当前位置:首页 >> 农林牧渔 >>

Lec 06 Tree Diseases


1 of 60

2 of 60

Can Fungi Cause Tree Diseases?
? Yes, indeed, fungi do cause tree diseases. And what is especially interesting is that in larger plants, we see some

specialization of pathogens for certain plant parts.

Lecture 06
Plant Diseases: Tree Diseases
South China Agricultural University

? Some fungi attack only roots, others only leaves, etc.

South China Agricultural University

3 of 60

4 of 60

Nightmare on Elm Street
? Yes, indeed, fungi do cause tree diseases.

The Elms (genus Ulmus)
? >30 species in genus – Asia has 23 or more – 2 spp live in tropics – 6 spp native to the northeastern U.S. ? New species are still being found in China, the center of diversity(多样性).

South China Agricultural University

South China Agricultural University

5 of 60

6 of 60

The Elms (genus Ulmus)
? >30 species in genus – Asia has 23 or more – 2 spp live in tropics – 6 spp native to the northeastern U.S. ? New species are still being found in China, the center of diversity.

The Perfect Shade Tree
? Street liners: fast-growing, easily transported, tolerant of soil compaction and different soil types. Dense canopy borne high above ground, few low branches. ? Shade, shelter: When planted in rows, they overhang the street forming a Gothic-style arch. Good for windbreaks. ? No.1 urban tree in U.S east of the Rockies, and in large parts of Europe and Asia.

South China Agricultural University

South China Agricultural University

1

7 of 60

8 of 60

The Elms
? Elms on the “old” Cornell campus

The Elms
? And then, this little beetle comes….

South China Agricultural University

South China Agricultural University

9 of 60

10 of 60

The Beetles
? Native elm bark beetle(Hylurgopinus rufipes) (above) is the primary vector in parts of the northern United States, New England, and all of Canada. ? However, temperatures below -6F kill the larvae(幼虫). ? European elm bark beetle (Scolytus multistriatus Marsh.) (below) is the major vector of the disease.

The Elms
? …and this fungus developed… ? Ophiostoma novo-ulmi, 新榆蛇口壳。 ? 无性态(粘束孢属)

South China Agricultural University

South China Agricultural University

11 of 60

12 of 60

Dutch Elm Disease
? Dutch Elm Disease(榆 荷兰病). ? The species Ulmus americana(美国白榆) is the most sensitive to the fungus. ? Caused this catastrophe throughout the American elm population of North America.
South China Agricultural University

Dutch Elm Disease
? Why “Dutch”? – First isolated in 1920 by a Dr. Schwarz in the Netherlands. ? Wilt disease that attacks elm (Ulmus ssp); caused by ascomycete fungi (genus Ophiostoma, formerly Ceratosystis). ? Vectored by beetles (fam. Scolytidae) , root graft and diseased logs.
South China Agricultural University

2

13 of 60

14 of 60

Dutch Elm Disease
? Symptoms and life cycle of the fungus

Dutch Elm Disease
? Symptoms and life cycle of the fungus

South China Agricultural University

South China Agricultural University

15 of 60

16 of 60

Life Cycle of the Disease
? Have a Saprophytic stage (in the bark, beetles emerge and carry to healthy tree) and a pathogenic stage (once introduced to a healthy host tree, moves from bark to xylem(木质部) and begins to attack. May then go back to bark to “reinfect” beetles).

Life Cycle of the Disease
? Life cycle of beetles and Ophiostoma are closely matched

South China Agricultural University

South China Agricultural University

17 of 60

18 of 60

Spread of O. ulmi and O. novo-ulmi
? Dutch Elm Disease

Arrival dates in the U.S.
? Dutch Elm Disease

South China Agricultural University

South China Agricultural University

3

19 of 60

20 of 60

Dutch Elm Disease
? Management – Plant resistant elms. – Remove infested trees. – Injection may prevent DED from spreading to nearby trees or cure trees with <15% disease.

Dutch Elm Disease
? With elms gone and the lessons of monoculture vividly etched(被侵蚀的) in our minds, replanting began… with red oak !!!

South China Agricultural University

South China Agricultural University

21 of 60

22 of 60

Oops!

