This document discusses fruit pathology, which is the study of diseases that affect fruits. It defines fruits and pathology, and explains that fruit pathology strives to understand the nature and causes of diseases in fruits. The document outlines the pre-harvest and post-harvest periods in fruit production and describes common biological and physical agents that can cause fruit diseases, such as fungi, bacteria, viruses, nematodes, pests, temperature, and humidity. It also discusses the impacts of fruit diseases, which include quality and storage life reductions and economic losses.

2. It is often said that crop diseases are not new to man. As a
matter of fact, it is as old as man, as references to crop diseases
were made even in the bible.
WHAT ARE FRUITS?
FRUITS CAN BE DEFINED AS;
the edible reproductive body of a seed plant. (Merriam Webster,
2008).
2

3. Although, botanists define fruit as;
the reproductive structure of an angiosperm which develops
from the ovary or an accessory part of the plant.
WHAT IS PATHOLOGY?
Pathology is “the study of the essential nature of diseases and
especially of the structural and functional changes produced by
them”. (Merriam Webster, 2008).
It is therefore the study of the origin, nature, cause and the
effects (symptoms) of the disease.

4. This is essentially the study of fruit disease.
MEANING OF FRUIT DISEASE
This is refers to the change in physiological, structural
and organoleptic attributes of fruit as a result of a “dis-
ease” condition brought about by various factors.
This leads to fruit production losses.

5. Therefore, fruit pathology strives to understand the nature
and cause of “dis-ease” in fruits before recommending
appropriate solutions. (Arinze, nd).
For disease diagnosis in fruit pathology,
Nature of the disease is investigated (infectious or not)
Causal agent should be identified
Mode of transmission (spread) should be known
Signs and symptoms such as wilt, fruit spot should be noted.

6. PRE-HARVEST PATHOLOGY
The pre-harvest period in fruit production spans from the
planting of the seed till maturation and harvest.
PRE HARVEST ACTIVITIES MAY INCLUDE;
Land preparation, planting, irrigation, weeding,
application of fertilizer.

7. Pre-harvest pathology of fruits therefore refers to the study of
disease condition depicted by the fruit during the period of planting
until harvest.
Diseases or disorders occurring in fruits at this stage can hinder the
fruit from reaching its potential and can influence post harvest
disease. (Joyce et al, nd).
Disease at this stage can be caused by;
Biological factors such as microorganisms , pest, weeds.
Physical factors such as temperature, humidity.

8. The post harvest phase in fruit production spans from the time of
harvest till final consumption.
POST HARVEST ACTIVITIES INCLUDE;
Harvesting, handling, storage, processing, packaging, transportation,
Marketing.
Post harvest pathology in fruit production refer to the study of
disease conditions that occur in fruits after harvest.

9. In the post harvest phase of fruit production, production loss
may occur as a result of;
Improper harvest practices
Rough handling of fruits
Inadequate storage facilities
Poor packaging
Also, wounds (trauma) caused by the above factors may pave way for
the infection of harvested fruits by microorganisms particularly
Bacteria and Fungi.

10. Specific agents of fruit disease may be classed as parasitic,
non-parasitic, or physical (Cappellini and Ceponis, 1984).
Also these agents can be classified as
BIOLOGICAL AGENTS such as pathogens (bacteria, fungi, viruses
and nematodes), animal and insect pests.
PHYSICAL AGENTS such as temperature ranges, climatic factors
and mineral availability. (Johnson et al, 2012).

11. BIOLOGICAL AGENTS; can be referred to as biotic factors influencing
disease development in fruits. They include;
Fungi: a major fruit pathogen that can cause diseases such as;
Anthracnose, this affects fruits like mangoes (Manifera indica).
Powdery mildew: which affects mostly apples (Malus spp).
Bacteria: causes diseases such as;
Bacterial canker in fruits like cherry (Prunus spp).
Bacterial spot in peach (Prunus persica).

12. Viruses; though not popularly implicated in fruit disease can cause
the following diseases;
Apical necrosis of pawpaw caused by “papaya apical necrosis virus”
Yellow spot disease of pineapple caused by “tomato wilt virus”.
Nematodes: these organisms can cause serious injuries on fruits
and this can serve as a portal of entry for other pathogenic
organisms.
Animal and Insect Pest: they cause physical harm to fruits thereby
reducing market value.

13. Fig 1: Brown disease of stone cherry. Fig 2: Anthracnose on mango
Fig 4: powdery mildew on an apple
Fig 3: Fruit spot on pear
COURTESY: THE AMERICAN PHYTOPATHOLOGICAL
SOCIETY

14. These are referred to as the abiotic factors involved in disease
development in fruits. They include;
Temperature: this can be classified as a climatic factor. Different
temperature ranges affect the keeping quality of fruits and can
make them susceptible to pathogenic attacks.
For instance, high temperature can cause “blossom end rot in citrus
fruit”. (Johnson et al, 2012).
High temperature can cause shriveling and wilting of fruits due to loss
of moisture.

15. Relative humidity: fruits primarily consist of about 70 to 95%
moisture therefore a change in this amount can affect quality.
(Arinze, nd). Therefore, relative humidity of fruits and their
environment should be considered particularly during storage.
Also, high relative humidity encourage attacks from pathogenic
organisms as microorganisms thrive in environments with relatively
high humidity.
For instance, excessive moisture can encourage the blossom end rot
of tomato. (Johnson et al, 2012).

16. Primarily, they cause disease and disorder to fruits. They cause
and/or enable the development of disease conditions in fruits.
Reduction of quality and market value especially as fruits are very
delicate products and their purchase relies on the satisfaction of
the consumer.
Reduction of storage life of fruits. Fruits being highly perishable
crops have short storage life even at best conditions. Therefore
these pathological agents further reduce their storage life. (Arinze,
nd).

17. Due to the severity of fruit production losses, various techniques
have been evolved to enhance keeping quality of fruits and in
essence, their market value. Some of these techniques are;
Conversion of fruits to juice
Preparation of preserves such as jams, marmalades, jellies from
fruits.
Pickling of fruits
Fig 5: Conserved Fruits (Fruit Juice).

18. The study of fruit pathology is essential in the
prevention, reduction and control of fruit
production losses.
It also aids in the maximizing of fruit products.

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20. 1. Merriam-Webster.com. Merriam-Webster (nd).
<http://www.merriam-webster.com/dictionary/.
2. Arinze, A.E. (nd). Plant Pathology and Post harvest food loss.
Journal of stored products, 104pp.
3. Joyce, D.C., Johnson, G.I. and Gosbee, M.J. (nd) Does Pre-harvest
Stress of Plants Affect Postharvest Decay of Their Fruit?. Disease
resistance in Fruits, 47pp.
4. Cappellini, R.A. and Ceponis, M.J. (1984). Postharvest losses in fresh
fruits and vegetables. In: H.E. Moline(ed) Postharvest Pathology of
Fruits and Vegetables: Postharvest Losses in Perishable Crops, Univ.
Calif., Agric. Exp. Sta., Bull. No. 1914 (Pub NE-87), pp. 24-30.
5. Johnson, M. and Sri .V. Chandra Sekhar. (2012). Principles of Plant
Pathology. Acharya N.G. Ranga Agricultural University.
6. Images: The American Phytopathological Society.