the study of diseases in plants PLANT PATHOLOGY: the study of diseases in plants PATHOGEN: Any disease causing agent Causes of diseases: Living factors Non-living factors

LIVING FACTORS ARE INFECTIOUS AND CAN SPREAD FROM PLANT TO PLANT These include: fungi bacteria virus insects nematodes rodents, birds, and other animals

Non-living factors do not spread from plant to plant These include: chemicals physical damage Nutrient deficiencies

In order to effectively treat a disease it is important to know whether the disease is infectious or non-infectious

FOR DISEASES CAUSED BY LIVING PATHOGENS TO OCCUR THREE CONDITIONS MUST BE MET 1. There must be a susceptible host plant 2. The pathogen must be present (even though it might not be seen) 3. The environment must be suitable for the pathogen to grow and thrive (temperature and humidity are important factors)

IF THERE IS NO PATHOGEN PRESENT THERE CANNOT BE A DISEASE!!!! when a disease seems to come from nowhere, it was just hiding until the conditions became perfect for it to grow and spread- remember, most pathogens are microscopic

VOCABULARY TERMS: 1) BIOTIC- living 2) ABIOTIC- non-living 3) FUNGUS- a living organism with no chlorophyll that reproduces by spores, not seeds. (examples: molds, yeasts, mushrooms (effects: leaf spot; fruit rot; stem rot; root rot) 4) BACTERIA- a one celled living organism. Bacteria have no cell wall and no chlorophyll (effects: leaf spot; fruit rot; stem rot; root rot)

VOCABULARY (continued) 5) VIRUS- microscopic ; not yet classified as living or non- living because viruses cannot survive on their own without a healthy host cell; viruses have an outer covering made of protein (effects: causes distorted, and/or stunted, and/or discolored growth 6) VIROID- viroids are smaller than viruses and do not have the outer protein covering (effects: same as viruses) 7) NEMATODE- a microscopic roundworm that usually lives in the soil and feeds on the roots of a plant (effects: stunted growth; distorted roots)

VOCABULARY (continued) PARASITIC SEED PLANT- a true plant with chlorophyll that attaches to a host plant and steals the nutrients from the host plant (effects: causes a general weakening of the host plant)

REMEMBER: MOST DISEASE THRIVE IN DAMP MOIST ENVIRONMENTS. AVOID OVERWATERING PLANTS AND TRY NOT TO CREATE PUDDLES IN THE GREENHOUSE THROW GARBAGE (soil, dead leaves, dead plants, etc.) in COMPOST or DUMPSTER- DO NOT THROW ON FLOOR OR LEAVE ON BENCHES PUT EMPTY USED POTS OUTSIDE