ALBERT R. MANN LIBRARY New York State Colleges OF Agriculture and Home Economics Cornell University SB 608.P65C|'J-"""'*" 608.P65cl7"""'''">"-"'"^y White I The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924002884405 WHITE PIITB WEEVIL DAMAGE IN THE VICIIITY OF ITHACA, HEW YOEK By Perkins Coville and J. S. Everitt 1920 A report on a study made in partial satisfaction of \^ requirements in the minor field of work for the degree of r Master in Forestry, Cornell University. c g 7 Tlie Result of Weevil Injury Table of Contents Page Introdneti on 1 Reasons for 5Jhis Study 1 Tjrpe of Inj'ury and Its Importance 3 General Conditions on the University Plantations 4 Past Work Done in Reference to the Weevil 7 History of the Weevil 7 Work of Graham 7 The Life History of the Weevil 8 Methods of Control 11 Pruning and Bum ing 11 Spraying 14 Pruning and Gaging 19 Netting 19 Summary of the Methods of Control 20 Data Collected on the Extent of Weevil Damage Near Ithaca, New York 22 Method of Field Work 22 Location and Description of the Areas Govdired 24 Summary of the Data Obtained on the Extent of ?/e evil Damage 25 Varna 25 Rifle Range I 25 Rifle Range II 28 The Country Club 29 The Behrends ' Farm 31 The Veterinary Woodlot 32 Page Summary of the Charts 34 BilDliography 46 Illustrations Page frontispiece - Hesult of Weevil Injury figure 1. Example of Side-shoot Competition 3 Figure £. Example of Natural Recovery 4 Figure 3. Example of Two Shoots Competing 4 Figure 4. Example of Good Natural Recovery 6 Figure 5. Example of Good Natural Recovery 6 Figure 6. Chart of Seasonal History of Weevilf Graham) 10 Figure 7, Example of Method of Pruning to Favor Side-shoot 13 Figure 8. Chart, Relation of Trees per Acre to Injury (Graham) 36 Figure 9. Average Height Growth of Normal and Weevilled Trees for the Period 1915 to 1919 inclusive 37 Figure 10. Annual Height Growth of Trees Weevilled in 1915 Compared with Height of Normal Trees for the Five Year Period 38 Figure 11. Annual Height Growth of Trees Weevilled in 1916 Compared with Height of Normal Trees for the Five Tear Period 39 Figure 1£. Annual Height Growth of Trees Weevilled in 1917 Conipared with Height of Normal Trees for the Five Year Period 40 Illustrations Page figure 13. Annual Height Growth of 0?rees Weevillea in 1918 Compared with Height of normal Trees for the Five Year Period 41 Figure 14. Annual Height Growth of Trees Weevilled in 1919 Compared with Height of Normal Trees for the Five Yaar Period 42 Figure 15. Average Annual Height Growth of all Weevilled Trees Compared with Normal Height Grov/th, 1915 to 1919 inclusive ... 43 Figure 16. Diagram Showing Temporary Total Loss per Acre in Current Hiight Growth Accord- ing to the lumher of Trees par Acre and the Percent Attacked 44 WHITE PIIIE WEEVIL' DAMAGE IH THE VICINITY OW ITHACA, NEW YOM INTRODUCTION Reasons for This Study . The white pine weevil (Pissodes strohi) is well known throughout the range of the white pine fPinus strohus) as a very destructive enemy to that tree. In 1915 and 1916 studies were made to determine the extent of the weevil damage in the vicinity of Ithaca, N. Y. , and the results were puhlished in part. Since that time the weevil injury has apparently heen increasing and these further investigations have "been carried on, to discover whether this is true and if so, to what extent. These investigations were confined to pure stands of young white pines, near Ithaca, both in plantations and in naturally seeded areas. This discussion will deal with the weevil only as a problem of management and will not enter into the entomological side of the question, except to give an idea of the life cycle of the insect, for a better understanding of its control. The two-fold purpose of the investigations was, therefore ". (1) To determine the extent of the injury in planta- tions and naturally seeded areas of white pine; (2) To work through a plantation, pruning out the weevil damage with the idea of proving or disproving the financial possibili- 2. ties of this method of control. In conneotion with the ahove , other methods will "be discussed, together with their costs of application and in so far as possihle, their suitahility for control. The Type of Injury and its Importanoe . Weevil injury is not generally serious enough to endanger the life of the white pine host tree. The reason for the great importance of the weevil menace lies in its destruction of the main shoot of the young pines. It always seems to attack the most rapidly growing individuals in the stand and to favor pure stands. The effect of this is to retard the dominant individuals in their growth, and allow the former suppressed ones to catch up. This upsets the process of natural thinning which would be brought about otherwise. The destruction of the main shoot has another important effect. It results in two kinds of malformation of the young pine. First, a forked trunk, and secondly, a "bayonet" trunk. In the first case, more than one of the side shoots has tried to take the place of the main shoot. It may be noted in the picture below that six shoots are trying for the position. It results, as the tree grows older, in several boles growing up side by side, none of ?