08421 - Vegetal Pathology

Learning outcomes

Students will acquire knowledge on the general aspects of plant pathology, such as biology, symptomatology and diagnostics of the major infective diseases of crops (caused by virus, viroids, mollicutes, bacteria and fungi) and of the abiotic stress alterations.

Course contents

A) Prerequisites
The student who accesses this course must know the fundamentals of chemistry, plant biology and physiology, genetics and agricultural microbiology. These foundations are provided by the basic teachings delivered during the first year of the course. It is advisable to pass the above training activities before taking the general plant pathology exam.
B) Didactic units
Module 1 -MICOLOGY (7 credits):

1. General Part:
History and definitions
Major milestones in the history of plant pathology. Specific definitions and terminology. Triangle and pyramid of disease. Postulates of Koch.
Pathogenesis
Parasitism and saprophytism. Biotrophic and necrotrophic parasites. Disease cycle. Inoculum, infection, penetration, colonization, reproduction, evasion. Primary and secondary cycle. Symptomatology.
The mushrooms
Structural, biochemical and morphological characteristics of the fungal cell and compared to the main classes of fungi and oomycetes; mycelium and hyphae; hyphal modifications; mode of growth, nutrition, reproduction. Classification. Main characteristics of the life cycles of the mushroom and oomycete classes. Mode of infection: penetration, colonization and quiescence. Main symptoms of fungal diseases. Identification and diagnosis.
The resistance of plants
Resistance forms - pre-existing and induced, structural and biochemical resistances. ROS and oxidative stress. Phenolic compounds.
'Host' and 'non-host' resistance. - The zigzag pattern. Molecular recognition and transmission of cellular defense signals. 'X gene gene' theory and coevolution. Resistance stability and durability.
Abiotic stress
Classification and importance of abiotic stresses - Recognition and symptoms - Adaptation and acclimatization.
Thermal stress - Thresholds. Cold stress: cellular mechanisms and reversibility. Symptoms. Heat stress, symptoms.
Water stresses - Nutritional stresses - Other stresses - Symptoms of defect or excess
Mycotoxins
Biochemical characteristics - formulas, persistence and stability, toxicity mechanisms and limit thresholds.
Mycotoxigenic mushrooms - Aspergillus, Penicillium, Fusarium, Claviceps.
Knowledge and skills to be achieved in the general part
Knowledge of specific terminology to be used in the descriptions of plant diseases, the cycle of the disease in the different phases and in the methods implemented by the different types of pathogen.
Knowledge of the main types of fungal pathogens of plants and their most important characteristics in attacking host plants, such as cellular and biochemical characteristics also in relation to their taxonomic classification. It includes the modalities of reproduction, infection and transmission of pathogens and classifies the symptoms in a generic way.
Knowledge of the main forms of structural and biochemical resistance of plants, genetic bases, molecular mechanisms of pathogen recognition and the signals necessary for the activation of forms of innate immunity. He knows the problems related to the stability and durability of the most effective natural forms of resistance of crops.
Knowledge of the main abiotic stress types and mechanisms related to the development of cold stress symptoms. Recognizes the main generic symptoms of these stresses.
Knowledge of the main mycotoxins, the mechanisms of action and toxicity for humans and animals, the activities of prevention and control from contamination.

 

2. Special Section:
Grape
Oomycetes: Plasmopara viticola (downy mildew).
Ascomycetes: Botyris cinerea (gray mold); Erysiphe necator (an. Oidium tuckeri) (powdery mildew); Rosellinia necatrix (woolly root rot); Phomopsis viticola (escoriosi).
Basidomycetes: Armillaria mellea (syn. Armillariella mellea) (fibrous root rot); Phaemoniella chlamidospora, Phaeoacremonium aleophilum -Fomitiporia punctata (complex of the mal of the bait).

