Crop Culture Report
The ColorMax viola series complements and completes a long-standing tradition of excellent viola breeding programs from Sakata.
True to form, the ColorMax varieties exhibit many of the most outstanding attributes a viola series needs in order to compete in today’s markets. Extra-large and vibrant blooms, unique in their shape and design, sitting atop short peduncles are what top growers, retailers and gardeners are craving. ColorMax comes in ten colors and a mix including a golden yellow that sets the bar for the most popular viola color for the landscape. The series is comprised of Clear Orange, Clear Yellow, Clear Purple, Berry Pie, Icy Blue, Lemon Splash, Popcorn, Purple Glow, Yellow Jump Up and a Mix. Several of these varieties, like Berry Pie and Icy Blue, exude such distinctive and novel colors – they will cause gardeners to stop to gaze at the entire retail display!
ColorMax seed can be sown in 512 and/or 288 plug trasy for pack or pot production, as well as multi-seeded into larger plug sizes (200’s, 144’s and up) for bigger containers, hanging baskets, and mixed decorative pots. A few key points to watch for in viola plug production are:
- Ensure the media pH is between 5.5 – 5.9
- Soil EC is <.75 (using a 2:1 slurry)
- At germination, soil temperature 64 – 68°F /18 – 20°C with a light vermiculite covering
- Avoid tip abortion due to Boron deficiency by supplementing with .25 ppm B in the fertilizer applications.
- If plug trays are placed in a germ chamber, pull trays and place in the greenhouse when the radicle emerges and begins to ‘hook.’ This will avoid hypocotyl stretch and prevent ‘floppy’ seedlings.
After germination and the cotyledons have expanded, lightly fertilize with 75 ppm N from a well-balanced fertilizer blend. Boron deficiency can occur, especially during the summer months, resulting in tip abortion. To avoid this, supplement with Solubor or Borax with a target of boron at 0.25 ppm added to the stock tank. Maintaining temperatures in the low to mid 60’s with good air-flow will greatly assist in keeping plugs compact and well-toned. After the initial feed, begin fertilizing with 100 – 200 ppm N from a well-balanced fertilizer containing trace elements. A calcium nitrate-based blend such as 15-3-20, works very well to build strong, compact plants.
Reduce fertilizer applications as the plants begin to bulk up and fill out the trays. When applying fresh water (no fertilizer), continue to supplement with trace elements, especially boron. Always monitor the soil pH and maintain levels between 5.5 and 5.9. Ideally, viola trays should be given higher light levels to control stretch. Reduce temperatures into the low 60’s and continue to provide good air movement to assist in establishing well-toned plugs. Maintain light levels up to 7,000 foot candles/75,000 lux, while watching for heat and water stress. Plant Growth Regulators (PGR’s) that can be utilized to control stretch include B-Nine (daminozide), Cycocel (chloromequat) and A-Rest (ancymidol). Always follow label directions, and to avoid over-exposure, a trial application over a small lot is recommended to look for any adverse reactions. To determine if PGR applications should be done, watch the internodes on a daily basis. If there is the slightest hint of internodal stretch, apply a PGR spray.
Transplant to finish:
ColorMax plugs should be transplanted into a well-aerated media mix with a pH of 5.5 – 5.9. Ensure the plugs are not set too deep to prevent stem rot, and non-uniform plants and blooming at finish. The ideal day temperatures should be in the 62 – 68°F (17 – 20°C) range, with night temps at 50 – 55°F (10 – 13°C). Fertilize with 100 – 200 ppm N from a well-balanced fertilizer to ensure a healthy start. After transplanting, violas are still sensitive to boron deficiency, so continue adding boron into the stock tanks. While providing all the ideal environmental inputs of temperature, light, moisture management levels and fertilizer, PGR applications may still be necessary in any geographical location. B-Nine (daminozide), Cycocel (chloromequat), A-Rest (ancymidol), and Bonzi (paclobutrazol) may be used on viola crops. Extra care should always be taken not to over-dose the crop, as stunting of the plants can and will occur if over-exposed with excessive rates. Always follow label directions.
The most common pests that can be seen on viola crops include fungus gnats, shore fly, thrips, spider mites, and whitefly.
Major root diseases include Pythium, Phytophthora, and Thielaviopsis. Thielaviopsis or Black Root Rot is often associated with high temperatures, high pH levels. Research indicates the disease is checked when the soil pH is 5.5 or lower. High ammonium levels should be avoided, as this can encourage the onset and spread of Thielaviopsis. Good sanitation practices and attention to proper moisture management levels works very well in preventing most incidences of diseases.