239 Evaluation of Spur-type Apple Cultivars on Dwarfing Rootstocks (2025)

001 Establishment of Methods in Evaluating the Susceptibility of Chinese Cabbage (Brassica campestris spp.) to Soft Rot Disease by Erwinia

HortScience, 1999

Three inoculation methods, including cutting of a leaf, drenching, and point inoculation, were compared in an effort to screen the susceptibility of Chinese cabbage to soft rot disease caused by Erwinia carotovora subsp. carotovora. Three- to 4-week-old seedlings from 10 lines of cabbage with 16-h-old bacterial culture were routinely used. Inoculated seedlings were kept at 25.0 ± 10.0 °C for 48 h with saturated water vapor using a plastic tunnel in a greenhouse. Sixty-day-old mature plants were produced and inoculated in a greenhouse. Severity of symptoms, which were observed from percentage of plant infected was scored as from 1 to 9, representing resistant to susceptible, respectively. The correlation between seedlings and mature plants from ten lines was evaluated among the three different inoculation methods. Point inoculation gave the most significant correlation (r = 0.843, P < 0.05) between seedlings and mature plants. A good correlation was also observed between point ino...

Studies on the Effect of Temperature on the Development of Soft Rot of Cabbage (Brassica Oleracea Var. Capitata) Caused by Erwinia Carotovora Sub Sp. Carotovora

Soft rot is one of the destructive diseases of vegetables including cabbage worldwide. Since the temperature is one of the important factors for destructive nature of disease during storage and transportation, experiments were conducted to standardize optimum temperature for the growth of pathogen which revealed pathogen could grow at all the temperatures from 15 to 40C. Marked higher growth was recorded at 30C and considerable growth was at 25 and 35C. During the study of effect of temperature on soft rot disease after 4 and 6 days of storage at different temperatures it was concluded that 30-35C mostly favor the soft rot in cabbage and thus emphasis is to be given to prevent the disease during the prevailing temperatures in the region, in order to prevent losses due to the disease in cabbage and other hosts of the same pathogen.

Resistance of 'Geneva' Apple Rootstocks to Erwinia Amylovora When Grown as Potted Plants and Orchard Trees

Acta horticulturae, 2002

The objective of the USDA / Cornell apple rootstock breeding project is to develop pomologically excellent rootstocks with resistance to biotic and abiotic stresses. Progeny of controlled crosses were selected for fire blight resistance following direct inoculation of seedling shoots with Erwinia. amylovora. Recently 3 rootstocks, 'Geneva (G.) 11', 'G.30', and 'G.16' were released for commercial sales and several other selections are in the final stages of evaluation. To compare their resistance with that of other apple rootstocks, liners of 48 different rootstocks were grown in the greenhouse, inoculated with differentially virulent strain E4001a and other highly aggressive E. amylovora strains, and the percent of the current season's shoot length blighted (SLB) calculated. The rootstocks most susceptible to direct inoculation were 'Budagovsky (Bud.) 9' (88% SLB), 'Ottawa 3' (87%), 'M.9' (86%), 'M.26' (80%), and 'Supporter 4' (69%), while 'M.7' (28%), 'G.30' (22%), 'G.16' (18%), 'G.11' (7%), and 13 other Geneva selections (CG.) (8-30%) were the most resistant. To evaluate the resistance of the rootstocks under orchard conditions, 3yr-old Royal Gala trees on 18 Geneva rootstocks and 6 check rootstocks were sprayinoculated with strain E4001a twice during bloom in May 1999. All trees developed severe infections in the scion. Presence of ooze on rootstocks was first observed on 16 June 1999. Greatest incidence of tree death by 15 Oct 1999 occurred on 'M.26' (92% and 60% on two clones), and 'M.9' (83%). No trees on 'MM.111', 'Marubakaido', or 'Bud.9' died. Of the commercialized 'Geneva' rootstocks, 'G.16' and 'G.30' had no tree death, and 'G.11' had 25%. Nine other advanced rootstock selections from Geneva had no tree death. In 2000, a natural blossom blight epidemic occurred in a duplicate planting of the 'Geneva' rootstocks at another location. The resistance observed agreed closely with that previously observed in the inoculated block.

