March 2011 Culture

Crop Culture Report: Calibrachoa Superbells Punch Series By Rick Schoellhorn

Known for their distinctive dark eye, these new additions to the Superbells line will make a statement in any garden application.

Calibrachoa is a group of plants that has really grown into an industry standard over the last ten years. Originally from Latin America, they were discovered in the same general area of the continent where petunia originated. In the early years after they began to show up on the market, they were called petunias (there are some that still hang on the taxonomic edge) and then later split off into their own genus, which has about 18 species. The most commonly used for breeding is C. parviflora, but we see different leaf types and branching habits as our industry's plant breeders experiment with additional genetics. A lot of today's breeding involves simply crossing market varieties and making selections, therefore we see hybrids of hybrids — some virtually impossible to tell apart unless one is an expert.

Beginning in 2007, Proven Winners began adding the Punch types to the Superbells series. This group of calibrachoa relies on the same basic genetics as the existing line, but goes back to some species from Latin America to give earlier flowering, better disease resistance and the distinctive dark eye that is really the main feature that differentiates the Punch varieties from the general Superbells series. Going back to native species for developing a new series, there are some slight differences in the early hybrids. For those growers interested in carrying something different than the run-of-mill calibrachoa, here are some primers on how to succeed best with the Superbells Punch series.

Currently there are three colors in the group: Apricot Punch, Blackberry Punch and Coralberry Punch. These can be roughly grouped into three main production categories, based on their production needs: 'Superbells Coralberry Punch' — same as the Superbells series in production; there are no real adjustments to make with these; well-branched and compact flowering size.

'Superbells Apricot Punch' — come from extremely early flowering crosses; this causes some issues for certain growers since they act as though they were day neutral and come into flower very early, and the plants begin flowering before sizing up. This can lead to overwatering and over-fertilizing if grown and cared for the same as most varieties in this series.

'Superbells Blackberry Punch' — breakthrough breeding and color, but a bit different than the rest of the line. A more upright habit and a thinner leaf means growers may want to look at a second pinch to keep the plants tight. Habit is somewhat similar to 'Superbells Blue'. It can be more open and airy earlier in the season. Make sure to give the crop plenty of light and cool temperatures once established. To avoid the second pinch, growers may want to do a drench with uniconazole 1 to 3 ppm drench or if a drench is not an option, try a low-volume spray at 20 40 ppm light spray of either paclobutrazol or 5 to 10 ppm uniconazole, or possibly 15 to 20 ppm spray of flurprimidol. 'Superbells Blackberry Punch', especially early in the season, will not color up like the rest of the Superbells series and flowers are never as solid of a canopy over the leaves, however, it rarely takes more than a few flowers to sell the plant since the color combination is extremely unique.

Basic Growing Tips:

Sanitation: Drench with a broad-spectrum fungicide shortly after planting; this is always a good idea regardless of the crop. Truban 30 WP and a mixture of Cleary's 3336F or Banol and Medallion are sufficient. Always use sterile growing medium and start with a clean, disinfected bench. pH: This remains the biggest issue growers seem to have with this crop, and we are constantly selecting for new cultivars with an expanding tolerance of varying pH levels, but always shoot for a pH somewhere between 5.5 to 5.8.

Fertilization: Using a balanced liquid feed at 150- to 200-ppm nitrogen with a full assortment of minor elements is all that is required. Watering should keep plants moist, but be careful especially in the early season not to overwater the crops. This is even more important as they are in the crucial rooting phase of production. Calibrachoa seem to require slightly more iron in general than other crops, adjust feed program to include iron at 1 to 2 ppm.

Light level: High light levels are always necessary with calibrachoa both to control stem stretch and also to promote heavier flowering. To succeed, make sure calibrachoa are getting bright light.

Pinching/Growth Regulators: For containers 6-inch and smaller, a pinch is required at transplanting only. For hanging baskets and containers larger than 6-inch, give a soft pinch at planting and trim around container just prior to hanging. Apply 5- to 10-ppm Sumagic, or a B-9/Cycocel (2,500/750) tank mix is quite effective. Applying 500-ppm Florel will promote branching and delay flowering only slightly.

Pest and Disease Management: One of the things Proven Winners has worked hardest at with the Superbells line is disease resistance, specifically root rot pathogens. Calibrachoa, in general, are sensitive to Pythium, Phytophthora and Thalaeviopsis. Superbells have higher levels of tolerance to these diseases than other calibrachoa. Keys to avoiding root rot related issues are maintaining proper pH, overall good sanitation and avoid overwatering.