It would add to the comfort of the Rose grower if he could feel that, having well performed his duty in the planting and pruning of his Roses, he had done all that was necessary to secure them long life and robust health.
Unhappily, this is not the case. There is a horde of voracious enemies to reckon with.
It is a little hard on the grower to have to wage a constant battle against insects and fungi. He is not unnaturally inclined to think that he has a grievance, and that Nature is rather unkind to him. Well, we must take her as she is because we cannot alter her. If she spared us the orange fungus and grubs we should be very grateful to her; but she does not, and there is an end of it. There is, however, one thing to be said - the better we grow our plants the less trouble we shall have. Strong Roses, growing vigorously in well-trenched, well-manured soil, are never so badly pestered as weak bushes, struggling for bare life in poor, hungry ground.
It may be well to take the worst enemies of Roses one at a time and give a little consideration to their mode of attack and methods of prevention.
The small caterpillars of Eriocampa Rosae attack the upper skin of the leaves, and cause them to become patchy. Sometimes the leaves are completely skeletonised. The attack may be checked by hand picking, or by spraying with soaparite, or by dusting with Hellebore powder.
The caterpillar of the sawfly, Blennocampa pusilla, is an all too familiar enemy. The Rose grower observes the leaves of his plants curl, and on examination finds a small caterpillar snugly ensconced in the enclosure. If he be made of common human clay, nothing satisfies him except crushing the lurking enemy with his finger and thumb, and, as a matter of fact, persistence in this somewhat bloodthirsty method of clearance is about the best course which could be pursued.
This, like the caterpillar of the Lackey moth, is most often found on fruit trees, colonising in a web-nest, but it sometimes spreads to Roses. The colony should be brushed out of the tree before it has time to get into active operations, and destroyed.
One of the worst of these is the caterpillar of the Geometer moth, which binds the leaflets together, and if disturbed makes for the earth on the end of a thread. Fourteen stone of humanity applied to him directly he gets there has been known to have a soothing effect. This pest, and other caterpillars that operate similarly, should be searched for in the bound and rolled leaves. Or the bushes may be sprayed with Paris Green.
One of the most troublesome of these is Emphytus cinctus, which feeds upon the edges of the leaves. It may be cleared off by hand picking, or Paris Green may be applied.
The larva of Paecilosoma candidatum is happily not a common enemy for his method of attack is insidious. He eats his wav into the young shoots. These may be cut off and burnt, but converting the grub into ashes does not altogether compensate for the loss of promising shoots.
The larva of Lyda inanita forms for himself a comfortable home by spirally arranging fragments of Rose leaves. Housing plans of this sort should be foiled by a vigorous pressure.
The grower sometimes finds holes in otherwise sound and healthy leaves, cut with remarkable evenness. These are the work of the leaf-cutter bee, Magichile centuncularis. She uses the parts removed for lining her nest. Unless her operations are very extensive little harm is done; if they become destructive, the bee or her nest must be sought for and destroyed.
Greenfly is a great enemy of Roses, especially in a dry spring. In the absence of heavy rain a vigorous hosing is advisable. Or the bushes may be sprayed with soaparite.
This is a curious moss-like growth, in reality a gall, protecting the larvae of the fly Rhodites Rosae. It is not usually present in dangerous numbers, but may be cut off to prevent spreading.
This does not, as a rule, trouble Roses very much, but is apt to cause damage when the plants are suffering from drought, especially in the case of Crimson Rambler. Growers of this Rose should avoid shallow, hungry soils in dry positions. Moisture, which encourages vigorous, healthy growth, will keep red spider at bay.
The larva of Tortrix Bergmanniana is a common pest on Roses late in spring. It must be checked by hand picking.