Mycology, Forest Pathology & Forest Protection (Mahadi)

A Sessional Report on Mycology, Forest Pathology & Forest Protection

Introduction:

Forestry is biological science and plant pathology is a useful part of forestry. Only the theoretical knowledge about plant pathology is not enough to acquire the proper object. Without direct observation nobody can learn about it. For this purpose, Sessional class and study tour are very essential for us. In Sessional class we learn how a matter is happened which is already learnt from theoretical class. Without field tour nobody can observe the happenings in the nature. Pests and diseases are common in trees and shrubs. In some cases, it is so severe that the whole ecosystem is jeopardized. Attempts are being made to control these problems. So a Sessional tour is arranged by our honorable course teacher Md. Kamruzzaman in Chittagong BFRI at 18th May, 2008.

Objectives of the tour:

To acquire knowledge about the pests and diseases of different plant species. To know about the symptoms, casual organism and their preventive measure of

different disease affected species. To observe the diseases of different species caused by fungus and insects.

Description of the tour Our honorable teacher Md. Kamruzzaman showed us the condition of different types of diseases on the way. Then they took part in short discussion about the diseases of different species, their symptoms, casual organism and their preventive measures.

Field Work Description

Pest and Diseases of different plant species

Disease: Leaf spot .

Leafs having localized area of diseased or discolored tissues. Some times dead portions of may fall of giving appearance hot is known as shot note.

Host: Dalbergia sissoo, Artocarpus heterophyllus

Pathogen Several pathogens were found responsible for causing leaf spot of Dalbergia sissoo. Causal organisms are; Cercospora sissoo Syd, Colletogloeum sissoo, phylllachora Dalbergiae Niessl. Phyllachora spissa Syd. Symptoms Cercospora sissoo attacks leaves mostly on the lower surface, producing yellowish to grayish green discoloration. Colletogloeum sissoo cause imperceptible sports on sissoo leaves. It is similar to Cercospora sissoo from which it differs only its size and number of septation of condia. phylllachora Dalbergiae causing leaf spot I sissoo and its attacks the upper leaf surface and produces shining black cushion like stomata which may occur scattered of in clusters. Phyllachora spissa attack the leaf and forms densely aggregated dot like dark stomata on irregular brownish infection. Control

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Spray with fermate solution of 2lbs/100 gallons of water is quicte effective to control the disease caused by Cercospora sissoo, Colletogloeum sissoo.

Disease: Leaf Blight

A general term to describe the shriveling and death of some or all of the foliage and young shoots of a plant.

Host: Dalbergia sissoo, mangifera indica.

Fig- Leaf Blight

Pathogen Rhizoctonia leaf web blight of Dalbergia sissoo caused by Rhizocctonia solani and amorpha of Tiamatephorus cucumeris. Another fungus named Alternaria alternate causes leaf blight on Dalbergia sissoo.

Symptoms The disease first appears on leaf close to the ground as water soaked grayish-brown blotches, which increase in size with the advancing fungal hyphye, and ultimately the fungus invades the entire leaf blade. The leaf lets show stomatoid aggregates on under surface and eventually turns brown. The infected adjoining leaf lets often join together by the fungal hyphae as if caught in a spider’s web hence the main of web blight.

Control The disease can be effectively managed through sanitation, within and foliar application of Bayleton 0.1% at 14thly intervals. Two or three application of the fungicides provides protection to the seedlings against the disease. The best control is by 0.2% Dithane M-45 and phenolmercry acetate, which both eliminated both the disease.

Disease: Canker

Canker may be localized death of stem tissues with a sunken dead center and raised margin. Canker may be annual or may persist for several years.

Host: Kanthal.

Pathogen: Nectrai haentatococca.

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Symptom The canker on jackfruit trees strat as blackening of barck generally at the bases of small dead branchlets. The dead area gradually expands and this is followed by light brown discoloration and death of sap wood underneath. As the tree increases in girth, the canker affected portion fails to add any new growth, and a depression usually develops. On the bark of the dead area small, rounded, reddish-yellow fruit bodies of Nectrai haentatococca develops profusely during the moon soon.

Control Naturally canker may be controlled through callus tissue formation. And the callus

tissue comes from the cambium tissue of the bark. Fungal attack on the surface of the canker can be controlled by using fungiside.