/hich is especially good for lumber. Fig. 1. 4. The second tjrpe of injury is more common. It is caused by one side shoot more or less successfully taking the place of the main shoot. The side shoot usually has a "bend, but Graham (1918) states that the trees sometimes become straight as they get older. If they do not straighten, the crook detracts from their merchantability as mature trees. The crook in the trunk can be noted in the following pictures. In Mg.2 the tree has grown a side shoot which has little or no competition from the others when taking the place of the main shoot. In 'Big.Z the two side shoots have conrpated until the tree was weeviled the second time and the shoot on the left was injured. This means that the right hand side shoot will now grow into the place of the main shoot, with less competition, but will probably have a crook in it. Wig. 2. Fig. 3. General Coaditions on the University Plantations The University owns several pure white pine planta- tions and the injury to these has been very severe in the past, Eo control work had teen tried on them and the dead tops, left from seTeral years of weevil damage, made it appear that weevil injury was on the increase. One of the Yarna plantations was investigated to discover the extent of damage. Pruning was tried as a means of correcting the form of the tree after injury, but the time allowed for the completion of this study was not sufficient to show whether this method is practicable or not, from a standpoint of silvicultural management. This plantation will he discussed later. ¥±g, 4. ffig. 5. 0?wo Examples of Good Natural Recovery After Weeviling Both trees have produced one strong side shoot each to take the place of the lost main shoot. 7. PAST WORK DOIE IN REFERMGE TO THE WEE VII History of the Weevil The white pine weevil fPissodes strohi) is one of our native insects and has prohahly existed in this country for a long time. Felt (1906) gives the following points in the history of the weevil : 1. Prof, W. D. Peck ascertained a nuniber of facts regarding its life history, early in the last century. E. Later Dr. Harris succeeded in adding to our knowledge of it's hahits. / 3. Dr. Fitch studied the insect in New York about 1857. 4. The late Dr. litner had it brought to his attention several tinss, once as attacking 150 Norway spruces. 5. In 1907 Dr. A. D. Hopkins worked out the complete life history of the insect. for more complete knowledge of the insect refer to Memoir 8, Volume 2, page 397 of the New York State Museum (1906) It is only in recent years that the insect has hecome of great importance and this is perhaps due to the fact that plantations are more valuable now than in past years, and white pine is being extensively planted as a foe est tree, the weevil tends to attack only the pure stands of white pine in costly plantations or seeded areas. Work of Graham Graham (1915), (1918) investigated the weevil in the vicinity of Ithaca, New York. His first work was confined principally to entomological considerations. Under the latter 8. date he published data on percentage of damage in stands of varying density, loss in height due to injury and loss in merchantability. Some of the curves which he published will be used for comparison with the results obtained in this study. He made a diagrammatic sketch, which is produced later, to show the life seasons of the weevil. The Life History of the Weevil The life history of the insect according to Graham (1918) is as follows : "There is but one generation in TSew York State. The adults appear on the pines about the time the earliest trees are beginning to leaf out and when the pine buds are just beginning to swell. They begin to feed at once upon the buds, usually those of the terminal, and in a few days OYiposition begins. "The eggs are laid in chambers hollowed out of the inner bark by the female, one or two eggs being placed in a chamber. As a rule the female remains on one leader until she has deposited her full quota of from 75 to 150 eggs The egg laying continues into July. "In from 6 to 10 days the eggs hatch and the young larvae burrow downward beneath the bark, feeding on the cambium layer. As they grow larger they consume all the inner bark and cut furrows into the wood. As soon as the larva is full grown it turns into the pith and there forms a pupal cell, or if the pith is already occupied by other larvae, it will make a cell beneath the bark and roof it over with shreds of wood. In about thirty days after hatching from the egg, the larva trans- 9. forms to the pupal stage. This lasts ahout two weeks and then the transformation to the adult takes place. The adult remains in the pupal cell for a week or more and becomes thorough- ly hardened before chewing its way through the wood to the out- side. After feeding on the new shoots of the pine for some time, the newly emerged weevils seek out a place in the litter beneath the trees and hibernate until the following spring." Hopkins (1907) was the first man to discuss the life history of the weevil fully. 10. 11. 