Plant path lab 8
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WHat are individual mass of spores called?
are survival structures as well
WHat are several masses of spores called?
- a sori
- are survival structures as well
What spores are contained in sori?
WHat phylum do smuts belong to?
- Phylum Basidiomycota
- subphylum Ustilaginomycota
What sexual spores do smuts produce
Teliospores and Basidiospores
Smut fungi are pathogens of what type of tissue?
Meristematic tissue or rapidly dividing cells
What are the three groups of smuts?
- Floral infecting smuts- Ustilago nuda
- seedling infecting smuts- Tilletia tritici
- local infecting smuts-Ustilago maydis
What conditions does loose smut of wheat and barley need?
High humidity and or rainfall in the spring while flowering
How do floral infecting smuts survive?
- as a dikaryotic mycelium in the embryos of infected seed.
- when the seed germinates mycelium grows toward the apical meristem and the hyphae colonizes the ovaries
Ustilago nuda does not form what spore type?
- Instead adjacent cells of the promycelium undergo plasmogamy to form the secondary mycelium which penetrate the ovary or stigma directly.
How does Ustilago nuda disseminate?
Once the teliospores are released from infected heads the wind disseminates them to other flowering heads where they germinate to form a promycelium.
How to control Ustilago nuda?
- Vitavax or dividend
- disease resistant cultivars
- planting uninfected seeds
Seedling infecting smuts
- Common bunt of wheat- Tilletia tritici
- infected plants produce kernels that smell like fish due to an oily compound in teliospores
- seeds look normal but are actually full of teliospores
- losses in both yield and quality
How to seedling infecting smuts survive?
as teliospores in soil or seeds
Describe the special plasmogamy of Tilletia tritici
- Teliospores germinate into promycelium with 8-16 primary basidiospores
- these basidiospores undergo plasmogamy by fusing in the middle with other basidiospores to form H-cells.
- this forms secondary basidiospores which germinate into dikaryotic mycelium.
Describe teliospores of Tilletia tritici
- they germinate as soon as moisture and temp are favorable
- do not survive for a long period of time
How to control seedling infecting smuts
- combination of disease resistant varieties along with fungicide treatments are necessary
- carboxin and difenoconazole are seed treatments
Describe local infecting smuts
- Corn smut or boil smut- Ustilago maydis
- found world wide
- galls are symptoms and are greenish white to silvery when young but darken with age
- galls fill with teliospores
- Immature galls are called huitlacoche and edible
describe local infecting smuts teliospores
- the can survive in the soil for many years
- germinate and make haploid basidiospores
- basidiospores are forcibly ejected and are wind disseminated
Describe Ustilago maydis hyphae
Different hyphae mating types fuse plasmogamy results in the formation of a dikaryotic mycelium
How to control local infecting smuts
disease resistant varieties
What causes Ergot disease?
- Claviceps purpurea-infects flowering parts
- needs cool wet climates
- infects cereals and grasses
- causes ergotism in animals
What are signs of Ergot?
- Sclerotium-replaces ovaries and usually only survive for one season in soil
- first sign is a creamy colored to golden colored honeydew that exude from flowers of infected plants
What type of spores does Claviceps purpurea produce?
Ascospores in a perithecium
What phylum does Ergot belong in?
Ergot environmental conditions
- Must have free water during flowering plus temps in the 9-15C
- release of ascospores must coincide with flowering
How to control Ergot
- Clean seed; limiting the introduction of ergot into clean fields
- crop rotations
- deep plowing
- removing weedy grasses from field borders
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