Term
| Agrobacterium-facilitated DNA transformation of plants |
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Definition
| A process by which the Ti plasmid and T-DNA of Rhizobium radiobacter are used to genetically engineer plants. The most common method for genetically engineering plants in the last 20 - 25 years. Foreign genes can be inserted into Ti plasmids and transferred into the DNA of the host plant. |
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Term
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Definition
| Symbiosis where one organism is harmed and the other neither benefits nor is harmed. Can be used to control pathogens or pests. |
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Term
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Definition
Castanea dentate
A major forest canopy tree. Prized for wood, tannins, and nuts. It was almost completely wiped out by chestnut bligth in the 1900s, and is now an endangered species.
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Term
| Angular leaf spot of strawberry |
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas ftagarlae. Symptoms include water soaking.
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Term
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Definition
A disease. Development at 26ºC causes few symptoms following inoculation. Develompent at 31ºC causes severe blight and heat stress.
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Term
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Definition
| Use on plants can lead to development of resistance to antibiotics, which could eliminate efficacy for plant diseases. Resistance in plant pathogens may transfer to human pathogens. Less than 0.1% of total antibiotic use in the U.S. is for plants, this mostly in fruit trees. |
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Term
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Definition
| Fungal structures which punch into cell structures. |
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Term
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Definition
| Morphologically similar to bacteria, but several genes are more closely related to eukaryotes. Non-pathogenic, but have the potential to be pathogens. |
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Term
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Definition
| An insect which transmits aster yellows phytoplasma. Controlled using mesh fabrics, or strips of reflective aluminium foil to confuse the insects. |
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Term
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Definition
A common monocyclic bacterial disease in Ontario. Caused by a phytoplasma mollicute Candidatus Phytoplasma asteris.
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Term
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Definition
| Aster yellows prefers warm, moist conditions. At 25ºC symptoms appear 8 - 9 days after phytoplasma is injected into the plant, and at 20ºC it takes 18 days. At 10ºCno symptoms develop. |
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Term
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Definition
| Aster yellows is controlled by controlling leafhoppers, removing diseased plants, using less susceptible species, and control of weeds which could be hosts. Sticky traps may be set for insects. |
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Term
| Aster yellows dissemination |
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Definition
| Aster yellows is transmitted by insects including aster leafhoppers, or by budding or grafting. Insects feed on plants and acquire the bacteria by sucking and injecting phloem sap. There must be an incubation period of 2 - 3 weeks for bacteria to multiply in the insect, then it is infected for life and can transmit the bacteria to plants. |
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Term
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Definition
| Aster yellows affects more than 300 hosts, including: brassica crops, lettuce, carrots, canola, potato, strawberry, celery, buckwheat, endive, flax, onion, parsley, parsnip, pumpkin, red clover, salsify, spinach, and tomato. Less susceptible hosts include verbena, salvia, tobacco, geranium, cockscomb, and impatiens. Weeds which may harbour the disease include plantain, dandelion, and Queen Anne's lace. |
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Term
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Definition
| A leafhopper transmits the phytoplasma by injecting it into the phloem. The phytoplasma are restricted to phloem tissue, where they systemically spread throughout the plant. After injection, it moves to the rest of the plant within 8 - 24 hours. |
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Term
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Definition
| Primary inoculum is phytoplasma that survive in infected, living perennial plants. Secondary inoculum is new infections. |
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Term
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Definition
A serious plant disease in the Canadian prairies. Instead of flowers, sterile leaf-like structures and pods form. Plants may turn purple or blue-green. Leaf hoppers spread the disease to canola on southern winds from the U.S.
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Term
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Definition
A plant disease. The shoot produces many stunted branches with chlorotic leaves. The root is excessively hairy, and cannot be sold for human consumption.
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Term
| Aster yellows phytoplasma (AYP) |
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Definition
| Plant pathogenic bacteria which cause aster yellows. Phytoplasma mollicutes. Bacteria that are obligate parasites of plant phloem tissue and insect vectors. |
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Term
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Definition
| Aster yellows overwiners in perennial plant hosts including ornamental, vegetable, and weed plants. |
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Term
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Definition
| Symptoms of aster yellows include chlorotic foliage, floral asymmetry and sterility, vascular necrosis, shoot or bud proliferation, stunting, witches' broom, abnormal shoot production, malformation of organs, reduction in quality and quantity of yield, and death. Flower parts develop as leafy structures. |
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Term
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Definition
| An essential step before infectio. Bacterial pathogens synthesize extracellular molecules such as proteins and cellulose microfibrils, which promote adhesion. Spres of many pathogenic fungi produce extracellular matrix of polysaccharide and glycoprotein which surround the spores and bind tightly to plant cuticles. Fungi may employ electrostatic mechanisms to attach to the host. |
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Term
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Definition
| A plant growth promoter. Encoded by T-DNA of Rhizobacterium radiobacter. |
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Term
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Definition
| Single-celled prokaryotes. There are approximately 1,600 known species, 100 of which cause plant diseases. Have a single circular DNA strand floating freely in cytoplasm, and may have additional plasmids. Have 70S or 80S ribosomes. Lack most internal strucutres found in eukaryotes, but have a cell wall that is rigid but does not contain cellulose. Exist as single cells or in clusters. Reproduce asexually by binary fission, with generation times as short as 20 minutes. Lack distinctive morphological features, and are classified based on stains, cell walls, physiology, and DNA sequences. Groups of bacteria based on shape include: coccus, coccobacillus, vibrio, bacillus, spirillum, and spirochete. |
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Term
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Definition
| Bacteria may be identified using bacterial streaming, external/internal symptoms, gram stain, observing growth and colony characteristics on certain agar media, nutritional tests, enzyme production, and pathogenicity tests. Metabolic tests for bacteria identification include aerobic/anaerobic growth, endospores, motility, catalase reaction, oxidase reaction, and glucose fermentation. Other methods include fatty acid profiles, serological methods (including antibodies), restriction fragment length polymorphisms (RFLPs), DNA probes, polymerase chain reaction (PCR), and DNA sequencing. |
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Term
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Definition
A disease. Symptoms include bacterial cankers.
