PWANI UNIVERSITY
NAME
:
IDDI KHAMISI CHUMA
REGNO
:
E37S/PU/3155/15
COURSE
:
BACHELOR OF EDUCATION SCIENCE
UNIT CODE
:
SZL B 404
UNIT TITLE :
APPLIED MICROBIOLOGY
TASK
:
SYMPTOMS OF FUNGAL INFECTION IN PLANTS
LECTURER
:
DR. MWAFAIDA
INTRODUCTION
A plant disease is any abnormal condition that alters the appearance or a function of a plant. This is
caused n by infectious fungi, bacteria, viruses and nematodes or by non-infectious agency such as sun
burns and mineral deficiency. Fungi infections accounts for 85% of plant diseases as they are widely
spread and more destructive compared to any other disease of plants. Fungi cause significant low plant
yields followed by reduction of crop quality and short life spans of plant due to death or changes in
biological processes such as assimilation, respiration enzyme activities and impairment in growth and
development. Individual species of fungi can parasitize one or many different kinds of plants.
SYMPTOMS OF FUNGAL INFECTIONS IN PLANTS
Symptom is defined as the changes brought about in the plant as a result of interaction of the plant, the
pathogen and prevailing environmental conditions. Sign, compared with symptom, is the pathogen seen
on the host plant. Symptoms caused by fungal pathogens mainly differ from the symptoms by rest of the
pathogens. These symptoms can be broadly categorized as following depending upon the processes
involved in the appearance of disease symptoms on the host.
a.
Necrotic symptom
These symptoms involve the death and destruction of plant tissues resulting in brittle appearance of the
tissue. All the symptoms in this category involve the necrosis of the tissue from the reaction with the
pathogen and result in the formation of dead cells and tissues.
The fungal pathogen in this case when reaches the host surface secrets enzymes which kill the tissue and
then digest the nutrients from the dead tissues, conversely the tissue death may also occur as a result of
the hypersensitive response (HR) which is the defense mechanism of host against the establishment and
spread of the pathogen on host. In any case, the symptoms produced can be either localized (at the point
of infection with host) or systemic (spreading though out the foliage, or stem, or entire plant). Following
symptoms involve death and destruction of host tissue as a result of pathogen infection.
i.
Leaf Spots
: These are the localized lesions produced on the leaves of the host plants as a result of
pathogen infection. Such as
Cercospora species and Alternaria species
Cercospora leaf spot (with shot
holes) on Plum leaf
ii.
Shot hole
: The dead tissue on the leaves falls out leaving behind holes. This symptom is common
