The Plum Sawfly lays its eggs on the flowers. The young maggots which develop tunnel their way into the developing fruit. The only signs at this stage are the tiny holes left by the maggots.

As the maggots feed on the fruit, often a gooey black liquid exudes from the holes.

The variety 'Czar' is one of the worst affected.

TREATMENT
Break the pest's lifecycle at two  points. First, in late winter and early Spring, gently loosen and turn the soil around the base of the tree with a trowel or hoe. This will expose the over-wintering pupae to birds who love to eat them.

The second action is to spray the tree with derris (available at most garden centres) as soon as possible when roughly half the flower petals have fallen.

If the above action is taken, next year it should not be necessary to spray again.

 

 

GO TO THE GARDEN PEST AND DISEASE MAIN PAGE FOR
PESTS AND DISEASES CLASSIFIED BY PLANT