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Term
| Bacterial canker of sweet cherry |
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Definition
A common bacterial disease in Ontario. Caused by Pseudomonas syringae pv. syringae.
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Term
| Bacterial canker of tomato |
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Definition
A common bacterial disease in Ontario. Caused by Clavibacter michiganensis pv. michiganensis.
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Term
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Definition
| Bacterial pathogens have no active mechanism for infecting plant hosts; they gain entrance through naturally occurring openings such as stomata, wounds, lenticels, hydathodes, or nectaries. |
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Term
| Bacterial rot of crucifers |
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas campestris pv. campestris.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Erwinia carotovora pv. campestris.
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Term
| Bacterial speck of tomato |
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Definition
A common bacterial disease in Ontario. Caused by Pseudomonas syringae pv. tomato.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas campestris pv. pruni.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas campestris pv. vesicatoria.
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Term
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Definition
| Streaming of bacterial ooze out of infected plant tissue in water. The ooze will sink in water. |
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Term
| Bacterial wilt of cucumber |
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Definition
A common bacterial disease in Ontario. Caused by Erwinia tracheipila. Symptoms include vascular wilt.
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Term
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Definition
A disease caused by Pseudomonas sp.
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Term
| Biolog ® Microbial Identification System |
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Definition
| A technique used to identify plant pathogenic bacteria. Isolated bacteria are identified to species by a series of nutritional tests. Proprietary tests measure cellular metabolism in a convenient MicroPlate test. Tests the ability of the bacteria to utilize or oxidize a pre-selected panel of over 90 different substrates. Tetrazolium violet is used to indicate utilization ot substrates. The panel creates a characteristic "fingerprint" that develops in 4 hours or less. This pattern is compared to an established databse to obtain identification. |
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Term
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Definition
Obligate pathogen
A pathogen that can grow and reproduce only in/on living hosts. Includes viruses, mollicutes, nematodes, and some bacteria and fungi. Cannot be cultured in sterile culture without the host. |
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Term
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas campestris pv. campestris. The most serious disease of crucifers including cabbage, cauliflower, broccoli, and turnips. Symptoms include vascular wilt. The pathogen enters the xylem through hydathodes from guttation droplets or through wounds made by insects. Bacteria cause vasculature to plug by producing xanthan gum.
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Term
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Definition
A disease caused by Erwinia sp.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Erwinia carotovora pv. atroseptica.
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Term
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Definition
A disease caused by Pseudomonas sp.
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Term
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Definition
A momocyclic disease.
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Term
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Definition
| A disease caused by Pseudomonas sp. |
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Term
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Definition
A disease caused by Xanthomonas sp.
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Term
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Definition
A disease caused by Rhizobacterium sp.
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Term
| Candidatus Phytoplasma asteris |
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Definition
| A plant pathogenic bacteria that causes aster yellows. A phytoplasma mollicute. |
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Term
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Definition
| A symptom of a bacterial disease. |
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Term
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Definition
| Proposed the Two Kingdoms model in 1758. |
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Term
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Definition
| Seed which has been checked for a disease, and is guaranteed to not contain the disease. |
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Term
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Definition
A disease which almost completely wiped out American chestnuts in the 1900s.
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Term
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Definition
| Reproduce asexually and sexually. |
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Term
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Definition
A disease caused by Xanthomonas sp.
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Term
| Clavibacter michiganensis pv. michiganensis |
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Definition
| A plant pathogenic bacteria which causes bacterial canker of tomato. |
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Term
| Clavibacter michiganensis pv. sepedonicus |
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Definition
| A plant pathogenic bacteria which causes ring rot of potato. |
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Term
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Definition
Many species were formerly known as Corynebacterium sp.
A genus of gram positive bacteria which are non-motile. Rod, comma, or club-shaped. Many are fastidious, xylem-limited. Causes bacterial cankers, wilts, and spots on leaves and fruits. Causes potato ring rot, tomato canker, tomato wilt, fruit spot, and fasciation. |
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Term
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Definition
| Symbiosis where one organism benefits and the other neither benefits nor is harmed. |
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Term
| Common bacterial blight of bean |
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Definition
A common bacterial disease in Ontario. Caused by Xanthomonas campestris pv. phaseoli. Causes leaf spot.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Streptomyces scabies.