11ETH0DS OF COM)RDL There has been very little investigation of methods for controlling weevil damage. Pour methods are known and have heen tried to a limited exrtent. These methods are : 1. Pruning and burning 2 . Spraying 3. Pruning and oaging 4. letting of the adult weevils Bach method is described separately below, and the relative merits of each is given at the end of the chapter. Pruning and Burning The purpose of this method is to remove the injured tops of the young pines while the weevil is still present, and to burn the tops immediately, destroying the weevil. If pruning is done between the middle of May and the middle of July, the weevil will be present either in the larval or pupal stage. Preferably the pruning should be done some time in early June. At that time, when the larvae of the weevil would begin burrowing down through the inner layers of the bark, and pruning would save a certain amount of future damage downward in the tree , the actual pruning would not cause the amount of injury that it would later in the growing season of the tree. Pruning can be of further benefit to the tree in correcting its form. After injury, two or more side shoots 12. Will compete for the place of the main shoot, as mentionea before. By picking out the most vigorous shoot, trimming back its nearest competitors, and removing undesirable ones, it is possible materially to aid this one shoot in taking its place as leader, with the least amount of crook and loss of growth. There is always danger of this side shoot itself being weevilled. Pruning was tried in one of the University plantations at Yarna, with the idea of obtaining cost figures for the operation. Uo control of any kind had been tried on the area and the pines averaged 90^S of weevil injury for the period from 1915-1919 inclusive. This is a high percentage of injury. The planta- tion is full of briars, but it was found that one man, trimming out the weevilled tops and snipping off the tips of all but one of the side shoots, could cover 250 trees an hour or better. These figures were got from 535 trees actually covered. Thus two men with hand pruning shears, and a boy to collect the tops • for burning, should be able to cover nearly four acres of 6 x 5 plantation, or about 4000 trees in an eight hour day. Below is given a table to show the future value of |1 expended for such control work, carried for various rotations at current rates of interest (compounded). It is possible for anyone to figure the area to be covered, and the number of trees. For square planting the number of trees per acre is equal to 43,560 divided by the square of the distance between the trees, i.e., for 6 s 6 it is 43,560 divided by 36 or 1210 trees per acre. With the current wages, find the cost per acre. Under the rotation being used and 13. Mg. 7. Method of Pruning to Give the Side Shoot a chance to take the place of the leader which was destroyed by the weevil. 14. the rate of interest that is obtainable, find the factor for §1 expended. Multiply the actual, or figured cost' by this factor to determine whether the operation of control will be a sound financial proposition or not. Rotation: (years) :' Rate of interest obtainable (per ce nt") 3 f ' 3i ; 4 : 4i value for each dollar 40 : |3.262 ■ $3,959 $4,801: ^^5.816 : $7,040 45 : 3.78E 4.702 5.841: 7.248 : 8.985 50 4.384 ■ 5.585 7.107: 9.033 : 11.467 55 5.08E ■ 6.633 : 8.646: 11.256 : 14.636 60 . 5.892 • 7.878 . 10.520: 14.027 : 18.680 65 6.830 • 9.357 : 12.800: Impractical for financial 70 : 7.918 11.113 15.572: reasons to carry costs beyond 80 : 10.641 • 15.676 : this point for a plantation. 90 : 14.305 ■ 22.112 100 : 19.219 Spraying Spraying has not been extensively tried out as a con- trol measure. We learn from the life history of the weevil that the adults which appear" about the time the earliest trees are beginning to leaf out, and when the pine buds are just beginning to swell, begin to feed at once upon the buds, usually those of the terminal"- Walden (1914) says that "Using insecti- cide spEays just previous to, and during this period should prove successful in combatting the weevil." Arsenate of lead and commercial lime sulphur are perhaps the best for this purpose. The following methods of making the spray solutions are published in Bulletin Uo. 248 of the N. Y. State College of Agriculture at Cornell : "Arsenate of lead Arsenate of Water loftfl 2 to 5 pounds ^^^ 50 gallons 15. Procure the arsenate of lead on the market For beetles and their larvae more than three (3) pounds is usually necessary. Arsenate of lead is to be preferred to paris green and other arsenicals on account of its better sticking qualities " Coamercial lime-sulphur . This solution can be obtained on the market, and is ready to apply when properly diluted with water. A hydrometer reading should be made before using. Thirty-two degrees Baumft is considered as standard and commercial brands should give this reading." In the same pamphlet is given the follaving, which can be prepared at home : " Home-made Concentrated lime-sulphur Solution Lump lime 40 pounds Sulphur 80 pounds Water 50 gallons use the best grade of lump lime obtainable. It should test 90 