Rose Pests and Diseases

The Importance of Good Cultivation

In controlling pest and diseases good cultivation is most important, as the maintenance of good health in plants greatly reduces the possibility of attacks. Good cultivation includes the thorough preparation of the soil at the outset, subsequent adequate manuring, but not over-manuring, and the continuous use of the hoe. It does not embrace the frequent application of the hundred-and-one fertilizers offered on the market. As I have said before, one good annual mulching with well-decayed manure in the spring is all that is needed by established roses, unless blooms are required for special purposes, when the risk of the effects of over-feeding is deliberately taken.

Spraying

The second point is in regard to spraying and the importance of seeing it is well done, together with a little knowledge of whether one is spraying against fungus disease or pests, and if the latter which kind of pest. It is not possible to outline all the various types of damage which come under the two categories, but where disease is concerned there are certain characteristics which indicate the particular trouble. The three main diseases which affect roses are mildew, rust and black spot.

In regard to insect pests there are two kinds, sucking-mouthed and biting-mouthed insects. With the first it is necessary to apply a contact wash to block up the breathing pores, and with the second a poisonous cover wash.

The insect pests in their respective categories are:

Sucking-mouthed insects:

aphides, leaf-hoppers, capsid bugs, thrips and scurfy scale insects.

Biting-mouthed insects: leaf-miners, stem and shoot borers, earwigs, caterpillars, chafers, sawflies, slubworms, weevils, etc.

The life stages of the green apple aphid (Aphi...

Image via Wikipedia

All spraying must be done in the cool of the evening, as if the sprays are applied in bright sunlight damage to foliage is certain to result. The disease or pest must be tackled early. For example, greenfly, the most common insect pest, can do great harm if allowed to multiply, and it does multiply at an alarming rate, whereas if tackled early it is extremely easy to control. Ordinary soapy water and even clear water is an effective deterrent, and trees can be kept quite clean from this pest and a number of other insects if syringed regularly. There is a number of excellent and effective proprietary washes on the market. If one of these is used care must be taken to see that it reaches every part of the bush, and a heavy washing until the leaves drip is essential. Against the leaf-devouring insects, the cover wash should be applied in a mist-like form so that a fine coating of poison covers the leaves.

Spraying against Sucking-mouthed Insects

Effective home-made washes for sucking-mouthed insects are:

(1) Soft soap and quassia made as follows:

Soft soap 1/4lb

Quassia 1lb

Water 10 gallons

Steep the quassia chips in a quantity of cold water for 12 hours, pour off the extract into the soap solution and make up to 10 gallons. As the quassia is only extracted gradually, the same chips may be steeped several times.

(2) Nicotine wash:

Nicotine (90 per cent) ¼ to 1 oz

Soft soap 2 oz

Water 10 gallons

The soft soap is dissolved in warm water, and when cool the nicotine is stirred into it and the solution made up to the desired quantity.

Spraying Against Biting-mouthed Insects

For biting-mouthed insects arsenate of lead is very effective, and is mixed up as follows:

Arsenate of lead 3-½ oz

Acetate of soda 7 oz

Water 10 gallons

The arsenate and acetate are dissolved separately in 5 gallons of water and the solutions then mixed together. This wash is also obtainable ready made in paste or powder form. There are also many other effective proprietary insecticides available.

03. May 2017 by Dave Pinkney
Categories: Rose Care, Roses | Tags: , , , , , | Comments Off on Rose Pests and Diseases

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