Practical 4 - Protozoa, Chromista and Lower Fungi

Tutorial : Preparing slide from fungal like and lower fungi

B. Plant disease specimens.

Downy mildew of cucurbits

Disease symptom

1. Club root disease

Development of disease - The single zoospore produced from resting spores penetrates root hairs and there develops into a plasmodium. After a few days, the plasmodium cleaves into multinucleate portions and each develops into zoospore. The zoospore are discharge outside the host through pore dissolved in the host cell wall. Some zoospore fuse in pairs to produce zygotes,which can cause new infections and produce new plasmodium. These zoospores penetrate young root tissues diretly, whereas older, thickened roots and underground stems are penetrate through wounds. From thesse points of primary infections the plasmodium spreads to corticl cells and the cambium by direct penetration.when it reaches the cambium, the plasmodium spread in all directions in the cambium, outward into the cortex and inward toward the xylem.

As the plasmodium pass through cell they become established in some of the cells which are stimulated to enlarge, divide abnormally and become up to five or more times the normal size.

Caused by Plasmodiophora brassicae. Infects cruciferous vegetables such as cabbage grown in Cameron Highland.
Main symptoms of hypertrophy (enlarge of roots appearing like spindles or clubs)

2. Shoot or flower blight

Caused by Choanephora cucurbitarum. Infects chilli and various solanaceous crops such as brinjal and okra.
Symptoms include leaf defoliation, fruits and shoot rot.

3. Damping off of seedlings

Damping off due to the Pythium sp. Phylum: Heterokontophyta.Class: Oomycota.Order: Peronosporales.Family: Phythiaceae.Genus: Pythium.

4. Potato late blight

Late blight is caused by the oomycete pathogen Phytophthora infestans.

5. Black pod of cocoa

The most commonly destructive diseases of the cacao tree are pod rots. A pod rot called black pod is caused by a (Phytophthora) that spreads rapidly on the pods under conditions of excessive rain and humidity, insufficient sunshine, and temperatures below 21 °C

6. Black stripe of rubber

'Tapping panel disease syndrome affected rubber plants showing (A) Healthy – free latex flow.(B)Infected
Caused by Phytophthora palmivora.Infects the tapping panel of rubber. Black stripes in stems and causing vertical splits on the bark.

7. Seedlings dieback and patch canker of durian

Durian seedling dieback - Phytophthora parasitica

8. White rust of kangkong

The symptoms of the disease are the appearance of white or creamy-yellow pustules that can occur on the leaves, stems or flowers, but most commonly on the lower leaf surfaces. The affected parts may become thick and curl inwards. When infection is severe, the size of the leaves decreases and the plant may become stunted.

C. SLIDES

1. Plasmodiophora brassicae