Eighteen strawberry genotypes were evaluated for their phenolic content and antioxidant capacity using several methods. High antioxidant capacity was found for `Harmonie', `Saint-Jean d'Orléans', and `Saint-Laurent d'Orléans', which were reported to have better shelf life than `Kent'. `Harmonie', `Saint-Jean d'Orléans', `Orléans', and some advanced selections had higher hydroxycinnamic acids, benzoic acids, and flavonols than `Kent'. The significant variation in antioxidant capacity and total phenolic compounds clearly shows the potential value of certain new cultivars and advanced lines as parents in a breeding program. The future plan is to examine individual antioxidant and their role in disease resistance and extension of shelf life and to use selected genotypes as parents to developed new lines.

Botrytis leaf blight (BLB) caused by Botrytis squamosa is a major leaf disease of onion. Various forecasting systems have been developed to help growers manage the disease. To improve forecasting reliability, the influence of temperature and wetness duration on B. squamosa infection was quantified by inoculating onion leaves with a conidial suspension and incubating them under various combinations of temperature (10-30°C) and leaf wetness duration (0-84 h). Infection was measured as the number of lesions per cm 2 of leaf and converted to the proportion of maximum infection (PMI). Regardless of leaf wetness duration, only a few lesions developed at 30°C and the number of lesions increased as the temperature rose from 10 to 20°C but decreased at 25°C. Between 10 and 25°C the number of lesions per cm 2 of leaf area increased gradually with increasing leaf wetness duration from 12 to 72 h. Relative infection was modelled as a function of both temperature and wetness duration using a modified version of the Weibull equation, which provided a precise description of the response of B. squamosa (R 2 = 0AE88). To facilitate field validation, receiving operating characteristic curve analysis was performed to determine the accuracy of various sets of criteria for establishing the length of an infection event based on field weather data. The total number of leaf wetness and RH >90% hours over a 72 h period was the best criterion, regardless of the wetness interruption pattern (sensitivity = 90AE91, specificity = 84AE62, area under the receiving operating curve = 0AE878). The model describing the relationship of PMI to temperature and leaf wetness duration, and field observations on airborne conidium concentration (ACC) were used to calculate the risk of infection (RI BLB ) as RI BLB = PMI · ACC. In 2009 and 2010, this risk index was compared to the observed rate of BLB progress (Rate BLB+5 days ) during the following 5 days. There was a linear relationship between RI BLB and Rate BLB+5 days indicating that this new risk indicator was reliable for predicting the risk of BLB development. These findings will help to improve the timing of fungicide applications for BLB management.

Khanizadeh, S., Ehsani-Moghaddam, B. and Levasseur, A. 2006. Antioxidant capacity in June-bearing and day-neutral strawberry. Can. J. Plant Sci. 86: 1387-1390. The present study was carried out to estimate the crude, hydrophilic and lipophilic antioxidant content of known and new advanced selections among June-bearing and day-neutral genotypes using Trolox equivalent antioxidant capacity method. Crude, hydrophilic and lipophilic extractions were prepared using 25 g of frozen fruits from each sample. In June-bearing strawberries, significant differences were observed among crude, hydrophilic and lipophilic antioxidant values of different selected genotypes. Mean of crude, hydrophilic and lipophilic antioxidants in June-bearings were estimated to be 20.4, 13.4 and 0.5 µmol TE g -1 FW, respectively, which were higher than those of the day-neutral genotypes (i.e., 13.2, 9.4 and 0.3 µmol TE g -1 FW). The present study revealed the importance of genetic background for determining the antioxidant potential in selected June-bearing genotypes and the possibility of production of new strawberry cultivars with higher levels of antioxidant capacity through breeding programs.

