Apple Growing Part 4

There are two great cla.s.ses of cover or green manure crops, leguminous and non-leguminous. A non-leguminous crop merely adds humus and improves the physical condition of the soil. In itself it adds no plant food, although it may take up, utilize, and leave behind plant food in a more available form for the tree's use. But in addition to these benefits, leguminous crops actually add to the soil plant food in the form of nitrogen which they have the ability to a.s.similate from the air by means of bacterial organisms on their roots.

NON-LEGUMINOUS CROPS.--The most important of the non-leguminous crops are rye, buckwheat, turnips or rape, barley, oats, and millet. The first mentioned are the most commonly used. Also in order of importance the following are the usual leguminous cover and green manure crops to be used: clovers, winter vetch, soy beans, alfalfa, cow peas (first in the South). In order to determine the relative advisability of the use of these various crops let us now look at some of their characteristics and requirements.

Rye is one of the best non-leguminous cover crops, especially in the young orchard, as it does not grow as well in shade as in the open. A particularly strong point about rye is that it grows rapidly quite late in the fall and starts early in the spring. Starting earlier than most crops in the spring, it makes a considerable amount of growth before the land is fit to plow. Especially in warmer climates rye should not be sown too early in the fall--not usually before September 1st--because of this too heavy growth. Rye is also adapted to a great variety of soils and hence will often grow where other crops will not do well. About two bushels of seed are required per acre.

Buckwheat is probably about equally as good as rye for an orchard cover crop, although it does not produce quite as much organic matter.

It will germinate at almost any season of the year even if it is very dry. It is a great soil improver because of its ability to feed and thrive on soils too poor for other crops, due to its numerous shallow feeding rootlets. It grows rapidly and covers the ground well, but like rye does not thrive as well in shade. Buckwheat should not be used to excess on the heavier types of soil as it is rather hard on the land. One bushel of seed to an acre makes a good seeding.

Turnips or rape often make good pioneer cover or green manure crops.

They are great soil improvement crops and it is comparatively easy to secure a good stand of them even in dry weather. Sown in late July in the North they will produce a great bulk of humus and add much moisture to the soil, especially if they cover the ground well. Their broad, abundant leaves and high tops also hold the snow well in winter. Cow Horn is the best variety of turnips to use, as it is a large, rank grower. Use one to two pounds of seed to the acre. Rape makes an excellent pasture crop in an orchard both for sheep and hogs, but especially for the former. Eight or nine pounds of seed are necessary to the acre.

Barley, oats, and millet are not as good crops as the foregoing, because, with the possible exception of millet, they make their best growth early in the season. Moreover they take up too much moisture from the soil at a time when the tree most needs this moisture. In fact they are sometimes used for this specific purpose on wet land in too wet seasons. Two to two and one half bushels of oats or barley and one to one and one half bushels of millet to the acre are necessary for a good seeding.

Although weeds can hardly be cla.s.sified as cover crops, they are often valuable ones. They grow rapidly and rank, making a large bulk of humus, without the expense of seeding. If they are not allowed to go to seed so as to scatter the seed about the farm, they often make the best of cover crops. This necessitates a mowing in September. Weeds are plants out of place, and when these plants are in place they are not necessarily weeds, as they have then become serviceable.

LEGUMES.--In general, legumes are more valuable as cover and green manure crops than non-leguminous plants, because as a rule they are more rank growers and more deeply rooted, as well as because they add nitrogen to the soil. But it is rather more difficult to secure a good stand of most legumes than it is of the crops previously mentioned for several reasons. As a rule the seeds are smaller and a large seed usually has greater germinating power than a small one. This often means much at the time of the year when the cover crop is sown. Then legumes are more difficult to grow, requiring better soil conditions.

Still these should be present in good orchard soils. Drainage must be good, the soil must be at least average in fertility and physical condition, it must not be sour--hence it is often necessary to use lime--and soils frequently require inoculation before they will grow legumes satisfactorily.

