1. The pear oyster scale is very injurious, especially on walls, if not checked at an early stage. The covering of the female is like a small oyster scale, hence the name. Scrape off any rough bark in winter, and apply the alkali or one of the other washes as a preventive. In May and June affected parts might be brushed with ¼ lb. of soft soap in a gallon of water. Tobacco or lime water might also be applied. Paraffin largely diluted may be used, but is dangerous in excess. Messrs Rivers in "The Miniature Fruit Garden" (p. 144) say: "Washing the parts affected with a mixture of soot, lime and sulphur will remove the roughness and restore the tree to health; the above mixed with skim milk is more enduring." As a believer from experience in soot and lime, I prefer this receipt, if the trees were not washed in winter.
2. The Blister Moth makes brown blisters on the leaves. It may be kept from laying eggs on the tree by syringing occasionally with soap-suds. Spraying with Paris Green just after the fruit is formed will do good. Half an ounce of best paste to 10 or 12 gallons of water, with some fresh lime added, will suffice for small gardens. Spray only in fine weather just after the petals have fallen. Paris Green is arsenic, and may poison bees if used too soon. The sprayer should avoid breathing over the mixture when making it up, should use gloves, work from windward, and not allow any spray to reach his flesh. A second spraying for this and other insects is often useful. Blundell, Spence & Co. (Ltd.), Hull, supply good paste. Price ½ lb. 1s., less for larger quantities. See also No. 3.
3. The Pear Leaf Mite causes small blisters on the leaves, but not the tunnels or galleries of the Blister Moth. It winters in the bud scales, and emerges in the spring. If the trees are washed and syringed, the attacks will be lessened. In (2) and (3) collect the blistered leaves as soon as seen, burn them and spray or syringe at once.
Miss Ormerod recommends a dilute paraffin emulsion sprayed over infested leaves. Dissolve ¼ lb. of soft soap in a gallon of water, add this while boiling to two gallons of paraffin, churn the whole with syringe or small pump for ten or fifteen minutes to make a perfect mixture. For spraying add 12 gallons of water to each gallon of the emulsion. Stir well while spraying, and try the mixture on a branch or two lest it be too strong; if so, add more water. This emulsion is good for the Blister Moth and the Slug-worm.
4. The Slug-worm is so called from the similarity of the larva of this sawfly to a small black slug. The worms feed on the upper surface of the leaves. Dust with quick lime two or three days in succession, or syringe with strong soap-suds and some tobacco water. Clean with pure water in a few days. The paraffin emulsion (No. 3) might also be used. Quick-lime scattered around the roots and forked three or four inches into the soil may destroy their cocoons. But beware of excess. The remedy may be worse than the disease.
Insects that attack leaves will also eat the skin of the young fruits if conveniently placed for them.
5. The Pear Sucker is a jumping plant-louse which early in the season sucks the juices of the tree about the axils of the leaves. They are covered with the exudations of the sap, which often drops on the ground. The visits of the ants should call attention to this pest. Syringe well with soft soap and water, ½ lb. to 4 gallons, and add tobacco water. Remove all rough bark (their hiding-places) in winter.
6. The Pear Gnat Midge (Diplosis pyrivora) may readily ruin a crop if unchecked. It is a recent importation among us. Both here and in the United States it is spreading with alarming rapidity. It is a small two-winged fly, with a black body having lines of yellow hair. The female pierces the flower-buds and lays her eggs in them. These soon hatch, and the young tiny grubs eat their way into the embryo fruit, keeping to the fleshy part, leaving the core and seeds alone. The pears turn brown, and then black. Cut them open, you will notice maggots. The fruit bursts or falls, the maggots form silken cocoons in the soil in which they pupate, and remain till the blossoms begin to expand next spring. Mr J. Fraser (editor of Gardening World) has kindly sent these details, and recommends (1) that the injured fruit be gathered and burnt; (2) that two inches of the ground beneath the trees should be taken up and burnt; (3) that kainit should be distributed round the trees in autumn. Kainit is said to keep off wireworm, and is recommended in the United States as a preventive against this pest. I think the mixture No. 2 or No. 3 should also be used, as insects may be deterred by the scent. Lime and soot spread over the ground in winter would probably do good.
7. Weevils devour leaves, buds, young shoots, even the skin of fruit. They feed by night, and may be shaken into a cloth off bushes. Lime and soot may lessen their attacks, either as a wash No. 2 or 3, or spread lightly round the stems, or as a powder over the leaves.
A special bellows for distributing any dry powder (as sulphur, lime, soot, etc.) can be had from De Luzy Fréres, 44A Harold Street, Camberwell. The price is 7s. 6d., carriage paid.