per cent of calcium oxide, and be free from impurities. Heat to boiling in a cooking vessel about 15 gallons of ?;ater; then gradually J)lace in it the 40 pounds of liiiie . As the liriie begins to slake, add the 80 pounds of sulphur. Aifter the slaking of the lime add enough water to make up the total volume called for, and keep the amount constant if evaporation is taking place. The mixture should be kept at the boiling point for practically one hour, or until all the lime and sulphur are dissolved. Constant stirring will be necessary. When additions of water are necessary, hot water should be used. "Place in an air tight barrel when cool and use as needed. A hydrometer reading should be made of the prepared solution and dilutions mode, according to the use at different 16. times." Walden fl915) did some rather limited experinBnts with sprays and puTalished the following results : "In 1914 e2qperinBnts to control the white pine weevil were started in a two acre block of white pine (Uo. 29) in the plantation at Rainhow. The land was planted in the fall of 1907 with 3-year transplants and in the spring of 1914 the trees were from 3 to 5 feet high. Weevil injury was first observed in 1913 and infested leaders were removed about the first of July." At the time that e3cperiments were started, leaders were missing from 93 out of a total of 2882 trees fdue to the weevil and other causes) The Tarlock was divided into four sections. On the first section, the leaders were sprayed with commercial lime sulphur, one part to eight of water- The second section was left as a check, untreated. On the third section the leaders were sprayed with lead arsenate, 1 oz. in 1 gallon of water (3 lb. in 48 gallons). On the fourth section the weevils were collected in a net as recommended in the report for 1914. In 1914 lime sulphur and lead arsenate applied May 7 and 8. , -,-,xjj?- On the fourth block the weevil was collected ixve times, viz., May 7, 14, 21, 28 and June 3. In 1915 lime sulphur and lead arsenate were applied May 7 and 11. Six collections were made with the net on the fourth block on the following dates : May 7. 14. 24, 28, June 4 and 18. 17. The Results in 1914 and 1915 Treatment Total Uo. of trees liime-silphur 1:8 830 Cheek 665 Lead Arsenate 1 oz. : 1 gal. Uet 6E6 761 Uumher of trees weeviled 1914 1915 2 E 3 14 5 8 6 7 Walden (1915) says "treating the leaders either to poison or repel the adults (when they come out) was suggested.. Some trees 8 to 10 feet high, which had previously "been injured severely, were used and applications made May 17." Extensive experiments on this were prevented by other work, hut the tahle on the next page shows the results obtained. "Applications should have been made about May 1, or perhaps earlier. Lead arsenate May 13 gave better results than a stronger solution (12 lb. to 50 gallons) applied 5 days later. "These experiments indicate that consjderable injury from the weevil can be prevented by spraying with lead arsenate at the proper time. Trees up to 4 or 5 feet in height can be sprayed with a good knapsack pump at small cost." 18. Material used treated Results of Various Sprays HO. of trees Noi of trees- losing leader Remarks Paste lead-arsen- 9 ate , 4 lb . : 50 gal . 1-1 oz. per gallon. Paste lead-arsen- 11 ate, 4 oz. per gal. Commercial lime- 3 sulphur, 1 pint to 1 gal. of water "One for all" 8 8 oz. to 1 gal. Whale oil soal 8 8 oz. to 1 gal. Tree tangle. foot 3 Checks 10 1 6 Ho injury from the treatment Ditto Ditto nearly all leaders treated showed injury. ITo injury. Ditto - good and fairly clnap The results of this showed that Lime sulphur Lead arsenate Whale oil soap - more e3q)ensive Tree tangle -foot - difficult to applF "One for all" - injures the trees Walden also makes the statement that "indications were that either substance (lead arsenate or lime sulphur) was of considerable value in preventing injury ty the weevil when sprayed on the leaders before the eggs were deposited.., It is too expensive for large plantations ." 19. Pruning and Caging Walden (1914) says that as a result of their work. "the only practical remedy that we have been able to advise is to cut the infested leaders in early juiy. before the adults emerge and store them in tight receptacles, covered with wire ^^^-^^ *° permit the escape of the parasite and not of the weevils." "This treatment where carried over a considerable area for several years will greatly reduce the number of weevils and consequently the amount of damage, as has been demonstrated in the white pine plantation at Rainbow. Here the infested leaders have been cut each season and placed in large garbage cans covered with wire netting. There are no cost figures available for such work, but judging from the similarity of this method and that of pruning and burning, it is safe to say that t'ha cost of this method would be the same, plus the cost of the receptacles. Graham (1918) gives wire cloth with 14 meshes to the inch as suitable for covering such receptacles. He also states that Eurotoma sp is the most important of the parasites. The larva of this Chalcididfly attacks the larva of the weevil. He gives the