Doc Code USTPC-CA-QF-01

University of Science and Technology Edition # 02

of Southern Philippines – Claveria
MOSCAT, Claveria 9004, Misamis Oriental Page No. 3
Website: http://claveria.ustp.edu.ph; Email: Effectivity 1ST Sem
claveriacampus@ustp.edu.ph SY 2021-2022

OFFICE/UNIT
COLLEGE OF AGRICULTURE
SUBJECT LEARNING ACTIVITY IN CROP PROT 111

Name: Mariel A. Caylan Course & Year: BSA 1A

Date Performed: September 25, 2021 Date Submitted:
-------------------------------------------------------------------------------------------------------------------------------
IDENTIFYING CAUSES AND SYMPTOMS OF PLANT DISEASES
Performance Task # 3
I. Introduction:

The normal physiological functions of plants are disturbed when they are affected by pathogenic
living organisms or by some physiopathogen. As disease progresses, it follows a disease cycle. Along the
way, there are signs, symptoms and syndrome that are manifested by the host plant.

II. Learning Objectives: At the end of the week, you should have:

1. Identified and characterized the causal organisms of plant diseases;

2. Differentiated symptoms, signs and syndrome;
3. Described the general symptoms of plant disease;
4. Characterized specific symptoms and signs of plant disease; and
5. Classified plant diseases.

III. Materials: diseased plants and plant part; hand lens, notes, pentel pen, masking tape, cutter, internet

IV. Learning Activities:

1. Diseases are caused by biotic agents. These biotic agents differed in their mode of attack and
symptoms in plants. In the table below, you are to fill out the needed information.
Table 1. Characterization of causal organisms
Microorganism Mode of Attack Characteristic symptoms
Bacterial pathogens infect plants
through natural openings such as
stomata, lenticels, hydathodes, leaf spots, blights, wilts, scabs, cankers
nectar-producing glands, and leaf and soft rots of roots, storage organs
Bacteria scars, which are mostly caused by and fruit, and overgrowth.
poor weather conditions, people,
tools and machinery, insects, and
nematodes.
Plants are affected by them
 because they destroy cells and/or
put them under stress. Infected  Birds-eye spot on berries
seed, soil, agricultural debris, (anthracnose)
adjacent crops, and weeds are all  Damping off of seedlings
sources of fungal diseases. Fungi (phytophthora)
Fungi are transmitted by wind and  Leaf spot (septoria brown
water splash, and also by spot)
animals, people, machinery,  Chlorosis (yellowing of leaves)
tools, seedlings, and other plant
material passing through
contaminated soil.
Nematodes that damage plants' Most symptoms associated with plant
roots, stems, leaves, and flowers nematodes are the result of
are classified as plant parasitic insufficient water supply or mineral
nematodes. Stylets are piercing nutrition to the tops: chlorosis
mouthparts found in all plant (yellowing) or other abnormal
parasitic nematodes. The coloration of foliage, stunted top
Nematode presence of a stylet is the most growth, failure to respond normally to
important diagnostic fertilizers, small or sparse foliage, a
characteristic that differentiates tendency to wilt more readily than
plant parasitic nematodes from healthy plants, and slower recovery
other nematodes. from nematode infection.

Algae suffocates plants, blocking Algal leaf spot is characterized by

light and preventing nutrients cushion-like spots on the leaf surface
Algae and CO2 from flowing through that are grey, green, brown, or orange.
the leaves. The plants in Some hosts may also have diseased
aquariums with a lot of algae will twigs and branches with reddish
eventually die. brown fruiting bodies that are girdled
and stunted.

2. A diseased plant may exhibit abnormalities. These could be symptoms, signs or syndrome. Try to
give a difference between these three terms.
Answer: A visible effect of diseases on the plant is known to as a symptom of plant disease. A
noticeable change in color, shape, or function of the plant as it responds to the pathogen could be one
of the symptoms. While a sign of plant disease is physical evidence of the pathogen. On the other hand,
syndrome is the sum of the effects which one disease has on a host, whether they occur simultaneously
or sequentially, and whether or not they are visible to the unaided eye.

