There is no obvious reason why this problem should have arisen although one factor in particular is suspected to be involved.
East Malling Research storage specialist David Johnson said the computer model used for predicting whether or not LTB is likely to arise indicated nothing untoward.
"We cannot see from the temperature data where the (2008) season went wrong," Johnson maintained. "According to our model, LTB should not have been a problem." He said that the answer might lie in crop nutrition.
A good fruit phosphorus (P) concentration is particularly important. Phosyn's Mike Stoker, who monitors fruit mineral levels, found that during July last year the P figure was the lowest that has ever been recorded.
"Whether that is the reason for the problem I don't know," Johnson admitted. "The important thing that growers can do is to intensify their phosphorus-spray programme early in the season."
Late picking can also induce LTB, he said, but there is no reason why growers should have picked later than recommended although some might have done so.
However, there was nothing at harvest time to indicate that LTB would be a problem.
Mild LTB did show up in the Marden Fruit Show Society's long-term farm-stored competition that Johnson recently judged with WWF Qualytech's Martin Luton.
Five of the 10 Cox class entries did have one apple or more affected by the disorder.
The class also had far fewer entries than the other dessert apple classes, he recalled. This could indicate that growers were not very confident about submitting entries.
The higher-than-normal incidence of LTB is "a bit of a mystery," Johnson said.