Methods for identifying plant diseases include checking for symptoms on specific plant parts, looking for signs of causal agents like fungal spores, and determining if symptoms are found across plant species or isolated to one. Modern molecular techniques allow for precise diagnosis, such as polymerase chain reaction (PCR) which amplifies DNA to detect bacteria, fungi and viruses through primer specificity. Other techniques are LAMP using multiple primers, RAPD analyzing DNA fragment polymorphisms, RFLP comparing fragment lengths after restriction enzyme digestion, and microarrays where probes detect complementary DNA sequences.