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Discussion
- Where the disease became evident there was a substantial response to fungicide application. In trials 6 and 7 where the disease epidemic was already well advanced, fungicides were still able to provide a useful yield improvement.
- The nature of this yield improvement varied a little from trial to trial. It was observed as better plant vigour and stature, which translated into more flowers and sometimes bigger flowers. The positive effect on assay was not expected and may be related to a reduction in plant stress.
- The lack of yield response in trials 4, and 2 appears to be due to a low incidence of Phoma..
- Why these trial sites produced a low disease incidence is unclear. It does not appear to be related to location, density or nutrition. Identifying the climatic and site-specific factors leading to disease outbreak needs to be a priority area in the development of an effective control strategy.
- Trials 6 and 7 indicate that Score may be more effective than Bravo, although there are certainly possible benefits in using the two in combination from a resistance management point of view.
- The current recommendation that has arisen from this trial work is
“to apply 250 mls per hectare Score + 1.4 litres per hectare Bravo 720 in mid August and again 4 weeks later. Use Score at 500 mls per hectare if disease symptoms are already evident.”
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Pyrethrum Industry:
A) Pyrethrum flowers
Brief History
Present production sites
Growth Conditions
Flowers of pyrethrumB) Survey
of diseases
Observation
Questions
Experimental Design
Results
Site descriptions
Graph results
Analysis of results
Site Comparisons
Effect of Fungus
Association of site factors
Other factors
Discussion
C) Treatment of Fungal Diseases
Introduction
Observations
Experimental design
Results
Discussion
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Cameron Spurr
Alistair Gracie
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