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Term
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Definition
A common monocyclic bacterial disease in Ontario. Caused by Rhizobium radiobacter. Occurs worldwide. Caused destruction of $400,000 of nursery stock in a year in Oregon and Washington, not including orchards and vineyards. A typical walnut orchard loses 1 - 2% of its trees every year to crown gall, costing at least $1 million per year. In Oregon one year 14,000 fruit trees had to be destroyed in a single season.
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Term
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Definition
| Crown gall prefers warm, moist conditions. |
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Term
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Definition
| Crown gall can be controlled by using disease-free seeds and plants, pruning of galls, roguing infected plants, biocontrol, avoiding injury during planting and management, managing root-chewing insects, cleaning all tools, and application of Galltrol and Gallex. |
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Term
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Definition
| Inoculum is disseminated in the soil. |
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Term
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Definition
| Crown gall affects 643 species in 140 genera of woody plants in 60 families. Affects mostly pome fruits, stone fruits, brambles, and grapes. |
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Term
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Definition
| Rhizobacterium radiobacter bacteria are stimulated by nutrients from roots, and develop flagella and move towards wound sites to attach to wounded cells. Ti plasmids replicate T-DNA which enter the plant cells and integrate into plant DNA. |
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Term
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Definition
| Primary inoculum is cells that overwinter in infested soils. Secondary inoculum is infested soil and cells on new cankers. |
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Term
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Definition
| Symptoms of crown gall are unsightly abnormal swellings and galls of various size and shape at the soil surface, on roots, twigs, and lower branches. Galls are smooth, spongy, and small at first with whitish overgrowth of plant tissue. There is poor growth and reduced yields. Severly infected plants may die. |
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Term
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Definition
| Crown gall overwinters in infested soils where it can live as a saprotroph for several years. |
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Term
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Definition
| Practices when caring for plants. Can be an environmental factor affecting plant disease. Includes pruning and cleaning of equipment. |
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Term
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Definition
| An ecosystem service. Inspiration for art, recreation, ecotourism, and education. |
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Term
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Definition
| A plant hormone encoded by T-DNA of Rhizobacterium radiobacter. Disrupts normal balance of cell growth of host plant, leading to production of galls. |
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Term
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Definition
| A visual outline of the series of events and life stages that occur in the development of a plant disease, the survival of the pathogen, and its interaction with the host. Easy to remember, and integrates all stages and relationships. The entire life cycle may not be present. Does not show seasonal relationship of pathogen and host. Principle stages include primary inoculum, dissemination, incubation, attachment, penetration, host recognition, infection, invasion, colonization, growth and/or reproduction of pathogen, symptom development, secondary inoculum, production of overwintering stage, and dormant period. Many diseases have more than one infection cycle per growing cycle, and often there are different cells and/or spores of the pathogen involved. |
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Term
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Definition
| The existence of a disease caused by a biotic agent requires the interaction of a susceptible host, a virulent pathogen, and an environment favourable for disease development. Plant disease is prevented upon elimination of any one of the sides of the triangle. |
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Term
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Definition
| A microscope used for low power magnification. |
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Term
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Definition
| Inoculum of pathogens is carried passively by wind, water, or insects. May be carried in contaminated seeds, transplants, animals, on boots, tractors, plows, or pruning shears. Humans are a major disseminator of plant pathogens by moving plants, lumber, and vehicles. |
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Term
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Definition
A disease of turfgrass that occurs under certain temperatures.
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Term
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Definition
| An invasive species which was brought to North America from Europe. |
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Term
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Definition
| Includes provisioning, supporting, regulating, and culture. |
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Term
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Definition
| An organism which lives inside a plant but does not cause disease symptoms. |
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Term
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Definition
| One of the sides of the disease triangle; there must be conditions favouring the disease. Factors include temperature, moisture, wind, light intensity and duration, oxygen levels, air pollution, nutrient deficiencies or excesses, cultural practices, soil properties, and other organisms including bacteria and fungi. |
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Term
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Definition
| An organism which lives on the surface of a plant. |
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Term
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Definition
| Growth of plant pathogenic bacteria on the surface of the plant without causing damage to the host. |
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Term
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Definition
A disease that can cause ergotism if eaten by humans or animals.
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Term
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Definition
St. Anthony's fire
An animal disease caused by eating ergot of rye. Symptoms include alternating sensation of burning and freezing, irritability, convulsions, gangrene, and death. In ancient times people were "cured" by visiting a monestary, where they could recover while eating uncontaminated bread. |
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Term
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Definition
| Proposed the Three Kingdoms model in 1886. |
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Term
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Definition
| A plant pathogenic bacteria which is the source of hairpin, and elicitor disease resistance in plants. Rod shaped with peritrichous flagella. Causes fire blight. An excellent colonizer of the surfaces of stigmas and nectaiies. Has epiphytic growth, and can often be found in healthy plant tissues advance of visible symptoms. Secrete extracellular polysaccharide. Become active in the spring, and spread by adjoining to healthy bark. In humid or wet weather they can ooze from cracks and lenticels in bark of infected trees. |
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Term
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Definition
Used to be known as Pectobacterium carotovora.
A plant pathogenic bacteria which causes soft rot. |
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Term
| Erwinia carotovora pv. carotovora |
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Definition
Used to be known as Pectobacterium carotovora pv. carotovora.
A plant pathogenic bacteria that causes bacterial soft rot. |
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Term
| Erwinia carotovora pv. atroseptica |
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Definition
| A plant pathogenic bacteria that causes blackleg of potato. |
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Term
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Definition
| A genus of gram negative plant pathogenic bacteria that cause blight, wilt, and soft rot, including slippery skin, sour skin, and soft rot of onion. Rod shaped with peritrichous flagella. Facultative anaerobes. Form white or yellow colonies. |
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Term
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Definition
| A plant pathogenic bacteria which causes Stewart's wilt of corn. |
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Term
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Definition
| A plant pathogenic bacteria which causes bacterial wilt of cucumber. |
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Term
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Definition
| Includes chromista, plantae, protista, fungi, and animalia. |
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Term
| Extracellular polysaccharide (EPS) |
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Definition
| Secreted by Erwinia amylovora. Creates a matrix that contributes to improved survival and biofilm formation. Plugs xylem vessels. Cells are extruded from lenticels in fine filaments, aiding in aerial dispersal. |
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Term
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Definition
A disease caused by Clavibacter sp.
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Term
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Definition
A disease caused by Erwinia amylovora. First reported in Ontario in 1840. It is most severe in southern Ontario. Native to North America, and was introduced to Western Europe. Outbreaks are periodic. It is polycyclic, but in Canada it can be monocyclic due to the short growing season.
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Term
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Definition
| Fire blight becomes active in the spring when temperature exceed 18°C. It prefers rain, heavy dew, and high humidity. In warm conditions infected plants may excude bacterial ooze. |
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Term
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Definition
Fire blight is may be controlled with resistant cultivars or pruning to promote open canopy and remove infected cankers and twigs. Prune at least 30 - 60 cm below the area of infected wood. Pruning away infected branches is the only way to protect plants that are already infected.
Chemical control include fixed copper application before bud break, antibiotic streptomycin in 4 - 5 day intervals during bloom, or injections of oxytetracycline. Disease risk prediction models such as Cougarblight or Maryblyt can help predict need for sprays.
Biological control includes bacteria or yeast to prevent infection. |
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Term
| Fire blight dissemination |
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Definition
| Erwinia amylovora is transmitted by bees, flies, and ants during pollination. The insects are attracted to bacterial ooze which is sweet and sticky. The bacteria can also be spread by wind, rain, pruning tools, or aerial strands of bacteria in exudate. |
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Term
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Definition
| Fire blight affects 103 hosts, including apples, pears, quince, several stone fruits, and other members of the Rosaceae family. |
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Term
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Definition
| Fire blight infection occurs when bacteria enter through wounds from insects, hail, or wind. They multiply quickly in nectar and enter tissues of the flower and fruit spur. Grow and move into hydathodes of the flower, and enter xylem to spread internally. Infection of the spur results in death of all flowers, leaves, and fruits on the spur. Bacteria enter the petiole and stem, initially colonizing and then moving through vessels into other tissues. Infection becomes internal or systemic within the host, and can spread rapidly within the xylem of infected plants, leading to death of large limbs or entire trees. |
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Term
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Definition
| Primary inoculum is cells that overwinter on margins of cankers and buds. Secondary inoculum is in flowers. |
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Term
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Definition
| A common bacterial disease in Ontario. Caused by Erwinia amylovora. Limits apple production in Ontario. Apple trees are often a graft of a scion and a rootstock, which could differ in susceptibility to fire blight. Infection of shoots at the graft wound can lead to collar and rootstock blight. |
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Term
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Definition
| A common bacterial disease in Ontario. Caused by Erwinia amylovora. It limitspear production in Ontario and prevents it in eastern USA and Michiga. |
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Term
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Definition
| Erwinia amylovora overwinter in holdover cankers on woody tissues, and infect during the flowering period of the crop in the spring. It spends 67 - 90% of the year in a dormant state. |
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Term
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Definition
| Symptoms of fire blight include blight, cankers, bacterial ooze, blossom infection, shoot infection, and shepherd's crook. Infected flowers become water soaked, shrivel, and turn brownish black, appearing burnt by fire. Dead leaves and fruit remain on branches. Nearby leaves develop brown-black blotches, then curl and shrivel. Ooze appears when flowers open. |
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Term
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Definition
| Plant diseases can reduce quality and quantity of food and fibre production. |
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Term
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Definition
| Plant diseases can make plants poisonous to humans and animals. |
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Term
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Definition
A disease caused by Clavibacter sp.
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Term
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Definition
| Fungi can enter a plant by directly penetrating with haustoria, appressorium, or intercellular mycelium. They may enter the subcuticular space, or enter through stoma, lenticels, hydathodes, wounds, or natural cracks between main and lateral roots. May kill and macerate cells ahead of its advance. |
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Term
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Definition
| Inoculum are spores or sclerotia. Reproduce asexually and sexually. |
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Term
|
Definition
A disease caused by Pseudomonas sp.
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Term
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Definition
| A symptom of a bacterial disease. Active gall tissue is composed of disorganized, dividing plant cells. There is hyperplasia and hypertrophy of plant tissues. Damage can be benign or deadly. |
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Term
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Definition
| A biological control product for crown gall. Applied to the galls. |
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Term
|
Definition
| A biological control product for crown gall. A 100% active ingredient culture of naturally occurring Rhizobacterium radiobacter strain K-84. Prevents disease by disrupting infectious processes, producing antibiotics toxic to R. radiobacter, and physically excluding the pathogen from wounds by colonizing available attachment sites. Can only be applied pre-planting; root dipping is the most common method of application. |
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Term
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Definition
| Sporulation from spores. Usually requires free water. |
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Term
|
Definition
| Has a strong tendency to withdraw water from a sample. Acts as a preservative. High refractive index. Can be helpful for seeing certain structures. The specimen may shrink and deform, especially algae and other water organisms. It is possible to seal a glycerin mount by applying nail polish to the sides of the cover glass. |
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Term
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Definition
| Bacteria which stain pink with gram stain. Cells have a second membrane, chemically different from the plasma membrane, external to the cell wall, and may have a gelatinous sheath external to the second membrane. Includes Rhizobium sp., Erwinia sp., Pseudomonas sp., Xanthomonas sp., and Xylella sp. |
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Term
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Definition
| Bacteria which stain purple with grain stain. Cell walls have five times as much peptidoglycan than gram negative bacteria. Includes Clavibacter sp., Streptomyces sp., Ralstonia sp., Curtobacterium sp., Rhizomonas sp., Burkholderia sp., Pectobacterium sp., and Acidovorax sp. |
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Term
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Definition
| One of the most important techniques of identifying plant pathogenic bacteria; often the first test performed. Separates bacteria into gram negative and positive species, based on differences in composition of the cell wall. Differences in cell walls of gram positive and negative bacteria can be related to disease-causing potential of the bacteria. Gram negative bacteria stain pink, and gram positive stain purple. |
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Term
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Definition
A disease that was disseminated from the USA to France in vine rootstock transported in the 1860s to give resistance to root aphids, Phylloxera.
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Term
| Grey snow mould of bentgrass |
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Definition
A disease which occurs under snow cover, in cold temperatures.
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Term
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Definition
Gummosis
A symptom of a bacterial disease. |
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Term
|
Definition
A disease caused by Rhizobacterium sp.
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Term
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Definition
| A common bacterial disease in Ontario. Caused by Pseudomonas syringae pv. syringae. |
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Term
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Definition
| Emergence of nematodes from eggs. Usually involves stimulation by plant exudates. |
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Term
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Definition
| A pathogen which is somewhere between a necrotroph and a biotroph. Have a period of biotrophy followed by necrotrophy. Includes Phytophthora infestans. |
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Term
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Definition
| Annual cankers and infected buds that form on branches diseased with fire blight in the previous season. Erwinia amylovora overwinters in holdover cankers. Removal of these cankers is accomplished by inspecting and pruning trees during the winter. You must prune at least 30 - 60 cm bleow the area of infected wood. Holdover cankers can be very small. |
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Term
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Definition
A characteristic wedge-shaped V of yellowing on the leaf tips caused by the saliva of the potato leaf hopper.
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Term
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Definition
| One of the sides of the disease triangle; the host must be present, and have a degree of susceptibility. Factors include genetics, age, growth stage, population density, plant health, and susceptibility. |
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Term
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Definition
| A select group of plant hosts to which a pathogen is pathogenic. May be one host, several hosts, or many hosts. |
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Term
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Definition
| Disease is most commonly caused by bacteria, viruses, fungi, and parasites. Fungi which attack humans attack at the periphery, hair, nails, and feet. Fungi cannot take the high temperature of human body temperature. |
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Term
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Definition
| There are 795 million people undernourished in the world. Poor nutrition causes 45% of deaths in children below the age of five: 3.1 million children every year. |
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Term
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Definition
| Tiny holes in leaves through which excess water can exit the plant. Bacteria may enter through hydathodes. |
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Term
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Definition
| A level of susceptibility. The host cannot be infected by a given pathogen. |
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Term
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Definition
| A plant hormone encoded by T-DNA of Rhizobacterium radiobacter. Disrupts normal balance of cell growth of host plant, leading to production of galls. |
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Term
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Definition
| Any part of the pathogen that can initiate infection. Includes primary and secondary inoculum. |
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Term
|
Definition
| A stain which kills living organisms, preserves fungal structures, and stains chitin in fungal cell walls blue. It is toxic. |
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Term
|
Definition
A polycyclic disease.
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Term
|
Definition
| A symptom of a bacterial disease. |
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Term
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Definition
| A symptom of a bacterial disease. |
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Definition
A disease caused by Pseudomonas sp. or Xanthomonas sp.
