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Evaluating the Use of PCR (Polymerase Chain Reaction) to Detect Phytophthora infestans in Field-infected Potato and Tomato Tissue 1997

Project Leader: Diane M. Karasevicz, Extension Associate III

Objective:

Evaluate the use of PCR (polymerase chain reaction) to detect P. infestans infection in field-grown potato tubers with late blight symptoms. The technique will also be used to detect P. infestans in above-ground potato tissue (stems, foliage) as well as in tomato samples (stems, foliage, fruit).

Results:

Fifty-six potato and tomato samples were evaluated for the presence of late blight (P. infestans) using both the relatively new technique called PCR and the standard technique of examining tissue for fungus spores. There were 19 cases of disagreement between PCR and sporulation results. Many of these were due to a previously unknown interference of foliage cell components with the extraction of P. infestans DNA. Other cases were due to problems with the overall running of the PCR technique during part of the season. In several cases late blight could be confirmed via PCR but not sporulation due to the badly decayed condition of the samples upon arrival. A key advantage of the PCR technique is the ability to detect P. infestans when decay microorganisms are present.