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Disease causes and treatments are identified
Each year, diseases cause major losses in greenhouse and nursery crops. Clemson researchers are studying the viruses and fungi that cause diseases and are offering growers some defenses against losses.

Studies into the genetic make-up of viruses found similarities between Nandina mosaic virus and Hydrangea ringspot virus. As a result of these studies, Clemson scientists developed sensitive molecular tests to detect, and distinguish between, the two viruses. These techniques will be used to identify plants that are free from the viruses to use for propagation material. Plants produced from these originals can be certified as free of the viruses.
(For more information, contact Simon Scott sscott@clemson.edu, Clemson Plant Pathology and Physiology Department.)

Plant pathologists at Clemson discovered a new species of the fungus Fusarium that causes crown and root rot in hosta. In the nursery, damage from this disease can be reduced through careful growing practices. Key steps are: avoid wounding the crowns and roots during cultivation, practice good sanitation, grow hostas in a peat-based container mix, keep the plants well watered, and dip both roots and crowns in a fungicide suspension before planting. Currently, research is underway to determine the most effective fungicides for managing Fusarium root and crown rot on hostas. 
(For more information, contact Steven Jeffers sjffrs@clemson.edu, Clemson Plant Pathology and Physiology Department.)

Another fungus, Phytophthora, causes root and crown rot on many ornamental crops, which results in major losses in nurseries and greenhouses. Studies are now underway to develop integrated management strategies for this disease.

Previous research demonstrated that these fungi are widespread in nurseries.  Current research is identifying the primary source of the fungus that initiates the disease in production facilities. Samples of water and soil are being collected from various locations to determine the occurrence and distribution of the fungi in nurseries and natural areas. The various species will be identified and stored, and then sample fungi from different sources will be tested for their ability to attack selected ornamental crops.

In another study, research revealed that individual species of Phytophthora have unique fatty acid profiles. Using this information, scientists will develop a database of profiles for the species of Phytophthora known to attack ornamental crops. Eventually, this database will be used to help diagnose disease problems submitted to the Plant Problem Clinic operated by the Clemson Cooperative Extension Service.
(For more information, contact Steven Jeffers sjffrs@clemson.edu, Clemson Plant Pathology and Physiology Department.)