Chestnut Blight
? Cryphonectria parasitica(寄生隐球赤壳)

South China Agricultural University

South China Agricultural University

23 of 60

24 of 60

Chestnut
? “… the most valuable and usable tree that ever grew in the Eastern United States.”

Chestnut Blight
? Introduction of Cryphonectria parasitica

South China Agricultural University

? In 1904, Herman Merkel, a forester at the New York Zoological Garden, found odd cankers on American chestnut trees in the park South China
Agricultural University

4

25 of 60

26 of 60

Chestnut Blight
? Introduction of Cryphonectria parasitica ? Animals and insects

Dispersal
? Ascospores are shot into the air after rain storms in the fall ? Rain (conidia)

? "rapid & sudden death of many branches stems & trees"
South China Agricultural University South China Agricultural University

27 of 60

28 of 60

How Does It Kill the Tree?
? Enters through fissures (裂缝) or wounds in the bark ? Grows in and under the bark, girdling(环割) the cambium(形成层). ? Kill the tree above the point of infection.

How Does It Kill the Tree?
? The leaves above the point of infection die, followed by the limbs. ? Within two to ten years the entire tree is dead. ? Not uncommon to find many cankers on one tree

South China Agricultural University

South China Agricultural University

29 of 60

30 of 60

Chestnut Blight
? “…a tragic(悲剧的) loss, one of the worst natural calamities(灾难) ever experienced by this nation”

Varying Outcomes: Europe
? The fungus was later introduced into Europe (for tree breeding) from America ? Moved through Europe killing European Chestnut ? However, it was observed that many trees, while infected and full of cankers, did not die...

South China Agricultural University

South China Agricultural University

5

31 of 60

32 of 60

Varying Outcomes: Europe
? Instead of sunken diffuse cankers, surviving European chestnuts had swollen cankers with evidence of "healing" along the margins.

Varying Outcomes: Europe
? Many forest pathologists began working on this healing canker ? Speculation that: – European Chestnut was less susceptible? – That the fungus had mutated? – That it was a different fungus altogether?

South China Agricultural University

South China Agricultural University

33 of 60

34 of 60

Hypovirulent Strains
? Italian and French scientists observed non-lethal cankers growing on trees in Italy (1960’s) – Found that strains of the fungus associated with the blight produced colonies of abnormal shape and pigment – Demonstrated that these strains contained some “contagious factor” responsible for the inability to produce lethal infections (i.e., Hypoviruses) ? In North America, hypovirus-infected strains have been found in stands in Michigan.
South China Agricultural University

Varying Outcomes: Europe
? Noticed that a different colored fungus was recovered from "healing cankers” ? Instead of the typical orange colored Cryphonectria parasitica fungus, a white-colored fungus was found. – White fungus was slower growing and produced fewer spores ? When you "sprayed" the white fungus on a "killing canker" the "killing canker" became a "healing canker" (Europe)

South China Agricultural University

35 of 60

36 of 60

Varying Outcomes: Europe
? Determined that the white hypovirulent(低毒性) strains had become infected with a simple dsRNA virus ? This virus was making the fungus “sick” ? A slower fungus allowed the tree to respond to a point where the tree could survive infection

Blight Control and Restoration
? Approaches: – Hypovirulent strains – Asian blight resistance – Forest management practices

South China Agricultural University

South China Agricultural University

6

37 of 60

38 of 60

Oak Wilt
? Dead oak in Austin, TX ? Kills red oaks first!

Oak Wilt
? Pictures of same oak tree taken two weeks apart

Distribution of oak wilt in 1988 (red)
South China Agricultural University South China Agricultural University

Oak Wilt
? A main way this disease spreads is through roots of adjacent trees that naturally graft to each other. So with oak wilt, you often get “infection centers” like this.

