Practical 6: Higher Fungi - Taxanomy and Pathological Importance (Phylum Basidiomycota)

INTRODUCTION

The phylum basidiomycota is considered as the most developed group among fungi consisting among others of the mushrooms, toad tools, puffballs and stink horns. The rust and smut fungi are included although considered to be lower within the group. The rust and smut fungi are considered as plants pathogens that caused millions of losses to crops annually. Also included are the root disease pathogens that caused serious damages to many shade and other tree crops. On the positive side, many species of mushrooms are edible and contribute to the food industry.

The basidiomycota differs from the other groups of fungi in that they generally produce sexual spores called basidiospores (usually 4 in number) on a structure called the basidium. This may be formed within a fruiting body called the basidiocarp altough this may be absent in many species.

   A.      PLANT DISEASE SPECIMEN

1)      Coffee leaf rust

Pathogen: Hemileia vastatrix underside of coffee leaves (yellowish spores)

2)      Maize/Corn rust

Pathogen: Puccinia polysora on maize leaf (rust coloured pustule)

DISEASE SYMPTOM

1)      Rust

a.       Groundnut rust

Pathogen: Puccinia arachidis

Symptom: Yellowish coloured pustules on leaves.

b.    Long bean rust

       Pathogen: Uromyces vignae

       Symptom: Yellowish coloured pustules on leaves.

                     

2)      Smut

a. Corn smut

Pathogen: Ustilago maydis

Symptom: Hypertrophy of seeds on the cob.

  

b. Sugarcane smut

Pathogen: Ustilago scitaminae

Symptom: Abnormal shoots, whip like with balck spores.

3. Blister blight of tea

Pathogen: Exobasidium vexans

Symptom: Spots forming blisters on the underside of tea leaves

    

4.  Pink disease

Pathogen: Corticium salmonicolor

Infects stems of rubber, cocoa, tea, mango, coffee

Symptoms: White mycelia turning to pink in color gave disease its name. Fungus does not produce basidiocarp.

5. Horse hair blight

Pathogen: Marasmius equi-crinus

Minor problem on stems rubber and cocoa

Symptoms: Observe black, hair-like rhizomorphs.

5. White thread blight

Pathogen: Marasmiellus scandens

Infects stems of plantation crops such as cocoa and fruit tree crops

Symptoms: White rhizomorphs on stems and leaves.

6. White root disease

Pathogen: Rigidoporus lignosus

Symptoms: White rhizomorphs on roots infected by disease. Serious on rubber and cocoa. Basidiocarps (wooden brackets) formed

7. Red root disease

Pathogen: Ganoderma philippii

Symptoms: Reddish rhizomorphs on roots mainly on rubber. Basidiocarps formed on above.

                                           

8. Brown root disease

Pathogen: Phellinus noxius

Symptoms: Infects roots of rubber and cocoa. May infect damaged stems/trunk and causes upper stem rot in oil palm. Basidiocarps formed.

9. Vascular-streak dieback (VSD) of cocoa

Pathogen: Oncobasidium theobromae

Symptoms: Basidiospores formed on leaf scars during wet weather. Infects young cocoa leaves with symptoms appearance usually only 2-3 months later. Caused stunting and death of seedlings, Leaf clorosis with green islands, rough bark appearance and streaking within vascular tissues. No basidiocarps formed.

10. Bunch rot of oil palm

Pathogen: Marasmiellus palmivorus

Symptoms: Infect oil palm fruits causing rotting of the mesocarps. White rhizhomorph on leaf fronds and fruits bunches. White basidiocarps (soft and mushroom like) on rotten bunches.

11. Basal stem rot (BSR) of oil palm

Pathogen: Ganoderma boninensis

Symptoms: Rots base of palms causing tress to fall. Basidiocarps formed (wooden brackets).