Preliminary Bulletin on Some Economic Insects and Plant Diseases of Indiana SB 824 .16 A5 1907 Copy 1 BENJAMIN W. DOUGLASS State Entomologist INDIANAPOLIS, INDIANA 1907 A PRELIMINARY BULLETIN ON Some Economic Insects and Plant Diseases of Indiana Benjamin W. Douglass State Entomologist INDIANAPOLIS, INDIANA 1907 INDIANAPOLIS \VM. B. BURFORD CONTRACTOR FOR STATE PRINTING AND BINDING 1907 o»of a Some Economic Insects and Plant Diseases of Indiana Office of the State Entomologist BENJAMIN W. DOUGLASS It has been claimed by eminent scientists that all the diseases of men common in Indiana, even to the notorious malaria of the swamps, were brought into this territory by the people who came from the older settlements. A similar statement would hold true for most of the insect and fungus parasites that infest the plants of the State. It has not been such a long time since it was possi- ble to grow fruit of all kinds and have a large percentage of per- fect specimens in the harvest. Today, however, there have been so many injurious insects in- troduced and so many fungus enemies have made their appear- ance that the problem of the horticulturist and the agriculturist is a great one, and one that will tend to increase instead of de- crease as time goes on. Today the fruit grower, even though he has but a few trees or berry bushes, must own a spray pump of some sort, and he must exercise a great deal of judgment in its use. Spraying has been played up for so many things that the novice is apt to be misled into thinking that it is a panacea for all orchard troubles, when, as a matter of fact, it is worthless unless done intelligently and with a proper regard for the re- quirements of the particular trouble involved. Before you start to spray be sure that you know what you are spraying for, and try to learn the best time to apply the proper spray or poison, and learn what that poison should be. We may divide the things that it is necessary to spray for into three general groups, each group requiring special treat- ment. First Group — Biting or Chewing Insects. This class includes all of the more common larval farms which damage the plant by actually eating the tissues. They may best be handled by an internal poison placed on the leaves or other plant parts that they damage. Of such poisons Paris Green is (2) 4 the most commonly used and is, perhaps, one of the best. Ex- amples of this group are the tomato worms, codling moths, elm- leaf beetles, etc. Second Group — Sucking Insects. Insects of this class damage the plants by inserting their mouth parts through the epidermis and securing their nourishment di- rectly from the interior of the plant. They can not be reached by any poison such as would kill the chewing insects, but must be treated with a remedy strong enough to kill them by direct contact. This fact makes the sucking insect an especially hard class to fight, as many of the things used to destroy them are apt to damage the plant as well. For this class of insects the most common remedies are Coal-oil Emulsion, "Whale-oil or other soap, strong tobacco juice, and the Lime-Sulphur-Salt wash. The San Jose and other scales and the plant lice are examples of this class of insects. Third Group — Fungus Enemies. • / There are almost innumerable parasitic fungi that infest wild and cultivated plants, and often they become a very serious pest and do tremendous damage. They consist of small, often micro- scopic, plant bodies, which live in the body of the "host" plant, as it is called, and gradually cause its death, either by the de- struction of the tissues or by the production of a direct poison. The universal remedy for all such fungi is a solution of copper sulphate, either pure or with the addition of a certain percentage of lime, to neutralize the free acid of the sulphate and thus pre- vent damage to the leaves of the plant. Then there is another group composed of both the plant and animal parasites, for which there is but little that can be done. Among these are the black knot on the cherry and the plum, and the blight in the pear, and the various kinds of borers that affect the boles of trees. While we know what the latter are, we have not ready means of combating them without destroying the trees. There are many problems that will come under this latter class, and each requires individual study to develop the point at which it may best be attacked. For the most part, how- ever, the problems that confront the farmer and tree grower of any sort can be found under one of the three first heads given, and the whole secret in the successful treatment of plant para- sites is to be sure of what you want to do and then do it thor- oughly. INSECTICIDES; For the First Group — Biting Insects. The best poison to employ for this class is undoubtedly Paris Green, as it is easily prepared and is cheap, and its presence can usually be detected owing to its color, thus preventing it being taken for any other substance, as it is very poisonous. It is an arsenic preparation, and when used in solution must be constant- ly stirred to prevent settling, as it is heavy and settles rapidly. It is often advisable to add a bit of lime to the Paris Green solution to prevent any damage to the foliage which might re- sult if it were used pure. On ordinary foliage, however, it is not necessary to use this precaution, as it is not probable that any harm will result from the use of the poison. It can be safely used in the proportion of one pound to one hundred and fifty gal- lons of water, and this proportion will prove effective for most purposes. Other arsenical poisons are not mentioned here owing to the lack of space and because none of them are any better than Paris Green and a discussion of them might tend only to confuse the intending sprayer. For the Second Group — Sucking Insects. This class of insects is a very hard one to reach by any method of spraying, and a great many different