The Ohio State University Learning Gardens
2004 Osteospermum Cultivar Trials


PART II
GARDEN TRIAL
Columbus Campus

By Monica Kmetz-González and Dr. Claudio Pasian
Department of Horticulture and Crop Science

This season, our Osteospermum Garden Trial was conducted in raised beds located just north of our Departmental greenhouses. Cultivars were evaluated first in our Greenhouse Trial (results posted at http://floriculture.osu.edu) from January through mid-May and then were outplanted to the Garden Trial. A total of 24 entries were screened outdoors from May 13 until early December, when the plants were pulled.

Take a look at our Trial Area: PHOTO 1    PHOTO 2   PHOTO 3   PHOTO 4   PHOTO 5

Cultural Schedule:

Bed Preparation: The raised beds were hand-tilled during the 1st week in May.

Planting. The plants were previously evaluated in in our Greenhouse Trial (4.5 inch pot size) and were then ransplanted to the raised beds on May 13. Five to six plants per cultivar were planted on 2 foot centers. A Plantshield drench was applied to the plants one day prior to transplanting.

Watering and Fertilization. Water was provided as needed by an overhead sprinkler system. Fertilization with Peters 20-10-20 at 200ppm N via Dosatron occurred post planting and at weekly intervals until mid-July. Plants were then fertilized every 2 weeks for one month until mid-August.

Weather Conditions. On average, it was a cooler summer throughout June, July and August, with below average temperatures and average to above average precipitation. The Autumn months of September, October, and November saw above normal temperatures, with below average rainfall for September, and above average rainfall for October and November. The first hard frost occurred in mid-November, and the season's first measurable snowfall occurred on November 25.

Pest and Disease Problems. There were no pest problems of note. Wilting of some plants was noted in early September and disease screens were performed. The main causal disease was Rhizoctonia. A few Fusariums were present also. More than likely, the weather conditions contributed to high disease pressure this summer. The trial was deliberately moved to raised beds this year out of an in-ground trial area in an attempt to reduce the likelihood of rampant disease.

Evaluations:

Explanation and Dates. There was minimal flowering activity except for a few entries in June and July. During those months, only qualitative data was taken. Of note here, the "Symphony" Series flowered consistently throughout this early to mid-summer period. The "Soprano" series had consistent but lower flower numbers during this same period. All other entries exhibited minimal flowering. Quantitative evaluations were performed on August 5 by the Trials Coordinator and on September 13 by the Trials Leader and Trials Coordinator. Overall ratings only were performed by the Trials Coordinator on November 7 and December 1.

Rating Scale. Ratings were based on a 1 - 5 scale: 1 = poor/not acceptable, 2 = fair, 3 = good, 4 = very good, 5 = excellent.

Rating Criteria. Plants were evaluated for the following characteristics:

  • Flower Number: 1 = Low, 5 = very floriferous (a "0" was recorded if no flowers were present)
  • Flower Quality: Aesthetics, color, health and appearance
  • Vegetative Vigor and Habit: Vegetative plant vigor, aesthetics/color, health, and appearance.
  • Overall: Overall rating for all plants in the grouping, taking all the above aspects into consideration.
  • Percent Plants Disease-Free. The percentage of plants that appeared to be free of Rhizoctonia and Fusarium diseases. (September rating only)
  • Percent Survival. The percentage of plants which survived during the trial period. (September rating only)

Not all criteria were evaluated each month. Criteria deemed most important for the specific time period were included.

RESULTS:

TABLE 1: August Rating.
TABLE 2: September Rating.
TABLE 3: November and December Ratings.

BEST of Trial:
June (Early Summer) through July (Mid-Summer):
 "Symphony" Series (Cream, Lemon, Orange, Peach, and Vanilla) all flowered well consistently. The "Soprano" Series (Light Purple, Purple, and White) had consistent flowering but lower flower numbers.

August (Mid-Late Summer):
"Soprano White", "Kalanga", "Cape Daisy Malindi", "Experimental 201089", "Soprano Light Purple", "Experimental V77-9B-3C", "Nairobi Improved", "Side Series Seaside", and "Margarita Rosita".

September (Early Fall):
note: Ratings were lower due to the onset of disease problems. "Margarita Carmen", "Soprano White", "Cape Daisy Malindi", "Margarita Rosita", "Cape Daisy Nasinga Cream".

November (Late Fall):
"Soprano White", "Cape Daisy Malindi", "Symphony Lemon", "Kalanga", "Margarita Carmen".

December (End of Trial Period): "Soprano White", "Symphony Lemon", "Kalanga", "Cape Daisy Malindi", "Experimental V77-9B-3C".

BEST DISEASE TOLERANT ENTRIES:
The following entries displayed no disease symptoms or mortality from the Rhizoctonia and Fusarium outbreak the trial area suffered in early September: "Margarita Carmen", "Soprano White", "Cape Daisy Malindi", "Bamba", "Kalanga", "Symphony Orange", and "Side Series Riverside".

Trial Coordinator Comments:
***The best all season performers were "Soprano White", "Margarita Carmen", "Cape Daisy Malindi", and "Kalanga".****

Acknowledgments:
Appreciation goes to David Snodgrass, our Greenhouse Coordinator, for his assistance. A huge thanks to our dedicated Annuals team of Master Gardeners - Caye Aiello, Joyce Gravlee, Ken Kotch, Kathy Krantz, Mary Straney, Juliet Taylor, and Bev Vogeley, who helped in all phases of the trial. We also thank Katherine Whitten and Dr. Lanny Rhodes (Ohio State Department of Plant Pathology) for disease diagnosis and recommendations.

And we thank the following companies for their participation in this year's Garden Trial: