| EFFECT OF HUMIDITY ON YIELD |
| 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). |
| Yield loss figures were calculated by comparing thousand-grain weights for the individual FHB pathogen treatments to that determined for the ambient uninoculated control. Results for 1995 are shown below. |
 |
| Losses ranged from 3.5 to 8% on inoculated plots at ambient humidity, with F. culmorum
producing greatest losses. |
| At high humidity significant losses were seen on all plots including the uninoculated control. Results from ear isolations indicated that the losses of 14.5, 14.5 and 13.9% on control, M. nivale and F. poae treated plots respectively could be attributed to infection by M. nivale. The losses on F. avenaceum, F. culmorum and F. graminearum inoculated plots, 13.9, 27.4 and 28.4% respectively, were caused in the main by the inoculated species. |
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