preparations have been tried from time to time, but with variable results. What has proved successful in one locality has, for one reason or another, entirely failed when applied by other experimenters at other places. The advent of the San Jose scale and the increasing numbers of the various species of plant lice have made spray- ing with contact poisons a rather recent development in agri- cultural practice, and today it is far from being an exact science. Any poison for this class of insects must be strong enough to kill the insect by contact and still do no damage to the tree, and this result is sometimes hard to obtain. We can not devote any time to a review of the experiments that have been car- ried on in various parts of the country for some time, but simply give the formulas of some of the preparations that have in some localities been found effective. Probably any of them will prove 6 effective and harmless to the tree if properly made and carefully applied. In no case should any spraying solution he so lavishly applied that the tree drips. It will require practice to develop sufficient skill to spray a tree just enough, that is, until it is com- pletely coated with the solution and no more. LIME-SULPHUR-SALT WASH. The following formula is one that is recognized and recom- mended by the foremost economic entomologists in the country, but it may be varied considerably without apparently detracting from its efficiency. Lime 50 pounds Sulphur 50 " Salt 50 " Water 150 gallons Add enough water to the lime to slake it thoroughly and im- mediately add the sulphur. Boil for an hour or so with only water enough to keep the mass liquid, until the solution be- comes a deep amber color. Have the salt dissolved in water and add it to the boiling mass. After it has all been mixed together, boil for at least another hour and then add water enough to make up the one hundred and fifty gallons, and spray it as soon as possible. It is more efficient when used warm, and some of the failures with this wash have undoubtedly been due to the use of stale solutions and to careless boiling. One objection to this wash is that it is decidedly "messy" to work with, and the man at the spray pump is certain to ruin his clothing and is fortunate if he keeps the spray from his eyes, thus causing serious inflammation. It is always advisable with this or any other spray to wear very old clothing that will never be used for any other purpose, and to protect the hands and face in some way. Automobile goggles would serve admirably to keep the spray from the eyes. The Lime-Sulphur-Salt wash can only be used during the dormant period of the year, as it is fatal to foliage. For summer use against the San Jose and other scales, and against the myriad forms of plant lice that are every year be- coming more and more common, there are several ways of using coal-oil effectively. There are now being made certain kinds of spray pumps that automatically spray a mechanical mixture of coal oil and water by the use of compressed air. The oil and water are carried in separate tanks and are conveyed in separate lines of hose to the nozzle, where they are mixed. Then there is the old and tried coal-oil emulsion, made by using any kind of strong soap to keep the oil from separating from the water. The emulsion has the advantage of staying on the affected parts of the plant for a longer time than the plain oil. Sometimes this is not to be desired, as the long application may result in foliage damage. Careless spraying is worse than no spraying at all, for it not only fails of its object but it is expensive, and it may possibly result in actual damage to the tree. This is especially true in the case of the sprays used for the control of the scale insects, and this department is in no way responsible for any damage that may result from the use of any spray, whether recommend- ed in these pages or not. The best that we can do is to advise the use of sprays that have proved effective in other cases. Under changed conditions the results may be altogether different. Effective spraying is largely a matter of individual requirement and must be intelligently worked out for local conditions. SAN JOSE SCALE. (Aspidiotus perniciosus Comstock.) So much has already been written relative to the danger aris- ing from infection with San Jose scale that no argument is nec- essary to convince the average citizen of the desirability of com- bating this pest with all the vigor that we can command. We will briefly review its important characteristics and, while it is not difficult to recognize, we will call attention to the fact that the genus "Aspidiotus" contains several other species that are very similar to the Aspidiotus perniciosus, and any of them may hecome very dangerous to plant life. Among these are the Put- nam Scale (Aspidiotus ancylus Putnam). This is an insect so similar to the San Jose Scale that even the most expert sometimes confuse them. It has been claimed that the Putnam Scale does not become numerous enough to damage a tree, and lliis state- ment has led some entomologists to make the mistake of calling San Jose scales by another name simply because they were not thick on the tree. In general, it should be remembered, it makes but little difference what the scientific name of any insect is if it is assured that it is doing damage to vegetation, and any scale that shows signs of attaining considerable numbers should be treated exactly as you would treat a well-authenticated case of San Jose scale. Life History. — The San Jose scale began life as a minute orange yellow insect, crawling freely about over the trunks and limbs of trees, whereupon its parent is attached. It is in this stage that the pest is most generally distributed by birds. It will crawl upon the feet and legs of the bird and be carried, pos- sibly, great distances before again happening to crawl off on an- other tree. • This period