Anthracnose is an important disease of grapevines caused by the fungus Elsinoë ampelina. In recent years, there have been regular outbreaks in humid grape-growing regions around the world. Young leaves and berries are reported to be highly susceptible to E. ampelina, but detailed and seasonal development of age-related susceptibility remains unclear. Experiments were conducted under greenhouse and vineyard conditions by inoculating 1 to-19-day-old leaves, flowers and berries at different phenological stages of three grapevine cultivars (Vandal-Cliche, Marquette and Vidal). Leaf susceptibility was highest when inoculated at 1-2 days old, and inoculated leaves were moderately susceptible at 3-6 days old and almost resistant when older than 6 days. The influence of leaf age on anthracnose relative severity was adequately described by an exponential decay model. The susceptibility of the inflorescences was high when inoculated from their initiation to the full flowering (50% fall of the caps), and the inflorescences/flowers were moderately susceptible until veraison, after which the berries were practically resistant. The flower/berry susceptibility as a function of degree-days accumulated since April 1 was modeled using a sigmoid model. Based on this model, 50% disease incidence is reached when 656, 543 and 550 degree days are accumulated for the cultivars Vandal-Cliche, Marquette and Vidal, respectively. These results suggest that the risk of anthracnose development is high from bud-break to fruit set, and on newly-emerged leaves either early in the season or following pruning. More knowledge on anthracnose epidemiology is needed, but these results could be used to improve timing of fungicide applications and pruning activities.

No abstract

Two hundred and nine hybrid seedlings developed by crossing Nertchinsk × M.9, Osman × Heyer 12, and Nertchinsk × M.26 were evaluated since 1970 in Agriculture and Agri-Food Canada (AAFC), Horticultural Research and Development center (HRDC), Quebec. Canada. `McIntosh' was used as the scion. Seven of these rootstocks obtained from crossing `Nertchinsk' with M.9 and M.26 were found to be winter hardy, disease resistant, dwarfing, with good yield efficiency and easier to propagate than O.3 under North Eastern Central Canada climate. O3A, a mutation of O.3 (Ottawa 3) was also added to the advanced lines and evaluated along with seven rootstocks in replicated trials compared to M.26, M.9, M.111 and O.3 in four locations during 1995–2002. These seven rootstocks (SJM15, SJM44, SJM127, SJM150, SJM167, SJM188, SJM189, along with O3A are being released for commercial evaluation.

Additional index words. Malus •domestica, fruit breeding, winter hardy, antioxidant, long shelf life ÔSJCA38R6A74' (Malus •domestica Borkh.) is a new high-quality cultivar with improved firmness, crispness, and much longer shelf life than ÔMcIntosh' and ÔCortland'. The fruit has superior flavor and does not abscise at maturity. The flesh is juicy, firm, crisp, and resistant to bruising. Flesh resists browning, making it an excellent candidate for fresh fruit slices, fruit salad, dried apple chips, and processing (juice, cider). The trademark ÔEden' is used for sale, distribution, and marketing (www.inspection.

On susceptible varieties, indirect damage to vines infected by Elsinoë ampelina range from reduced vigor to complete defoliation while, on berries, damage ranges from reduced quality to complete yield loss. Limited knowledge about the relationship between weather conditions and infection makes anthracnose management difficult and favors routine application of fungicides. The influence of leaf wetness duration and temperature on infection of grape leaves by E. ampelina was studied under both controlled and vineyard conditions. For the controlled conditions experiments, the five youngest leaves of potted vines (Vidal) were inoculated with a conidia suspension and exposed to combinations of six leaf wetness durations (from 0 to 24 h) and six constant temperatures (from 5 to 30°C). A week after each preset infection period, the percent leaf area diseased (PLAD) was assessed. At 5°C, regardless of the leaf wetness duration, no disease developed. At 10 and at 15 to 30°C, the minimum leaf wetness durations were 4 and 6 h, respectively. Above the minimum wetness duration, at temperatures from 10 to 30°C, PLAD increased linearly, with increasing leaf wetness up to 12 h, and then at a lower rate from 12 to 24 h. The optimal temperature for infection was 25°C. Relative infection was modeled as a function of both temperature and wetness duration using a Richards model (R2 = 0.93). The predictive capacity of the model was evaluated with data collected in experimental vineyard plots exposed to natural wetness durations or artificial wetness durations created using sprinklers. In total, 264 vineyard infection events were used to validate the controlled experiments model. There was a linear relationship between the risk of infection estimated with the model and the observed severity of anthracnose (R2 = 90); however, the model underestimated disease severity. A risk chart was constructed using the model corrected for vineyard observations and three levels of risk, with light, moderate, and severe risks corresponding to ≤5, >5% to ≤25, and >25% leaf area diseased, respectively. Overall, 93.9% of 132 independent observations were correctly classified, with 100, 29.4, and 9.4% of the light, moderate, and severe risks, respectively.