larva of another fly, Lonchaea rufatarsus as commonly found on weeviled shoots, and says that these parasites must always be depended on for a large part of the control work. Netting. Pelt (1914) recommended using a iBt having a diameter of 15 inches to collect the weevil on white pine leaders. "This work should begin in April, as soon as the weather is 20. moderately warm, and be continued for several weeks at intervals of a week or ten days. Practical work done this season shows that it is possilDle to make four collections from an area of white pine at a cost of :a.E8 per acre." It was found that a large proportion of the weevils could be captured by placing the net well down on the side of the leader and rapping the opposite side, above the net with a stick. The following is the result of five collections made at Rainbow : Het 337 trees No. infested 9 per cent 2.64 Check 116 " " " 8 " "6.79 Pour collections at Portland : Uet 1,462 trees No. infested 141 per cent 8.00 Check 1,009 191 18.91 Summary of the Methods of Control The primary factor in the application of any method of control for commercial plantations is the cost. It can be seen by referring to the interest table on page 12, that every dollar spent on a plantation when young, represents a much larger amount at the end of the rotation, which must be sub- stracted from the gross income from such a plantation. For ornamental plantations, groves or individual trees, one can afford to spend a greater amomit, as they are SI. not planted or grown on a commercial basis and no income is expected from them. Summarizing the various methods we find that : 1. Pruning and turning, thought advisahle in the past, destroys the parasites of the weevil which are important as a means of natural control. The cost is not excessive, and the method is fairly successful. 2. Spraying with lead arsenate and lime sulphur (the only two sprays that are suited to the needs of the situation) is, according to Walden, "too expensive for large plantations." The success of spraying is, as yet, rather douhtful, though it has seemed successful on small areas, whete it has been tried. 3. Pruning and caging combines a somewhat greater cost, over pruning and burning, with a considerably greater success, if carried out conscientiously for a period of years. 4. Netting, though not extensively tried as yet. seems to offer possibilities. The cost is not excessive, and the parasites would still be left on the area, as advocated under No. S. Walden (1914) says "any method to prevent the depositing of eggs is preferable, even though it costs more, to removing the leaders after injury." With this in mind, it would seem that netting were the best means of any of the above. The cost is medium, there is no removal of any portion of the tree's growth, most of the weevils are prevented from laying the season's eggs, and the parasites can be left on the area to work to the detriment of the next generation, the following year. 22. DATA COLLECTED ON THE EXTENT OF WEEVIL DAMAGE NEAR ITHACA, NEW YORK Method of Field Work In working with naturally seeded areas, square plots, one rod on a side were laid out with a chain tape. The trees on the plots were carefully counted and the per cent of the weeviled trees was taken down. If the seeded area was of considerable size, more of these plots were laid out in re- presentative sections, and treated in the same manner. Work- ing through the area, measurements on a tree were taken and entered on forms, one of which is shown on the following page. This form was used for all the work, whether in seeded areas or in plantations, eiccept in the work at Varna. In plantations, the percentage of weevil damage was obtained by covering a row of trees, taking data on each one, and computing directly from the form. Rows were generally followed from one side to the other, running through the center of the plantation to get fair averages of the damage. To get costs for the operation of pruning the trees, several days in July were spent at Varna in this work, the number of trees covered and the amount of time spent, being recorded. This gave a means for computing costs per 1000 trees, which can be applied to plantations of any spacing as discussed under No. 3. At Varna counts were made only on the per cent of damage by years. 25. Form used for the Golleotion of Growth and Weevil Damage Data Plot Ho Size Acres Location Number of trees per acre Average age of stand. .. .years lumber of trees infested fj of total number 1919 Growth inches 1918 Growth inches 1917 Growth inches 1916 Growth inches 1915 Grov/th inches Method of using form. Beginning with the 1919 growth of the main shoot, measurements were taken for each year (1919-1915 inclusive) and entered under the growth column for the proper year. Under the column of years was put a symbol indicating whether the tree had been weeviled that year or not. If weeviled and recovered, that was noted also, but in the final computation of the notes, there were not enough data to warrant any definite statement on the percentage that were weeviled and recovered, and the data were not used. 24. Looation and Description of the Areas Covered All the stands oovered in this study are located bear Ithaca, lying in an easterly, northeasterly, or southeast- erly direction from the city. 1. A pure white pine plantation, owned by the University and lying just north of the state raad railroad crossing, due north of Varna. This plantation is spaced 6x6. In 1919 the trees were IE years old and averaged about seven feet in height. 