Where the clovers grow well they make excellent cover crops as well as green manure crops. The chief difficulty with them is that of obtaining a good stand in a dry midsummer. The mammoth red and the medium red clovers are probably the best of their genus on the heavier soils, while crimson clover is best on sandy soils and where it will grow, on the lighter gravel loams. The latter is especially well adapted to building up run down sandy soils. Although it is somewhat easier to secure a stand of this clover, alsike does not grow rank enough to make a good cover or green manure crop. Most clovers are deep rooted plants and therefore great soil improvers physically as well as being great nitrogen gatherers. The amounts of seed required per acre for the different kinds are about as follows: mammoth fifteen to twenty pounds; red (medium) twelve to fifteen pounds; crimson twelve to fifteen pounds; and alsike ten to twelve pounds.

Where it can be readily and successfully grown alfalfa is really a better cover and green manure crop than the clovers. It is deeper rooted, makes a better top growth, and therefore adds more nitrogen and more humus to the soil than the clovers. It cannot be recommended for common use, however, as it is so difficult to grow except under favorable conditions. It requires a more fertile soil than clover, a soil with little or no acidity, good drainage, and usually the soil must be inoculated. Only where these conditions prevail can alfalfa be generally recommended.

Vetch is an excellent cover and green manure crop, forming a thick, close mat of herbage which makes a good cover for the soil. It is very quick to start growing and a rapid grower in the spring. It also adds larger quant.i.ties of nitrogen. The hairy or winter vetch lives through the hard freezing winters. Summer vetch, although an equally good grower, is killed by freezing. One bushel of seed is required per acre and the seed is expensive, which is the greatest objection to the use of this excellent crop.

Two other less well known and used leguminous crops are well worth trial as cover crops--soy beans in the North and cow peas in the South. Both are great nitrogen gatherers and as they are rank and rapid growers add large quant.i.ties of humus to the soil. Under favorable conditions they will cover the ground with a perfect mat of vegetation in a very short time. Being larger seeded, it is considerably easier to obtain a stand on dry soils and in dry seasons than it is of the smaller seeded clovers. It is usually best to sow in drills the ordinary width, seven inches, apart.

Cow peas are universally used as a cover and green manure crop in the South, but they do not thrive so well in the North. One and one half to two bushels of seed are required per acre. In the North the earlier maturing varieties of soy beans are almost equally good. One to one and one half bushels of seed are sown per acre.

Leguminous cover crops are also the best and the cheapest source of nitrogen for the apple orchard, after they are well established. Their use may be overdone, however. Too much nitrogen results in a growth of wood at the expense of fruit buds. To avoid this it is often advisable to use non-leguminous and leguminous crops alternately, when the orchard is making a satisfactory growth. Sometimes also these two kinds of crops, as buckwheat and clover for example, may be combined with good results. When this is done one half the usual amount of seed of each should be used.

EARLY PLOWING.--Many people make the common mistake of thinking that a green manure crop must be allowed to grow until late in June in order to secure the maximum amount of growth. There are several reasons why this is not good practice. In the first place cultivation is most essential in the early spring as has been pointed out. Then moisture is better conserved by plowing under the crop early and a better physical condition of the soil secured. Plowing early in the spring warms up the soil and sets plants to work more quickly. Lastly, material rots much more quickly in the early spring when moisture is more abundant, which is very important.

An apple tree is as much a crop as anything grown on the farm and must be so regarded by those who would become successful orchardists. When it is not properly fed and cared for, good yields of fruit may not justly be expected. Especially is this true of an orchard which is being intercropped. But because of the fact that an apple tree is not an annual crop but the product of many years' growth, because its root system is deeper and more widely spread out than those of other crops, and because the amount of plant food removed in a crop of fruit is comparatively small, fertilization is less important than many persons would have us think. It is a fact that where orchards receive good cultivation and a liberal supply of humus commercial fertilizers give but medium results.

ELEMENTS OF FERTILITY.--Three elements are necessary for the growth of apple trees, nitrogen, phosphoric acid, and potash. To these lime may be added, although its benefit is indirect rather than direct as a plant food. How badly any of these elements may be needed depends on the soil, its previous treatment, and on the system of management. By learning what are the effects of these elements on the tree and fruit we may determine under what conditions, if any, their use is advisable.

