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  • Author or Editor: Kevin Vander Kooi x
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Cavity spot of carrot, caused by several species of Pythium, is endemic in many carrot production areas of the world, including the Holland/Bradford Marsh region of Ontario, Canada. Field trials were conducted from 2002–04 to determine if carrots with different pigments varied in susceptibility to the disease. Carrots from the USDA breeding program at the University of Wisconsin were seeded in muck soil (pH 6.4, 60% organic matter) on 28, 30, and 27 May, harvested 22, 22, and 23 Oct., and assessed for disease on 5, 8, and 10 Dec. 2002, 2003, and 2004, respectively. The carrots were white (W 105-7), yellow (W 102-1), dark orange (W 101-23), red (W 104-3), and purple (W 106-3). Cultivar `Cellobunch' was included in 2003 and 2004. Twenty-five carrots of each of four replicate plots were assessed in 2002 and 2003, and 50 carrots were assessed in 2004, for disease incidence and severity [disease severity index (DSI), based on the size of the largest lesion per carrot]. Disease incidence was moderate in 2002 and 2003 (34%, 33%), and high in 2004 (60%). Consistent differences in susceptibility to cavity spot were identified over the three years of trials. The purple carrot had the lowest incidence (12%) and severity (7 DSI) of cavity spot, followed by the dark orange carrot (39%, 22 DSI) as compared to the susceptible yellow carrot (58%, 41 DSI). There was no difference in disease reaction between the yellow and white carrots. `Cellobunch' had the same reaction as the dark orange carrot. Studies are needed to determine whether the pigments themselves cause differences in the disease response.

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Globe artichoke (Cynara scolymus L.) is a high value cool season crop which requires vernalization to induce flower formation. The climate in Ontario does not allow for survival of perennial cultivars or for consistent natural vernalization of annuals. Three methods of vernalization were tested: a controlled environment chamber, a lighted cold storage, or GA3 application in the field. Plants, cv. Green Globe Improved, were grown in a greenhouse set at 25 °C day temperature in 72-cell Styro-foam trays in a peat mix. At 4 weeks, plants receiving vernalization were transferred to growth chambers, or lighted coolers (four standard 8 foot cool white fluorescent lamps) at 10 °C for two weeks. The others stayed in the greenhouse. GA3 treatments (PROGIB, 15 g ai/ha) were applied at 2, 4 and 6 weeks after transplanting. Cultivars Green Globe Improved, Imperial Star, Emerald, and Large Green Globe were evaluated in separate trials. Trials were conducted at Simcoe, on coarse sand in a high heat area, and Kettleby, on organic soils in a cooler area of Ontario. Shortly after planting at Simcoe several 30 °C days occurred which devernalized and injured the crop. Artichokes grew well at the Kettleby site. Vernalization in the growth chamber was most effective and resulted in the earliest bud formation and highest total yield (1503 cases/ha). Large Green Globe was not well adapted to Ontario conditions. Imperial Star and Emerald produced the highest yields, 2180 and 1779 cases/ha, respectively. Globe artichokes can be grown successfully as an annual crop in cool production areas of Ontario.

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Chives, (Allium schoenoprasum) consumption and production are increasing in Ontario. Rust (Puccinia allii F. Rudolphi) has been a problem with some chive cultivars for some growers, and in Ontario, basic information on production is nonexistent. The objectives were to identify cultivars with high yields, disease resistance and winter survivability. Plantings of six cultivars of chives were established in 2002 and 2003 in two contrasting environments, on organic (Kettleby) and mineral (Simcoe) soils; and one cultivar of garlic chives (A. tuberosum) at Kettleby. Leaves were harvested to a length of 30 cm, weighed and assessed for visible signs of rust. In Spring 2003, the number of dead plants was recorded to determine the overwinter survivability of each cultivar. Performance varied among cultivars and between locations. In Simcoe, Staro produced the highest yield in 2002 while generic (unnamed) chives produced the highest yield in the second year. In Kettleby, yield was similar among cultivars in 2002 but in 2003 generic chives produced the highest yield. Overwinter survival also varied between locations and second season yields were much higher in Kettleby. Less snow cover and subsequent winter injury is a possible explanation for the lower yields and poorer winter survival in Simcoe. No symptoms of rust were found in either location. Chives are a viable crop in Ontario, and appear to have different adaptability to regional soils and climates.

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