of activity continues for, at most, a day or two, when the young scale settles down and begins to secrete the plate or scale proper which cements it firmly to the bark. It grows during the summer, feeding on the plant juices, which it draws through the bark with its probocis, and in early fall the eggs are fertilized in the body of the female by the winged male. At the approach of winter the insect (still containing the half- grown young) ceases feeding and becomes dormant, to resume feeding at the first sign of warm weather. Early in June the young attain their full size and emerge from the body of the parent, thus completing the life cycle. The production of young is continued throughout the season, two broods appearing, one in August and one early in October. Adult Scale. — The adult scale appears as a small, rounded plate, grey in color, the center darker and elevated, the whole insect not more than one-sixteenth of an inch in diameter. On a badly-infested tree the scales will be so close together as to completely hide the bark, giving the branch an unhealthy, scurfy look. SCUEFY SCALE. (Chionaspis furfurus'Fitch.) While common and widely distributed, this scale has seldom be- come numerous enough to cause any material damage. As will be seen by the illustration, the male and female dif- fer considerably in form and size. At one stage in its life his- tory the male is winged, as are the males of the majority of the scale insects. «) Under favorable conditions this scale may become destructive, and wherever they seem to be multiplying it would be advisable to use on them the same measures recommended for the San Jose Scale. COTTONY MAPLE SCALE. (Pulvinaria innumerabilis Rathvon.) During, the past two years the cottony maple scale has killed many trees in Indiana. It has not been confined to maples en- tirely, for trees of several other genera have been attacked and killed. Little or no attention has been paid to it in spite of its deadly character. Life History. — After hibernating on the twigs of trees all win- ter, the female lays large quantities of eggs in May and June. It is at this season that the scale is most conspicuous, clinging to the under side of the twig and surrounded at one end with great masses of cottony padding, which is developed from the body simultaneously with the eggs. This cottony substance is persistent on the branches through the summer and until worn off with wind and rain. The eggs hatch in a short time and the young at once migrate to the leaves, where they attach themselves in rows along the veins and begin feeding. They grow rapidly, and as summer ad- vances the males and females are differentiated, the males de- veloping wings. At the approach of fall the fertilized females attach themselves to the under sides of the twigs, where they remain all winter. The male dies at the end of the summer. Treatment. — Winter spraying with Lime-Sulphur-Salt wash or with whale-oil soap is the best means of controlling the cottony scale. On affected trees the leaves fall persistently throughout the season, often ending with the death of the tree. These leaves should be carefully raked up and burned, as they are an active source of infection for other trees. Summer spraying would have to be very thorough to be ef- fective, as every leaf on a badly affected tree is a host of in- numerable scales. Sometimes a tree that has been completely stripped of its leaves and seemingly killed will put forth a new set of foliage in the fall, but it is not likely that such a tree could withstand the succeeding winter. 10 PLANT LICE. (Aphids.) There are many kinds of plant lice that affect cultivated plants. Almost all of them are dangerous and require prompt treatment. Many lice, such as the cherry and apple aphids, winter in the egg state, and the eggs are laid on the young twigs of the trees. In this way they may be distributed in nursery stock. The woolly apple louse forms a characteristic grayish cottony mass about it. It feeds on the apple and is one of the worst pests we have to deal with. Owing to the fact that one stage of the in- sect infests the roots of the trees, it is very difficult to treat, and a tree that is badly infested should be destroyed and the ground thoroughly dug up and exposed to the air. It will be safe to replant the same spot with another tree, but not with an apple. I have had partial success in treating this louse with carbon bisul- phid, using an ounce of the liquid in each of several holes punched in the ground around the tree at a distance of about two feet from the trunk. During the season of 1907 the common oat louse became so plentiful that many fields of oats were ruined. The only practi- cal treatment so far suggested is to burn over the fields and thus reduce the number of individuals to affect next year's crop. The same field should not be planted in oats again without a rotation crop of clover or corn. The number of lice was due probably to the peculiar weather conditions of the preceeding spring. Ac- companying the presence of the oat louse was a characteristic red rust that sometimes affects the grain regardless of the pres- ence of any insect. Lice on the rose bushes sometimes become so numerous as to kill the tender growing tips or to destroy the foliage. In green houses it is a common practice to use tobacco smoke — in the open a strong, solution of tobacco made by boil- ing cheap clippings and stems will prove very effective if sprayed on the affected parts. For any of the lice this tobacco solution is a standard remedy. Where there is a large area to be treated the coal-oil emulsion will be found to be cheaper and perhaps more effective. 11 SAN JOSE SCALE. SLIGHTLY ENLARGED. m 12 OYSTER SHELL SCALE. ENLARGED. WHERE IT BECOMES AS COMMON AS SHOWN IN THIS SPECIMEN THIS INSECT IS QUITE AS INJURIOUS AS THE SAN JOSE SCALE. 13 v •-' . " >" 1 \ i - ... 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