Practical 6 - Higher fungi (Basidiomycota)

Preparing slide from fungal culture (Basidiomycota)

INTRODUCTION

The Phylum Basidiomycota is the most developed group of fungi. They can causes millions of losses to crop anually but also can contribute to the food industry as many species of mushrooms are edible.

A. PLANT DISEASE SPECIMENS

(i) Coffee leaf rust

Observation: Yellowish spores of Hemilea vastatrix on the underside of coffee leaves.

(ii)  Maize/corn rust

Observation: Rusted coloured pustules caused by Puccinia polysora on maize leaves.

 DISEASE SYMPTOMS

 (i) Rust

Groundnut rust caused Puccinia arachidis.

Long bean rust caused by Uromyces vignae.

(ii) Smut

• Corn smut caused by Ustilago maydis.
• Symptom of hypertrophy of seeds on the cob.
• Sugar cane smut caused by Ustilago scitaminae
• Abnormal shoots, whip like with black spores.

(iii) Blister blight of tea

• Caused by Exobasidium vexans.
• Symptoms of spots forming blisters on the underside of tea leaves.

(iv) Pink disease

• Caused by Corticium salmonicolor
• Infects stems of rubber, cocoa, tea, mango, coffee, etc
• White mycelia turning to pink in color gave disease its name.
• Fungus does not produce basidiocarp.

(iv) Horse hair blight

• Caused by Marasmius equicrinus.
• Minor problem on stems of rubber, cocoa, etc.
• Observation: black, hair-like 

(vi) White thread blight

• Caused by Marasmiellus scandens
• Infects stems of plantation crops such as cocoa and fruit tree crops etc. 
• White rhizomorph on stems and leaves

(vii) White root disease

• Caused by Rigidoporus lignosus.
• Symptoms: white rhizomorphs on roots infected by disease
• Serious on rubber and cocoa

(viii) Red root disease

• Caused by Ganoderma philipii
• Symptom: reddish rhizomorphs
• Mainly on rubber

(ix) Brown root disease

• Caused by Phellinus noxius 
• Infects roots of rubber and cocoa 
• May infect damaged stems/trunk and causes upper stem rot in oil palm

(x) Vascular streak dieback (VSD) of cocoa

• Caused by Oncobasidium theobromae
• 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 chlorosis with green islands, rough bark appearance and streaking within vascular tissues.
• No basidiocarps formed.

(xi) Bunch rot of oil palm

• Caused by Marasmiellus palmivorus 
• Infects oil palm fruits causing rotting of the  mesocarps
• White rhizomorphs on leaf fronds and fruit bunches
• White basidiocarps (soft and mushroom like) on rotten bunches

(xii) Basal stem rot (BSR) of oil palm

• The most serious threat to oil palm growing industry in Asia
• Caused by Ganoderma boninense
• Rots base of palms causing trees to fall

B. SLIDES

(i) Puccinia graminis

• Caused wheat rust
• Stages in the macrocyclic life cycle:

Stage 0: spermogonium and receptive hyphae on barberry leaf.

Stage 1: aecium and aeciospores on barberry leaf.

Stage 2: uredium amd uredospores on wheat stems/leaves. Stage that shows the rust symptoms.

Stage 3: telium and teliospores on wheat stems/leaves. The basidiospores are formed in stage 4 on wheat, and this subsequently infects barberry.

(ii) Ustilago maydis

Teliospores (black spores, roundish and spiny)

(iii) Exobasidium vexans

The tea leaf sections showingparts where bliisters are formed on the undersides of leaves.

(iv) Coprinus

Basidiocarp (soft) of mushrooms

(v) Section of basidiocarps

The section of basidiocarps (hard brackets) of most root disease pathogens such as Rigidophorus and Ganoderma sp.

C. DISEASES CYCLE

Puccinia graminis tritici

Hemileia vastatrix

Ustilago maydis