Blueberry Stunt

If fall colours show early in your blueberry field, take a close look for blueberry stunt disease. A bright red colour sometimes develops on infected shots in late summer and early fall.

Blueberry stunt is a serious disease that is seldom observed, or at least diagnosed, in Ontario. It is caused by a mycoplasma, and it can be spread in infected planting stock, or by the sharp-nosed leafhopper.

Infected plants become stunted (Figure 1, 2) , and new leaves are cupped under, small and yellowed at the edges ( Figure 3) . Sometimes infected bushes show a characteristic bright red colouring on leaves of certain shoots (Figure 4). Control of blueberry stunt is drastic: you must remove infected bushes.

Because blueberry stunt is caused by a mycoplasma, it is difficult to verify. Only a few laboratories in Canada provide PCR testing for this type of disease. The Pest Diagnostic Clinic (uoguelph//ca/pdc) has recently been equipped to identify diseases caused by mycoplasmas, for example: blueberry stunt. If you suspect this disease, contact the pest diagnostic clinic for diagnosis (519-767-6256) . If you confirm that stunt is present, remove-infected bushes. First, however, control any leafhoppers that may be feeding, to prevent further spread of the disease.

Figure 1: The blueberry bush in the middle is infected with stunt.

Figure 2: Symptoms of blueberry stunt include shortened internodes
and a bushy appearance to shoots.

Figure 3: Symptoms of blueberry stunt include downward
cupping of leaves and marginal yellowing.

Figure 4: A bright red colour sometimes develops on blueberry shoots infected with stunt.

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