Walker (70) suffered a torn Achilles tendon in his right leg early this week when he attempted to repair the rose trellis at his Mosgiel home.
Strong winds damaged the trellis and Walker tripped over an outside metal chair while attempting to fix the trellis.
"I was placing a bit of trellis back to its original position when I collected the leg of a metal outdoor chair which sent me to the ground,'' Walker said.
"After dropping the trellis, dodging a couple of planters, doing a pirouette around a tree and a beautiful forward roll and tuck I finished face down on the lawn.''
His leg must remain in plaster for six weeks and this will not give him enough time to come right before the Trans Tasman series.
"I'm devastated and frustrated. I had no option but to pull out.''
Walker will be replaced by Laurie Guy (Wellington) who was sixth in last year's New Zealand PBA rankings.
The Trans Tasman event will be held at Hastings from August 30 to September 1.
Guy is the brother of New Zealand tennis representative Steven Guy.
It is the third time Walker has injured the Achilles tendon in his right leg.
He was forced to pull out of the Bowls Dunedin team competing in the inaugural quadrangular representative match 28 years ago, after doing the Highland Fling.
He injured the same Achilles a few months later when on holiday in Wanaka.
This left him with a weakness in his calf muscle.
"During the last summer season I developed painful tendonitis in my left ankle and got through my games with great discomfort.''
"As the winter season developed I got tendonitis to my right ankle and the medical staff gave me a moon boot to wear.''
Walker won the Trans Tasman title last year when he beat promising 26-year-old Australian Ben Twist 5-11, 9-6, 2-0 in the final at the Cabramatta Bowling Club in SydneyWalker and Twist are the only bowlers to have played in all six Transtasman PBA Challenges.
Walker has been the most successful bowler in the event and has won the Trans Tasman Challenge individual final twice.
He won in 2012 and was runner-up in 2010.
New Zealand bowlers have won the individual title five times.
The other winners are Murray Glassey (Hawke's Bay) in 2013 and 2014 and Raika Gregory (Hamilton).
Walker has also withdrawn from this weekend's world indoor qualifying pairs at the Westpac Bowls Stadium but played in the qualifying singles from a wheelchair last night.