2 (a) This stand is a 6 x 6 plantation and stands on the site of the University rifle range, on the Cortland road, about three-fourths of a mile beyond Forest Home. Situated on the range proper, the plantation in question is just to the north of the 200 yard firing position. In 1919 the trees were 10 years old and averaged6 feet tall. (b) A small planted area at the south and of the 200 yard firing position. It is planted 3x3, apparently with the same stock as used in 2 (a), but averages about eight feet, tall. nearby are plantations of Scotch pine which have apparent- ly been slightly weevilled, but no work was done on theip. 3, A planted knoll on the north border of wJmt is known as the Country Club Woods. The trees are spaced 4x4, and 12 to 15 feet tall and 12 or 13 years old. This is a rapid- ly growing stand. 4. An area of natural seeding. This is apposite the rifle range on the south side of the Cortland road. The trees stand in a pasture near the top of a low hill, and have seeded in from the mature pines above. The land belongs to Paul Behrends. 25. 5. A seeded area of alaout three acres situated on the property of the University known as the Veterinary Woodlot. The pine has seeded in from all four sides of the pasture, and the stand is quite thick in some places. The trees average 12 to 13 years old and seven feet tall. The pasture is directly south of the Veterinary barn. Summary of the Data Ohtained on the Extent of Weevil Damage Varna In connection with the pruning of the trees on the Varna plantation, data were gathered on the per cent of injury for each of the last five years. Seven rows on the north side were taken, two more running east and west, approximately through the center of the plantation and two more along the southern boundary of the plot. The seven rows on the north showed 88.5 per cant of weevil injury. for the last five years. The two central rows showed 92.5 per cent and the two southern rows showed 95.0 per cent for the same years. Taking the total of 472 trees covered, the following is the per cent weevilled by years : -j_929 5 pe r cent 1918 30 " 1917 39 " 1915 22 " ■^^■^^ *i6B75 " more than once during that period. 26. fhe total per cent of injury is misleading for it was found that atout 14.3 per cent of the trees weevilled had been weevilled more than once . On the north side were many cases of trees weevilled three times and occasionally one that had ?/lth- stood four attacks without dying, though such trees were usually in very bad shape. The only reason that can be suggested to explain the slightly greater percentage of injury on the southern side is that this side is producing somewhat larger trees than the north. The Rifle Range I. This plantation is about 2^- acres and is spaced 6x6, 1210 trees per acre, and the trees are about six feet tall. They average 10 years of age from the seed. The percentage of weevilling by years is as follows for the 78 trees covered : 1919 V*? V^^ cent 1918 25.0 " " 1917 30.0 " " 1916 23.0 " " 1915 _5.0 90.7 per cent The actual per cent of trees weevilled is 82 and 8 per cent of all the t*0es have been weevilled more than once. In this plantation very fa* of them have been weevilled more than twice, in the following tables the first column is the growth of the main shoot in the year of weevil injury, if the shoot ,a; otherwise it shows the growth of the side shoot which recoverei 27. is taking the place of the weevllled leader. As we are only interested in the part of the tree which is going to form the bole of the tree, it is not necessary to specify whether it is the main shoot or the side shoot which will form it. The second column gives the growth of the same shoot for the second year (the year after weevilling) and will show how nearly this shoot has again attained normal growth. Column III shows the growth in the year preceding the attack of the weevil. These will he given similarly for each plot. I II III Year Weevilled Year after Year "before (inches of growth in height) 1918 11.8 13.0 14.54 1917 11.5 11.85 17.4 1916 9.87 11.0 8.8 lormal growth of healthy trees in this Area 1919 14.7 inches 1918 14.7 " 1917 12.6 1916 13.7 1915 7.0 " An average of 12.5 inches for five years. It is possible to get soma interesting comparisons from the three colrmms and the normal rates of growth given n the above table. Taking, for exa^nple the year 1918. we find (in column I) that the weevilled trees only grew 11.8 iiiches on the average for that year. The normal growth given for 1918 is 14.7 inches. Therefore the trees lost nearly th.ee inches in growth as compared with their healthy neighbors. In colun. II 28. the weevilled trees grew bettej-- 13.0 Inches. This would he the 1919 growth of trees weevilled in 1918. Looking