much in healthy as in dead or dying tissues. Cladosporium maculicola, Elsinoe veneta, Alternaria alternata, Aureobasidium pullulans and Pollaccia radiosa were also frequently isolated. The isolation frequencies from necrotic and healthy plant tissues were significantly different between sites and isolation methods. The incubation in moist chambers revealed significantly more fungal isolates and a higher species richness (38 species) than isolations on PDA. However, 16% of the fungal species were exclusively recorded from cultures. Therefore, a combination of several isolation methods is recommended for surveys of fungal communities associated with trees.

Fungi Occurring on Aerial Constituents of Cultivated Blackberry ( Rubus fruticosus L.) in Norway

Cultivated blackberry (Rubus fruticosus) was recently introduced in Norway, and most plantings were established in the 1990's. Many of these plantings died back or had severe damage on leaves and stems. Plant pathogens incombination with frost injury were suspected to be the cause of the damage. In 1998-99, field and greenhouse plantings of blackberry were surveyed for the occurrence of plant pathogenic and saprophytic fungi. A total of 33 different fungi were identified in 18 cultivars from 23 plantings (19 field and 4 greenhouse). Of these, 12 were pathogenic fungi, while 21 were non-pathogenic, secondary invaders. The most important pathogens on the canes were (common name in parenthesis) Septocyta ruborum (Purple blotch), Gnomonia rubi (Gnomonia canker) and Sydowiella depressula (Sydowiella canker). Pathogenic fungi of less importance on the canes were Elsinoe veneta (Anthracnose) and Coniothyrium fuckelii (Cane blight). Peronospora sparsa (Downy mildew) was the most important fungus attacking leaves. On fruits Botrytis cinerea (Grey mould) was the most prevalent pathogen. Cladosporium spp. (Cladosporium rot) and Penicillium spp. (Blue mould) were frequently observed on fruits, but did not seem to be of significant importance. Other minor fruit rots were due to Colletotrichum gloeosporioides (Bitter rot) and Mucor sp. (Mucor rot). Phragmidium violaceum (Blackberry rust) was found on canes and leaves, but was of minor importance. G. rubi and S. depressula caused damage mostly in the thornless cultivars, and P. sparsa was found almost exclusively in the thornless cultivar 'Loch Ness'. Both thorny and thornless cultivars were damaged by S. ruborum. In greenhouses the major fungal problem was B. cinerea.

WHAT'S GOING ON IN THE WORLD OF RUBUS BREEDING?

WHAT'S GOING ON IN THE WORLD OF RUBUS BREEDING?

The histology of lesion development in raspberry canes infected by Elsinoe veneta

SummaryA histological survey was made of the canes of several raspberry genotypes inoculated in the field and glasshouse with Elsinoe veneta. Acervuli bearing conidia developed on all genotypes and hyphae penetrated the cortex, polyderm and phloem inducing extensive cell divisions, utilisation of starch reserves and deposition of suberin and lignin‐like materials in these tissues.The results indicated that the polyderm was invaded via the passage cells at an early stage in its development. Phloem fibre cells surrounded by lignified middle lamellae were rarely infected, but since the fibre bundles did not form a complete sheath around the vascular tissues, hyphae spread between the bundles to invade the phloem in all genotypes. The deposition of suberin and lignin‐like materials in host cells in the cortex, phelloid cells of the polyderm and phloem partially restricted the spread of mycelium.

A method for in vitro production of conidia of Elsinoe veneta and the inoculation of raspberry cultivars

SummaryConidia of two isolates of Elsinoe veneta were consistently produced in vitro by a 3‐stage culture system in which sparsely sporulating microcolonies produced on corn meal agar were used to ‘seed’ Czapek‐Dox V8 juice agar. E. veneta then sporulated on this medium if dises were floated mycelium uppermost on sterile distilled water for 24 h at 25°C. Both isolates also produced microconidia in vitro.Only the growing apices of raspberry canes were susceptible to infection. Of 12 genotypes inoculated in the glasshouse, a red raspberry derivative of Rubus coreanus, EMRS 2769/9, was the most resistant and the black raspberry selection SCRI 815286 and cv. Malling Delight were the most susceptible. Of four red raspberry cultivars inoculated in the field cv. Malling Orion was the most susceptible. Inoculated flowers and developing fruits produced malformed fruits because infected drupelets were smaller or slower to ripen than uninfected ones.

A Check List of the Fungal Pathogens of Rubus Spp. (Rosaceae) in Victoria.

Twenty species of Rubus growing in Victoria were surveyed for fungal pathogens, as part of a study on the biological control of European blackberry (Rubus fruticosus L. agg.). Twenty-three pathogens were recorded, but only three were common in introduced Rubus spp. the rust fungus Keuhneola uredinis (Link) Arth. (Uredinales), the leaf spot fungus Septoria rubi Westend, (Sphaeropsidales), and the anthracnose fungus Elsinoe veneta (Burkh.) Jenkins (Myriangiales). The rust fungus Phragmidium barnardii Plowr. & Winter was commonly found only on Rubus parvifolius L., a native species.

Rubus coreanus as donor of resistance to cane diseases and mildew in red raspberry breeding

Strong resistance to the cane diseases Elsinoe veneta, Didymella applanata and Botrytis cinerea, and to Sphaerotheca macularis, occurred in F1 and BC1 derivatives of an accession of Rubus coreanus. Resistance to cane spot (E. veneta) was polygenic.

PROGENY PERFORMANCE OF SEVEN RED RASPBERRY VARIETIES IN NOVA SCOTIA

Progeny from 21 crosses among 7 red raspberry varieties were evaluated with respect to yield, winter hardiness and resistance of canes to anthracnose (Elsinoe veneta). Seedlings of the varieties Trent and Rideau showed the greatest bud survival, especially when crossed with other varieties. The highest yielding progeny was Mailing Promise × Trent and this was not changed by adjusting yields for bud survival or number of canes per plot. Resistance to anthracnose was found in progenies of Viking, Willamette and Early Red and inheritance of anthracnose resistance seemed to be additive.

STUDIES ON THE PHYSIOLOGY OF ELSINOE VENETA

A study was made of the effect of certain nutritional and environmental factors on the growth and pigmentation of the mycelium, the sporulation, and the germination of the conidia of a "convoluted" isolate of Elsinoe veneta (Burkh.) Jenkins, the fungus responsible for the anthracnose disease of raspberries. This isolate utilized with varying degrees of efficiency various mono-, oligo-, and polysaccharides as well as certain organic alcohols as its sole source of carbon for growth. Either a nitrate, ammonium, amino, or imidazole nitrogen compound supported the fungus in culture. Maximum growth of the mycelium occurred in the presence of soluble starch and asparagine, whereas optimum sporulation of the conidia was obtained on media containing potato starch and sodium nitrate. In general, the production of conidia was markedly reduced on media favorable for excessive vegetative growth. Both a decrease in the volume of the medium and in the concentration of either a specific nutrient or of total nutrients adversely influenced the production of mycelium. Temperatures above 30 °C. and below 21 °C. decreased the percentage germination of conidia and restricted the growth of the fungus. Growth and sporulation occurred over a wide range of pH values. The optimum initial pH for both growth and sporulation was 4.0. E. veneta produced conidia and grew as well in continuous darkness as in alternate diffuse light and darkness. Young potted raspberry plants growing in the greenhouse, when inoculated with conidia produced in culture, developed typical anthracnose lesions on the canes.