r / / ,j . i o 1 Issued Jin U.S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— CIRCULAR No. 139. L. O. HOWARD. Entomologist and Chief of Bureau. DAMAGE TO SUGAR CANE IX LOUISIANA BY THE SUGAR-CANE BORER. BY T. C. BARBER, / and Expert. jTO'. : GOVERNMENT PRINTING OFFICE : 1011 DOCUMENTS QEPT U.S. DEPOSITORY B UREA U OF ENTOMOLOGY. L. 0. Howard, Entomologist and Chief of Bureau. C. L. Marlatt, Entomologist and Acting Chief in Absence of Chief. R. S. Clifton, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. Chittenden, in charge of truck crop and stored product insect investigations. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of south rn fit Id crop insect investigations. F. M. Webster, in charge of cereal and forage insecl in i < siigalions. A. L. Quaintance, 171 charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. D. M. Rogers, in charge of pn r, nting spread of moths, field work. RoLLA P. Currie, in charge of editorial work. Mabel Colcord, in charge of library. Southern Field Crop Insect Investigations. W. D. Hunter, in charge. F. C. Bishopp, H. P. Wood, W. V. King, G. N. Wolcott, engaged in tick investi- gations. W. D. Pierce, J. D. Mitchell, E. S. Tucker, T. E. Hoi.loway, G. D. Smith, E, A. McGregor, Harry Pinkus, W. A. Thomas, Thomas Lucas, engaged in cotton boll weevil iti i < si igations. A. C. Morgan, G. A. Runner, S. E. Crumb, engaged in tobacco insect investigations. T. C. Barber, C. E. Hood, engaged in sugar-cane and rici insect investigati F. C. Pratt, engaged in cactus insect most igations. It. A. Cooley, D. L. Van Dine, Wilmon Newell, A. F. Conradi, C. C. Km mb- h \ak, collaborators. Circular No. 139. United States Department of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD, Entomologist and Chief of Bureau. DAMAGE TO SUGAR CANE IN LOUISIANA BY THE SUGAR-CANE BORER. (Diatrsea saccharalis Fab.) By T. C. Barber, Agi a' and Expert. (The work upon which this circular I is conducted In direct cooperation with the Louisiana Sugar Experiment Station, Audubon Park, New Orleans, La.). [NTR< >l>M I [ON. The sugar-cane borer (Diatrsea saccharalis ' Fab.) has been the most serious insect enemy of sugar cane with which the Louisiana planter has had to contend for many years. In a bulletin of the Louisiana Experiment Station :> Dr. W. C. Stubbs gave an exhaustive account of the probable source of introduction in 1856, in cane imported from Soul h America, lie also referred to numerous cases of severe infesta- tion which occurred at various times previous to L880. In 1880 s Dr. L. ( ). Howard conducted investigations on this insect, and men- tioned that the first specimen was sent in to the Department of culture at Washington in L878. lie also cites several instana I previous severe infestation, one occurring as far back as 1857 "along the Lower Mississippi." In 1893 Prof. II. A. Morgan published a bulletin on the "Sugar-Cane Borer and its Parasite," ' in response to a demand for informal ion following a severe outbreak of the cane borer in L890. Another severe outbreak in Louisiana in L900 was foil* by the publication of Bulletin 70, referred to above, in which Dr. Stubbs gave the first statement as to the actual amount of financial damage caused to sugar cane bj the cane borer (p. 889). In t lie case of one factory, where fair comparison was obtainable between cane form which attacks the stalks of corn, previously confused wlth-DtaraM taccharalu, has been found 'I Q. Dyarol th ; to a news] I by him under the name Entomological >. vol. 22, no. " ill.) Bui. To. 2d scr., La. Exp. stu.. llatou Kongo, La., 1902, W. C. Stubbs and 11 a. Morgan. • ' Bui 9, 2d set I 11 '2 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BOBER. uninfested and infested for a number of consecutive years, he esti- mated the damage at $136,335 for three years on plant cane alone, or $45,445 per year, nearly $1,000 per day during the grinding season for this one factory. When it is considered that most of the area devoted to cane growing in Louisiana is infested with the borer, it can easily be appreciated from the above figures that the total financial loss must be enormous. One of the special lines of work planned by Mr. D. L. Van Dine, when the laboratory for the investigation of sugar-cane insects was established by this Bureau in 1910, was the determination of the various classes of