1. What is a disease? A pathological condition of a part, organ, or system of an organism resulting from various causes, such as infection, genetic defect, or environmental stress, and characterized by an identifiable group of signs or symptoms.
2. Why is the Greenhouse a great place for disease causing organisms to grow? The GH environment is ideal for plants therefore it is ideal for organisms. The GH environment is free from natural enemies of organisms.
3. What are 4 types of disease org. that affect GH crops? A.Virus – A small particle of DNA that cannot survive on its own and must have a living cell to replicate itself.
A. - More about Viruses … –Extremely small –No chemical control measures exists. –Only known cure is to get rid of the infected plants. –Prevention is crucial !!! 3. What are 4 types of disease org. that affect GH crops?
B. Bacteria – Single-celled organisms. – Difficult to control, get rid of the infected plants
3. What are 4 types of disease org. that affect GH crops? C. Nematodes – Tiny worms that feed on the roots of plants. – Most are not harmful. – Some chemicals exist to control them.
3. What are 4 types of disease org. that affect GH crops? C. Nematodes
3. What are 4 types of disease org. that affect GH crops? D. Fungi Eukaryotic organisms of the kingdom Fungi. Lack chlorophyll and vascular tissue. Range from a single cell to the largest living organism. The kingdom includes the molds and mushrooms.
Some Examples of GH Crop Diseases Tobacco Mosaic Virus Damping Off (Pythium or Phytophthora sp.) Fusarium wilt (Fusarium sp.) Powdery Mildew Sooty Mold Blossom End Rot
(ToMV) will cause disfigurement of the leaves and stunted growth. Sucking insects or hands and tools of workers in the greenhouse can transmit the virus. Prevent the disease by using resistant cultivars and making sure all workers wash hands with soap and water after handling any tobacco products. Tobacco Mosaic Virus
Typical symptoms include a light and dark green mottling on the leaf tissue. Stunting of the plant Leaf blade will reduce in size (fernleaf) Tobacco Mosaic Virus
Blackening at the soil line of young seedlings or collapsed roots. Caused by soil- born fungi. Make sure seeding media is sterile and well drained. Damping Off (Pythium or Phytophthora sp.)
Often called the "yellows" due to the overall yellow color of the plant, sometimes starting with older leaves. Browning of vascular tissue in stem indicates the fungus is clogging those tissues, causing wilting. Roots turn brown, and taproot may rot away. Choose Fusarium resistant cultivars and destroy all infected vines. Fusarium Wilt (Fusarium sp.):
Powdery Mildew White or gray powdery fungus over the surface of leaves, stems, flowers, or fruit of affected plants. These patches may enlarge until they cover the entire leaf on one or both sides. Leaf curling and twisting may be noted before the fungus is noticed. Severe powdery mildew infection will result in yellowed leaves, dried and brown leaves, and disfigured shoots and flowers.
It's caused by a deficiency in calcium. Tomato plants that suffer from water stress or extreme fluctuations in moisture are prime candidates for blossom- end rot. Prevent by keeping soil evenly moist and well mulched. Add lime if you have an acidic pH and low calcium; add gypsum if your soil is alkaline and calcium- deficient Blossom End Rot C.C.
Sooty mold is a charcoal black fungus that appears as a black coating on the surface of leaves, fruits, twigs and branches of many deciduous and evergreen shrubs and trees. This fungus is not pathogenic to plants but obtains its nourishment from insect honeydew Sooty Mold
How do plant diseases spread? Knowing how these diseases spread will help prevent the diseases and will help us manage the disease if it is present.
Powdery Mildew The fungi which cause powdery mildew are spread by spores produced in the white patches. These spores are blown in the wind to other parts of the plant or to other plants during the growing season.
Tobacco mosaic virus *Can be spread by contact (plant to plant) *Transfer (plant to person – person to plant) (Plant to tools – tools to plant) *Insects can carry (whitefly)
The fungus can be spread from stalk to stalk or through the soil from the root system. Damping off
The fungus can be spread from stalk to stalk or through the soil from the root system. Fusarium Wilt
Since this is a result of a calcium deficiency, it does not spread from plant to plant Blossom End Rot