Final part 2 Flashcards
Haustoria-
Specialized absorption structures produced on parasitic plants
Epiphytes:
Physiologically dependent, no chlorophyll or leaves. Ex: Spanish moss
Holoparasites: .
Dependent entirely on host; biotroph. Small leaves, scales. Contains chlorophyll.
Hemiparasites: Dependent of host for water and minerals. Contains chlorophyll and leaves.
Dependent of host for water and minerals. Contains chlorophyll and leaves.
4 major groups of parasitic plants:
- Broomrapes, holoparasite. Host: sunflower.
- Dodder, holoparasite. Host: wide range of perennials.
- Witchweeds, hemiparasite. Host: corn.
- Mistletoe, hemiparasite. Leafy Host: Hardwoods. Dwarf host: conifers
How are parasitic plants managed?
Protection: Provide adequate water and nutrients for host plant.
Avoidance: Choose planting sites where chance of parasite is low.
Exclusion: Impose quarantines.
Eradication: Herbicides, selective pruning, hand-pulling plants.
Trap crops:
: (example) host crop is planted to stimulate seed germination then plowed before weed germinate.
how is witch weed managed?
trap crops
Disease:
injurious and progressive; gets worse over time.
injury:
damage caused by transitory interaction with insect, chemical, or unfavorable environmental conditions
Winter burn:
Or desiccation, rust occurring of evergreens caused by low soil moisture, freezing temperatures and harsh winds
Sunscald:
Winter time injury to tree trunks, caused by the sun—deciduous
Etiolation:
plants grown in the absence of light.
Which minerals are most likely to be toxic?
Boron, Manganese, Copper
What is acid rain/precipitation?
Air pollutants, such as sulfur and nitrogen oxides, react with H2O to form sulfuric and nitric acids
How does acid rain affect plant growth?
Causes chlorosis, defoliation, and stunting of trees- forest decline.
What causes injury due to herbicides?
Misapplication, spray drift, movement of water, and chemical residues.
List three other causes of abiotic diseases
Excessive or deep cultivation, construction, girdling of trees by fence wire
Immunity –
Freedom from attack and injury by pathogen
Tolerance –
Ability of plant to survive effects of disease without suffering serious injury or great crop loss
Escape –
Apparent resistance
Constitutive (passive) defenses –
mechanisms are in place whether or not the pathogen is present; waxy cuticles
Induced (active) defenses –
mechanisms develop in response to attempted entry and/or establishment of pathogen; cork layers
o Tyloses –
form in xylem
Outgrowth of adjacent protoplasts
Plug xylem vessels and stop movement of pathogen
which types of pathogenss have all 3 types of variations?
parasitic plants
fungi
nematodes
Which types of pathogens have only mutation as a source of genetic variation?
bacteria and viruses
Pathogenicity –
ability of pathogen to cause disease in a plant species (virulence)
What is the gene-for-gene hypothesis?
“For each gene in the host capable of mutating to give resistance, there exists a gene in the pathogen capable of mutating to overcome that resistance.”
Mass Selection:
slow improvements, select seed of highly resistant plants in a field with natural disease infection.
Pure line or pedigree selection:
select highly resistant plants, propagate progency of each plant separately.
Recurrent selection or backcrossing:
desirable but susceptible cultivar is crossed with a resistant cultivar or wild relative.
Production of Hybrids: Cross two lines containing different genes for resistance.
Cross two lines containing different genes for resistance.
Marker-assisted selection:
Used with traditional breeding methods, use molecular biology to identify R genes on chromosomes
Genetic engineering:
Transfer of specific genes b/t organisms using enzymes and laboratory techniques instead of traditional biological crossing.
Name three methods of exclusion.
Quarantines, Pathogen-free seed, and pathogen-free propagative parts
Hypovirulence:
using a virus that infects pathogen, reducing its
Name four methods of reducing leaf wetness.
Fans, improve soil drainage, row orientation
Cross-protection:
inoculate with a mild strain of virus to protect against infection
inorganic fungicides are strictly ?
protective
2 common fungicides:
Captan and Bravo
Amphimobile:
phloem-mobile; move both upward and downward within plant.
What does FRAC stand for?
Fungicide Resistance Action Committee
What types of pathogens are killed by antibiotics?
Bacteria, mollicutes and some fungi.
Define integrated pest management
Combination of cultural, biological, physical and chemical controls.
