27342 - Plant Pathology and Pathometry

Learning outcomes

Students will acquire knowledge on: 1) the general bases of plant diseases caused by biotic and abiotic agents; 2) major infective crop diseases with severe economic impact; 3) the measurement of disease symptoms; 4) principle of disease control in according to the recent legislation of integrated or biological disease management.

Course contents

A) Prerequisites

Students attending this course will have good knowledge of plant biology physiology, agricultural genetic and microbiology. Such skills are provided by the courses of the first and second years.

B) Teaching Units

1. General plant pathology
2. Plant disease measurement
3. Principles of disease control
4. Specific plant diseases and their control

1. General plant pathology (total teaching unit 15 hours)

Introduction to plant pathology (2 hours) - Fundamental concepts. Disease definition and the concept of plant disease. Differences between disease and damage. Economic and social importance of plant disease. Infectious and non-infectious diseases. Differences between symptom and sign of disease. Morphological and physiological alterations. 

Symptoms (1 hour) – Localized and systemic, specific and non-specific, internal and external. Types of symptoms: discolouration, changes in size and shape, necrosis, stunting.

Diagnosis (1 hour) - Visual analysis of symptom appearance on plant and on crop in the field. Gathering of information of agronomic and climatic conditions during crop cultivation. Collection of symptomatic samples. Observation of samples. Koch's postulates.

Disease classification (1 hour) – Etiological criterion: biotic and abiotic diseases. Pathophysiological criterion: epiphytic diseases, trophic diseases, necrotic diseases,  auxonic diseases, vascular diseases, lytic diseases and wood diseases.

Pathogenesis (2 hours) - Disease cycle: inoculation, spore germination, infection, production and dispersal of inoculum, winter survival. Monocyclic and polycyclic diseases. Endemic and epidemic diseases.

Pathogens (6 hours) - Morphological, biochemical and biological features of fungi, bacteria, oomycetes, viruses, and phytoplasmas. Biotrophic and necrotrophic pathogens. Quarantine-listed pathogens.

Plant (host)-pathogen interaction (2 hours) - Non-host plant, incompatibility or host resistance, compatibility. How plants defend themselves against pathogens (pre-existing and induced defences).

Knowledge acquired in the teaching unit 1:

Specific terms to use in plant disease description.

Different type of plant pathogens and main characteristics.

Disease cycle phases in relation to the pathogen, the environmental factors and vegetative plant phases.

Main diseases and alterations caused by abtiotic factors.

2. Plant disease assessment (4 hours)

Methods of disease assessment. Incidence, severity and economic threshold of the disease. Disease indexes. EPPO standards.

Knowledge acquired in the teaching unit 2:

Usefulness of plant disease assessment.

Calculation of disease incidence and severity.

3. Principles of disease control (7 hours)

Fundamental concepts (1 hour) – Importance of plant disease control in relation to economic and environmental sustainability and to healthy crops. Possibility to reduce disease severity by action on the pathogen, the environment and on the plant. Concept of integrated disease management.

Cultural practices to prevent diseases (2 hours) - Crop rotation, tillage, fertilization, irrigation, selection of the cultivar(s) and site of cultivation, plant and soil management, pruning. Methods to prevent the spreading of soil-pathogens.

Phytosanitary products (2 hours) – Meaning of the term "phytosanitary product". Short background on the law rules of plant protection products (Reg. CE n.1107/2009, Dir. CE n. 128/2009, D.Lgs. n. 150-14/08/2012, Reg. CE n. 396/2005). About the National Action Plan (PAN) for the sustainable use of phytosanitary products. Label and formulation of products. Toxicological classification of substances  (CLP Reg. CE n. 1272/2008).

Characteristics of fungicides (1 hour) – Specific terms to use in plant disease control. Preventive and curative fungicides. Pre-harvest interval. Maximum level of residue. Re-entry interval. Modes and mechanisms of action. Resistance of pathogens to fungicides.

Short classification of fungicides (1 hour) - Inorganic: copper, sulphur and carbonates. Organic: dithiocarbamates, phtalimides, BSI, QI, SDHI, anilinopyrimidines, CAA, fenilamides, acetamides, and phosphonates. Mechanism of action of main groups.

Natural Phytosanitary products (2 hour) - Natural substances. Fungal and bacterial microorganisms for plant disease control. Mechanism of action of antagonistic microorganisms.

Other control means (1 hour) – Steam soil treatment, solarization and biofumigation.

Knowledge acquired in the teaching unit 3:

Principles of plant disease control.

Different control methods.

Principles of integrated and biological disease managements.

Knowledge of law rules of plant protection products.

4. Specific plant diseases and their control (7 hours)

This part develops main diseases of important crops, their symptoms, epidemiology and basic elements of control measures.

• Grapevine (2 hours)

Downy mildew (Plasmopara viticola), grey mold (Botryotinia fuckeriana, an. Botrytis cinerea), powdery mildew (Uncinula necator, an. Oidium tuckeri), yellows disease and blackwood disease by phytoplasmas.

