October 2009

Begonia Sparkle Series By Ryan Hall

Tuberous begonias bred from Begonia boliviensis parentage are quickly becoming a mainstay crop for color growers. These cultivars are known for their vibrant pendulous flowers of orange, red and pink. New colors are being developed which include yellow and even white. Boliviensis-type begonias are tuberous in nature and perennial in frost-free climates. Specimens of the species Begonia boliviensis form huge tubers that send up thick succulent stems each spring that are covered with lancolate leaves and hundreds of electric orange flowers.

The Sparkle series from Pacific Plug & Liner have taken this new world novelty and transformed the genetics into a commercially viable line. The begonia Sparkle series is notably more compact than competing series and is naturally branching, requiring little to no pinching. This new series is ideal for small container production such as 4-inch and 1-gallon containers. The series is available in three colors: Scarlet, Salmon and Pink. Rooted liners are available for the 2010 season.

Scheduling

Begonia Sparkle can be finished from spring through fall. Four-inch pots require five to six weeks of grow time; 1-gallon containers require six to eight weeks of grow time; and hanging baskets planted with three plugs per pot will finish in six to eight weeks. Begonia Sparkle requires 14 hours of day length to ensure active growth and flowering. Schedule transplanting dates that correspond with these day-length requirements.

Culture

Sparkle begonias like a well-draining mix that is moisture retentive. Peat and peat-perlite based mixes work well for this crop. Tubers can be sensitive to rot and overdrying; avoid extreme wet or dry conditions. Liners should be watered in well after transplanting but not to the point of heavy saturation. Boliviensis-type begonias thrive in warm temperatures and high light. Sparkle should be grown at a minimum temperature of 60¡ F and receive a minimum of 14 hours day length. Early crops should receive supplemental lighting from HID lights to ensure quality growth.

Sparkle varieties are regular feeders and should receive a constant rate of 200-ppm nitrogen. Nitrate-based feeds will ensure compact, nicely toned plants. Avoid excessive salt buildup, as this can damage the plant. Sparkle begonias should be grown at a slightly acidic pH level of 5.8-6.0. Levels below 5.5 have been known to cause stress and leaf distortion.

Maintain light levels of at least 4,000 foot-candles. It is imperative to keep Boliviensis-type begonias actively growing; too low of light and/or temperatures will encourage dormancy and disease problems. Sparkle begonias are naturally branching and do not require mechanical pinching. If one does feel the need to pinch, do so early and pinch at the third node. Pinching above the fifth node will induce dormancy.

Growth Regulation

The Sparkle series of begonias is naturally compact and does not require growth regulation. If growth regulation is desired, trial low rates of B-Nine (daminozide) at 1,000-ppm spray and/or low rates of Cycocel (chlormequat chloride) at 250-ppm spray. Frequent low-rate sprays of Cycocel have proven to be more effective than fewer high-rate applications.

Pathogens

Boliviensis-type begonias are susceptible to Botrytis, Pythium and Thielaviopsis. Excellent air movement and ventilation are critical for quality growth and avoiding these pathogens. Excessive soil moisture can encourage rot. Preventive applications of fungicides are beneficial if growing conditions are not ideal. A proper growing environment and sanitary conditions are the best practices to ensure quality, problem-free growth. INSV can be a problematic virus on begonias. One should be vigilant in the control and monitoring of thrip populations. Symptoms of INSV are typically represented by necrotic black spotting and/or yellow-brown ring spots.