under the normal growth for 1919, we find 14.7 inches. The weevilled trees, their second year after weeviling, have 1.7 inches less growth than the healthy trees, and are not fully recovered. It has been thought that trees are more liable to be attacked if they are of the dominaj; class,- that is, if they are taller than the average of the stand of which they are members. Again taking the year 1918, in column III, we find the growth the year before weevilling. This is the 1917 growth of trees weevilled in 1918. The weevilled trees grew 14.54 inches. The normal growth for 1917 was 12.6. Therefore the weevilled trees grew more vigorously than the ones not attacked and added nearly 2 inches more growth than those trees. This idea applies to the other years as well. The data for any one plot is in- sufficient to prove anything conclusively, but the data for all the plots are averaged and corapared in similar way at the end of this chapter. The Rifle Range (continued) II. This area is a plantation spaced 3x3, or 4840 per acre, and only about i an acre in extent. The trees average 10 years of age from seed and the earliest infestation was at five years of age. They average five feet tall. Sixty-two trees were covered. The damage by years is as follows : X919 20 p er cant 1918 23 " " 1917 30 " " 1916 23 " " 1915 13 " " 109 per cent E9. The actual per cent of trees weevilled is 90 and approxiniately 16 per cent of the trees have been weeyillea more than once. I II III Year Weevilled Year after Year before Inches of Growth in Height 1918 IE. 4 17.0 17.71 1917 11.6 13.4 15. E 1916 9.14 14.3 13.4 The normal growth for these years on this area was : 1919 18.0 inches 1918 EO. 1917 18.7 " 1916 15.0 1915 16.0 " An average of 16.5 inches for the five years.. The Gonntry Oluh ■ This area is about E acres in extent and is planted 4x4, or E7SE trees per acre. The trees are IS to 13 years old from seed and average from IE to 15 feet in height. The yearly weevil damage for the five years on 80 trees covered was as follows : 19^9 5 per cent 1918 2E.5 " " 1917 37.5 " " 1916 7.5 " " 71 It 2,915 E. 5 75.0 per cent 30. The actual per cent of trees weevilled is 65 and 10 per cent of the trees have "been weevilled twice. This site was the most remarkahle covered and produced growth of as much as 40 inches in one pine during the year 1915. In that year almost one-third of the trees produced 30 inches or more. I II III Year Weevilled Year after Year hefOFe Inches of Growth 1918 16.3 16.2 21.2 1917 20.0 18.7 29.0 1916 15.0 17.0 25.0 The normal growth on this area was as follows : 192,9 18 . 3 inches 1918 22.0 " 1917 22.7 " 1916 27.4 " 1915 27.0 " An average of 23.5 inches for the five years. 31. Behrends' Farm This area comprises aToout one-fonrth of an acre of very thick natural seeding. The central portion which was covered in making the estimate averaged ahout 8500 trees per acre. It was estimated that 65 to 70 per cent of the trees were weevilled. The trees were of different ages, "but aver- aged 10 years old from the seed, and 6 feet in height. Due to the great density of this stand it is almost impossihle to get accurate figures. By laying off square rods with a chain tape,,, and keeping within the area so laid off, close approximations were obtained. The weevil injury per cent by years for 8£ trees taken was as follows : 1919 0.0 per cent 1918 6.5 " 1917 35.5 " 1916 25.0 " 1915 3.2 " 71. S per cent In this area onlj 5 per cent or so had been weevilled a second time. ^^^ I II III Year Weevilled Year after Year before Inches df Growth 1918 9.0 11.0 16.5 1917 12.1 12.36 19.36 1916 13.75 12.5 21.6 The yearly growth of normal trees was as follows : ^93^9 11.82 inches 1918 13.27 32. ^91''' 15.0 inches 191S 19.54 " 1915 21.0 n An average of 16.13 inches for the five years. !Phe Veterinary Woodlot a?his area is about three acres in extent and because of the size of the plot and the varying density of the seeding, a strip one rod wide was run from the east side to the west side, through the middle of the field. The trees averaged 12 to 13 years old from seed and seven feet tall. Pine seed trees stand on all four sides of this field though it is planned to harvest those to the north this winter (1919-20). The seedlings started with a density on the east side equal to 3200 trees per acre, decreased to about 500 per acre in the center and increased to 1700 on the west side. The total strip averaged 1000 per acre. The weevilling by years was as follows : 1919 per cent 1918 18.8 " " 1917 14.1 " " 1916 11.7 " " 1915 17.7 " " Fifty-six per cent were actually weevilled. About six per cent were weevilled more than once. I II III Year Weevilled Year after Year before Inches of Growth 1918 10.0 13.0 11.0 1917 7.3 9.8 11.0 1916 8.7 9.7 13.3 33, The normal growth for healthy trees ?;as as follows : 1919 15.9 inches 1918 10.1 " 1917 9.0 " 1916 9.9 " 1915 11.5 This is an average of 11.3 inches for the five years. Trees in the shade near hy showed only E per cent weevil over all years. 