INTERIOR PLANTS DISEASES Disease Definition v Disease abnormality
INTERIOR PLANTS DISEASES
Disease Definition v. Disease- abnormality in structure or function caused by an infectious agent that injures or destroys v. Often the most limiting factor v. Consider during plant selection
Two Disease Classifications v Infectious- damage which is caused by a pathogen or living organism v Noninfectious –physiological injury that destroys the plant’s value and are called disorders.
Disorders Sunburn Overwatering
Terminology v Pathogen -organism causing disease: § fungi § bacteria § viruses § nematodes & mycoplasms- (not much of a concern in the interior environment) v Host - Organism the parasite lives on
Part of Nature v Normal part of nature v Cultivation increases diseases § cultural practices have changed § uniform genetic background § grown in pure stands v Suitable environment is usually wet, humid, and warm to hot
Method of Dispersal v Air currents v Splashing water v Insects v Mites v Cultural practices
Disease Triangle v There are 3 conditions necessary for disease to occur § a susceptible host § a virulent pathogen § a favorable environment v These make up the disease triangle. If any one is missing, disease can not occur
Disease Complexes v Disease complex- multiple pathogens occur when plant roots are damaged before stress v Successions occur § Initial colonizers of the roots § Successions of fungi § Invasion of diverse saprophytes § Tissue then supports other organisms
Disease Process v 4 steps to the disease process: § infection- organism enters the plant § incubation- Pathogen inhabits the host and without producing symptoms § symptom development- interaction § inoculum production- pathogen produces propagules
Disease Control Agents v Prevent pathogen establishment v Plant resistance v Alter the environment v Sanitation v Pesticides
Fungi v Most common v Lacks chlorophyll; microscopic v Germ spores, germ tube on plant surface, penetration v Fungus grows filaments called hyphae (coll. the mycelium) v Control with fungicides and watering
Fungal Disease Cycle
Bacteria v Tiny organisms that contain cytoplasm enclosed in a cell wall; no nuclei. v They do not require a living host for replication and growth. v Most are saprophytes; some are infectious v Pathogenic species are usually bacillus (rods), the others are spirilla or cocci v Control by planting resistant species
Bacterial Disease Cycle
Viruses v Nucleic acid with a protein coat. v Visible with an electron microscope v Parasitic an multiply in living cells v Primarily transmitted by feeding activities or vectors v Control by controlling the vector
Virus Disease Cycle
Fungal Rots v. Root Rots - brown, mushy roots due to too much water. § Wilt, yellowing § Abscission of leaves from the base up § Death of the roots results
Root Rots v. Rhizoctonia v. Pythium v. Phytophthora v. Sclerotium v. Fusarium
Rhizoctonia v. Known as: damping-off, wire stem, head rot, crown rot v. Attacks: Aglaonema, Begonia, Cissus, Chamaedorea, Hedera, Hoya, Peperomia, Philodendron v. Reddish-brown mycelium v. Hyphal branches at right angles
Rhizoctonia in Carnations
Pythium v Water mold favored by wet conditions v Known as root rot, damping-off § Wilt; progressive yellowing from the base up; exterior of root sloughs off and leaves the core giving a thread-like appearance to the roots; dark color § Aglaonema, Aloe, Chamaedorea, Dieffenbachia, Pothos, Philodendron
Damping Off v Pythium – Root and stem rot § Unsterile soils, more water, poor air circulation § Spread by infested soil § Brown roots and blackened stem § Use dust protectants, improve drainage
Pythium in Geranium
Lilium with Scortch or Pythium
Scorch on Lillium
Phytophthora v Phytophthora is closely related to Pythium and produces leaf spot § Late blight, foliage blight, fruit rot, crown rot, root rot § Leaf damage, collapse of the plant § Aglaonema, Dieffenbachia, Hedra, Kalanchoe Peperomia, Saint Paulia
Sclerotium v Sclerotium - White fungus on the substrate surface and the plant; sclerotia (spore-like resting bodies) the size of mustard seeds § Brassaia, Chamaedoria, Dieffenbachia, Dracaena, Pothos, Peperomia.
Stem and Leaf Disease v Do not wet foliage v No excess water v Similar to root rot with cause and care
Powdery Mildew v Ersiphaceae - Powdery Mildew § Change in temperature, cold and damp § White powder on the leaves; younger leaves curl; dwarfed and deformed foliage and flowers § Use fungicides
Powdery Mildew
Botrytis on Geranium v Botrytis – leaf spot § Moist atmosphere poor cultural practice § Prevention; reduce humidity; resistance; avoid injury
Fusarium Wilt v Causes root rot § Lower leaves turn yellow and sometimes wilt; entire plant becomes chlorotic; roots blacken and mushy § Prevention is the best defense; aeration, pasteurization § Agalaonema, Asapragus, Dracaena, Spathiphyllum
Fusarium on Carnation
Verticillium Wilt v Soil borne; enters through roots & attacks the vascular system § One of the most distructive fungi § Yellow leaves which die from the base to the top; whole plant stunted; no flowers § Culture-indexed cuttings
Verticillium on Chrysanthemum
Ascochyta Ray Blight v Fungus attacks flowers and buds § Spores transported by splashing water or air currents § Completely rots the whole flower § Sanitation; remove contaminated materials
Ascochyta on Chrysanthemum
Rusts v Puccinia or Rust § Red brown dusty spots on the leaves § Resistance is possible § Sprays help
VIRUS v Virus § Distortion § Change of color § Hard to treat § Indexing of mums
Aster Yellows v Viral symptoms, leaf-hopper vector § Green flowers § Plant dies in a few months § Control the insect
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