Our project began in 2009 for the purpose of evaluating the potential of pomegranate in Florida. Interest has grown remarkably and the project was opened to homeowners and hobbyists in 2010.
Resources. As of 2011, there are 85 accessions in the CREC collection. The accessions were collected from the USDA National Clonal Germplasm Repository, CA, local nurseries and homeowners. One surprise in the project was to discover important collections at the USDA Southeastern Fruit and Nut Research Lab in Byron, GA, and the University of GA at Tifton.
Most of the accessions have been established in a Foundation Block at the Citrus Research and Education Center, Lake Alfred. A duplicate Foundation Block has been established with the Mid Florida Citrus Foundation at Water Conserv II, Winter Garden. Cick on the Water Conserv II button for more information.
Propagation. We have been working with a commercial propagator for rooting cuttings. We have supplied semi-hardwood and hardwood cuttings of all sizes from about 1/4 to 1/16 inches in diameter. The cuttings have been supplied without regard to the time of year. They are treated with a commercial rooting hormone, placed in a peat mix and rooted in ca. 16 weeks with percentages >75%. The rooted cuttings are grown off in a greenhouse or shadehouse in 1-gallon containers where they are now trained to a single stem with no branching for a length of ca.12 to 18 inches. Our results confirm that pomegranates are easy to propagate, but it may require 3 to 4 months to achieve maximum rooting percentages.
Cultivar selection, orchard design, plant training. What should I plant is a frequently asked question without an obvious answer so far. We are encouraging cooperators to try any of the cultivars available until we have enough cultural data to answer the question. One of our first plantings was set out at Water Conserv II in May, 2009. Another, larger set of additional cultivars was planted in April, 2011. Click on the Water Conserv II button for more information.
The growth of our earliest planted pomegranates along with observation of older plants in dooryards and nurseries suggest that a spacing of 12 x 20 feet should be adequate for commercial plantings. A wider spacing of 14, 16, or 18 x 18 feet, has been recommended in GA depending on geographic location, cultivar, and anticipated canopy training program. There are mature plants at the University of GA Ponder Farm, Tifton, and their size would seem to justify the wider spacing. However, spacing may depend on the type of training practiced. Plants trained as bushes may develop broader canopies and require more space. Plants trained to a single trunk with the vase-shaped canopy may need less space in the row. Neither training method has been evaluated in Florida although the single trunk provides a means to attach a wrap like those on citrus trees to shield against damage from pesticide applications. Preliminary evidence does not indicate that a wrap helps prevent suckers which need to be removed each year, generally when the plants are dormant. The suckers do not necessarily need to be discarded as they are a source of cuttings for propagation. Limited evidence also indicates that wraps may be harmful for the same reasons sometimes observed with citrus. Ants build nests inside the wrap which can lead to damage and we have noticed other damage of unknown cause to the trunks of developing pomegranate plants.
Nutrition and irrigation practices. Pomegranate apparently does not require any special irrigation management other than to avoid overwatering and chronically wet conditions. Little is known about fertilization practices and practical experience in Florida is evolving. Therefore, until further information is obtained, it is suggested that pomegranate plants be treated as if they were orange trees regarding irrigation and nutrition. Plant tissue analyses obtained from a California lab support that recommendation. However, pomegranate plants are very responsive to fertilization and can change from yellow to green virtually overnight after receiving a modest application, by citrus standards, of fertilizer.
Pest, disease, and weed management. Pomegranate is a minor crop in the U.S. even though in California, where most pomegranates are grown, there are an industry-estimated 35,000 acres. As a result, there are few materials registered for use on pomegranates.
Pomegranate pests are numerous, but few have been encountered so far at the propagation and nursery stages or in our cooperator trials. The primary pest has been aphids. The more troublesome issue is diseases. We have encountered the leaf spotting caused by Cercospora punicae [ 2010 field day handout] which is easily controlled with copper. Our observations suggest that there may be differences among selections in susceptibility to this fungus. We have also learned that Cercospora infections, if left uncontrolled, lead to premature leaf loss. However, the most serious problems manifest in the fruit and lead to drop or infections that render the fruit unappealing if not unusable. Some of the genera thought to be involved are Xanthomonas, Cercospora, and Botryosphaeria. Species of Aspergillus and Colletotrichum have also been isolated from infected fruit. Investigations into pest and disease identification and management in pomegranates are needed. Because of a humid climate and rainfall in the summer months when the fruit are developing, the results of those studies are likely to be the foundation for successful pomegranate culture in the southeastern U.S. One herbicide trial has been conducted with young plants in containers. The results are available here. Also, see the cultural information at Water Conserv II.
A number of products have been approved for use in California to control pests . Web data (http://www.pesticideinfo.org/DS.jsp?sk=6015) show that sulfur, several herbicides, and imidacloprid are among the most commonly used.
Root-knot nematode. Pomegranates are reported to be susceptible to this nematode which is everywhere in Florida and when present, galls can be observed on the roots. Preplant organic soil amendments apparently have some value is assuring plant establishment, good growth and helping diminish any damage from the nematode. See page 8 in the following publication, http://edis.ifas.ufl.edu/pdffiles/NG/NG03200.pdf, for some ideas.