Indexing for plant pathogens
This chapter outlines the various procedures used to eliminate fungal, bacterial, and viral pathogens from vegetatively propagated plants. Indexing, simply stated, is testing various plant parts for the presence of any plant pathogen. The chapter focuses on the strategies employed in the floriculture industry to eliminate the major plant pathogens from the Florists' geranium. One method for the elimination of systemic fungal and bacterial plant pathogens from geraniums is accomplished using a procedure called culture indexing. Plant pathogenic viruses are submicroscopic particles consisting of nucleic acid surrounded by a protein coat. The most common serological method used is enzyme-linked immunosorbent assay (ELISA). Bioassays are accomplished by mechanically inoculating an indicator plant with sap extracted from the test plant. If visual selection of virus-free clones is not possible, there are several techniques available to eliminate viruses, including: exploiting erratic virus distribution within plants, chemotherapy, heat or thermotherapy, and meristem tip culture.