Barlow told Grower that apple growers have had problems sourcing sufficient numbers of pickers this year, since the Government scaled down SAWS from 25,000 workers to just 16,250 workers from Bulgaria and Romania only.
Like many soft fruit growers, Barlow said top fruit farmers have been forced to use "unemployable" pickers from other parts of the EU.
He said: "There have been problems in terms of sourcing sufficient numbers and also because the quality of pickers has declined considerably compared to previous years - despite the fact that they are being paid premium rates. This emphasises once again the importance of SAWS.
"It's very important that the labour deficiency is corrected as quickly as possible as it is causing major problems for the top fruit industry. We (in the industry) feared that (this) would happen - and it has happened."
He added that, in light of these difficulties, supermarkets should put their price wars aside and remember growers.
"It's important that buyers and their superiors within the multiples appreciate that growers' costs have also increased - by some 15 per cent in the past year.
"Despite the fact that (the multiples) are engaged in increasing competition (with one another), growers need to see these sorts of increases or the multiples will not be able to get the UK produce their customers desire."
On a positive note, Barlow said that the relatively dry weather of the past few weeks has "made a huge difference" to top fruit harvesting this season.
He said: "It has enabled growers to get on with their picking.
"We were very worried at the end of August that there might be real difficulties getting in and out of the orchards."
He added that crops of Gala and Braeburn are expected to hit record numbers this season because of massive industry investment.