HORTICULTURE HORTICULTURE What is Wrong with My Raspberries?
By Mark Longstroth
District Extension Horticultural & Marketing Educator
As time goes on I get to see a lot of problems in raspberries. I have started this collection too help other people figure out what they have. This is a work in progress and I up date it when I can, usually in the winter.
Disease Problems:
Orange rust
see E-1730, Raspberry Diseases in Michigan
Late leaf
rust infecting the fruit. This is a minor disease and there are no controls. This should
not be confused with Orange rust see E-1730, Raspberry Diseases in
Michigan
Insect Problems:
The Japanese Beetles love raspberries! I can always
predict their emergence here in Michigan. They seem to appear just before raspberry
harvest. There are no good organic controls. Traps are effective but have the disadvantage
of attracting the beetle from long distances. When using Japanese beetle traps be sure to
set the traps outside the planting. I would set the traps 100 to 150 ft away and empty to
contents daily. Insecticides will kill the beetle if used at high enough rates but new
beetles will quickly move into the planting to take their place. Applications of
insecticides to control the grubs which feed mainly on grass roots seem to be the most
effective way to keep this beetle down.
Raspberry cane borer 
(Oberea bimaculata Olivier) or Raspberry girdler is a
Cerambycid or long horned beetle. Wilting of the shoot tips in the summer are a sign that
this pest is out. Two girdles about an inch apart are located at the bases of the wilting.
The insect lays its eggs in the cane and then girdles the stem above and below. The larvae
hatches and then borrows down the stem. Homeowners may simply remove the girdled section
of stem with the egg inside to control this pest.
The Potato leaf hopper is a pest which comes north into
Michigan each year. It does not over winter in Michigan. The adult injects a toxin in the
plant when it feeds causing the edges of the leaves to become yellow and the leaf to curl
up or down. Potato leafhoppers are easily killed with insecticides and affected plants
such be treated as quickly as possible rto reduce damage. Affected leaves do not recover
but new leaves are usually not injured. Plants can be attacked at any time in the season.
Be vigilant whenever your neighbor has a problem and near hay fields after mowing. I have
seen this pest on apples, blueberries, raspberries, wine grapes and numerous ornamental
plantings.
Herbicide Injury:
Command is a 
common herbicide used on soybeans. It is very volatile and drifts
to nearby plantings. The symptoms are distinct and easily recognized. The injury is
temporary and the plants will grow out of it if they are not killed but the herbicide will
stunt growth during the growing season and will reduce fruiting and fruit set.
Other Injuries:
Sunburn is a fruit problem also called Solar Injury or White Druplet
Disorder. It is prevalent on red raspberries during hot weather. Shade cloth will reduce
this problem. Some growers claim that anti-transpirants are effective.
