Osteospermum Cultivar Trial 2004
In 2004, we conducted osteosper-mum/African daisy trials in our departmental greenhouses on the Columbus campus for the seventh consecutive year. We evaluated 26 entries from four source companies in the trial period from January through early May. Rooted cuttings were received from participating companies between January 2 and 16.
During the week of January 8-16, we rooted cuttings of 20 plants per cultivar, with the exception of two experimentals from Proven Á Winners. Liners were then transplanted into 41?2-inch pots. Our potting media was MetroMix 360, and the greenhouse temperature remained at 72° F day/night. On February 12, we pinched plants to 5-6 nodes. Cold vernalization initiated on February 26 with day/night temperatures of 46° F. On April 8, cold temperatures ended, and warm temperatures of 65° F days and 55° F nights were maintained through the end of the trial. On April 19 cultivars with no vernalization requirement (or minimal vernalization needs) were at peak flower. During the weeks of April 27 through May 2, a majority of cultivars were at peak flower (vernalization-requiring cultivars).
For fertilization, we used Greencare 17-5-17 at 200 ppm nitrogen, three times per week. Two disease problems arose during the trial. Pythium root rot was detected on some plants in late January. Plants were then drenched with Plant Shield (BioWorks) at the maximum rate on January 28 as a preventative measure for further problems. In mid-April, Botrytis was detected, and treatment with Heritage (Syngenta) took place on April 23. For this cultivar evaluation, no growth regulators were used. This provided a good indicator of the natural growth habit of each cultivar.
Four evaluations, using specific criteria, were made to judge the performance of each plant. The first was plant height to top of flowers (see Figure 3, left), which was measured on May 3.
During the second evaluation, the main cultivar evaluation (see Figure 1, page 66) was performed by the trials leader and trials coordinator. This evaluation was taken on April 29, when the majority of cultivars were at peak flowering.
Evaluation criteria ratings were based on a scale of 1-5: 1 = poor/not acceptable, 2 = fair, 3 = good, 4 = very good and 5 = excellent. Plants were evaluated for the following characteristics: