Stewarts Wilt of corn

1
(No Transcript)
2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
Stewarts Wilt of corn Erwinia stewartii
Blight phase Seedling phase
Flea beetle
8
Stewarts wilt forecast
Winter temperature index sum of average
temperature (F) for December, January, and
February.
9
Sources of Primary InoculumMandate Control
Principle and Tactics
Fungi Oomycetes Bacteria
All Pathogens
Soil
Seed
Viruses Bacteria Fungi
Living plants
Host residue
Viruses Phytoplasma
Viruses Phytoplasma
Vectors
Weeds
10
Long-Term Survival of Plant Pathogens
Inoculum forms of pathogens are subject to
predation, antibiosis and parasitism
Chlamydospores
Oospores
Sclerotia
11
Survival of Pathogens host residue
12
Early Blight of PotatoPathogen survival in host
residue
Mycelium and conidia in host residue
Conidia
13
Apple Scab Management to reduce primary
inoculum in leaf litter

• Pathogen survives in leaf litter on orchard floor

14
Brown stem rot (BSR) of soybean Phialophora
gregata (PG)
Adee and Grau Pl Dis 1995
15
(No Transcript)
16
Brown rot of apple Monilinia fructicola
17
(No Transcript)
18
Verticillium by Vine Removal Fall 2004
Vine Removal
No Vine Removal
19
Marketable Yield by Vine Removal 2004
No Vine Removal
Vine Removal
20
Control of Dutch Elm Disease Sanitation
21
Cultural Practices -Focus on inoculum prune
branches with cankers to remove inoculum of
Erwinia amylovora
Cankers provide primary inoculum in spring
22
Peach shoot blight Phomopsis sp.
23
Impact of pruning on shoot blight of peach
(Phomopsis)
No pruning
pruning
24
Eradication of inoculum in host residue removal,
crop rotation or burial
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
Effect of deep plowing on lettuce drop and
spatial pattern of S. minor
31
Early leaf spot of peanut Cercospora arachidicola
32
Strip tillage
33
Early leaf spot of peanut Cercospora arachidicola
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
Diseases of Perennial Hosts
Powdery Mildew of GrapeUncinula necator
Downy Mildew of GrapePlasmopara viticola

• Why heavy reliance on fungicides?
• Social
• Preferred varieties are susceptible
• Epidemiological
• Close association between host and
• pathogen
• Sanitation has limited value for polycyclic
  diseases timing of arrival, not density of
  primary
• inoculum most important

Apple Scab Venturia inequalis
39
Tuber soft rot caused by Erwinia carotovora in
relation to calcium content From Soilborne Plant
Pathogens Management of diseases with macro-
and microelements (APS Press, 1989)
40
Tuber soft rot caused by Erwinia carotovora in
relation to calcium content