Horticulture 429 Floriculture Crop Production Dr. Terri Starman Cut Roses

Introduction Rosa L. hybrids 100 genera 2000 species Rosa genera are woody Production has shifted to areas near the equator High light and cool temperatures

Rose Morphology Woody Thorns Upright, trailing, or climbing 5 petals Fruit is called a hip Flowers are white, pink, yellow, orange or red and blends Powdery mildew, blackspot and Botrytis

Rose Propagation Seed for breeding Bud grafting for cut flowers R. X noisettiana is used for rootstock Stenting is a form of grafting that is replacing bud grafting

Stenting Seedlings rootstocks of R. chinensis Single leaf bud scion is placed into a downward cut Held with a small clothspin Union occurs within 3 weeks Under fog, mist or in high humidity 75 0 F (24 0 C)

Flowering Control and Dormancy Day neutral Flowering is recurrent, year-round Flower initiation is not dependent on environment Floral differentiation occurs shortly after axillary buds are released from apical dominance Transition from vegetative to reproductive occurs in 4 to 21 days, when axillary shoots are 1.25 to 1.50 inches long

Flowering, cont. Axillary buds from the upper nodes form flower buds sooner and with fewer leaves than lower nodes The speed and quality of a subsequent cut flower crop are dependent on the nodes remaining after the flower is harvested Irradiance, temperature and available CO 2 influence growth and development of roses in greenhouses

Temperature Development increases as temperature increases including the rate of axillary bud break, shoot development, leaf unfolding, & flowering Excessively high or low temperatures increase number of blind shoots F night, F cloudy day, 75 0 F sunny day

Light and Water Light is very important and supplemental light is used in northern latitudes 8 to 24 hours/day 300 – 1000 fc Good quality water Perimeter bench watering Constant flow tray systems grown in rock wool blocks or coir dust, water is recirculated

Nutrition 1500 ppm CO 2 Routine media and tissue testing are necessary Organics used in traditional beds Liquid application ppm N Nitrate: Ammonium is 5:1 in summer and 10:1 in winter

Media, Spacing and Support Soil, amended and mulched pH 5.5 to 6.0 Newer production systems are hydroponic 1 to 1.4 ft 2 / plant Three rows across a bed Three layers of wire with openings 6 X 6 inch or 6 X 8 inch

Pinching and Pruning 1.To remove broken roots or shoots and reduce cane height at planting. Prior to planting, broken roots and shoots are removed and cane height reduced leaving 3-4 dormant axillary buds. 2.Once planted and new shoots begin to elongate, flower buds are removed at either one of two stages of growth. If a soft pinch then 2X. a.Soft pinch- flower buds smaller than a pea b.Hard pinch- flower buds larger than a pea

3.To harvest flowers – leave 1, 2, or 3 nodes or cut below the “knuckle” i.e. junction of axillary shoot and stem from which it is growing. Below the knuckle is used if height reduction is desired. Above the knuckle is used to control the rate and number of return shoots. Leaving less nodes = slower growth, longer stems, and more leaves. Pinching and Pruning

4.Five to 8 weeks prior to a major holiday, depending on cv., to ensure a large number of flowers available for a holiday, sacrifice flowering shoots by pinching to produce more flowers at the same time. 5.After Mother’s Day into late June plants are severely cut back to a height of 2-3 feet to rejuvenate old plants. Pinching and Pruning

Scheduling and Timing Traditional method –peak production for major holiday –dependent on temperature, light & last pinch and position of last cut –6-8 weeks Bending or Arching method

A visit to Rose Gene Technology Watsonville, CA Formed in 1998 to focus on breeding and production of roses for cut flowers. They produce mini plants and one-year old plants

Bending or Arching Production continues uninterrupted Higher quality due to light penetration Longer stems are produced Increase stem thickness Uniformity of stem length Easier to harvest Eliminates support wires Harder to control spider mites

Insects and Diseases and Physiological Disorders Spider mites, thrips, aphids, whiteflies, caterpillars, shore flies, and fungus gnats Biological control of thrips and mites is possible Mildew (Sphaerotheca) and Botrytis Environmental control of diseases Bullhead flowers i.e. flowers are not tapered at the apex caused by too low temp. or thrips and cultivar susceptibility

Diseases Water condensation occurs when temperatures fall below the dew point. Guttation of water along the edges of leaves also occurs. Drying must occur to prevent disease establishment. Increase the temperature 1.5 to 3 0 F when the relative humidity reaches 85-87% and open the vents slightly. This will help control mildew and Botrytis.