Video transcript: The fungus forecast: protecting crops from attack

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December 2010

Dr Neal Evans, Rothamsted Research
This is Winter oil seed rape which is a really important crop in the UK. After wheat and Winter barley it is the third most important crop and the reason it is so important is that it is a break crop allowing growers to grow something different from cereals so it is actually a very important crop in terms of food. We grow it to produce edible oils and it's also used in lubricants and it is becoming quite important in terms of bioenergy in terms of bio-diesel.

Video shows Dr Evans talking in a field of oil seed rape, also showing that some leaves are infected with the leaf spot pathogen

This is Winter oil seed rape in the Autumn. This is a healthy leaf as you can see and here we have one that is infected with the light leaf spot pathogen. We have got pathogen. You can see the lesion here with dark pigmidia producing spores and the pathogen grows down the leaf and down the petiole into the stem and if this happens early enough in the autumn it can reach the steam base where it sits over the winter time and then as the Spring temperatures start to warm up this can then develop into a stem canker into the base of the plant which, if left untreated, can cause girdling of the stem before harvest, the development of the cankers at the base here and, as you can see, it cuts off the water supply to the oil seed rape plant and the plant can die before harvest.

Video shows examples of infected stems with cankers

The major disease of oil seed rape that grows in cankers in the North of England and Scotland is light leaf spot which is a disease thank affects the leaves themselves at this time of year, in late Autumn and Winter, but can infect the developing floral structures and pods of the oil seed rape crop in the Spring time.

The main problem with controlling both of these diseases is that it is very hard to actually know when you actually need to spray in terms of fungicide to control and, in the case of like leaf spot, it's actually whether you need to spray at all in a particular year.

Video shows map of the UK showing widespread incidents of infection

So what we have been doing here at Rothamsted is using some of our modelling techniques to look at these two diseases to understand the epidemiology of the diseases and then, using meteorological data, to actually forecast whether the diseases are going to be a problem in a particular season.

The way that the forecast helps the growers is that previous to the actually forecast being available, farmers didn't have the time to go out into the field to look for the disease themselves so what tended to happen was that they would go in and spray anyway on a sort of calendar basis whether a spray was actually needed or not. Now that growers have the forecast they can actually look at their computer models that we generate and see whether the light leaf spot disease is going to be a risk for them in their particular crop.

Video shows several annual UK maps each showing the UK split into 10 regions, each region is marked with a percentage to show likelyhood of infection

This is a really good example of science helping out the whole of the industry because we start off with mathematicians producing models which then allows us to tell growers exactly when their crops are at risk from these potential diseases. Obviously if they don't have to spray then they save money, they save time and ultimately it is beneficial to all of us because we can grow crops here in the UK whilst minimising the amount of pesticide input to those crops.