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Definition
| A symptom of a bacterial disease. |
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Definition
| A symptom of a bacterial disease. |
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Definition
| A plant pathogenic bacteria which causes stunting. |
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Definition
| Tiny holes in tree bark, through which the tree has gas exchange. Bacteria may enter through lenticels. |
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Definition
| An environmental factor. There are some diseases in which light intensity and/or duration can affect plant or pathogen life stage. |
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Definition
| A microscope that includes low and high magnification. |
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Definition
| An environmental factor. Moisture is required for most pathogens prior to host infection. Dispersal of many plant pathogens is affected by the splashing or running of water. Most underground plant diseases increase in severity with increasing soil moisture. Some pathogens cause more severe symptoms when the host plant is water stressed. |
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Definition
"Soft skin"
Gram positive bacteria which lack a cell wall. The smallest and simplest self-replicating prokaryotes, 0.3 - 0.5 μm in size. Vary in shape. Reproduce asexually by binary fission. Resistant to antibiotics including penicillin which target cell wall formation. Usually have a smaller genome than other bacteria. Includes spiroplasmas and phytoplasmas. |
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Definition
| A disease with only primary inoculum, and no secondary inoculum. Only one cycle of growth and reproduction occurs in one growing season. Includes brown rot of stone fruits. |
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Definition
| A symptom of a bacterial disease. |
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Definition
| Symbiosis where benefit comes to both organisms. |
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Term
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Definition
| A symptom of a bacterial disease. |
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Definition
Non-obligate pathogen
A pathogen that can live on either living or dead hosts. Includes most fungi and bacteria. Can be cultured in sterile culture. |
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Definition
| Tiny holes on a plant which produce nectar. Bacteria may enter through nectaries. |
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Term
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Definition
| Inoculum are eggs, juveniles, or adults. Reproduce by producing eggs. |
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Definition
| Nematodes can enter a plant by direct penetration through stoma. |
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Term
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Definition
| Symbiosis where no benefit or harm comes to either organism. |
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Definition
| Encoded by the T-DNA of Rhizobacterium radiobacter. A unique carbon source for R. radiobacter on the outside of the gall. Amino acid derivatives, different from normal plant products. Can be used only by the bacteria as their sole carbon and energy source, providing them with a unique food source no other bacteria can use. |
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Definition
| An organism that lives on or in some organisms and obtains its food from the latter. |
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Term
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Definition
| Inoculum are seeds or plant fragments. Reproduce by producing seeds genetically different from their parent(s). |
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Definition
| Symbiosis where on organism benefits and the other is harmed. |
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Definition
| An entity that can cause a disease. One of the sides of the disease triangle; the pathogen must be present, virulent, and abundant. Factors include amount of pathogen, virulence, genetics, dispersal efficiency, survival efficeincy, ecology, and reproductive method and fitness. |
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Definition
| Causes a disease. Only relevant when talking about a specific plant host. Pathogenicity can be cultivar-specific. |
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Definition
| A technique used to identify plant pathogenic bacteria. Bacteria is inoculated onto various plant hosts, to identify species and/or pathovar of a bacteria. |
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Definition
| Bacteria that have flagella attached at various points on the cell. |
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Term
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Definition
| A plant pathogenic bacteria that is a hemibiotroph. |
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Term
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Definition
| A type of mollicute. Non-helical shape. Includes aster yellows. |
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Term
| Pierce's disease of grapes |
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Definition
A disease caused by Xylella sp.
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Term
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Definition
| Disease is most commonly caused by fungi, bacteria, viruses, and parasites. Plants are susceptible to fungi because they do not produce body heat. |
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Term
| Plant-associated bacteria |
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Definition
| Most are saprotrophs that do not harm living plants, but some are plant pathogenic bacteria. |
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Term
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Definition
| Can cause regular losses, catastrophic losses, quality reduction, secondary losses, future losses, storage losses, restricted production, costs of control, losses in natural resources, aesthetic losses, environmental losses, toxic or medical losses, and direct or indirect social and political losses. |
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Term
| Plant pathogenic bacteria |
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Definition
| Bacteria that are mostly rod-shaped, except for Streptomyces. About 1 μm wide and 2 μm long. Most have flagella and produce viscous polysaccharide slime which is important in disease development and protecting the bacteria. Bacteria are limited by ambient temperature and moisture, nutrient availability, competition from other microbes, and host health and genetics. Bacterial diseases are usually difficult to control because of rapid reproduction, easy spread, easy entry into host cells, overwintering cells are protected, and there are few effective chemical controls. The best strategy is to prevent plant bacterial diseases. |
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Term
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Definition
| An extra-chromosomal DNA fragment found in Rhizobium radiobacter cells. Leaves the cells and integrates into host plant TNA. |
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Term
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Definition
| Bacteria that have flagella attached to the end of the cell. |
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Term
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Definition
| A disease with both primary and secondary inoculum. Multiple cycles of growth and reproduction occur in one growing season. Includes late blight. |
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Definition
A disease that was disseminated from the Andes to Europe in 1840.
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Definition
Empoasca fabae
The most damaging insect pest of alfalfa in Ontario in most years. Can be a vector for viruses and mollicutes. |
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Definition
A common bacterial disease in Ontario. Caused by Clavibacter michiganens pv. michiganens.
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Definition
A disease caused by a biotroph that cannot be cultured without a live plant. A parasite.