injury caused by the cane borer. Observations and experiments were conducted by the writer in 1910. It was discovered that the borer is responsible for much more injury than is apparent at first sight. Its harmful work begins with the destruction of eyes of seed cane, reducing the stand during the following year; con- tinues through the growing season of the cane by stunting its growth, and causing damage from windstorms, owing to the weakening of the stalk due to the burrows and girdles; and ends by causing a much lower percentage of juice, which is again of a much poorer quality in infested canes than in uninfested canes. The last is an important form of injury, which appears to have been overlooked by investigators and planters. Moreover, the holes made by the cane borers are the chief means of entrance to the stalk afforded the various fungous diseases of the sugar cane. The tonnage yield per acre is reduced by borers, and the average weight of canes otherwise similar in appearance is found to be reduced by borer infestation. These points will be explained in detail under the following head- ings: Injury to seed cane; injury to growing cane; injury to mature cane and juice. INJURY TO SEED CANE BY THE SUGAR-CANE BORER. The buds of cane are favorite places for the attack of the young borers while the stalk is growing, due to the softness of the tissue compared to the woodiness of the rind of the cane stalk in other locations. The young larvae of the sugar-cane borer will enter the buds or eyes of the cane, and in nearly every ease the attack will result in the destruction of the bud. Frequently canes will be seen in which more than 50 per cent of the buds have been destroyed by the borer. Of course, many borers enter the stalk at other places, around and between the joints, as an average cane will contain only from (I (o 15 joints, while canes will often be found with from 6 to 10 borer holes in a single joint. In nearly every case of severe iufesta- DAMAGE TO SUGAB < \M Bl MM ST7GAR-< \ N I BOBER. 6 fcion, however, it will be found that a considerable percentage of the eyes has been desl royed. In order to secure definite data as to the extent of this injury, a number of borer-infested canes were picked up at random from a pile of cane on a property which probably represents typical condi- tions in Louisiana. The eyes were then counted until 100 were reached, and the number of injured eyes tinted. No attention was paid to the amount of borer infestation in each stalk, beyond ascer- taining: that at least one borer hole was visible. In the first 100 eves counted 23 had been destroyed by the borers. On repeating the above experiment it was found that is eyes had been destroyed in the second lot of 10 I, making a total of 11 eyes destroyed out of a total of 200, or 20.5 per cent. The infestation of the plat from which this cane was secured was approximately determined at 53 per cent, which would indicate that Over 10 per cent of the entire number of eyes in the plat had been destroyed by borers. The e feet of this is to km luce the stand of cane the following year by reducing the number of viable eyes in the planted cane. The borers also damage the seed cane to a certain extent by absorbing a considerable amount of the sap or juice which nature intended to he used to nourish the buds when they commence to grow, but this injury probably does not assume much economic importance. INJURY TO GROWING CANE BY THE SUGAR-CANE BORER. When the cane sprouts in the spring a certain amount of damage is done to it by the larvaa of the first brood, which bore into the hearts of the young and tender si ts. Very frequently the terminal leaves t urn yellow, and on being pulled come out of the whorl of the plant bodily. Examination reveals the fad that they have keen almost cut off in the heart of the plant, and often the small worm is found in the excavation. It is likely that this source of injury causes considerable damage to the stand of cane, although no experi- ments have yel keen made to determine the percentage of injury . Borers are also responsible for very considerable damage by wind- storms. After a sm ere windstorm in the fall the observer can notice two e fects upon sugar cane. In some cases the cane will be blown prostrate, being left lying nearly horizontally upon the ground. In other cases many of the stalks are broken by the wind, sometimes clove to the ground, sometimes in the center or near the top of the cane. In the case of cane which has been blown over, it will • become more or less upright, and in anj event it will continue growth. The greatest injury produced upon it i^ crooked and bent stalks, which are troublesome to harvest. 