3. Although, plants exhibited different symptoms, they could be grouped into five general
symptoms. Examine at least 15 plant parts that you were required to bring in the laboratory.
Group them together based on general symptoms. Assign number to your specimen for ease of
defense.

Table2. General Symptomatology

Plant Picture Description of symptoms General Symptoms
No.

The color of the leaf

1 changes from yellowish Necrotic Symptoms
to brownish.

Yellow spots are seen in

2 the leaf. Necrotic Symptoms

The leaf is wilted and has

3 a yellowing and browning Necrotic Symptoms
spotty hue.

Leaves are wilted, have a

4 brown color. Necrotic Symptoms

5 Leaves are wilted. Necrotic Symptoms

Certain leaves are wilting,

and the color of some
6 leaves has changed from Necrotic Symptoms
green to yellowish and
brownish.

Leaves have holes and

7 slits, have a leaf that have Necrotic Symptoms
a color light brown.
 Some leaves have wilted,
8 some leaves have Necrotic Symptoms
changes of color which is
the color brown.

The plant was completely

9 dead. Necrotic Symptoms

Some leaves have been

wilted, color changes
10 from green-violet to Necrotic Symptoms
brown.

Color changes of leaves

11 from green to yellow. Necrotic Symptoms

Some of the leaves have

become wilted, while
12 others have changed Necrotic Symptoms
color from green to
yellow and brown.

Leaves have seen holes

13 and slits. Necrotic Symptoms

The plant has withered in

14 some parts. Necrotic Symptoms

There are several holes

15 and slits in the leaves. Necrotic Symptoms
4. Based on the general symptoms you had described above, give the specific symptom of the
disease. Sequence your answer based on the order above.

Table 3. Diagnosing the symptoms

# Specific symptoms # Specific symptoms
1 Yellowed Leaves 9 Wilted
2 Yellowed Leaves 10 Dieback
3 Dieback 11 Yellowed Leaves
4 Wilted 12 Yellowed Leaves
5 Dieback 13 Leaf Holes
6 Yellowed Leaves 14 Wilted
7 Leaf Holes 15 Leaf Holes
8 Dieback

5. The causal organisms could be identified based on the proof of their presence. These we call
as signs. Identify the presence of the following pathogens.

Table 4. Signs of Pathogen

PATHOGENS SIGNS
 Leaf rust (common leaf rust
in corn)
Fungi  Stem rust (wheat stem rust)
 Sclerotinia (white mold)
 Powdery mildew

 Bacterial ooze
 Water-soaked lesions
Bacteria  Bacterial streaming in water
from a cut stem

 None – the viruses

Virus themselves can’t be seen

Parasitic Green Algae  Often found on the leaf

surface in the form of burnt-
orange to brown spots.

6. Diseases could be classified based on the plant part they infect. Try to classify these in your
own way and give at least one example.

Table 5. Classification of plant diseases

Plant part affected Classification of plant disease
The leaves are yellowish to brown in color Biotic Disease
and have several holes in it.
VI. Question:
1. Differentiate the effect of biotic and abiotic agents of plant diseases.
Answer: Abiotic diseases are non-infectious and do not spread from plant to plant, but
they are frequent and should be addressed when assessing the health of any
plant. While biotic disease is an infectious disease produced by living organisms. They
are classified as plant pathogens when they infect plants.

2. How are you going to minimize the effects of physiopathogen. Cite example to your
answer.
Answer: There are a few things that may be done to reduce the physiopathogen's
effects. These may be done by finding or creating a well-balanced soil and maintaining the
health of your plants by regular watering, mulching, trimming, and fertilizing.

VII. References:
https://www.canr.msu.edu/news/
signs_and_symptoms_of_plant_disease_is_it_fungal_viral_or_bacterial
https://mrec.ifas.ufl.edu/lso/SCOUT/Nematodes.htm
https://www.researchgate.net/publication/29744576_Cephaleuros_Species_the_Plant-
parasitic_Green_Algae
https://cropwatch.unl.edu/soybean-management/plant-disease
https://www.bbg.org/gardening/article/disease_prevention

VIII. Assessment: