last year, one of my raspberry plants had early die back of all of the tips of the plant. I presumed it was raspberry crown borer. No other plants seemed to be effected all the way through to the beginning of winter. Skip forward to spring and many of the tips of the floricanes had tip die back but the plants seem otherwise completely unaffected, is this still possible raspberry crown borer or just frost damage? My raspberries are rated for zone 4 and I live in zone 5 but I left them clipped up to my trellis without protection. Also if I do truly have a raspberry crown borer problems, would they affect the primocanes this early in the season or would they not do damage until later?
Cut into dead can and look for tunnels and frass in center (should be foam like and white-tan) also usually have some bulges on canes within bottom foot. Just the tips after winter is likely cold damage but cutting open cane will verify (either there’s foam like pith or there frass ie sawdust)
But if its a crown borer, would there only be tunnels close to the crown?
Crown Borers would cause entire cane die-back.
Inspect the live-dead junctions of the die-back tips for swellings or holes.