4 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BORER. In the event of the stalks being broken, however, the damage is very different. In this case the growth of the cane stops, and the buds on the top joints below the fracture sprout and commence to glow. The process of growth draws upon the supply of sugar stored in the parent cane, so that the cane is not only prevented from reaching its fullest maturitj 7 , but also stands a very good chance of losing a percentage of the sugar already stored up in the stalk. A close examination of a cane field after a heavy wind will show that to borer injury is directly due the great majority of broken stalks. A cane will seldom break in a wind unless the stem has been phys- ically injured, and examination of broken stalks nearly always shows that the breaks occur at a borer girdle or a large burrow near the surface of the cane. The burrows and tunnels in the stalks frequently concentrate upon a certain joint, with the result that it will be mate- rially weakened and will snap off at the slightest provocation. Many canes are literally girdled by borers, a tunnel being made just inside the rind completely around the cane and only the center is left to hold up the top. To a large extent, also, borers are directly responsible for the spread of fungous diseases in sugar cane. In order that the fungus may enter a plant it is nearly always necessary for the spores to settle on an excision or wound in the rind of the cane. These openings are furnished in great numbers by the borer holes. Dr. C. W. Edgerton, 1 in "Some Sugar-Cane Diseases, " advises that all "seed" cane showing external evidence of borer injury be thrown out, as a preventive of fungous diseases. L. Lewton-Brain 2 , in considering the rind disease ( Melanconium sacchari), says: Whenever it is possible to trace the discoloration to its starting point, this will always be found to be a wound of some sort. The wound may be a borer hole, a leaf- hopper puncture, or a wound made in stripping, the borer wounds being perhaps most favorable to the fungus, especially in the older parts of the stalk. INJURY TO MATURE CANE BY THE SUGAR-CANE BORER. AMOUNT OP INFESTATION. In order to determine the extent of borer infestation an elaborate examination of canes was made during the fall of 1910. The gen- eral practice was to examine 100 canes across each end of a plat and 100 canes across the middle. These hundreds were divided into 4 groups of 25 canes each at different points in the row. This plan \\ as modified in varying degrees as circumstances made it necessary or advisable. In all, the infestation was approximately determined in 9 plats planted to cane. Of these 9 plats 3 were in stubble and 6 i Bnl. 120, La. Exp. Sta., p. 12, 1910, 2 Bui. 7. Hawaii Sugar Planters' Association Experiment Station, 1907. DAMAGE TO SUGAB CANE BY THE SUGAB-CANE BORER. 5 in plant cane. The leasl injury t«> a cane l>\ a borerserved to throw- it into the infested column. The general results are shown in Table I : Tabli 1 Infestation by thi sugar-cam borer. of cane. Number ISortT free. Ined. 1,900 603 1,297 1,100 341 3,000 944 2,050 age of in- festation. Plant cane. .. Stubble cane. All canes 69 68.63 In addition to the canes referred to in the table, two other large lots were removed from the plats for other purposes and examined for borer infestation. One hundred canes were taken from a planl- cane plat for determining the comparative weights of infested and uninfected canes. These canes were infested to the extent of 72 per cent. From a stubble plat 734 canes were removed for determining the effect of the borer upon the sugar content of the cane. Of these canes 393, or 53.54 per cent, ^ ere infested. Both of these experiments are described in detail elsewhere. Adding these counts to the pre- vious number we have a total of 3,834 canes, of which 1,313 were borer free and 2,521, or 65.75 per cent, were infested by the borer. i \i!