Fungi and fungi-like organisms inflict huge yield losses globally despite the abundant use of fungicides. Plant pathogenic fungi cause disease symptoms on all plant parts (seed, seedling, leaves, fruits, and root). Symptoms may include spots and blights on leaves, stems, and fruit, rots of tubers, cankers, damping off, seedling and plant diebacks, galls, and wilts. Their early detection in infected plant tissue will ensure taking preventative measures.
Fungal disease diagnosis at the Plant Health lab consists of classical approaches based on visual disease symptoms, hyphal and spore morphology, shape and size of conidia and other fruiting structures. Fungal infections are often systemic, and plant tissue is surface sterilized followed by incubation either on sterile filter paper under humid conditions or incubated on selective media for their successful isolation and identification. In some cases, molecular methods such as PCR and DNA sequencing are used to resolve the causal species.
Plant viruses are obligate parasites that infect host plants and use their cellular machinery to replicate and proliferate. They can gain entry into a plant in many different ways, including vectors (i.e., nematodes, aphids, whiteflies), vegetative propagation and wounding. The symptoms associated with virus infection can vary greatly and can be confused with other common abiotic and biotic stressors. They can affect many different marketable parts of plants (i.e., leaves, flowers, fruit and stems), resulting in reduced yield and quality. Once a plant is infected with a virus, it is infected for life, and depending on how the virus is transmitted, it can spread to neighbouring healthy plants in a field or greenhouse.
Diagnosis of viruses by eye is very challenging due to their variation in symptoms. A laboratory test is the most reliable form of diagnosis, such as an enzyme-linked immunosorbent assay (ELISA) or a polymerase chain reaction (PCR) test. The Plant Health Lab currently offers PCR testing for grapevine and strawberry viruses.