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Term
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Definition
| Based on symptoms, presence of large numbers of bacteria at the infected area, and absense of other pathogens. |
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Term
| Prevention of bacterial disease |
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Definition
| The most effective method of controlling plant bacteiral diseases. Methods include resistant hosts, disease-free transplants and seeds, destroying infected materials, copper-based chemicals, antibiotics, bacterial antagonists, minimizing leaf wetness, eliminating vectors, sanitizing plant-handling equipment, avoiding plantint in too wet or too dry soil, avoiding storage in high moisture, crop rotation, and activated resistance. |
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Definition
| Inoculum which causes the first original infections of the season. |
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Definition
| Includes archaea and bacteria. |
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Definition
| Reproduce asexually and sexually. |
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Definition
| An eosystem service. Production of food, water, fibre, and fuel. |
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Definition
| A genus of gram negative bacteria with several polar flagella. Colonies are usually white on agar media. Some non-pathogenic species promote plant growth. Plant pathogenic species are common on foliage and fruits of plants, and in the rhizosphere, and can cause bacterial cankers and galls. Causes leaf spot, gall of olive, banana wilt, blight of lilac, canker blast, bud blast, and slippery skin, sour skin, and soft rot of onion. |
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Term
| Pseudomonas syringae pv. syringae |
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Definition
| A plant pathogenic bacteria which causes bacterial canker of sweet cherry and halo blight of bean. |
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Term
| Pseudomonas syringae pv. tomato |
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Definition
| A plant pathogenic bacteria which causes bacterial speck of tomato. |
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Term
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Definition
A disease. Symptoms in the shoot of the plant are only apparent when the plant is water stressed.
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Term
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Definition
A weed related to carrots. Can be affected by aster yellows.
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Term
| Ratoon stunting of sugar cane |
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Definition
A disease caused by Xylella sp.
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Term
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Definition
| An ecosystem service. Regulation of climate, water quality, and pollution. |
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Term
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Definition
| A level of susceptibility. The plant has properties that prevent or impede disease development by a given pathogen. |
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Term
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Definition
Used to be known as Agrobacterium sp.
A genus of plant pathogenic bacteria which cause crown gall, twig call, cane gall, and hairy root. Symptoms include galls. |
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Term
| Rhizobacterium radiobacter |
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Definition
Used to be known as Agrobacterium tumefaciens.
A rod-shaped plant pathogenic bacteria with peritrichous flagella. Found in the rhizosphere. Causes crown gall. Plasmids are a vector for genetic engineering; the Ti plasmid and T-DNA play a critical role in inciting symptoms and disease, and can be used in Agrobacterium-facilitated DNA transformation of plants. |
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Term
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Definition
Used to be known as Agrobacterium sp.
A genus of gram negative plant-associated bacteria. Rod-shaped with peritrichous flagella. Form white colonies. AN endophyte, living inside root nodules of legumes, helping plants fix nitrogen. |
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Term
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Definition
| Structures in which Rhizobium sp. bacteria live, fixing nitrogen. |
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Term
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Definition
| A pathogen whic subsists exclusively on dead organic matter. |
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Term
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Definition
| A symptom of a bacterial disease. |
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Term
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Definition
| Newly grown branches which may be greafted onto rootstock. |
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Term
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Definition
| Overwintering structures of some fungi. Tightly packed hyphae with a dark colour. Filled with melanin which can protect against UV radiation, and is slightly toxic. |
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Term
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Definition
| A plant pathogenic fungus which is a hemibiotroph. |
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Definition
| Inoculum produced from primary infections. |
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Term
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Definition
| Proposed by Ruggiero et al in 2015. Kingdoms are bacteria, archaea, protozoa, chromista, plantae, fungi, and animalia. Plant diseases may be caused by organisms from every kingdom except archaea. |
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Term
| Sherlock ® Microbial Identification System |
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Definition
| A technique used to identify bacteria. Rapid microbial identification system used worldwide. Can identify over 1,500 bacterial species. Based on gas chromatographic analysis of cellular fatty acid methyl esters. Each microorganism has a specific profile. Add-on software can identify over 2,200 microbial species by gene sequencing. |
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Term
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Definition
A common bacterial disease in Ontario. Caused by Pseudomonas sp. and Erwinia sp.
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Term
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Definition
A disease caused by Erwinia carotovora pv. carotovora. Affects stored fruits and vegetables.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Pseudomonas sp. and Erwinia sp.
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Term
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Definition
| A symptom of a bacterial disease. |
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Term
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Definition
| An environmental factor. Soil pH affects severity of plant diseases for some soil-borne pathogens. Soil pH affects pathogen and plant nutrition, which can weaken a plant. Host-plant nutrition affects the rate of growth and the state of readiness of plants to defend themselves against pathogenic attack. |
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Term
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Definition
A disease caused by Streptomyces sp.
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Term
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Definition
A common bacterial disease in Ontario. Caused by Pseudomonas sp. and Erwinia sp.
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Term
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Definition
| A type of mollicute. Helical shape. Includes stunt disease of corn. |
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Term
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Definition
| A plant pathogenic bacteria which causes potato scab. |
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Term
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Definition
| A genus of gram positive plant pathogenic bacteria that is filamentous. Have aerial chains of conidia and branching filaments, similar to fungi but smaller. Found in the soil. Many produce antibiotics. Causes potato scab, and soil rot of sweet potato. |
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Term
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Definition
A common bacterial disease in Ontario. Caused by Erwinia stewartii.
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Term
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Definition
A disease caused by a spiroplasma mollicute.