<>\ mi rops In five instances the same number of tops as of canes were exam- ined and showed a distinct correlation between the infestation of the two parts of the stalk, the infestation in the tops increasing to corre- spond with the increase in the infestation of the cane-. This is \ n-\ suggestive as to the value of clean burning of the trash after removing cane from a severely infested held. The data on this point are given in Table II: Tabli II Infestation of tops by the sugar-cant b Varieties. Per cent infestal ion in canes. Percent infestation in to] Purple 59 79 81 5 7 D ;i 17 i Purple 31 CEXTI r INI BSTATION. That ii is the tendency of the borers to seek the noddle of the plat ia suggested by the fact that in 1 cases the highest percentage of infestation was found in that portion, while in only l case was the 6 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BORER. lowest infestation found in the middle of the plat. On the other hand, in 6 cases out of 7, where comparison could be made, the lowest infestation was found at the ends of the plats. It may be said in general that the highest infestation will be found in the most luxuriant cane. CHARACTER OF INFESTATION' IN' PLANT CANE AND STUBBLE CANE. In fall plant cane the majority of the infestation is in the. upper half of the cane, while in stubble cane the infestation is more notice- able near the ground, although the whole stalk is more or less infested. This may be due to the earlier sprouting of the stubble cane in the spring, thus causing it to be liable to attack from the early broods of borers-; and also a certain number of borers may hibernate in the stubble, thus being present in the spring to infest the early sprouting cane. On the other hand, fall plant cane does not appear above the ground as early in the spring as stubble, and as the adults that appear in the seed cane are too delicate to dig through the soil to the surface they perish underground. A field of fall plant cane may be regarded as borer free in the spring, and will become infested during the following summer from outside sources, probably to a degree depending upon the severity of infestation in the surrounding terri- tory. The fact that the most evident borer injuiy occurs in the lower half of the stalk in stubble cane makes the damage greater than in plant cane for several reasons. The first is that the actual mechanical injury by the borer is in the lower joints, which are more mature and have the greater sugar content. Again, the presence of the borer burrows and tunnels in the lower joints affects the flow of sap to the top of the cane, thus interfering, more or less, with the growth of the whole cane. Also, the joints near the base of the plant tend to become hard and woody following borer attack, thus increasing the percentage of fiber and decreasing the percentage of juice. Inciden- tally the latter point increases the difficulty of grinding, as was called to the attention of the writer by a sugar-house manager attributing the breaking of some machinery to the crushing of heavily infested sugar cane. EFFECT "1 INFESTATION UPON THE WEIGHT "1 CANE. In order to find oul the effect of borer infesl at ion upon the weight of cane, 100 stalks were picked out and carefully averaged in size. All were cut off the same length. Xo attention was paid to borer infestation in selecting the canes, and the opinions of several gentle- men were consulted, all canes larger or smaller than the average being thrown out and replaced by others until on examination it was impossible to select canes larger or smaller than the others. DAMAG1 TO SITGAB CANE Bl I 111. SI G \;:-< \ These canes were then examined for borer injury. 72 being found infested and 28 borer-free. The smallest damage to a cane by a borer was sufficient to place it among the infested canes. The canes were then weighed, with the results shown in Table III: [] Effect of borer attack upon Number Weight of canes. weigh) Of canes per ton. weighl borer. weight due to borer. 28 103 Pounds. 3. 