Stem Rusts - Intro

Stem Rusts - Intro
- Overview of Rusts
  - a class of Basidiomycetes - (Uredinomycetes)
  - obligate parasites
  - sneak entry (=Ninja) & no host defense response
  - host vigour
  - most require alternate hosts
    - primary/ aecial
    - secondary/ telial
  - up to 5 spore stages
- Generalized Life Cycle (DSB)
  - basidiospores (1n)
    - generally thin-walled - short distance
    - infects 1º host
    - via stomata or new epidermis (never periderm)
    - inter-cellular mycelia (btwn host cells)
    - haustoria - penetrate cell wall, not membrane, osmosis
    - haustoria - penetrate cell wall, not membrane ... osmosis
  - pycniospores (spermatia) "start of sex"
    - not 'infective spores'
    - fertilization - "start of sex" - creates a dikaryon
    - insects
    - bring + to - (visa versa)
  - aeciospores (dikaryotic)
    - blister-like structures under the "skin"
    - thick-walled - many km
    - infect 2º host - inter-cellular mycelia & haustoria
  - urediniospores (still dikaryotic)
    - orange pustules on leaf - "rust"
    - quick 'cycling time' - week(s)
    - many cycles over the summer
    - increases infection on 2º host
  - teliospores (2n) - "sex finally finished ... whew!"
    - two 1n nuclei fuse ... 2n
    - may overwinter
    - produce 4 basiospores (1n)
- Stem Rusts Overview
  - Native
    - Endocronartium - DSG
    - Cronartium (DSS, DSC, DSF) - hard pines
  - Introduced - DSB
    - Asia - Europe - NA (NY-05, BC-10)
    - by 1960's - range of hosts (soft pines)