Disease: Wilt Disease

Wilting is characterized by loss of turgidity and collapse of leaves.

Host: Dalbergia sissoo.

Pathogen: Fusarium solani, Fusarium dalbergiae

Fig: Agaricas

Symptoms1. Yellowing and dying of leaves in acropetal succession in older trees.2. The leaf drop-off, rendering the branches increasingly bare.3. Affected tree dies within three months.4. The outer sapwood exhibits a characteristics pink strain. And the strain may extend up

the stem to about 3m from the ground.

Control

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1. In the sissoo plantation wilt disease can be controlled by increasing moister content of the soil by irrigation. During the irrigation land should not be under water continuously, since aeration is necessary for the healthy growth of roots of sissoo.

2. Elimination of the pathogen from the soil is not possible either chemically or by crop rotation. Proper selection of site having light textured soil with adequate soil moisture and good drainage is important for raising plantations free from wilt disease.

Disease: Die- Back

The major cause for the death of the trees in the plantation is fungi mainly, Ganoderma lucidium, Polyporus spongiosum and Fusarium oxysporum. Bacterial rots and several other fungi were also found, but there were not primarily involved in killing the plants.

Host: Mango

Pathogen: Ganoderma lucidum

Symptoms The die-back disease has more specialized symptoms than wilt. The die- back of trees take place by successive stages, the symptoms being thinning

of leaves and crown, drying up of the ends of the branches, table topped condition and stage-headedress in extreme cases small dry twigs keep on falling continuously, leaders dry up and the tree looks like a blunt stub containing thick branches.

Control For controlling the disease the following measures should take place

Select resistant strains of the plant and its parts for breeding and propagation. Bordeaux paste (50%lime +50% copper sulphate+water) should be painted on

the fresh cut surfaces of the trees.

Fig- Fruit Body

Disease: Chlorosis Partial or complete absence of normal green colour of leaves and presence of yellowish colour throughout the surface but leave veins are remain green colour.

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Causes Usually chlorosis is occurred due to

o O2 deficiencyo Virus attacko O3 pollution

Disease: Bamboo Blight Bamboo blight is a disease of the culms where the main symptom is a die back. The blight first affects new culms but has been briefly continues in older ones. The best time for observing bamboo blight is from September to December. Host.Bambusa balcooa( Bhaijja).

Pathogen: Sarocladium oryzae

Symptoms1. Mortality of Bamboos, particularly those in the village groves, mainly occur in two

stages-i. Mortality of very young emerging culms generally within heights of 40

cm andii. Mortality of newly growing culms which attain heights of about 1m to

5m.2. Blight significantly affects culms in August.3. Due to discoloration and decay, break down at the maximum point of decay.4. Wet rotten patches may develop on the inter nodes.5. The newly growing culms fail to develop.6. Light brown to brown discoloration of the newly growing culms.7. Discoloration may occur at the top or at the soil level.8. One year old truncated bamboo shows the presence of light brown transition zone of

advancing infection on the rind of the culms.9. Splitting of such portion of the culms would reveal the presence of fine thread like

whitish mycelia of a fungus.

Control The bamboo blight can be controlled to a large extent by improving culture practices such as removal of blighted culms, burring debris in situ in culms in April and adding new soil in and around clumps in April-May, before the onset of monsoon and by the application of a fungicide Dithane-M 45 as a soil drench.

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LAB WORK

Isolation method of fungi from the disease and healthy specimens:

Apparatus: Petridishes, spirit lamp, beakers, knife, forceps, scalpels, fluxes, tissue paper, needles, piece of wood, cotton etc.

Chemical:

Streptomycin sulphate, Malt, Agar powder, Sufficient distilled water, rectified spirit etc.

1. Sterilization of Laboratory Glass wares:

Petridishees were washed and then fully dried. After wrapping them with paper and

placed into the metallic containers. The container along with petridishes, beakers and fluxes,

tissue paper etc needed for isolation was sterilized by autoclaving for 20 minutes at 15psi at

121oC temperature. Other laboratory equipment such as knife, forceps, scalpels etc. was

sterilized with rectified sprit and subsequent burning over flame of a spirit lamp. The

chamber (laminar Air flow) in which the sterilized inocula were placed and other transferring

works were done was also sterilized with Ultra-violet for at least 30 minutes. The bench was

also wiped with cotton soaked in rectified spirit. The hands were wiped with cotton soaked in

rectified spirit up to the elbow.