54 565.0 Pounds. Pi Borer 72 For fun her results a wagonload of cane was taken to the sugar- bouse, and was t here separated into two lots, infested and un infested. Of the 734 canes, 393, or 53.54 per cent, were infested. The least injury by borers placed a cane in the infested lot. Each lot of cane was then weighed separately on platform scales. The 393 infested canes weighed 694 pounds, an average of 1.76 pounds per cane, while the 341 borer-free canes weighed 626 pounds, or an avera 1 .8 I pounds per cane. T u;i .i I \ '. i • borer attack. Cunes. Number of canes. Weight ;e Number weight of ennes per cane, per ton. per ton borer. weight borer. Borer-free 341 393 694 Pounds, 1.84 t.76 1,087 1,136 Borer-infested 4.31 On the basis of Table IV the difference in yield between borer-free and borer-infested cane fields would amount to a loss of aboul I ton of cane per acre when the borer-free cane gives a yield of 25 tons per acre. EFFECT OF BO >N I n tCE. The following series of experiments was carried out to ascertain jusl what damage the cane borer inllicts upon the cane juice, in add it ion to t he physical damage to i be cane plant : leriment /. Six stalks of D. 71 cane were --elected, three being heavily infested by the borer and three being borer-free. The stalks were cut into four samples, as follows: (1) :\\ bottom joints, borer-free canes. '■'<\ bottom joints, borer-infested canes. ■'11 top joints, borer-free canes. (4) 3} top joints, borer-infested canes. 8 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BOEER. Samples 1 and 3 and samples 2 and 4 were thus from the same canes. Each sample was carefully weighed, run through a 3-roller hand mill, and the weight of juice from each sample recorded. The juice was then analyzed, the latter operation being kindly performed by Mr. W. G. Taggart, chemist at the sugar experiment station. Sample 2 (bottom joints) showed, compared with sample 1, losses due to the borer of 4.59 per cent of juice, 2.6 per cent total solids, 4 per cent sucrose, and 12 per cent purity, and an increase of solids not sugar of 0.8 per cent. Sample 4 (top joints), compared with sample 3, showed losses of 7.27 per cent of juice, 4.2 per cent total solids, 4.9 per cent sucrose, and 13.7 per cent purity, and an increase of solids not sugar of 0.8 per cent. It can thus be seen that the borer not only reduced the juice quantitatively but qualitatively as well and to a more marked degree. Placing these figures on a basis of 1 ton of cane to the sample, we have the following results: Sample 2 showed losses of 91.8 pounds of juice, 35.2 pounds of total solids, 59 pounds of sucrose, and a percentage loss of sucrose of 34.04 per cent. The increase in solids not sugar was 8 pounds per ton of cane. Sample 4 showed losses of 145.4 pounds of juice, 68.6 pounds total solids, 70.9 pounds sucrose, and 46.43 per cent sucrose actual loss, with an increase of solids not sugar of 5.4 pounds per ton. The average production of the total borer-free cane (samples 1 and 3) was 163 pounds sucrose per ton of cane and of the total infested cane (samples 2 and 4) 98.1 pounds sucrose per ton of cane. This gives an average loss of 64.9 pounds, or 39.81 per cent, of sucrose per ton of cane due to the borer. The results of this experiment are given in tabular form in Table V. Table V. — Analysis si § Hi 09 a o o a O .d t- O) o o 3 3 3 . a. 5, £ a o a a o o M 3 o C o i. 3 O .S3 Z i $•5 ►J 1 >> -*> . 3 t- BO " 3 ►J 1 3 J bottom joints borer- free canes Grams. 1,512 1,008 1,282 985 Grans. 419 582 783 530 62. 33 57.74 61.08 53.81 PjcI. 4. 59 7.27 P.ct. 16.6 14.0 16.1 11.9 P.ct. 2.6 4.2 P.ct. 1.3 1.9 1.4 1.3 9.3 19.2 12.0 17. 1 P.ct. 1.4 2.2 2.2 3.0 P.ct. 13.9 9.9 12.5 7.6 P.ct. 4.0 4.9 83.7 71.7 78.6 64.9 P.cL 2 3 3! bottom joints borer- infested runes 3J top joints borer- 12.0 4 top joints borer- infested canes 13.7 NOTE.— Samples 1 and 3, 2 and 4, were from tbe same canes. Each sample consisted of portions of three canes. Analysis made Nov. 10, 1910. |i\.M u;i TO SUGAB CANI Bl Mil SUG \i: I \M BOB] R. Table V.—Ana D. 74) of the borer injury to sugar cam Continued. BESUXTS 01 V.BOVE \\\l . '. \ BASIS OF 1 io\ OF CAN! I 1 1 !•: SAMPLE. — § - V 6 Z Nature of sample. a "3 | "3 M "3 S3 Pi Is III a c 3 . 3 a S3 o 13 § u 2 8 ~ 'r ~ o ~ = a o p, o 3 Q O U,' l" 3 3 . « d S3 ■9 B, o 1" 3 • x -_ en O o 3 3 . 6 c. S 3 in J = 9 M - S" 3 1 ;sj bottoi 2,000 L6». Lbt. 1 171.7 35. -' Lbs. l& 2 17.1 l 1.0 t6«. :,.7 E6». 17.4 Hi'. 3 5. 1 Lbs. 173.3 1 l-l. 3 152. 7 si. s /./..v. p.rt. 2 3 3A liotto :u top Joint J. mm 1,154.8 1,221.6 01, 07ft -' 59. i) 34.04 4 joints borer- 1 1 i /. ■ t ' : ini lit ofsu- ton: ■ 163. Samples 2 and I. . 39. "I 1 /•.