FEW plants are exempt from disease, and these exemptions are seldom worth cultivating, which is simply another way of saying that all desirable plants are subject to ills of one kind or another. Some plants are of such strong and sturdy constitution that they are able to withstand them without being greatly injured by them, while others suffer under slight ones, and often succumb altogether from severer ones, unless prompt and energetic means are taken to stay their progress.
Many plants are injured by overwatering. Because of defective drainage surplus water cannot escape from the soil, and as a result it becomes sour, and the plants take on a sickly look. The old leaves become yellow and drop off. Their new ones are weak, and the general condition of the plant is highly unsatisfactory. If it is inclined to bloom most of its flowers will blight. Applications of fertilizer with a view to strengthening the plant and encouraging healthy development are abortive. In .fact, they simply make a bad matter worse.
In a case like this there is only one thing to do: Correct faulty drainage, and give diseased roots an opportunity to resume normal action.
In most instances, giving the stagnant water a chance to run off, and taking precautions against a recurrence of the trouble, will set matters right, after a little, provided the surface of the soil is stirred and put in a condition to admit air freely for the purpose of purifying and sweetening it. But if the trouble has existed for some time it may be necessary to remove a good deal of the old soil, and to cut away the ends of diseased roots, after which the pot should be filled with fresh earth, and water applied in very moderate quantities until the plant shows, by renewed growth, that it has put forth new feeding roots.
Great stress has been laid upon the necessity for good drainage in the chapter devoted to a consideration of that subject, and in order to more fully impress the importance of it upon the reader, I want to say right here:
Whenever the surface of the soil in a pot looks wet and heavy, and continues to look so, examine its drainage system and make sure that there is nothing wrong there. Do this before your plant settles into a state of chronic ill-health.
Sometimes one's plants will take on a sickly look, but examination will show that the drainage is not responsible for the trouble. It may take some time to ascertain that worms are at work in the soil. You will probably find your first proof of this in the little flies that will be found emerging in great numbers from the surface soil. Further examination will show larvae there from which these flies are hatched, and it will also doubtless show you worms feeding on the tenderest roots of the plant-small white worms that do not look dangerous, but are capable of doing a great deal of mischief, if let alone, because their attack on the roots robs the plant of vital force by sapping what is really its life-blood.
The most satisfactory remedy that I have any knowledge of for this condition of things is lime water.
To prepare the remedy, put a piece of fresh lime as large as an ordinary coffee-cup in a ten-quart pailful of water. Care must be taken to have the lime perfectly fresh, as the air-slacked article is valueless. The lime, if fresh, will cause a bubbling and boiling of the water, shortly after it has been dropped into it, and this will continue until it has dissolved. There will be a white sediment that will settle to the bottom of the pail. Pour off the clear water and apply this to your plants in quantities sufficient to saturate all the soil in the pots. Do not dilute it any, and do not apply it in small quantity, as many do, fearing to injure their plants by using too much. Water can hold only a certain amount of the active properties of lime in suspension- never enough to injure any plant except those which object to lime in any form and any quantity. It is necessary to make the application large enough to affect all the soil in order to have it beneficial, as a small amount, wetting only a small spot, will simply cause the worms to shift their location. One application may not be sufficient. Wait three or four days, then make careful examination of the soil, and if any worms are found repeat the operation. Do this until you are unable to find a worm.
Worms are seldom found in fresh, clean soil. They are sometimes introduced in it by the use of barnyard manure not old enough to be thoroughly decayed. Often they breed in the dregs of tea or coffee used as a mulch. Avoid any and everything calculated to favor their production.
Angle or fish worms often work among pot-plants, but I have never been able to see that they do much harm. Doubtless the holes which they make in the soil may sometimes allow the water to run off so rapidly that it does not have time to soak in properly, and in this way plants may be injured through their agency, but never, I think, by a direct attack of the worms. Still, most persons object to them. They can be driven out of the soil by applying water containing spirits of camphor. Use a tablespoonful of the latter to five quarts of water. Apply a quantity sufficient to penetrate all the soil in the pot.
I have been told by many correspondents that all kinds of worms can be expelled from pots by sticking parlor matches, brimstone-end down, into the soil about the plants- five or six matches to a pot; also that a tea of black pepper will produce a similar result. I have not tried these remedies, being satisfied with the lime solution advised, but those of my readers who are fond of experimenting can do so, and perhaps they may find them of benefit. I would suggest, however, trying them on a plant which you do not care very much about, as the result might not be what you would like to have.
Of late years many plants have been afflicted with a disease of fungoid character. The edges of their leaves will turn brown and soon become dry enough to crumble under the touch. Frequently yellow spots will appear in the leaves. These will enlarge, become brown, and the tissue of the leaf will crumble away, leaving a hole that has the appearance of having been made by an insect. No insect can be found, however, and the owner of the plant is mystified. The trouble originates from spores of fungus that float about in the air. They settle upon a leaf, and soon affect it as described. Few plants escape the ravages of the disease when it secures a foothold in a collection. It does deadly and rapid work, and prompt action is necessary to counteract its destructive influence.
The only remedy I have ever found for it is Bordeaux mixture-a preparation of copper sulphate and fresh lime. This is what small-fruit growers and nurserymen depend on to protect their orchard products from the ravages of the various fungoid diseases now so prevalent in all parts of the country. The mixture can now be obtained of florists and plant-dealers in paste form, soluble in water. This is what every amateur gardener should procure instead of attempting to prepare the mixture for himself, as the process is a somewhat elaborate one. Instructions for using it will be found on the cans in which it is sold. Regular and persistent use of it will keep the disease in check, if it does not wholly rid your plants of it.
Roses and a few other plants are sometimes attacked by mildew. You may know of this by a curling of the young leaves, and a white substance, like dust, that will be found on many of them. This disease is generally the result of cold drafts, exposure to a low temperature alternating with a higher one, and a lowering of the vitality of the plant from various causes. It seems to have something of a fungoid character, which makes it possible for it to communicate itself to other plants by spores in rooms where drafts can not be held responsible for its spread. The remedy is protection from all cold currents of air, and dusting the affected plants, while damp, with flour of sulphur.