But this only occurs, of course, if Botrytis spores are present on the flowers. We have carried out extensive testing of the effects of relative humidity on flower infection under controlled conditions to define just how dependant infection is on relative humidity. On the other hand, humidity has only a very small effect on stem wound infection. This is backed up with our findings for stem infection. But flower infection actually increases in the warmer weather.
More flowers abort and drop off, reducing yield potential.
This is not as serious as it sounds, because the flower lesions become far less aggressive - the Botrytis does not reach back into the truss, as most infected flowers just drop off. The plant is also able to produce more flowers to compensate in the warmer weather. What we have found is that quite a number of fungi are antagonistic to Botrytis , and will prevent it infecting a fresh wound. The best of them work better than fungicides. We have collected fungi from commercial greenhouse tomato crops and tested them for effectiveness against Botrytis .