The Ohio State University Learning Gardens
2003 Osteospermum Cultivar Trials

By Monica Kmetz-Gonzˇlez and Dr. Claudio Pasian

PART II.  GARDEN TRIAL

Our Osteospermum Garden Trial was conducted in an in-ground bed located just north of our Departmental greenhouses. All cultivars from the Greenhouse Trial were outplanted to this Garden Trial. Additional entries for this outside trial only brought the total number of cultivars screened to 23.

See pictures of each cultivar in Table 1 below.

Cultural Schedule:
Bed Preparation: In April, Surflan was applied to the trial area for weed control. The area was slightly amended and tilled in late May.

Planting: Plants previously in the Greenhouse Trial (4.5 inch pot size) were transplanted in-ground on May 27. 4 plants per cultivar were planted on 2 foot centers. New arrivals for the Garden Trial only were transplanted on June 12. These plants were received in 2 1/4 inch to 3 inch pot sizes. 6 - 8 plants per cultivar were transplanted on 1.5 foot centers. Rootshield granular was applied post-planting on June 12.

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 at 2 week intervals on July 3, July 17, and July 31.

Weather Conditions. A cool, wet May delayed initial planting by 10 days. Weather conditions throughout most of the trial period were cooler than normal with above average rainfall (based on central Ohio conditions).

Pest and Disease Problems. There were no pest problems of note. There appeared to be some initial Pythium problems on a few plants post-transplanting. Phytophthora and Rhizoctonia were diagnosed on a few cultivars on July 22. All plants received a drench of Cleary's 3336 and Subdue on July 24. Weather conditions contributed to higher disease pressure this summer in all of our in-ground trials.

Evaluations:
Dates. No June evaluation was performed this year, due to the later than usual transplant dates, and the slow growth rate of the plants initially because of the cool, wet conditions. Monthly evaluations beginning on July 14 were performed by the Trials Coordinator.

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
  • Vigor: 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 Mortality. The percentage of plants lost due to disease problems.

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

      RESULTS:

      Evaluation results are presented in (Table 1) . The table is ranked in descending order of the July OVERALL rating.

      BEST of Trial:
      July (Mid-Summer):
      'Experimental 201089', 'Symphony Orange', 'Experimental V77-9B-3C', 'Symphony Cream', 'Symphony Lemon', 'Symphony Vanilla', 'Margarita Maria', 'Margarita Carmen'.

      August (Late Summer):
      'Symphony Orange', 'Symphony Lemon', 'Symphony Peach', 'Symphony Vanilla', 'Margarita Carmen', 'Experimental 201089', 'Experimental M2-139 (Orange)', 'Soprano White', 'Soprano Purple'.

      September (Early Fall):
      'Margarita Carmen', 'Experimental 201089', 'Margarita Maria', 'Symphony Lemon'.

      October (Late Fall):
      'Experimental 201089', 'Margarita Maria', 'Margarita Carmen', 'Symphony Orange', 'Symphony Lemon', 'Soprano White', 'Symphony Cream'.

      Trial Coordinator Comments:

      • The best all season performers, both as I observed and as the data concluded, were 'Margarita Maria' and 'Margarita Carmen', 'Symphony Lemon' and 'Symphony Orange' ('Symphony Cream' and 'Symphony Vanilla' followed closely), and 'Experimental 201089'.
      • The top finisher in the Greenhouse Trial, 'Experimental V77-9B-3C', suffered high mortality in the Garden Trial due to Phytophthora and Rhizoctonia disease problems. This may be due to location or genetics or both. At the time of the September flower rating, the one remaining plant of this cultivar was flowering profusely.
      • A side note, as of this date, (late November), many plants were still blooming in the Garden after multiple frosts.

      We look forward to our 2004 Garden Trial which will be conducted in a raised bed trial location adjacent to our in-ground trial area.

      Acknowledgments: Appreciation goes to David Snodgrass, our Greenhouse Coordinator, for his assistance. A big thanks to our Annuals team of Master Gardeners - Joyce Gravlee, Ken Kotch, Kathy Krantz, Sue Nelson, Mary Straney, Juliet Taylor, and Bev Vogeley, who helped in all phases of the trial. We also thank Dr. Steve Nameth (Ohio State Department of Plant Pathology) for disease diagnosis and recommendations.And we thank the following companies for their participation in this year's Greenhouse Trial:

      ECKE = http://www.ecke.com
      ECKE/SAKATA
      FIDES North America = http://www.fidesnorthamerica.com
      PROVEN WINNERS = http://www.provenwinners.com