34. IJotes Regardinp^ Charts In the following pages are a series of charts, page 36-44 inclusive, showing in graphic fom the data that appear in the tahles of several plots that have been given on the preceding pages. In the present study the influence of the factors of soil, moisture, light, etc., have been disregarded, under the assumption that since the trees considered have been averaged by such small plots, these factors would not vary appreciably within the limits of a given plot. The charts therefore show only the comparative growth in height of trees which have been weevilled and trees which have not. G?he study of growth comprises so many different factors that it seemed desirable in this study to base the conclusions reached on the one factor of weevil injury. Normal growth has been taken as the growth of trees which have not been injured, or growth on injured trees at any time before they were injured. Since trees that make abnormally good height growth in aay year axe those that are weevilled the next year, it can be seen that the figures which have been taken as normal growth are lower than if the normal growth of the plantation had not been upset by weevil injury. In figure 9 it would appear that weevilled trees had lost only fire inches in a period of five years as an average, or one inch per year. It can be seen, however, by looking at figures 10-14 inclusive, that the trees lose 35. from one-half to five inches on the are r age . for any one year of the five years. The trees weevilled in the seasons of 1915. 1917 and 1918 grew a good deal more than the normal in the year hefore injury. When all the trees attacked over the five year period are averaged together, there are, besides those injured in any one year, four other classes of trees which either were having good growth before injury or were well on toward recovery. The figures of height growth of these classes offset one another, so that the average loss appears small. In figure 15 the average normal height growth for each year is given. In comparison with this is given the average height growth of the weevilled trees, i.e. the value for 1915 is the growth in height for trees weevilled in 1916. This will serve to show the great loss. If it is remembered that the weevilled trees usually were abnormally good in gafowth, it can be seen that the loss is no doubt greater than shown. Figure 16 is brought out merely to give a general idea of the loss in height growth for various spacings and percentages of infestation. It is as accurate as pSissible for the data at hand, but so many factors enter into the calculation that it does not deserve too serious consideration. The average loss per tree per year for weevilled trees was found to be 9.68 inches and this has been worked out as the basis of the chart. This figure is the average for all spacings, per cent of injury, and years. Hence this chart shows all data as progressing in equal values. 56 M.g-ura 8 /o ^^ 30 ^o ^o CO 70 80 fo roo ■ I ' ; ' ' 1 ' ■ ■ ' I ■ ' ' I ' I L) ■ ; I , I i ; r '■ : ' ■ i ; ; j -f-T .pi imH- tp , Slrbes if O'r 191S, to; i9i9 .ICineaiiis^i^Tr^ TA OR A CAHPEMTeR ITigure 10 tnjonnTomts or the college of civil engineering, cornej.l u/iives-jitv .veyage Heigiit Growth of Tree^ ■^®®^?f3-i^^i^ 1^1 1915 Compi^^Q,! ^wl^tli ' Height of Korma Tr^es for five Year Beriod.^ I t M Ttf-TT il'*- // (V /K 14/ /V'(4/ Figure 11 39 mnual Hsi.iit Growth 'of Tree^ptl^fj'" '' Wesvillea in 19iG ;Qionrpa?;;e:d with the Height ,p|;riJorniai:, Trees for the JPive Year reriod. t /^ f £^ /V iV /Y \^ /1/n/ /f/6 ///^ Ci^e/: ii^ifure 12- 4^ tOUATMIESOFTHECgLL ECEOFCIVIt ENGINECniwC .cmiKgll UNIVERSITy m 3B W ^-nal Height Gi'dwl^h for TraeC 1 m ffffl Iseevillaa in I9l7 Compare a, wj;:tliT 'mm Height of Hormsl Trees for'^'Ee^"' f tfh# ;r /f/6' /V \A/ /y iA^ /V vy /v w A/ w /f /^ ///7 /fyS /f/ f <7>^er 'ieure 13 41 IMOWTOmpW '"^■-"i-'-'^'- 'Jf C IVIL tNGINEtRmC COBWai. IWV Ei^siTy ^^tffil-^ I ':'- ■ Height' ■ "" ' • ■■'■■ "!||L innual/Gr ov/tji .of^^smMMl' •wm in 1918 ComipaiPQ.^ Period, "iZ ^Iguxe 14 jMATOaiE'^ Of THECOUEGE Of CIVIL ENGlNEtRIMG. COBNEIL UWWEffSlTY SIP /f/6 /f/f (7rey: 43 ;i60R»TOSl£S OFTHECOLLESE Of CIVfL ENGIWE ERIW6, CORNELL U\«Iuf|»sitY ij'igure -15. IRiit W- • - H '^1WlS^yM!M&^^'''^^ AttQtt&H;: iiGlgJli (&OWth Of All ^Trees We evil led i&it lormal Height Qwq- lEoriod^ 1915 - -1919 f ~m ///^ / f/7 /f /d /f/ f 0,/ e/^ I'^igure 16 l-l£FL^p3^|rri if^Wf^^P^ ^iQgrim sllowliiKJtsniiorary' total loss u4e_ira;mbs^^cirtTe^s h^y ore ^d tde ^peM I Traas per Acre 45 BIBLIOGMPBY 1. Graham, S. A. , 1915. The White Pine Weevil. Unpuhli- shed thesis in the Lihrary of the Department of Entomology, Hew York State College of Agrioulttire , Ithaca, N. Y. 2. , 1918. Study of the White Pine Weevil Damage on the Luther Forest Preserve. Library of the Department of Forestry, Hew York State College of Agriculture, Ithaca, N. Y. 3. , 1918. The White Pine Weevil and Its Relations to Second Growth White Pine. Journal of Forestry? XVI, 2 : 192. 4. Hopkins, Dr. A. D. , 1907. The White Pine Weevil, U.S.D. A. Giro. 90, Bureau of Entomology. 5. Felt, Dr. B. P., 1906. K. Y. State Museum, Memoir VIII, 2 :397. 5. , 1914. Conn. Agr. Exp. Sta. Report, 1914, 2 : 173. 7. Walden. B. H. , 1914. " 4 : 308, 268. 8. . 1915. " " " " " 19^5' 2 : 173.