HomeRaspberriesRaspberries: Primocane tips are wilting

Raspberries: Primocane tips are wilting

Wilting of primocane tips may be caused by disease or insect activity:

Fire Blight – is a bacterial disease of raspberries and blackberries. Thornless blackberries seem to be particularly susceptible to this disease, caused by the bacterium Erwinia amylovora.

Primocane tips wilt and curve in a characteristic shepherd’s-crook shape

Raspberry bush with brown, dead primocane. Primocane looks dry and is recurved into a shepherd's hook shape.
Shepherd’s hook caused by fire blight. Photo courtsey of A. Schidler, MSU.

Infected tissues may be covered with bacterial ooze under warm wet weather conditions.

Brown, dried-out fruiting tip on raspberrt. Fully-formed fruits and leaves appear dry, brown, and rigid.
Photo courtesy of A. Schidler, MSU.

 

Raspberry bush with many healthy canes. A single brown primocane is present. Brown cane has dry leaves. The tip of the cane is sharply hooked downwards.
Fireblight on raspberry.

More raspberry fire blight information

Raspberry Cane Borer – (Oberea bimaculata) sometimes referred to as cane girdler, lays an egg in a d-shaped hole cut near the tip of primocanes  …

Close-up of raspberry stem section with oval-shaped depression cut into surface. One side of the depression is curved, while the other side is more straight, resembling the letter D. The depression is one-third of the width of the stem. An elongated, beige-tan egg is visible in the center of the depression. The egg is almost as long as the depression but narrower in width.
Raspberry cane borer (Oberea bimaculata) egg in raspberry primocane stem.

… then girdles the cane both above and below the egg.

Close-up of raspberry cane covered in puncture marks. Tissue surrounding puncture marks is brown. Puncture marks are arranged in 2 neat, horizontal lines across the entire stem. One larger hole is placed between the horizontally-girdled region.
Girdling of fruiting cane and egg deposition site, symptomatic of raspberry cane borer activity.

This causes the primocane tips to wilt, and in some instances, to break.

A raspberry floricane appears snapped in half approximately 3-5 inches from the tip.
Removing and disposing of the broken-off tip of a floricane can prevent the next generation of insects from hatching.

If tips are not removed below the girdle, then eggs will hatch and larvae will burrow down the cane into the crown.

More Cane Borer (Girdler) and Rednecked Cane Borer information.

Rednecked Cane Borer – (Agrilus ruficollis) lays its eggs on canes from mid-May to early July. Larvae burrow into canes where they tunnel in a spiral fashion.

Close-up of stem with vertical splits in the bark. Splits are 1-2mm and bordered by brown tissue. A small larva with a yellow-green body composed of many cubelike segments is visible below the splits. Larva has dark brown head, no antenna, and is shaped like a thin rod.
Red-necked cane borer (Agrilus ruficollis) larva making its way down a raspberry cane.

Swellings often develop around the tunnels.

Raspberry stem with swath of swollen, purple-red tissue. Discoloration extends slightly beyond swellings. Section of stem where discoloration is prevalent has several smooth bumps.

Infested canes wilt and die or become weakened. Girdled canes are also more susceptible to winter injury.

Raspberry cane with one ripe raspberry at tip. Leaves on stem are lighter in color than on neighboring canes. Some leaves are bronzed at edges. Leaves at base of cane are healthy and dark green.

More Cane Borer (Girdler) and Rednecked Cane Borer information.