1. Plant Diseases A disease is defined as any type of injurious abnormality A pathogen is any biological agent that causes an injurious abnormality

2. Plant diseases There are 4 types of commonly recognized pathogens –Virus –Bacteria –Fungi –nematodes

3. Signs and Symptoms Symptom is the plants response to attack by a pathogen Sign is structures produced by the organism ( spore producing structures, mycelium)

4. Virus Tobacco Mosaic Virus

5. TMV

7. Virus symptoms Unthrifty plants –Slow to grow –Mosaic light spots and stripes

8. Aster Yellows Acts like a virus but is a mycoplasma

9. Virus indexing If you are buying cloned plants they will often say Virus Indexed. That means they are tested and proven to be virus free. very important when buying raspberry plants or strawberry plants

10. Bacteria- fire blight

11. Fire Blight

12. Bacterial symptoms Rapid spread, can be spread by wind or insects,humans Soft rots producing snotty oooz Can be really smelly

13. Fungi Botrytis – Grey Mold

14. Fungus

15. Signs: mycelium, fruiting bodies Symptoms: necrotic areas, wilt when fungus attacks the roots Phloem blockage, xylem blockage

16. Nematodes Root Knot Nematode

17. Nematodes Feed on roots and allow secondary infections Cause small tumors on roots

18. Damage to plants by fungi bacteria and nematodes can be classified in 3 types –Direct damage by feeding –Toxins injected into the plant –From secondary infections that enter via the physical damage caused by the primary agent

19. Crop infesting diseases are troublesome because they will continue to reproduce and feed UNTIL 1. The food is used up 2. the environment becomes unfavorable 3. they are destroyed by some predator/ disease

20. Disease transmission Water is necessary for fungus infection Insects Humans Infected seed Infected soil – brought in on shoes or tractor tires

21. Curing or avoiding plant disease? Any of the previous factors can be interrupted Cultural control –Roguing, sanitation, plowing plant refuse under, stirring the soil to expose egg masses, keep plants healthy, avoid smoking, regulate pH, hot water treatment of seed, Chemical control

22. What are those letters? · V Verticillium Wilt Virus · F Fusarium Wilt Virus · N Nematodes · T, TMV, ToMV Tomato Mosaic Virus · BSK Bacterial Speck · ST Stemphyllium (Grey Leaf Spot) · FCR Fusarium Crown Rot