39 of 60

Oak Wilt
? Note oak wilt here

40 of 60

South China Agricultural University

South China Agricultural University

41 of 60

42 of 60

Oak Wilt
? symptoms

Oak Wilt
? Has not been found on landscape oaks in Oklahoma

Live Oak – Intervienal Chlorosis

Red Oak – Marginal Necrosis

South China Agricultural University

South China Agricultural University

7

43 of 60

44 of 60

Oak Wilt
? Management – DO NOT WOUND OAKS IN THE SPRING! – Reduce inoculum ? Eliminate infected trees and firewood – Stop below-ground spread ? Break root grafts: vibratory plow, backhoe, trencher, chemicals (VAPAM) – Intervascular injection of select trees ? Systemic fungicides
South China Agricultural University

Oak Wilt
? Lift cycle of oak wilt fungus ? Aerial view of Oak Wilt infection center moving through oak forest

South China Agricultural University

45 of 60

46 of 60

Oak Wilt
? Management – Buffer zone/trenching – Sanitation – remove infected material – Pruning – treat pruning tools with clorox – Wound paint on pruning cuts and wounds – Careful with firewood – Chemical stem injection – ALAMO – Replanting with non susceptible hosts
South China Agricultural University

Sudden Oak Death
? Phytophthora ramorum - Tan Oak Symptoms

South China Agricultural University

47 of 60

48 of 60

Sudden Oak Death
? Phytophthora ramorum - Rhododendron Symptoms

Dogwood Anthracnose
? One of the more recent catastrophic tree diseases showed up on flowering dogwood in Southeast NY in the early 1980s, first as spots on leaves…(山茱萸炭疽 病)

South China Agricultural University

South China Agricultural University

8

49 of 60

50 of 60

Dogwood Anthracnose
? It turned out that the disease was caused by a fungus(毁杀座盘 孢) new to science… ? Probably introduced to North America from somewhere in the Orient.

Tar Spot of Maple
? Rhytisma acerinum,(槭斑痣盘菌) ? 危害挪威槭的叶片,引起槭树漆斑病。子囊果在落叶 中越冬。子座扁平,线圈状排列,黑色,柏油样,由 其内部产生子囊盘。每一个成熟的子座表面特征性地 具有放射状的裂缝。春天,子座沿裂缝开裂,露出子 囊盘,释放出子囊孢子。

South China Agricultural University

South China Agricultural University

51 of 60

Tar Spot of Maple
? In a “wave year of infection” this disease can kill all of the leaves of host trees by mid-July.

Tar Spot of Maple

52 of 60

? Spots overwinter on leaves on the ground and split open the following Spring to produce spores in creamcolored “divots” like these.

Note: Only Norway maples are affected.

South China Agricultural University

South China Agricultural University

Tar Spot of Maple

53 of 60

Tar Spot of Maple

54 of 60

? First symptoms of new infection in spring: faint yellow spots

? First symptoms of new infection in spring: faint yellow spots

South China Agricultural University

South China Agricultural University

9

55 of 60

56 of 60

White Pine Blister Rust
? the nemesis of North American white pines ? blister rust cankers: sugar pine / whitebark pine

White Pine Blister Rust
? Top kill in whitebark pine

South China Agricultural University

South China Agricultural University

57 of 60

58 of 60

White Pine Blister Rust
? Widespread mortality in western white ? before...

White Pine Blister Rust
? Pruning research in sugar pine

South China Agricultural University

South China Agricultural University

真菌性检疫对象名单(1996) 真菌性检疫对象名单(1996)
? 对外检疫对象: – 榆荷兰病(Ceratocystis ulmi) – 栎枯萎病(C. fagacearum) ? 对内检疫对象: – 落叶松枯梢病(Physalospora laricina) – 板栗疫病(Cryphonectria parasitica) – 毛竹枯稍病(Ceratosphaeria phyllostachydis) – 松疱锈病(Cronartium ribicola) – 松褐斑病(Lecanosticta acicola) – 松针红斑病(Dothistroma pini
South China Agricultural University

59 of 60

60 of 60

Questions, Comments, and Complaints?

South China Agricultural University

10


相关文章:
后端基本概念
(LEC,DRC,LVS 等) 6 楼:DFT 7 楼:低功耗 8 楼:面试 9 楼:名词解释 ...并且它们之间有时序要求 预知不同 clock 会有不同的 clock tree insertion ...
更多相关标签:
oral diseases | infectious diseases | diseases | chronic diseases | avian diseases | the type of diseases | digestive diseases | structure diseases |