Pome
Ascomycetes: Venturia inaequalis (an. Spilocaea pomi, sin. Fusicladium dendriticum) (apple scab); Venturia pyrina (an. Fusicladium pirinum) (pear scab); Podosphaera leucotricha (an. Oidium farinosum) (powdery mildew of the apple tree); Neonectria galligena (an. Cylindrocarpon mali) (cancers from nectria); Monilinia fructigena (an. Monilia fructigena), Monilinia laxa (an. Monilia laxa), Monilinia fructicola (an. Monilia fructicola) (jewels see also stone fruit); Neofabraea alba (sin. Gloeosporium album) (lenticellar rot of apples and pears); Stemphylium vesicarium (brown maculation of the pear tree)
Notes on post-harvest alterations and main physiopathies.
Drupacee
Ascomycetes: Taphrina deformans (peach bubble); Podosphaera pannosa (sin Sphaerotheca pannosa var.persicae - an. Oidium leuconium) (powdery mildew of the peach, apricot, almond, etc.); Phomopsis amygdali (sin Fusicoccum amygdali) (peach spindle), Stigmina carpophila (sin Coryneum beijerinckii) (corineo of stone fruit); Monilinia fructigena (an.Monilia fructigena), Monilinia laxa (an. Monilia laxa), Monilinia fructicola (an. Monilia fructicola);
Strawberry
Oomycetes: Phytophthora cactorum and Phytophthora fragrariae; Pytihum sp. (radical decay)
Ascomycetes: Sphaerotheca macularis f. sp. fragrariae (Oidium fragrariae) (powdery mildew); Botrytis cinerea (gray mold); Colletotrichum acutatum (anthracnose)
Forest plants
Oomycetes: Phytophthora spp.
Ascomycetes: Cryphonectria parasitica (chestnut bark cancer);
Basidiomycetes: Armillaria mellea (syn. Armillariella mellea); caries of wood
Sugar beet
Ascomycetes: Cercospora beticola (cercospora)
Basidiomycetes: Thanatephorus cucumeris (syn. Rhizoctonia solani) (rhizottoniosis)
Potato and Tomato
Oomycetes: Phytophthora infestans (downy mildew)
Ascomycetes: Fusarium spp; Alternaria alternata and Alternaria solani (alternariosi)
Cereals
Ascomycetes: Septoria tritici (wheat septoriosis); Fusarium spp. (fusariosis of the ear); Mycotoxin-producing fungi in corn
Basidiomycetes: Elements of rust
Knowledge acquired in the special part:
He knows the main fungal and oomycete diseases of the vine, pome fruit, stone fruit, strawberry, actinidia, forest, horticultural plants and cereals in Italy.

 

Support to didactic Activities Supporting Module 1
Laboratory activities (will take place by dividing the activity into shifts)
The laboratory activities are focused on two types of experiences: i) demonstration of Koch's postulates and ii) recognition of phytopathogenic fungi under an optical microscope. For the first experience, artificial infections will be carried out on plant tissue from material grown in vitro. The developed symptoms will be displayed in the next shift and the pathogen re-isolated in vitro. In the second experience, the student will be involved in the preparation of slides, in the observation of fungal structures under a microscope and in their description.
At the end of the exercise unit, students are invited to report the observed fungal structures in a short report.
Skills consolidation activities
This part of the course will be dedicated to consolidating the knowledge administered giving particular attention to the needs gradually represented by the students.
Alternative classroom activities
Seminars, projection of educational videos, examination of samples of sick plants and analysis of symptoms.
Laboratory activities
The laboratory activities are aimed at recognizing phytopathogenic fungi and their reproductive structures under an optical microscope. At the end of the exercise unit, students are invited to report the observed fungal structures in a short report.
Field activities
Analysis of diseases and their symptoms directly in the field at the agricultural garden or at farms.
Skills consolidation activities
This part of the course will be dedicated to consolidating the knowledge administered giving particular attention to the needs gradually represented by the students.

