Apple leaf-hopper

Press, Volume CXII, Issue 32862, 10 March 1972, Page 11

Apple leaf-hopper

Prevailing climatic conditions greatly influence the incidence and severity of many pests and diseases. For instance, warm damp and humid weather favours the onset of rots such as grey mould (botrytis) on strawberries and powdery mildew is always more prevalent in a dry season. A pest which is always more common when temperatures are up and conditions are dry is the apple leaf-hopper. .The apple leaf-hopper, popularly known as the canary fly, looks very much like a miniature edition of a grasshopper with an over-all yellow colour — hence the common name. As its name also implies, it is predominantly found on apple trees but hawthorns also figure on its diet and it has been recorded on plum trees. It is usually a pest of minor significance, but in high temperatures with little or no rainfall it can increase to the extent that crops are considerably affected. At the present time some very severe infestations have been seen on unsprayed trees. The leaf-hopper is found predominantly on the underside of the leaf on which it

i- feeds by sucking out the sap e from the foliage. This causes f jthe leaves to gradually i assume a more and more r speckled yellow appearance d j much depending on the e | severity of attack. Badly y affected leaves may drop pre- - (maturely. A side effect is v| blemishes on the fruit from a I their excrement. The mottled a appearance of the leaves i caused by their feeding can 1 create the mistaken imprese sion of virus infection though in fact the two symptoms are , quite distinct. e There are two generations i of leaf-hoppers produced duri ing the year. The eggs of 1 one lot are laid in bark of • the tree about now and the generation are laid -(some time in December, in 3! the mid-ribs and veins of >ithe leaves. The young are si pale green to greenish white . and similar in appearance to r the adults, but are wingless. - The wings of the adult more >1 or less envelop the whole ) : body; when disturbed they 3 [jump up and about rather s than fly. / Where a regular spray i schedule is adhered to these insects should not present a i problem. Carbaryl, D.D.T. or - maldison will give good t control.