Nitrogen promotes the growth of new wood and leaves, giving the latter a dark green color. In fact the color of the leaves and the amount of the wood growth are usually good indicators of the need of nitrogen.

Nitrogen in excess develops over vigorous growth and prevents the maturity of wood and buds. It always has a tendency to delay the maturity of the fruit by keeping it growing late. On many varieties it tends to produce poorly colored fruits.

When trees are making a normal amount of growth in a year--say a foot to three feet or more--and when the leaves are of good size and a dark green in color, there is little need of nitrogen. But when trees are not growing satisfactorily and the leaves have a sickly yellow color, then the need of nitrogen is evident. On early soils and in long growing seasons nitrogen may be more freely and safely used than under other conditions.

The effect of phosphoric acid and potash on the tree and fruit is much more uncertain. They are supposed to influence the quality and the flavor of the fruit, giving better color and flavor, and this they undoubtedly do to some extent. Potash probably gives the leaves a darker green color. The precise effect of these two elements is at present a subject of much discussion, one set of investigators maintaining after a long and careful investigation that these effects are too small to be worth while, and the other claiming that they have a marked effect in the ways above indicated. The only safe guide is the actual local result. If the fruit is satisfactory in every way it will be of little use to try fertilizers. On the other hand, if it is not, then it will pay to experiment with them. The needs of and the results on different soils are so variable that it is always wise to experiment on a small scale before using fertilizers extensively.

STABLE MANURE.--The necessary plant food is best supplied by stable manure applied at the rate of ten loads per acre for a light application to twenty loads per acre for a heavy application. This amounts to a load for from two to five mature trees. Such an application will not only go far toward supplying the necessary nitrogen, phosphoric acid, and potash, but especially if coa.r.s.e will add considerable humus and improve the physical condition of the soil.

Except on land which washes badly, manure should be applied in the fall and winter. It should not be piled near the trunk of the tree but spread uniformly over the entire surface of the ground. It is particularly important to spread the manure under and beyond the farthest extent of the branches as this is the most important feeding root area of the tree.

COMMERCIAL FERTILIZERS.--Where manure is not available or where it cannot be applied in sufficient amounts, commercial fertilizers may be resorted to, after they have been experimentally tested out.

Leguminous cover crops are the best source of nitrogen, as has been indicated, but where these do not grow well, or in seasons when they have for some reason failed, nitrate of soda or dried blood are good subst.i.tutes. From two hundred to three hundred pounds of one or the other of these may be applied broadcast in the spring soon after growth is well started and all danger of its being checked by frost or cold weather is past. It is well to apply the nitrate of soda in two applications a few weeks apart, especially on soils which are leachy and in wet seasons, as part of the nitrogen may leach away if all is applied at once. These should be thoroughly worked into the soil with a spring-tooth harrow.

To supply the other two elements, from two hundred to four hundred pounds of treated rock phosphate or basic slag for the phosphoric acid, and the same amount of sulphate of potash for the potash, should be applied at any time in the early part of the season, preferably just before a light rain, and worked into the soil as before.

Home-made wood ashes are a good source of both these elements, and especially of the potash. They cannot be purchased economically in any quant.i.ty, but on the general farm there could be no better way to utilize the wood ashes made around the place than by applying them two or three bushels to a full grown tree every year or two. Wood ashes are also a good source of lime, being about one-third calcium oxide.

Thus a large amount of available plant food will be supplied to the tree, and where it is needed should result not only in better wood growth but in the formation of vigorous leaf and fruit buds for the following year.

Lime is not usually considered as a fertilizer except on soils actually deficient in it. But it will usually be advisable to apply from one thousand five hundred to two thousand pounds of fresh burned lime or its equivalent, in order to correct any natural soil acidity, to hasten the decay of organic material, to increase the activity of the soil bacteria, and to improve the physical condition of the soil by floculating the soil particles and helping to break up lumpy soils.

Lime also helps to liberate plant food by recombining it with certain other elements in the soil. All these effects make a more congenial medium for the leguminous crops to grow in, and it is frequently advisable to use lime for this purpose alone. After this first heavy application about 800 pounds of lime should be applied per acre every four or five years.