Studies on status and host range of soft rot disease of cabbage (Brassica oleracea var capitat) in Kashmir valley

Cabbage (Brassica oleracea var. capitata) is one of the most important vegetable crops grown in Kashmir throughout the year. The crop suffers considerably because of soft rot. Survey conducted during 2008-09 revealed that soft rot of cabbage is prevalent in all the vegetable markets of Kashmir Valley. The disease was considerably higher in two of the districts viz. Anantnag and Baramullah than Srinagar. The highest incidence was recorded in Anantnag. Upon isolation the causal pathogen responsible for soft rot in cabbage under temperate conditions of valley was identified as Erwinia carotovora sub-sp. carotovora. Studies on host range of the bacterium under artificial inoculation revealed that all the seven tested vegetable species, representative of the families, were susceptible to soft rot.

Screening Cabbage Cultivars for Resistance to Black Rot under Field Conditions

HortTechnology, 2020

The use of resistant cultivars against Xanthomonas campestris pv. campestris (Xcc) is considered a critical management practice for black rot (BR) management in cabbage (Brassica oleracea var. capitata). Although most studies that have evaluated resistance to BR were conducted in greenhouses without accounting for yield, there is a clear need to investigate cultivar performance under field conditions. The objectives of this study were to evaluate commercial cabbage cultivars for resistance to BR and determine yield and head quality under field conditions. Field experiments with eight cultivars (Acclaim, Bravo, Capture, Celebrate, Cheers, Melissa, Monterey, and TCA-549) were conducted in two cabbage growing seasons, Fall 2018 and Spring 2019. Fields were spray-inoculated with Xcc (3 × 105 cfu/mL) at 35 and 49 days after transplanting in Fall 2018 and Spring 2019, respectively. Cabbage BR severity was evaluated at weekly intervals starting from 7 days postinoculation (DPI) until harve...

Spread of Erwinia Amylovora in Apple and Pear Trees of Different Cultivars After Artificial Inoculation

Acta horticulturae, 2011

In the present study the correlation of visual fire blight symptoms and the migration of a virulent E. amylovora strain within the tissue of susceptible and tolerant apple and pear cultivars was investigated. Flowers and shoots of commercial apple cultivars were artificially inoculated. Three cultivars diverged in terms of symptom expression after flower and shoot inoculation, respectively: 'Fuji KIKU 8' ® and 'Topaz' ® developed severe symptoms on shoots but only a relatively low number of flowers were infected. Conversely, 'Golden Delicious Kl. B Laimburg' ® displayed severe necrosis on shoots but was the least susceptible of all the cultivars after flower inoculation. Apple and pear cultivars that have a regional importance for large trees in extensive orchard management were tested for their susceptibility to artificial shoot inoculation. In our experiments the susceptibility (i.e., expression of shoot necrosis) of investigated apple cultivars for commercial and traditional orchards was compared and ranged from 17 to 50%. A lesion length of more than 60% was observed for only one apple cultivar ('Brentewinar'). The opposite situation arose in the tested traditional pear cultivars where 61% showed 60% lesion length. In this study the visual symptoms did not correspond with the spatial distribution patterns and the quantities of E. amylovora within the plant tissue. In apple cultivars most bacteria remained near the site of inoculation. However, in two tested apple cultivars, and in all tested pear cultivars, the pathogen could be detected even in the rootstocks. Also in pear trees, large numbers of the pathogen could be detected in non-inoculated shoots and further downwards. Even the pear cultivar 'Harrow Sweet' and the apple cultivars 'Schmiedberger Renette', and 'Rewena', which had been considered less susceptible, showed an extended endophytic bacterial dissemination. These findings may have an impact on both the evaluation of new cultivars and on sanitary measures regarding fire blight control.

INFECTION OF ERWINIA AMYLOVORA ON DIFFERENT APPLE VARIETIES AND THE IMPACT ON FRUITS QUALITY

Fire Blight (FB) caused by Erwinia amylovora is the most feared bacterial disease in the genus Malus and other genera belonging to Rosaceae family, causing severe losses in orchards in favourable years, unmarketable fruits quality and even completely trees dieback, especially in highly susceptible genotypes. Currently E. amylovora is of quarantine concern in many countries all over the world and continue to conquer new territories. During 2018-year, six apple genotypes ('Golden Delicious', 'Idared', 'Gala', 'Jonagold', 'Fuji' and 'Jonathan'), within an orchard located in the proximity of Craiova city, Romania, have been assessed for their response to the infection to Erwinia amylovora and the impact of the pathogen attack on fruits yield and quality. The response of apple genotypes to the Fire Blight (FB) attack ranged from moderately resistant/susceptible ('Golden Delicious' and 'Fuji') to highly susceptible ('Idared', 'Gala', 'Jonagold' and 'Jonathan') depending on genetic background and environmental conditions. Fruits chemical parameters Total Soluble Solids (TSS), Total acidity (TA), Total Sugar (TS) were significantly affected by the pathogen attack in all apple varieties.

