Reasons for testing
- Some foliar diseases are difficult to identify by eye e.g.
- An infrequently seen disease may be difficult to identify.
- Early identification allows timely management decisions to be made.
- Virus infection of seed crops can occur with very mild or no foliar symptoms.
- Home grown seed crops, which are not inspected for certification, should be tested to ensure quality. More …
- Soil tests can indicate the presence of:
- black dot
- More details
- To assess the incidence of disease in a growing crop:
- walk the crop in a “W” pattern
- take samples of leaves or tubers from individual plants to make up the required sample size
- To assess the incidence of disease in harvested tubers:
- sample from as many different boxes or areas in the store as possible
- To assess the presence of disease in soil:
- walk the field or area in a “W” pattern
- take samples of soil along the “W” and mix well before sub-sampling
- for more information see the method for sampling for black dot in soil
- Check with the analysis laboratory the size of the sample required for that type of analysis.
- A sample of healthy tissue may sometimes be required for comparison.
- Ensure that packaging meets the requirements to keep the sample in good condition and prevent leakage.
- Do not send samples over the weekend.
See this Links page for laboratories which perform disease analysis.
Always check with the laboratories for analyses currently performed and for prices.
Notes on testing for diseases
Blemishing disease updates 2011 (includes soil tests for Rhizoctonia and black dot)
Disease test updates 2011 (Examples of types of tests available but check with laboratories for current information)
Early blight 2010 (Recognising and controlling early blight)
Black dot 2010 (Assessing the risk of tuber infection)