CHAPTER VII

INSECTS AND DISEASES AFFECTING THE APPLE

It is a common saying among farmers who have grown apples on their farms for many years that there are many more pests to fight than there used to be. How often we have heard a farmer tell of the perfect apples that grew on a certain tree "when he was a boy," before people had generally heard of codling moth, San Jose scale, apple scab, or other troubles now only too common. "We never sprayed, but the apples were fine," he says. Is this the usual glorification of the mythical past or is it true? In all probability it is a little of both, but it is undoubtedly true that insects and fungous diseases have increased rapidly of late years.

REASONS FOR PEST INCREASE.--When there is an abundance of food and conditions are otherwise favorable, any animal or plant will thrive better than when the food supply is scarce and conditions unfavorable.

As long as apple trees were scattered and few in number there was not the opportunity for the development of apple pests, but as soon as they became numerous the prosperity of bugs and minute plant parasites was wonderful to see. Another factor which has been at least partly responsible for the great increase in our insect life is that man has upset nature's balance by destroying so many birds, and, by interfering with their natural surroundings, driven them away. Birds are great destroyers of insects, and their presence in the orchard should be encouraged in every possible way. Add to these facts the marvelous fecundity of the insect tribe, and the increase is less remarkable. Loss from these orchard pests has now run up into the millions. It has been estimated that the loss in the United States from wormy apples alone is over $11,000,000 annually. Thus has the necessity for fighting these enemies of good fruit arisen.

In order successfully to combat an insect or a disease it is very necessary to have a somewhat detailed knowledge of its life history and to know its most vulnerable point of attack. It is impossible to work most intelligently and effectively without this knowledge, which should include the several stages of the insect or disease, the point of attack, the time of making it, and when and with what it can be most easily destroyed. The number of insects and diseases which affect the apple is so great that it is simply out of the question to treat them all in detail here. We have therefore selected nine insects and three diseases as those pests of the apple which are most common and whose effects are usually most serious. The essential facts in their life histories and their vulnerable points will now be pointed out.

The method of study may be taken as applicable to any other pests which it may be necessary to combat.

INSECT PESTS.--Of the many insects which affect either the tree or the fruit of the apple, the nine selected probably inflict the most damage and are the most difficult to control of all those in the Northeastern States. According to their method of attack all insects may be divided into two cla.s.ses: biting and sucking. Biting insects are those which actually eat parts of the tree, as the leaves or fruit. These are combated by the use of stomach poisons as we shall see in the following chapter. Sucking insects are those which do not eat the tree or fruit directly, but by means of a tubelike proboscis suck the juices or sap from the limbs, leaves or fruit. Of the biting insects the five which we shall discuss are: (1) codling moth, (2) apple maggot, (3) bud moth, (4) cigar case bearer, (5) curculio. The four sucking insects discussed are: (6) San Jose scale, (7) oyster sh.e.l.l scale, (8) blister mite, and (9) aphis or plant louse.

1. THE CODLING MOTH, the most insidious of all apple pests, is mainly responsible for wormy apples. The adult is a night flying moth with a wing expanse of from one-half to three-quarters of an inch. The moths appear about the time the apple trees are in bloom. Each female is supposed to lay about fifty eggs which are deposited on both the leaves and fruit, but mostly on the calyx end of the young apples. The eggs hatch in about a week and the young larvae or caterpillars begin at once to gnaw their way into the core of the fruit. Three-fourths of them enter the apple through its blow end.

After twenty to thirty days of eating in the apple, during which time they become full grown and about three-quarters of an inch long, they leave the apple, usually through its side. The full grown caterpillar now secretes itself in the crevices in the bark of the tree or in rubbish beneath the tree and spins a tough but slight silken coc.o.o.n in which the pupal period is pa.s.sed. This lasts about a fortnight, when the process is sometimes repeated, so that in the Eastern States there are often two broods each season.

The most vulnerable point in the career of this little animal is when it is entering the fruit. If a fine poison spray covers the surface of the fruit, and especially if it covers the calyx end of the apple inside and out, when the young larvae begin to eat they will surely be killed. It is estimated that birds destroy eighty-five per cent. of the coc.o.o.ns on the bark of trees.