Module 2 - VIROLOGY AND BACTERIOLOGY (3 credits):
1. Pathogens (Total teaching unit 10 hours)
1.1 Viruses and Viroids (4 hours)
Historical notes, structural and molecular characteristics. Taxonomic classification and classification. Symptoms. Infectious cycle: Replication. Transmission mode. Transmission by vectors. Diagnosis and struggle.
1.2 Bacteria (4 hours)
Structural, biochemical and morphological characteristics of the bacterial cell also in relation to the systematic classification. Infection modalities: dissemination, penetration, quorum sensing. Types of bacteriosis (parenchymatic, vascular and mixed). Main symptoms. Diagnosis and struggle.
1.3 Mollicuti (2 hours)
Phytoplasmas and Spiroplasms. Historical notes, structural and molecular characteristics. Taxonomic classification and classification. Symptoms. Method of transmission and containment.
Knowledge acquired in teaching unit 1:
• Knows the most important characteristics of pathogenic viruses, viroids and bacteria (including phytoplasmas) of plants and their ways of attacking host plants. It includes the methods of replication, infection and transmission of the pathogens mentioned above and classifies their symptoms in a generic way.
2. Special part (Total teaching unit 10 hours)
2.1. Vine (2 hours)
virosis
Curl complex, leaf curl, curly wood.
phytoplasmoses
Golden Flavescence and black wood
bacterial
Black sore, Bacterial tumor, Pierce's disease
2.2 Pome fruit (2 hours)
phytoplasmoses
Pear tree, apple tree broom
bacterial
Bacterial fire stroke
2.3. Stone fruit (2 hours)
virosis
Sharka, latent mosaic of the peach tree.
bacterial
Bacterial spotting of stone fruit
2.4. Horticultural, sugar beet and cereals (2 hours)
virosis
Cucumber mosaic, Tomato virosis, Rizomania, Wheat mosaic, tapered potato tuber
phytoplasmoses
stolbur
bacterial
Bacterial blight and maculation of the tomato
2.5. Actinidia (1 hour)
virosis
Actinidia virus
bacterial
Bacterial cancer
2.6. Olive tree (1 hour)
bacterial
Mange of the olive, Complex of the rapid drying of the olive (CoDiRO)
Knowledge acquired in teaching unit 2:
• Knows the main viral and bacterial diseases of vines, pome fruits, stone fruits, actinidia, vegetables, cereals and olive trees in Italy.

3. Didactic Activities Supporting Module 2 (Total teaching unit 10 hours)
The activities of exercises will be carried out in one or more shifts, in relation to the number of students, at the laboratories and the greenhouse complex of the Department of Agricultural Sciences.
Laboratory exercises:
The activity will consist of carrying out a serological diagnostic test to specifically identify the presence of proteins produced by pathogens (viruses, bacteria or fungi) in a plant matrix. The plant samples will be supplied "blind" to the students who will carry out all the salient phases of the essay assisted by the teacher and other expert staff. The final results will be discussed and interpreted with the teacher.
Greenhouse exercises:
The activity will consist in the execution of a biological test for the detection of viral agents. Students will perform a mechanical inoculation of one or more viruses on appropriate test plants. The plant material will be provided by the teacher or, alternatively, can be procured by the students. The results obtained will be interpreted by the students led by the teacher.