>/' i ri merit 2. — The remarkable figures obtained in Experiment 1 showed the advisability of conducting a further experiment upon a larger scale in order to obtain more conclusive results. For this experimenl 30 canes were selected ai random from 1). 71 cane. Of these n» were borer-free, l<> were medium infested (1 to 3 joints per cane showing borer injury 1 , .and lit were heavily infested (5 or more infested joints per cane). It should be remarked thai the infestation in the heavily infested canes was not so heavy as was the infestation of samples 2 .and -1 of the firsl experiment, in which every joint was infested. Bach sample of 10 canes was separately weighed, run through the hand mill, and analyzed exactly as had been done with the samples of the first experiment. The analyses were again made by Mr. W. G. Taggart. The results obtained fully upheld those oi the firsl experiment. Sample 2 (medium infested) showed losses due to the borer of 0.3 per cent juice, l per cent total solids, 1.2 per cent sucrose, 2.2 per cent purity, and an increase of solids not sugar of 0.1 per cent. Sample :i (heavily infested) showed losses of 2.3 per cent juice, 3.4 per cent total solids, L6 per cent sucrose, I -'.7 per cent purity, and an increase of 0.7 per cent solids not sugar. Reduced to a basis of I ton of cane to the sample, the results wore as follows: Sample '_' (medium infested) showed losses per ton of cane of 6 pounds juice, 13.19 pounds total solids, L5.46 pounds sucrose, 8.78 per cent actual loss of sucrose, and an increase in solids not sugar of ] 15 pounds. Sample:; (heavily infested) showed losses per ton of cane of 46 pounds juice. 17.85 pounds total solids, 10 DAMAGE To sn.AK < ' A X F. |;\ THE SUGAR-CANE BORER. 60.72 pounds sucrose, and an increase in solids not sugar of 7.73 pounds. Comparing the percentage loss of sucrose in the heavily infested cane of this experiment, 34.51 per cent, with the average loss of samples 2 and 4 in the first experiment, 39.81 per cent, and con- sidering that the latter cane was more thoroughly infested than the former, it will be seen that the results of the first experiment werenoi exaggerated to any great degree by reason of the smallness of the samples. The complete results of this experiment are shown in Table VI. Table VI. — Analysis of sugar cane (D. 74) to determine effect on sugar content of the borer injury to cane. 1 Nature of s C3 o o u B *o o 0) 3 s .s — © ■a 3 +3 So 3 •a aS o 3 I OS 6 'i 7 w . o C i ~ 3 o OS.Q 3 2 o sample. s "3 O w ;3 *3 (U o VI o 3" -/. 3 — — o o 3 ° >. a o a; o 01 o O o 8 8.2 3 3 ■- OS 3 « - OS 'A ? £ p-i A r- J a a> CO A - A Gms. Gms. P.ct. P.ct. P. c(. P.ct. P. «. P. cf. P.ct. 1 Borer-free 9,990 6, 108 61.1 17.1 1.6 1.1 11.1 14.4 84.2 2 Medium infested 11,081 6,735 60.8 0.3 16. 1 1.0 1.7 1.2 12.9 13.2 1.2 82.0 2.2 3 Heavily infested 8,824 5,190 58.8 2.3 13.7 3.4 2.1 1.8 21.4 9.8 4.6 71.5 12.7 Note. — Each sample consisted of 10 canes. Each of the medium-infested canes i ontained from one to three infested joints, and each of the heavily infested canes five or more infested joints. Analysis made Nov. 12, 1910. RESULTS OF ABOVE ANALYSIS FIGURED ON A BASIS OF 1 TON OF CANE TO THE SAMPLE. ©" oi !j5S £ o O u 9] Nature of 3 'o 3 O 3 -a "3 . ■5 3 3 » 3 S ■5 w ■ X3 a> 0J 3 . 3 o 3 *-= "•go P. - £ 3 O 10 .Q •/: 3 — » - sample. ■s — •- 2° (O o 3 3 S2 Bk © = 3 ■ss* 6 '5 ago y; O X C3 O - - Cj © - » o - 1 § S-"3 5 O 3 m " 3 OX5 ill Lbs. Lbs. £6s. LJs. £6s. £6*. Lbs. i&s. ite. Lbs. Z6s. P. c/. ] 2,000 1 ''22 _'ns 96 19.55 13.44 L75.97 2 Medium in- i '1 2,000 1,216 (i 195. 77 13. 19 20.07 1.12 14.59 1.15 160. 51 15.46 ! 8.78 3 Heavily in- fested 2,000 1. 176 46 161.11 47. 85 24.69 6.14 21.17 7.73 115.25 60.72 34.51 Experiment 3. — In order to confirm the results of the two foregoing experiments, and also to secure additional accurate data upon a larger scale, a third and larger experiment was conducted early in December, 1910. A wagonload of D. 7-4 cane was taken to the sugar bouse and was there divided into two lots, borer-infested and borer-free, the least sign of borer injury throwing a cane upon the infested pile. Of the 73 I canes, 393, or 53.54 per cent, were infested. Each pile of canes was loaded separately upon a wagon and weighed on the platform scales. The 393 infested canes weighed 694 pounds, DAMAi iUGAB < \m: By i li I SUGAB i A.1 11 an average of L.76 pounds per cane, and