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Fig: laminar Air flow

2. Preparation of culture media

Cultivation of fungi is an important tool for studying their nutritional requirements,

response to physical, chemical and biotic environments and also for proving their

pathogenicity on specific host plants. The selection of a satisfactory media for stimulating

growth and sporulation of particular fungus is important. Any rich carbohydrate source will

support fungal growth but PDA (Potato Dextose Agar), MA (Malt Agar), Corn Meal Agar;

Oatmeal Agar etc. are the most commonly used media.

2% MA has been used in our experiment. For the preparation of 2% MA agar media 20gm of

malt, 20gm of agar powder and 1Liter water were used. At first malt was added into water

and boiled until dissolved. Then agar powder was added into the suspension and boiled.

Media was then autoclaved for 20 minutes at 15 p.s.i at 120 º-125 ° C temperatures. We

stored this media in refrigerator for further use.

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Fig ;Incubetor

3. Prevention of Bacterial Contamination

The inhabitation of bacterial contamination and growth is a major problem in

culturing fungi. This problem was overcome by using antibiotics such as streptomycin

sulphate 0.075% solution, which was added to the media just before pouring the media on the

petridishes

4. Preparation of Inocula from selected samples

The diseased samples (Leaf blight of Mohua) were sterilized. Then the inocula were

cut from the sterilized samples by the sterilized knife. The inocula were about 1 mm to 1.5

mm in size. All the above mentioned works were done into the sterilized chamber.

Fig: Leaf blight of Mohua

5. Planting of Inocula8


After cutting the inocula from the sterilized samples, the inocula were placed on the

sterilized media that was previously poured and solidified into the sterilized petridishes. The

whole works were done into the sterilized chamber in order to conduct a Bacterial

contamination free experiment. The inocula were put on the media with the help of sterilized

forceps about 1cm far from the edge of the Petri-dishes.

Infected plant Sections from margin Sterile forceps Tissue sections Sections are of lesion placed in used to transfer blotted with placed on nutrient

10% Clorox for sections sterile paper medium in petri Different durations towel to remove dish clorox excess

Sections placed on in correct immersion A pure culture of the pathogen is obtained by nutrient media in (e.g.90º) only the subculturing a segment of the pathogen order of immersion pathogen survives growth in the previous plate into a new plate time in clorox in center of section with nutrient medium. & grows out of tissue

Fig-5: Preparation of solid media in petri dishes and the test tube slants.6. Isolation of fungi

Fungal pathogens may be isolated from leaves as illustrated in figure. 5-10 mm2

sections are cut from the margin of the dead portion of leaf and placed in a sterilized media.

If we used several sections then the duration in the sterilizing solution can be varied. This

may increase the chance of obtaining a section free of contaminants. Sections are then

removed with sterile forceps and blotted dry on sterile paper. If they are put directly on

nutrient medium it may prevent germination or growth of pathogen spores or hyphae.

Sections are then placed on nutrient medium and incubated. Those that yield only one fungus

are likely to yield the pathogen. A small portion of the fungal growth from this section can be

transferred to new plate of culture media,

producing a pure culture.

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Conclusion:

Bangladesh is a small country with heavy population. On the other hand our forest

resource is not sufficient to fulfill our present demand. The sessional work which we have

done helps us in properly identifying the fungal attacks on the part of the body of the plant

species. Through this work we have been cleared about the method of find out the fungal

diseases of plants. By the application of this knowledge we will able to provide proper

treatment of the fungal diseased plants. As a results our forest resources will be increased.

References1. Rahman, M.A. 1981, Bamboo blight in the village groves of Bangladesh.2. http//helios.bto.ed.ac.uk/bto/microbes/armill.htm#Enzymology.3. Blanchard, R.O. and Tatter, T.A. field and laboratory guide to Tree physiology,

Academic Press, New York, London.

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Documents

Mycology, Forest Pathology & Forest Protection (Mahadi)