Module 3 - DEFENSE PRINCIPLES (Total teaching unit 2 credits):
Importance of the defense of crops from pathogens and general characteristics of the defense (Total teaching unit 2 hours)
Importance of the defense of plants from diseases in modern agriculture for the reduction of economic losses, for the protection of consumer health and in respect of environmental sustainability. Skills required for plant protection management. Possibility of intervention on pathogen, environment and host to reduce the severity of diseases. Defense characteristics according to the type of evolution of a disease: difference between monocyclic and polycyclic pathogens. Integrated defense concept and its fundamental lines.
Agronomic defense means (Total teaching unit Total teaching unit 4 hours)
Possibility to reduce the evolution and severity of diseases through the choice of the cultivation environment, the crop including the healthy propagation material, the time and method of sowing, the planting density, crop rotation, management soil, prevention of the spread of the inoculation of telluric pathogens, management of the plant (pruning and farming systems), fertilization, irrigation and mulching. Defense impact on greenhouse crops.
Legislative means to protect crops from dangerous harmful organisms (Total teaching unit 4 hours)
Rules aimed at protecting the national / community territory from the introduction of dangerous pathogenic organisms and from those equally dangerous but already present. Phytosanitary surveillance: objectives, implementation, quarantine organisms, compulsory struggles, new adversities and harmful organisms at risk of introduction, certifications.
Plant protection products: chemical, synthetic and natural means (Total teaching unit 8 hours)
Definitions and nomenclature, behavior of plant protection products towards the plant (covering and penetrating products), behavior towards the pathogen (products with preventive and curative action), biological activity of fungicides on pathogens (methods and mechanisms of action). General characteristics and hints of the most important groups of inorganic products (minerals) such as copper and sulfur and organic (synthetic) products. Natural products recently introduced on the market of plant protection products. Main formulations of plant protection products and understanding of a commercial label (composition of plant protection product, danger symbols, use, respect for the safety period).
Plant protection products: microbiological means (Total teaching unit 4 hours)
Fungal and bacterial microorganisms antagonists of pathogens, main sectors of use and methods of administration. EU approved antagonists and marketed in Italy. Methods and mechanisms of action of antagonists both of a direct type against pathogens and of an indirect type through the involvement of the plant. Compatibility of antagonists with fungicides.
Physical vehicles and biofumigation (Total teaching unit 2 hours)
Use of steam for soil geodisinfection. Solarization or heating mulch. Burning of plants, connected to phytosanitary emergencies prescribed by the competent authorities. Thermotherapy and remediation of propagation material against virosis and phytoplasmosis. Soil biofumigation.
Defense strategies based on pathogens (Total teaching unit 2 hours)
Special features and possibility of defense of plants from fungi, oomycetes, bacteria and viruses in an integrated defense perspective.
8. Didactic Activities Supporting Module 2 (Total teaching unit 4 hours)
Alternative classroom activities
Projection of educational videos, viewing of labels of commercial formulations of plant protection products, simulation of the setting up of an integrated defense plan for a crop.
Skills consolidation activities
This part of the course will be dedicated to consolidating the knowledge administered giving particular attention to the needs gradually represented by the students.

 

 

Readings/Bibliography

ALL MATERIAL DISTRIBUTED PER LESSON.
BOOKS:

Belli, 'Plant Pathology', 2012, PICCIN publisher, Padua.
Agrios, 'Plant Pathology', 2004, ELSEVIER Academic Press publisher
Lorenzini G. and Nali C. 'Principles of Phytoiatrics', 2012, Edagricole Bologna

Teaching methods

1. Class lectures: through the class lectures the student will acquire the knowledge necessary to understand the general characters of plant pathogens and the resistance forms of plants. 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: the student will be directly involved in general practices commonly used in a laboratory of plant pathology 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 DISTAL, in Cadriano and in local farms in order to examine plant diseases symptoms.

Assessment methods

Verification of the learning of the teaching of plant pathology through written or oral tests that will focus on the topics covered in the lessons of the two courses. The written exam will consist of closed questions with different answers. In the oral exam, the answers to at least six questions on the topics covered in class will be evaluated. The test must be passed in a global way and it is necessary that the candidate reaches the mark of 18 thirtieths in both courses of the integrated course. The commission will evaluate the scores achieved in each of the two courses and make a weighted average with the CFU of the different modules.

Teaching tools

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

Laboratory exercises will take place in the teaching laboratories of BIO1 (first floor, via Fanin 44/46).

Office hours

See the website of Elena Baraldi

See the website of Claudio Ratti

See the website of Roberta Roberti