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  • Author or Editor: Miguel Vilchez x
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Powdery mildew caused by Erysiphe aquilegiae var. ranunculi is one of the major diseases affecting field-grown delphiniums (Delphinium spp.). Two lath house and two field experiments were conducted in 2003 and 2004 to evaluate nine delphinium cultivars for resistance to the disease. ‘Blue Bird’, ‘King Arthur’, ‘Cameliard’, and ‘Galahad’ were consistently more resistant [0–1.1 disease severity (ds) on a 0–5 scale] than ‘Casa Blanca’, ‘Blue Shadow’, ‘Belladona’, and ‘Bellamosum’ (2.9–5.0 ds). ‘Oriental Blue’ was moderately resistant (0–3.3 ds). Spearman's coefficients of rank correlation were significant for all pairs of experiments (0.70 ≤ rs ≤ 0.98; P ≤ 0.0354) except for the 2003–04 field experiments (rs = 0.66; P = 0.0525). Pearson correlation coefficients between experiments (0.86 ≤ r ≤ 0.99) were highly significant (P ≤ 0.0027). Disease severity values from lath house evaluations were almost identical to those from field evaluations.

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California has an extensive strawberry (Fragaria ×ananassa L.) industry that has built its reputation on the production of large volumes of fruit that are evenly and fully developed. While some fruit deformity occurs every year, in various counties during the 1997-2000 seasons there were higher than usual numbers of uneven or “catfaced” strawberry fruit. It was thought that the presence of the fungus Cladosporium cladosporioides (Fresen.) G.A. De Vries on flower anthers may have interfered with pollination and increased cull rates. We collected and incubated flower anthers to determine the fungal populations on such tissue and found that C. cladosporioides accounted for the majority of the culturable fungal colonies present. However, while 100% of a flower's anthers were colonized with C. cladosporioides after spray inoculations, the incidence and severity of malformed fruit were not significantly different from untreated flowers. Physically removing all anthers shortly after anthesis likewise did not result in significant differences in fruit quality when compared to untreated control flowers. We conclude that C. cladosporioides colonization of flower anthers has a minimal impact on fruit quality under most field conditions.

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