Although this means using a more expensive spray programme and summer pruning to remove infected shoots, the extra cost and effort are well worthwhile.
Unless well-controlled from the moment the trees are planted, the disease can cause unacceptably high tree losses and pruning costs, and reduce yield potential and class I grade-out.
For these reasons HDC commissioned East Malling Research (EMR) plant pathologist Dr Angela Berrie to carry out a trial to find the most effective means of preventing canker attack using an integrated approach.
She admitted that an integrated programme is costly, though - especially removing lesions by pruning and the use of extra fungicide sprays. She compared this programme with a standard fungicide programme on two Gala/M9 orchards sites. Gala was chosen because it is particularly prone to the disease.
Each orchard was split into two plots, with a standard fungicide programme applied to one and a best-practice programme including additional fungicide treatments to the other. The latter was applied at key timings, pre- and post-blossom and leaf fall. In addition, each plot was halved and canker shoots removed in the summer from one half but not the other.
Both main plots received a full scab/mildew programme of Cuprokylt and Dithianon plus Scala pre-flowering, and Systhane plus Captan or Nimrod plus Captan or Rubigan plus Captan post-bloom.
The main difference between the plots was that the best-practice plot had extra sprays - (Bellis) late bloom and Folicur pre-leaf fall - while both plots had Cuprokylt at 10 per cent leaf fall.
On one site, the best-practice approach greatly reduced the number of new cankers and the incidence of fruit rot compared with the standard programme, Berrie reported.
On the other site the reduction in new cankers in the best-practice plot was less marked and the incidence of fruit rot was too low for any difference to be detected. The trial continues until March 2009.