2. APPLE MAGGOT.--It is fortunate that the apple maggot, often called the railroad worm because of its winding tunnels all through the fruit, is not as serious a pest as the codling moth for it is much more difficult to control with a poison. A two-winged fly appears in early summer and deposits her eggs in a puncture of the skin of the apple. In a few days the eggs hatch and the maggots begin to burrow indiscriminately through the fruit. The full grown larvae are a greenish white in color and about a quarter of an inch long. From the fruit this insect goes to the ground where the pupal stage is pa.s.sed in the soil. The next summer the fly again emerges and lays its eggs.

Spraying is not effective against this insect as the poison cannot be placed where it will be eaten by the maggots. The best known remedy is to destroy the fruit which drops to the ground and for this purpose hogs in the orchard are very effective. The distribution of this insect in the orchard is limited and it has shown a marked preference for summer and autumn varieties.

3. THE BUD MOTH closely resembles the codling moth in form and size, but differs from it in color and life history. The larvae, after hibernating through the winter, appear as little brown caterpillars about May first or as soon as the buds begin to open, and a week or two later begin their work of destruction. They inflict great damage on the young leaf and fruit buds by feeding on them. When full grown the larvae, cinnamon brown in color with a s.h.i.+ning black head, are about one-half inch long. They then roll themselves up in a tube made from a leaf or parts of leaves securely fastened together with silken threads. In this coc.o.o.n pupation, which lasts about ten days, takes place. Early in June the moths appear. There is but one brood in the North. These insects can be successfully combated with a poison spray applied early before the buds open.

4. THE CIGAR CASE BEARER winters in its case attached to a twig. When the buds begin to open in the spring it moves to them, carrying its case with it, and begins to feed on the young and tender buds. By the time the leaves are well open, it has fed a good deal on the tender buds and young leaves and is ready to make a new and larger case. This it does by cutting a leaf to suit and then rolling it up in the form of a cigar, whence its name. In this case the larvae continue feeding about a month, causing much injury to the leaves, although this is not as serious as the mutilation of the young buds in the spring, before the tree is fully leafed out.

About the last of June pupation takes place and in about ten days the moth emerges. The eggs are then layed along the midribs of the leaves and hatch in about fifteen days. The newly hatched larvae become leaf miners during August, and migrate to the branches again in the fall where they pa.s.s the winter. These leaf and bud eating insects can be destroyed by applying a poison to the buds before they open and again later to the opening leaf and flower buds.

5. CURCULIO BEETLES pa.s.s the winter under leaves and gra.s.s. In the spring they feed on the blossoms and the tender leaves. As soon as the young fruits are formed the female deposits her eggs in a puncture made just inside a short, crescent-shaped cut in the little apple. The eggs soon hatch and the young grubs burrow into the fruit to the core where they remain two or three weeks, or until full grown. The larvae then bore their way out of the fruit and drop to the soil where they pupate. The earliest of the beetles to emerge again feed on the fruit.

The princ.i.p.al damage from this pest comes from the feeding of the beetles and the work of the larvae, although the latter is not as bad in the apple as in the stone fruits. A poison on the young foliage as soon as the beetles begin to feed is the best method of combating curculio. Jarring the tree is not as practicable with the apple as it is with the plum.

6. THE SAN JOSe SCALE, one of our worst apple tree pests, is a sucking insect extracting the juices of the tree from the trunk, limbs or branches, or even from the leaves and fruit when it is very abundant.

At first the growth is checked only, but as the insects develop their work finally results in the death of the part, unless they are destroyed. The insect winters in an immature condition on the bark under a grayish, circular, somewhat convex scale about the size of a pinhead. The young, of which a great many broods are produced, are soft bodied but soon form a scale. In the early spring small two-winged insects issue from these scales.

After mating the males die, but the females continue to grow and in about a month begin the production of living young--minute, yellow, oval creatures. These young settle on the bark and push their slender beaks into the plant from which they begin to suck out the sap. In about twelve days the insects molt and in eight to ten more they change to pupae, and in from thirty-three to forty days are themselves bearing young. A single female may give birth to four hundred young in one season and there are several generations in a season. This great prolificacy is what makes the scale so serious a pest.