• Pome fruits (2 hours)

  Apple scab (Venturia inaequalis, an. Spilocaea pomi), apple powdery mildew (Podosphaera leucotricha, an. Oidium farinosum), pear brown spot (Pleospora herbarum, an. Stemphylium vesicarium), pear bark canker (Valsa ceratosperma, an. Cytospora vitis), fire blight (Erwinia amylovora).

• Stone fruits  (1 hours)

  Peach leaf curl (Taphrina deformans), twig cankers (Fusicoccum amygdali, syn. Phomopsis amygdali) and brown rot (Monilinia spp., an. Monilia)

• Herbaceous crops (1 hour)

  Potato and tomato late blight (Phytophthora infestans), tracheomycosis (Fusarium oxysporum f.sp., Verticillium spp.), bacterial leaf spot of tomato (Xanthomonas campestris pv. vesicatoria), Tomato Mosaic Virus (ToMV).

• Root diseases of trees (0.5 hour)

  Armillaria root rot (Armillaria mellea, sin. Armillariella mellea), white root rot (Rosellinia necatrix) and crown rot (Phytophtora cactorum).

• Abiotic stresses in brief (0.5 hour)

Caused by heat, cold, drought and nutritional stresses, air pollution and by extreme environmental factors.

Knowledge acquired in the teaching unit 4:

Symptoms of the main diseases and abiotic stresses of agricultural and ornamental plants.

Disease epidemiology.

Disease control measures.

Teaching support activity (24 hours)

Activity in lecture rooms

1) Training seminars on

- Cereal diseases and their control: Fusarium head blight (Fusarium spp.), foot rot (Gaeumannomyces graminis tritici, Rhizoctonia cerealis, Pseudocercosporella herpotrichoides), rusts (Puccinia spp.) and powdery mildew (Erysiphe graminis f. sp. tritici).

- Sharka of stone fruits (Plum Pox Virus, PPV)

- Esca grapevine disease

- Mycotoxins in food

2) Projection of educational movies.

3) Plant samples showing disease symptoms.

4) Assessment of disease severity by using specific scales.

5) Reading and discussion of fungicide product labels and safety sheet.

Laboratory activity

1) Fungal pathogens recognition at optical microscope.

2) Disease control strategies and fungicides allowed for the application on plants and their characteristics.

3) At the end of the activity, students will be invited to write a brief report.

Field activity

1) Assessment of disease symptoms at the agricultural garden of the Dipsa, at the University experimental farm in Cadriano (BO) and at other farms.

Consolidation activity

This part of the course will be dedicated to the consolidation of the knowledge provided during the lessons, with particular attention to the needings raised by the students.

Readings/Bibliography

• Belli G. (2012). Elementi di Patologia Vegetale, Piccin Editore, ISBN: 8829921297.
• Matta A. et al. (2017). Fondamenti di Patologia vegetale, Patron Editore, ISBN: 9788855533829
• Agrios G.N. (2005) Plant Pathology, Academic Press (USA), ISBN: 9780120445653 - This textbook can be used by students who wish to make the exam in English.
• Lorenzini G. & Nali C. ‘Principi di Fitoiatria’, 2012, Edagricole Bologna, ISBN: 8850653883.

Teaching material will be upload in the "Isegnamenti on line" at the end of each lesson. Students of this course are automatically registered to the platform, however they have to check their name in the list and to register thamselves manually in the case that their name is not listed.

Teaching methods

1) Class lectures

Knowledge acquirement a) necessary to understand the general characteristics of fungi, bacteria, viruses and phytoplasmas pathogens of agricultural and ornamental plants; b) principles of integrated and biological disease control; c) of the methods to measure plant diseases; d)  on the main abiotic stresses. 

This knowledge will be monitored during the course through a continuous interaction between teacher and student. This will possibly involve also the discussion of some interesting papers on the main topics covered during the lessons. This will allow to stimulate the critical sense communication skills of the student.

2) Practical activity

Learning of: a) observation and assessment of disease symptoms; b) general practices commonly used in a laboratory of plant pathology and crop protection; c) consultation of databases ad web sites to plan disease managements and to learn the key aspects of plant protection products, in order to practically apply the theoretical knowledge acquired during lessons.

3) Guided tours

Student will be accompanied in guided tours to the agricultural field of University, in Cadriano (BO) and in local farms in order to examine plant diseases symptoms.

Assessment methods

Written exams in Italian language. Written exams in English upon prior and reasoned request. Esams will cover all the issues raised in the lessons and in training seminars. In particular the exams will take place in June (two exams) in July (one), in September (one), in December (one) and in January/February (one or two exams). Exam dates will be listed in "Alma esami" and in the hompage of the teacher in the "latest news" section. The exam consists of 33 closed questions. Each question will have 4 answers with only one is right. Exams will take place in computer lab.

Teaching tools

Overhead projector and personal computer will be used for class lectures.

Laboratory exercises will take place in the Teaching laboratories of

• Biology I - 1st floor – North Wing, n. 46.
• ICT and multimedia – 1st floor – North Wing, n. 44-46.

Office hours

See the website of Roberta Roberti