EFFECT OF SEED TREATMENTS ON MANAGING THE SEED BORNE INFECTION OF XANTHOMONAS CAMPESTRIS PV. CAMPESTRIS CAUSING BLACK ROT IN CABBAGE

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is the most serious disease of the crucifer crops worldwide, which is identified as a seed borne disease. Black rot is widely seen in the Central and Uva provinces where cabbage is cultivated. Under local climatic conditions it is unable to produce cabbage seeds. Therefore, Sri Lanka completely depends on imported cabbage seeds. The imported cabbage seeds are heavily infected with Xcc. In this study seed treatment methods were tested for Xcc growth inhibition. H2O2 (concentrations 15 percent, 10 percent, 5 percent), Cu2O (concentrations 10 percent, 5 percent, 1 percent), CuOCl (concentrations 10 percent, 5 percent, 1 percent) and Hot water treatment were used as seed treatments to estimate the Xcc inhibition. The data for Seedling Vigour Index, Germination Percentage and Disease Incidence (DI) were used with 4 replicates. The significant differences between the control and the treatments were verified based on ANOVA (analysis of Variance) and means were separated (Dunnett’s Test). According to the results all the treatments were able to inhibit the growth of Xcc (p = <.0001).When p < 0.05 the Disease Incidence is significantly reduced. 10 percent CuOCl (DI=1.2), 5 percent CuOCl (DI= 2.3), 10 percent Cu2O (DI=2.3) showed a high Xcc growth inhibition under in vitro conditions. In Xcc inoculated seeds DI = 70.5. The seed treatment with 10 percent Copper oxychloride showed the highest Xcc inhibtion (DI=1.2). In one replicate it showed 0 disease incidence. The average germination percentage and the seedling vigour index (SVI) of 10 percent CuOCl treated seeds were 87.5 and 4.10. The average germination percentage and the average SVI of the Xcc inoculated cabbage seed were 83 and 2.5 under in vitro conditions. These results should be further tested under in vivo conditions.

Effects of Petiole Calcium Status, Petiole Location, and Plant Age on the Incidence and Progression of Soft Rot in Chinese Cabbage

Journal of the American Society for Horticultural Science

Sand nutrient cultures (containing different Ca2+ compositions) were used to modify the petiole Ca2+ concentrations in Chinese cabbage (Brassica campestris Group pekinensis). Petiole sections (6.5 cm2) from inner and outer leaves, 30 and 60 days after transplanting, were inoculated with Erwinia carotovora ssp. carotovora to evaluate resistance to soft rot incidence and disease progression. Xylem exudates collected from the plants in the sand nutrient culture were analyzed for Ca2+ concentration. Elevated petiole Ca2+ concentrations were not correlated with the development of soft rot in inoculated petiole sections. Plant age and petiole position (inner and outer) did not consistently affect soft rot development. There was a trend of reduced soft rot in inoculated petiole (inner) sections of ‘Hakuran’ plants as the xylem exudate Ca2+ levels increased.

111 Successful in Vitro Micropropagation of Purported Blight-resistant Chestnuts (Castanea spp.)

Hortscience, 1999

The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, and Workshops). The Poster abstract numbers correspond to the Poster Board number at which the Poster will be presented. Three inoculation methods, including cutting of a leaf, drenching, and point inoculation, were compared in an effort to screen the susceptibility of Chinese cabbage to soft rot disease caused by Erwinia carotovora subsp. carotovora. Threeto 4-week-old seedlings from 10 lines of cabbage with 16-h-old bacterial culture were routinely used. Inoculated seedlings were kept at 25.0 ± 10.0 °C for 48 h with saturated water vapor using a plastic tunnel in a greenhouse. Sixty-day-old mature plants were produced and inoculated in a greenhouse. Severity of symptoms, which were observed from percentage of plant infected was scored as from