the 34] borer-free canes weighed 626 pounds, an average of 1.84 pounds per cane. This gi an average loss in weight of 0.08 pound per cane. In 1 ton of cane like each of tJ ese samples there would be L,087 borer-free canes and 1,136 borer-infested canes; or, in other words, it would require 49 m< infested canes to make a ton than of borer-free canes. On a (Too basis of 25 tons of uninfested cane per acre, this would show a loss of about I ton of cane per acre due to the borer. Each lot of cane was then run through the mill separately and a sample of the juice taken. The 626 pounds of borer-free cane gave i:;i pounds of juice, or 68.85 per ( enl extraction, while the 694 pounds of infested cane gave 155 pounds, or 65.56 per cent extraction. The loss of juice due to the borer was thus 3.29 per cent. The two samples df juice were analyzed by Mr. W. (•. Taggart, and showed a loss due to the horer of I..") per cent total solids, 2.1 per cent sucrose, and .").(i per cent purity, with increases of 0.1 per cent glucose ami ti..", per cent solids not sugar. Figured on a basis of I ton of cane per sample, the losses are 66 pounds of juice, 30.69 pounds total solids, 36.57 pounds, or 19.33 per cent, sucrose, and increases of 0.72 pounds glucose and 5.17 pounds solids not sugar. The results of this analysis are shown in Table VII: Table VI I . inalysis of su borer injury to < 9 = o I = 99 O O a y. ~ . -■ - " a 1- — 2 GD — Si "Z 3 o 3 to u -5 ■a ■- O 3 •A o A Id y - 3 o Eh ■d "^ ^ •3 3 g = Z •s.~z o A C C3 - = 3_ 3 n 3 . = .=, "H *o d © V) d o w O . - 3 Purity. Nature of a u s ZL *- "3 © M Mia ^ 2 Borer-free. 1 341 Lbs. 1.84 1.76 Lbs. Lbs. 431 P.ct. P.ct. 16. 7 15.2 P.ct. 1.5 P.ct. 1.0 P.CI- 2. 1 2.0 P. r, . 13.7 11.6 'i'i . P.ct. "5.6 -The above sam pi n load which was taken to the sugar i 1 infested and injur LTS OF ABOVE ANALYSIS ! [Gl RED ON A BASIS OF 1 TON OF CAN; THE SAMPLE. . re of 0* s u o "3 ^ S E © 3 3 n - — o o — . - ? i pie. o "" \0 o « O »3 o a O 3 = o — ^ u. 'Z •s ,d tx o O O 5 3 — 2 = 5 &•« CO ■t. O 3 -; - ^ Lo». Zos. Lbs. Lb*. 2,000 1,311 199. 27 30. 66 34.08 13. 1 1 0.72 152.08 19. 33 12 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BORER. It should be noted as having a bearing on all of these analyses that the lower the purity of the juice the lower is the percentage of total sucrose that is recoverable in the form of sugar. Therefore the percentage loss of sugar in the impure samples somewhat exceeds the loss of sucrose. The sucrose which can not be recovered is approximately equal in amount to the glucose present. On this basis the present experiment would show a production of 176.26 pounds sugar per ton for the borer-free cane, while the borer-infested cane would give 138.97 pounds sugar, a loss of 37.29 pounds per ton of cane, equaling a loss of 21.16 per cent sugar, which is 1.83 per cent in excess of the sucrose loss. It may be computed from the figures in Table VII that an acre of borer-free cane yielding 25 tons of cane of the above quality would yield 4,716.25 pounds sucrose per acre, while if it were infested to the same degree by borers, the }ield under similar conditions would be 23.92 tons of cane and 3,637.75 pounds of sucrose per acre — a loss of 1,078.50 pounds sucrose per acre. SUMMARY. The sugar-cane borer damages cane in the field by destroying a considerable percentage of the eyes, thus reducing the stand of plant cane; by stunting the growth of the cane, owing to the physical injury of the stem; by admitting fungous diseases through the wounds in the stem; and is the main cause of injury by the wind, owing to the weakening of the stalk due to the tunnels and burrows. These classes of injury have been appreciated by planters. It now develops that there is another and very important class of injury which has been overlooked. This is the reduction of botli the quantity and quality of the juice, which is dealt with specially in this circular. It becomes evident that both the planters and the man- ufacturers are vitally interested in the work of the sugar-cane borer. Investigations of methods of control in the field are now under way. The results will be published in due time. In the meantime planters are referred to the bulletin on the subject (Bulletin 70), by W. C. Stubbs and H. A. Morgan, of the Louisiana Experiment Station. o UNIVERSITY OF FLORIDA 3 1262 09216 7963