Discula destructiva, the causal agent of dogwood anthracnose, has caused severe mortality in dogwood over the last 30 years. Although considerable research has been done with dogwood anthracnose, the infection process by D. destructiva is still obscure. A resistant cultivar of Cornus florida, ‘Appalachian Spring’, was discovered and released by the Tennessee Agricultural Experiment Station. However, the resistance mechanisms are unknown. The objectives of this research were 1) to determine the sequence of events in the infection process of D. destructiva in C. florida and 2) to determine how host resistance affects infection events of D. destructiva on flowering dogwood. At 3 days after inoculation (DAI), majority of conidia germinated and hyphae were observed on the leaf surface. Direct penetration by D. destructiva hyphae was observed without appressorium formation. At 8 DAI, hyphae were aggregated between the cuticle and epidermis and grew intracellularly in epidermal cells, palisade parachyma, and spongy mesophyll cells. At 16 DAI, chloroplasts were intact but decompartmentalized and infection sites were clearly defined. Acervuli were detected at 20 DAI and were fully developed at 24 DAI on adaxial and abaxial leaf surfaces. Sporulation (ruptured acervuli) was observed at 20 DAI. This clear understanding of the infection process can be used to look for resistance mechanisms in dogwood germplasm. A resistant line would expect to slow or inhibit one or more infection events. There was no statistical difference between the percentages of germinated conidia on susceptible and resistant cultivars of flowering dogwood one day after inoculation (DAI). However, the resistant cultivar, ‘Appalachian Spring’, significantly suppressed the growth of D. destructiva conidial germ tubes at 2 DAI, 3 DAI and 4 DAI when compared to conidial germ tubes on leaves of the susceptible cultivar ‘Cloud 9’. Observed resistance may be due to smoother wax crystals on adaxial leaf surface and significantly thicker cuticle observed on leaves of ‘Appalachian Spring’. An unknown compound, observed highly concentrated in resistant but lower in susceptible cultivars, may be important as a resistance mechanism. These strategies reduced the inoculum potential of D. destructiva and play important roles in why ‘Appalachian Spring’ is resistant to dogwood anthracnose. These results provide new ways to use conidia germination test and germ tube growth measurement for detecting resistant cultivars.

The objectives of studies undertaken here were to identify the species of Colletotrichum associated with coffee berry anthracnose in PNG, gain an understanding of the infection process and factors affecting it, assess the impact, if any, of anthracnose on coffee quality and identify suitable chemicals for anthracnose control. A total of 40 isolates were collected from PNG and their cultural and morphological characteristics on PDA were studied and used to identify the species. Species identification was further confirmed by molecular characterisation using RFLP and DNA sequencing of the ITS region of the rDNA. After species identification only two isolates were selected to represent C. gloeosporioides and C. acutatum for further studies. Studies on conidia germination and the effects of conidia concentration, temperature, relative humidity and pH affecting germination were done on TWA, followed by studies on the infection process on coffee berries and the influence of temperature on germination and appressoria formation in vivo. For assessment of effect of anthracnose on coffee quality, 100 samples of ripe berries were assessed for disease incidence, followed by processing of the berries to green bean and data on bean defects (black bean) together with anthracnose incidence subjected to appropriate statistical analysis. A similar procedure was followed using disease severity but the samples were from one farm only. The closing work on chemical control was done by screening 16 different fungicides for the control of C. gloeosporioides and C. acutatum. With the 40 isolates, 29 were identified as C. gloeosporioides and 11 as C. acutatum. This is the first report of C. acutatum on coffee in PNG. Identification of the species was further confirmed by RFLP groupings where C. gloeosporioides and C. acutatum were separated at 574bp and 584bp respectively and DNA sequence homology identified the PNG isolates with C. gloeosporioides and C. acutatum accessions. Optimum conditions for conidia germination in relation to spore concentration, temperature, and pH are 1 x 106 spores/ml, 21 - 29°C and pH 5 - 7 respectively for C. acutatum and for C. gloeosporioides 1 x 106 spores/ml, 25 - 31°C and pH 5 - 7 respectively. Humidity is not a limiting factor for activity of both species. Infection process for both species is similar where conidia germinate to produce the germ tube which swells at the tip to form the appressoria. The appressoria produce an infection peg which is responsible for berry cuticle penetration and cell colonisation (resulting in typical anthracnose symptom expression) and eventual sporulation. C. acutatum has not been reported elsewhere as a pathogen of coffee and this is the first report of C. acutatum causing infections on both ripe and mature green berries. Anthracnose incidence did not correlate well with coffee bean defects, but anthracnose severity v suggested that coffee quality could be affected by anthracnose. The most effective fungicide for anthracnose control is thiram alone or thiram alternating with propiconazole.

Foodborne diseases form a large group of infectious diseases. These substantial diseases are occurring more in developing countries but they do not avoid developed countries. The originators of the disease are bacteria and their toxins, viruses, parasites and prions, whose source is an infected person or animal. The disease is passed on by contaminated soil, contaminated water and food, sometimes contaminated items. Greatest importance in the prevention of foodborne disease are nonspecific measures, protection of drinking water, safe food production, waste disposal, functional sewer system, rodenticides and insecticides measures and of course the principles of personal hygiene, certain standards of hygiene and health education of the population. Intestinal infections are preventable. The consumer can effectively protect by following the fundamental principles established by the World Health Organization. The aim of this study was to explore knowledge of foodborne disease prevention measures and compliance with these principles by adolescents in the Milevsko region. The theoretical part of the study summarizes the basic information about intestinal diseases and describes their effect on health from a variety of perspectives. The preventive measures which everyone should be aware of and apply them in everyday life to protect health are described in great detail. The paper summarizes the information about the process of spreading foodborne diseases and epidemiological measures focused on supply, routes of transmission and susceptible individuals. The theoretical part includes basic information about specific intestinal infections which are most significant for the population in the Czech Republic. Briefly described are treatment of these diseases and the most important legislative measures. In the research part quantitative research was applied by questionnaire. The research groups were students of higher secondary vocational schools and vocational schools in the region Milevsko. Three hypotheses were formulated. Statistical hypothesis testing was performed using the t test. The values of the achieved significance level are compared with a predetermined level of significance. The first hypothesis assumed that knowledge about prevention of intestinal diseases is higher among girls than boys. This statement has not been confirmed. Knowledge of the principles of prevention does not differ according to the criteria of gender. Two further hypotheses assumed that the observance of hygienic measures in the prevention of foodborne disease is higher among girls than among boys and higher for high-school graduates than apprentices. These hypotheses are valid. Precautionary principles are indeed respected more by girls than boys and high-school graduates than apprentices. The carried out research shows that adolescents in the region Milevsko have a good knowledge of foodborne infections and do known also essential preventive measures. However, knowledge of these rules does not mean they are applied in practice. The results showed that some rules, such as washing fruits and vegetables before eating, adequate boiling or roasting of food, especially hand hygiene before eating food or after contact with an animal are observed by a smaller percentage of respondents than that reported knowledge of these principles. A positive finding is that respondents comply with certain rules, without being aware of them, such as the principle of proper preservation of precooked food. Foodborne diseases are diseases which can be prevented in compliance with precautionary principles. Especially in the Czech Republic, where nonspecific principles are at a high level. It is up to each user/consumer how consistent these principles will be. Respecting preventive measures is a prerequisite for reducing the incidence of foodborne disease in the population.