Potato common scab (Streptomyces scabies (Thaxt.) Waksman & Henrici) is a major disease of potato (Solanum tuberosum L.), due to the unmarketability of affected tubers. For identification of the most common scab-tolerant material, and for developing molecular markers for common scab tolerance, more information is needed on the genetic basis of common scab tolerance. Phenotyping common scab susceptibility is difficult because of the large variability in disease symptoms among tubers from a single plant, ranging from no common scab to severe pits. Two years of field data were collected for scab reaction on a segregating tetraploid population (MSL603, 160 individuals). Continuous variation in common scab susceptibility phenotype was observed among the progeny, with a normal distribution suggesting common scab disease phenotype is a genetically complex trait. Transgressive segregants were also observed, but they are skewed toward susceptibility. A greenhouse-based screening procedure was evaluated to discern tolerant from susceptible potato lines. A subset of ten individuals from this population were selected (five resistant, five susceptible). For the greenhouse study, soil was inoculated with a pathogenic S. scabies strain MSDPZ at a concentration of 3 X 10 8 CFU/ml. This greenhouse assay effectively discerned tolerant and susceptible individuals. There was a moderate correlation between the greenhouse study and the field trial. The greenhouse assay may provide information that would complement field data in identifying resistant clones.Resumen La sarna común (Streptomyces scabies (Thaxt.) Waksman & Henrici) en una enfermedad muy importante de la papa (Solanum tuberosum L.) debido a que los tubérculos afectados no son comerciables. Para la identificación del material más tolerante a la sarna común y para desarrollar marcadores moleculares para tolerancia a la enfermedad se necesita más información sobre la base genética de la tolerancia. La fenotipificación de la susceptibilidad a la sarna común es difícil por la gran variabilidad en los síntomas de la enfermedad entre los tubérculos de una misma planta, que varían desde la ausencia de sarna a presencia de hoyos profundos en los tubérculos. Se colectaron datos durante dos años sobre la reacción a la sarna en una población tetraploide (MSL603, 160 individuos). La variación continua del fenotipo susceptible a la sarna común fue observada entre la progenie, con una distribución normal que sugiere que el fenotipo de la enfermedad es una característica genéticamente compleja. También se observó variación transgresiva, pero sesgada hacia la susceptibilidad. Un procedimiento de tamizado en invernadero fue evaluado para diferenciar las líneas de papa tolerantes de las susceptibles. Un subgrupo de 10 individuos de la población fue seleccionado (cinco resistentes, cinco susceptibles). Para el estudio de invernadero, el suelo fue inoculado con una cepa patogénica MSDPZ de S. scabies a una concentración de 3 x 10 8 UFC/ml. Este ensayo de invernadero distinguió efectivamente in...

The rutabaga, also known as the swede turnip, is grown on ≈2000 ha in Canada. During the spring of 2006, a grower in Prince Edward Island noticed an advanced level of decay in his stored rutabagas (cv. Thompson Laurentian). About 80% of the stored crop was affected. Lesions on the surface of affected roots were circular to ovate and ranged in size from 10 to 50 mm. The lesions were light brown, with dark borders and some concentric zones evident near the perimeter of the affected tissue. Root tissue within the lesions was shrunken and often wrinkled. Sectioning the root through the lesion revealed an internal advancing dry rot, with an irregular border and cavities that contained white mycelium. Isolation from diseased tissues yielded fungal cultures, which were determined to be Fusarium avenaceum using morphological and molecular criteria. Successful completion of Koch's postulates determined that F. avenaceum was indeed the causal agent of rutabaga dry rot. To the authors’ knowledge, this is the first report of F. avenaceum causing disease in rutabaga in Prince Edward Island, and likely only the second observation of its occurrence in North America. Dry rot, incited by F. avenaceum, may need to be considered as part of the spectrum of postharvest pathogens of rutabaga.

Onion thrips (Thrips tabaci Lindeman (Thysanoptera: Thripidae)) can be a pest in organic onion production on Prince Edward Island. This study was to examine the effect of planting time and variety on infestation levels and damage by onion thrips on cabbage (Brassicae oleraceacapitala (L.)). A field site was planted with 2 main and 8 lesser varieties of cabbage over 4 planting dates. Some varieties were short season and harvested on July 31 with longer season varieties harvested on September 2. Blue sticky traps were used to capture thrips migrating into the field site from July 22–September 2. Traps were counted weekly and cabbage heads within the field site were visually surveyed for thrips. At harvest, heads were weighed and measured, thrips damage was assessed then the head was dissected and thrips counted on the first four layers of the head. Thrips exhibited a preference for Lennox over Bronco throughout the season although thrips populations were not high enough to effect economic damage in 2014. Planting date influenced cabbage head weight and size with later plantings yielding the largest heads. Use of planting date and variety to avoid thrips populations is discussed.