84587 - Control Of Disease In Organic Plant Production

Course Unit Page


This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Good health and well-being Sustainable cities Climate Action Life on land

Academic Year 2021/2022

Learning outcomes



The aim of this course is to provide an overview of the current scientific knowledge about different organic approaches to regulate diseases, restricting to a minimum pesticide use without losing a high nutritional quality of the production and an adequate return and satisfaction of the producers. A special attention will be posed to the production of high-quality, disease-free, vegetative propagation material.

Course contents



General aspects and elements of epidemiology: organic and biodynamic agriculture, goals of conventional, low-input and organic agriculture (o.a.), allowed, restricted and prohibited fertilizers and pesticides in o.a., premium price, trends of organic production and unresolved problems for organic growers; development of epidemics: range of pathogens, the disease cycle, dissemination by air, water, vectors and humans, overwintering of pathogens. The effects of climate changes on pests, diseases and weeds.

General management of diseases in o.a.: biodiversity enhancement, consequences of monoculture and uniformity within species, mechanisms by which biodiversity can reduce biotic and abiotic stresses in both phyllo- and rhizosphere; other general practices: crop rotation, choice of rotation crops and their sequences, soil health management, composts and manures in o.a, green manure, general tillage decisions, water management in organic systems and effects on foliar and soilborne diseases, problems due to soil erosion and mismanagement of irrigation water.

Preventive control options: regulatory control methods, inspections, quarantines and crop eradication. Xylella fastidiosa and Tomato ringspot virus: two examples of quarantine pathogens in Italy. Control methods that mechanically eradicate or reduce the pathogen inoculum, breeding of resistant varieties, sampling and high-output detection methods of pathogens. Biological diagnosis: woody and herbaceous plant indicators. Use and production of pathogen-free propagation material, thermotherapy and meristem tip culture for obtaining virus-free plants.

Direct protection of plants from pests and pathogens in o.a.: resistance of pathogens to chemicals, limitations and drawbacks of the application of specific biocontrol agents. Currently allowed agents (in U.E.) of mineral origins: copper, sulfur, potassium bicarbonate, hydrated lime and others: activity, formulations, phytotoxicity, and ecotoxicological profile of these pesticides. Direct protection by biological control: microbial communities, biomass, activity and disease suppression in both phyllo- and rhizosphere, commercially registered biological products, suppressive soils and mycorrhizae. Viral parasites of bacteria (fagi) and fungi (mycovirus), biological control of Endothia parasitica. Natural compounds that can induce systemic resistance (SAR or ISR) in plants allowed in o.a; the “recovery” phenomenon in phytoplasma diseases: recent knowledge and practical applications.


Organic management and control of airborne diseases: economic consequences of losses caused by airborne pathogens, effects of macro- and micronutrients on basic functions of plant resistance, disease control strategies in organic systems: enhancement of soil microbial biomass and activity to encourage the breakdown of pathogen resting structures, interactions of weeds and surrounding vegetation with diseases, influence of epiphytes and endophytes on plant-pathogen interaction. Direct control of airborne diseases: currently used agents, properties and optimal use of plant protection products, decision support systems (vite. net).

Organic management and control of soilborne diseases: soil quality and soil health in organic and conventional farming systems, soilborne diseases in organic versus conventional agriculture, factors associated with pathogen and disease suppression in o.a. Importance of free-living and beneficial nematodes in organic farming, plant damage caused by plant-parasitic nematodes, virus transmission by nematodes, nematode management by crop rotation, suppressive soils and biological control. Direct control of soilborne disease by biofumigation, soil solarization and steam sterilization.

Organic management and control of seedborne and vectorborne diseases: production of healthy seed and propagation material as one of the key issues in the organic production cycle, economic importance of seedborne diseases, important seedborne diseases of cereals and vegetables. Correlation of disease control to the position of the pathogen on or in the seed, physical seed treatments and with agents of natural origins, effects of treatments on seed germination. Examples of vectorborne plant diseases, organic perspectives on vectorborne diseases, control of vectors by predators, hyperparasites, physical barriers (nets), mating disruption and natural insecticides. Principles of biotremology.


The aim of this action is to provide an overview of general management, preventive control options and direct protection against insects, pathogens and weeds in high value crops. Just in case it should be pandemic problems. the practical rounds in farms will be replaced by specific seminars.



Organic apple and pear disease management: general crops characteristics and management, elements of important diseases (apple scab, powdery mildew, fire blight, apple proliferation and pear decline, viral diseases, fruit diseases and twig cankers). Control strategies: mechanical and physical control, direct control strategies with pesticides allowed in o.a., biocontrol agents and resistance-inducing products.

Organic grape disease management: general crops characteristics and management, elements of important diseases (downy mildew, powdery mildew, botrytis gray mold, black rot, root and wood rot diseases, grapevine yellows). Site selection, agronomic practices e.g canopy management, mechanically breakdown of pathogens resting spores, use of resistant/tolerant cultivars (interspecific cvs.). Direct control strategies in humid and arid climates: use of copper and sulfur compounds in organic vineyards, recent restrictions of copper use in the U.E., application of specific biocontrol agents.

Organic vegetable disease management: challenges of disease management for organic vegetables, management strategies e.g use of resistant cultivars, site selection, cultural practices, planting strategies, use of healthy seed and propagation material. Organic watermelon disease management against insects, pathogens and weeds.



Power points and articles will be distributed during the course and are also available on the platform virtuale.

Elementi di Patologia Vegetale di G. Belli, Piccin Editore (available in the library)

Plant pathology – fifth ed., di G. Agrios (available in the library)

Plant diseases and their management in organic agriculture di AA. VV., APS press (available in the library).

Teaching methods

During the course, the general issues related to an organic management to regulate diseases in several crops based on four cornerstones (biodiversity enhancement, good general crop management, use and production of pathogen-free seed and propagation material and of resistant cultivars, direct control of diseases) will be discussed. The economic consequences and the epidemiology of some diseases will be the basis of the organic management of specific crops. The course will be complemented by practical farm rounds with low-input and organic management.

Assessment methods

The examination is oral and will contain a series of questions to ascertain the student’s theoretical knowledge of issues presented in the course.

Teaching tools

The course will be held in Bologna, Plesso di Agraria, viale Fanin 40-50, during the second period of the year, in a room equipped with PC facilities, video projector and teams platform. Seminars on specific targets could eventually be held.

If in doubt, see the website or contact Carlo Poggi Pollini at 051-2096725 or carlo.poggipollini@unibo.it

Office hours

See the website of Carlo Poggi Pollini