Monitoring of diseases

Monitoring refers to the surveillance of processes in agricultural crops to obtain data and knowledge on diseases. Disease is assessed visually for obvious symptoms and by infestation frequency (percent of plants infested), and infestation severity (percent of plant tissue infested). The distribution pattern in the field stand is also important. There is also the possibility of an infestation survey for early detection of disease without visible symptoms. Here, random sampling is analyzed in the laboratory for pathogen genetic material using PCR testing.

Monitoring is carried out personally. Here, many years of experience on the farm and the right timing of the control play an essential role. In disease-sensitive periods or when the weather is conducive to disease, it is even advisable to carry out checks several times a day. Alternatively, consultants assist in crop inspection.

In addition, public warning services document first occurrence, infestation intensity and damage thresholds for the main cultivation areas of a crop variety in a country or region. Additional information on disease occurrence can be obtained from official advisory services.

Warning services are based on forecasting models. They are adapted to the respective climate zones and have been established for many years. Their values are based on the interaction of weather data, growth stages, infestation pressure in the region or previous year's infestation and variety susceptibility. Weather stations distributed across the country measure precipitation, humidity, air pressure, sunshine hours and wind. Based on these weather data, constantly updated and easily understandable models are created by the Plant Protection Warning Service for viticulture, orcharding, arable farming and horticulture and processed in graphs.

For example:

In viticulture, Plasmopara viticola and Erisyphe necator- pressure are calculated from the parameters humidity and atmospheric pressure

In orchards, there are very good forecasting models for the bacterial disease fire blight (Erwinia amylovora; precipitation, blossom stage) and the fungal disease scab (Venturia inaequalis; all climatic parameters, previous year's infestation, variety). For many other diseases, a risk can be well estimated: the fungal peach leaf curl (Taphrina deformans) has its germination window in the bud stage and must be controlled at this time. Bacterioses such as Pseudomonas occur after frost (microcracks) or after leaf fall (wounds).

For arable crops prediction models particularly for cereal diseases such as rust fungus, powdery mildew, and Septoria, among others, are available. Pre-harvest monitoring and early warning systems for mycotoxins in cereals and maize enable crop quality to be assured through timely fungicide application. For powdery mildew diseases other than in cereals, good empirical data on the temperature-humidity combination are available. For potato, recommendations for optimal late blight (Phytophthora) control can be calculated

In addition, for certain diseases, computer programs have been developed for farmers that use weather data to show scenarios for infestation development. Crop- and country-specific technical literature is also available.