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Term
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Definition
| A symptom of a bacterial disease. Internodes are not as long, reducing plant height. |
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Term
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Definition
| Variation within a species exists in all pathogens. Different strains of a species can vary in ability to cause disease in different plant hosts, and antibiotic resistance. Symbolized as "subsp.", "ssp.", or "pv". |
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Term
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Definition
| An ecosystem service. Primary production of biomass, nutrient cycling, nitrogen fixation, and soil formation. |
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Term
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Definition
Overwintering
Pathogens may overwinter on or in the soil, in perennial plants, on vegetative propagative organs, or on or in insects. |
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Term
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Definition
| A host factor. Hosts may be immune, susceptible, or resistant. |
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Term
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Definition
| A level of susceptibility. The host can be infected by a give pathogen. |
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Term
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Definition
| The living together of two dissimilar organisms. Includes neutralism, mutualism, commensalism, amensalism, and parasitism. |
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Term
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Definition
| A technique for viewing hyphae and spores. A clean piece of clear tape is pressed onto the specimen and peeled off then examined. You cannot use a stain with this method. |
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Term
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Definition
| An environmental factor. Pathogens and plants require certain minimum and maximum temperatures to carry out their activities. When temperatures are below or above the optimum for the pathogen, but near optimum for the host, the disease develops more slowly. |
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Term
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Definition
| Propozed by Ernst Haeckel in 1886. Kingdoms include plants, animals, and protista. |
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Term
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Definition
| A plasmid in Rhizobacterium radiobacter. Includes an open reading frame, virulence region, T-DNA, and opine catabolism. |
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Term
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Definition
| A disease caused by Clavibacter sp. |
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Term
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Definition
A disease caused by Clavibacter sp.
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Term
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Definition
| DNA in the Ti plasmid of Rhizobacterium radiobacter. It moves into host DNA, and causes cell division and uncontrolled growth in the host plant. It codes for production of cytokinins, indoleacetic acids, and opines. Includes a left border, auxin, cytokinin, opine, and right border. |
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Term
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Definition
A disease caused by Rhizobacterium sp.
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Term
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Definition
| Proposed by Carl Linnaeus in 1758. Kingdoms included plants and animals. |
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Definition
| A symptom of a bacterial disease. The causal agent enters and multiplies in the xylem of the plant host, plugging water flow. The plant wilts and the shoot dies. |
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Term
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Definition
| A pathogen factor. Capacity to cause disease. |
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Definition
| Obligate intracellular parasites that lack metabolism, and are not capable of replication outside of a host. It is debated as to whether viruses are living organisms. Reproduce by replication in host cells. Can undergo recombination. |
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Term
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Definition
A disease caused by Xanthomonas sp.
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Term
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Definition
| A symptom of a bacterial disease. Dark green to black, water-soaked leasions. Occurs early in an infection. |
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Term
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Definition
A disease caused by Erwinia sp.
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Term
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Definition
| An environmental factor. Increases spread of plant pathogens. Increases wounds on host plants. Accelerates drying of wet plant surfaces. |
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Term
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Definition
| A symptom of a bacterial disease. A dense mass of shoots that grows from a single point, producing a structure resembling a broom or a bird's nest. It is mroe visible in the winter. |
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Term
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Definition
| A product which is derived from fermentation of Xanthomonas campestris pv. campestris bacteria. A colourless polysaccharide slime produced byt he bacteria to plug vasculature of the host plant. Acts as a natural stabilizer or thickener. Discovered by the USDA from experiments involving bacteria and various sugars to develop an agent similar to corn starch or guar gum. Used in food production, agriculture, cosmetics, and pharmaceuticals. Found in fake blood, toothpaste, diary products, salad dressings, and marinade sauces. |
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Term
| Xanthomonas axonopodis pv. phaseoli |
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Definition
| A plant pathogenic bacteria which causes bean blight. |
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Term
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Definition
| A plant pathogenic bacteria with several pathovars that attack different hosts. Causes black rot of broccoli, cauliflower, and other leafy vegetables. |
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Term
| Xanthomonas campestris pv. campestris |
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Definition
| A plant pathogenic bacteria which produces xanthan gum when combined with corn sugar. Attacks cruciferous plants including cabbage, cauliflower, and turnips. Causes black rot of crucifer. |
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Term
| Xanthomonas campestris pv. citri |
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Definition
| A plant pathogenic bacteria which attacks oranges and other citrus fruits. |
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Term
| Xanthomonas campestris pv. phaseoli |
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Definition
| A plant pathogenic bacteria which causes common bacterial blight of bean. Attacks bean hosts. |
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Term
| Xanthomonas campestris pv. pruni |
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Definition
| A plant pathogneic bacteria which causes bacterial spot of peach. |
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Term
| Xanthomonas campestris pv. vesicatoria |
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Definition
| A plant pathogenic bacteria which causes bacterial spot of tomato. |
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Term
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Definition
| A plant pathogenic bacteria which causes angular leaf spot of strawberry. |
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Term
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Definition
| A genus of gram negative plant pathogenic bacteria which are rod shaped. Motile by means of one polar flagellum. Colonies are yellow on agar media. All species are plant pathogenic, and cause leaf spots, vascular wilts, and bacterial cankers. Cause leaf spot, cutting rot, black venation, bulb rot, citrus canker, and walnut blight. |
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Term
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Definition
| A genus of gram negative, xylem-limited bacteria. Difficult to isolate, and require complex media for growth. Transmitted by xylem-feeding leafhoppers and spittlebugs. Causes Pierce's disease of grapes and ratoon stunting of sugar cane. |
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Term
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Definition
| When bacteria enter xylem, they can spread rapidly through the plant. |
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Term
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Definition
| Chlorosis. A symptom of a bacterial disease. |
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