| EFFECT OF HUMIDITY ON PATHOGEN INFECTION |
| The work presented here forms part of a three-year
project funded by the HGCA on the 'Epidemiology and control of fusarium ear
blight' (Project Report No. 143). |
| The incidence of wet weather (high humidity) is the most important factor in the development of FHB. |
| The effect of humidity on FHB and mycotoxin production was assessed in trials carried out between1994 and 1996.
Symptom development, ear infection, mycotoxin production and yield loss were assessed under three humidity regimes
ambient, medium (>70%) and high (>80%). Control of humidity was achieved using mist irrigation. |
| In 1994, individual plots were inoculated with one of the four FHB pathogens;
Fusarium avenaceum, Fusarium culmorum, Fusarium poae or
Microdochium nivale. In subsequent years inoculation with Fusarium
graminearum was also included. Plots were inoculated at early anthesis (GS60). |
| Isolation of Fusarium species present on the ear was carried out at GS65, GS75 and 85 to identify
the species responsible for the symptoms assessed. Shown below are the GS85 results from 1995. |
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| F. avenaceum, F. culmorum and F. graminearum were isolated predominantly from
plots where they were inoculated, increased levels of isolation resulting from increased humidity. |
| Natural infection, caused by F. poae, was recorded in all plots at all humidity levels,
with highest levels found on the medium humidity plot. |
| M. nivale, also originating from natural sources, was commonly isolated from all plots at medium and
high humidity with levels greatest at high humidity. M. nivale was not isolated from plots at ambient
humidity, suggesting there may be a threshold level below which significant disease caused by M. nivale
will not develop on the ear. |
| Recovery of M. nivale and F. poae from high humidity plots was reduced where F. avenaceum,
F. culmorum or F. graminearum had been inoculated. |
| Return to FHB Index page |
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RAPID ACCESS TO THE LATEST REGIONAL CROP PEST AND DISEASE LEVELS |
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