; j University of Illinois Library at Urbana-Champaign^ A <">i— r» Wt '&P _®y >£€ ^-^T»^ s <•* "° t; o CO I-H iH vH 10 CO CD . lO r-l •~~ -H r-l D i IH CD V VH O a not re s remo a i) en not re mot re CD 03 93 4_> O • tij O IH O "o IH 8 O E 0 IH 0 IH aT IH aT aT i IH 3 oT oT • -t-> ri 3 3 ri c X td c" 3 Treatment u th copper carbon th Bordeaux mix :h copper carbon ;h Bordeaux mixl ith copper carbo ith Bordeaux mi ith copper carboi th Bordeaux mix ed >|H '£ 'fe '^ •£ & fe ^ 1-4 « 4) (L) flj — -< 4-> 4-> 4J a rrj rrj rrj rrj tJ rtf rrj TH, •• V CU 1— 1 • rt ^ 1 hH Or^J 1— 1 I— 1 h- 1 hH hH hH |> h— 1 > X hH a -- rt <4H . O C 3 O f> a'» 1907.1 BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 487 It will be seen from a perusal of the above table that spraying in most cases reduced the amount of bitter rot among both windfalls and picked fruit, effecting a saving of from 8 percent to 14 percent of the entire crop, or from 40 percent to 61 percent of the fruit liable to infection (Plats VIII and VI, respectively). In Plats II, III, and IX, however, the percentages of rot ran very high in spite of the spraying, indicating either that these plats were more severely infected than the others or that the spray was ineffective in prevent- ing the ravages of the disease. It is probable that both causes af- fected the result somewhat for even in Plat VI, where the control was most complete, the protection was far from perfect. The results clearly indicate, therefore, that spraying but once or twice with Bordeaux mixture or copper carbonate solution is not a perfectly effectual way of controlling bitter rot. The removal of affected fruits, too, apparently failed to prevent the spread of the disease. CONCLUSIONS FOR 1901 While the work during 1901 yielded no data of sufficient con- clusiveness to warrant definite recommendations for the treatment of bitter rot, it as least served the useful purpose of pointing out lines along which the work should be conducted in succeeding sea- sons. Particularly was it valuable in emphasizing the necessity of having all conditions of the plats under as perfect control as the nature of the experiment would permit. In the work of 1902 and in all subsequent work every care was taken to make the experimen- tal conditions as perfect as possible. The following important fac- tors were especially considered in conducting the investigations : i. The Infection Factor: — The success of experimental work in spraying for any disease must be very largely dependent on the uniformity and amount of infection of the plats under consideration. If the infection is not uniform throughout, inaccuracy in results is bound to occur unless very complete precautions are taken to over- come the influence of variable infection. If the amount of infection is very slight in all the plats, no wide differences in results can occur, and small differences leave doubt as to whether the results are to be ascribed to fluctuations in infection or to differences in the treat- ments of the various plats under investigation. In case of bitter rot of apples the infection factor was found to be exceedingly variable and very difficult of control, and the follow- ing precautions were taken to eliminate its unevenness and uncer- tainty. (a) In all experiments orchards were selected which in previous years had been severely and uniformly attacked by bitter rot, and in which it was confidently expected that, in a season at all favorable to the development of the disease, bitter rot would be present in sufficient quantities for experimental purposes. 488 BULLETIN No. 117. [August, (b) The experience of 1901 having shown that the precaution of selecting orchards known to have been infected in previous years was insufficient to insure good experimental conditions for investi- gations on spraying for bitter rot in any particular season, plans were made to continue experimental work over a series of years in certain orchards, and thus insure satisfactory conditions at some time or other during the progress of the experiments, and eliminate by large totals the effects of uneven or uncertain infection. (c) A large number of orchards were used in the experiments in order to lessen the factor of variability in infection. In all, twelve orchards were employed and some seventeen series of experiments were conducted in the course of the five years of bitter rot investi- gation. (d) As a further precaution the plats of trees were made un- usually large, for investigations of this kind, numbering for the most part from fifteen to thirty or more trees to the plat, with con- trol plats of at least ten trees each. Where more than three plats were concerned in an experiment, as was the case in most of the orchards selected for work during 1903, 1904, and 1905, two or more check or control plats were reserved in each series in order that the amount of infection in each part of the orchard might be more accurately measured and adjoining plats compared therewith. 2. The Crop Factor : — The amount of the crop, in a number of instances, proved to be an exceedingly important consideration in the experimentarwork with bitter rot. The years 1901, 1903, 1904, and 1905 were all more or less unfavorable for the apple crop in Illinois, and on this account certain of the experimental orchards yielded disappointing returns. Where the crop was light and scat- tering the disease spread much less rapidly than where the crop was large and the apples hung closely together. Thus the infection in these orchards was less uniform than in orchards producing good crops. Moreover, in certain orchards the crop was so light as to make the investigations of comparatively little value, one or two series of experiments being abandoned on account of the failure of the trees to set a crop of apples. The measures taken to guard against failure of the experiment through failure of the crop were practically the same as those adopted to guard against failure from uneven and uncertain infec- tion, i. e., continuing the experiment over a considerable number of years, conducting experiments in several orchards each year, and using large numbers of trees in each plat. In addition to these pre- cautions, where the plan of the experiment would permit it, or- chards were chosen for experimental work after the fruit had set, as in the Allen orchards near Carbondale in 1903, thus practically insuring a crop. V 1907.] BITTER ROT OF APPLES, HORTICULTURAL, INVESTIGATIONS. 489 3. The Weather Factor : — The weather factor is so closely as- sociated with the infection factor as to need only passing mention in that connection. But it is also important in its influence on the treatments given the various plats, since heavy rains wash off some of the spray materials and thus unavoidably interfere to a greater or lesser extent with the plan of the experimenter. Again the only recourse of the investigator is to extend his observations over a series of years and average his results or wait for favorable conditions. 4. The Variety Factor: — Certain varieties have been found to be more susceptible to bitter rot than others, though it is probable that no variety is entirely immune from the disease. For the sake of uniformity, therefore, the most of the work was confined to the Ben Davis, a variety which is fairly subject to the disease and is more extensively grown in the bitter rot regions of Illinois than any other. A very complete series of experiments was carried on, how- ever, in an orchard at Flora, with the Willow Twig variety, an apple notoriously susceptible to the bitter rot fungus, and a few isolated experiments were conducted on Jonathan, Winesap, and Huntsman varieties in other orchards at various times. For the most part the experiments were made in blocks of trees composed almost wholly of one variety, and in cases where the plats contained more than one variety the results for each are recorded separately. 5. Factor of Preparation and Application of Spraying Materials : In the work of 1902 and in all subsequent seasons every care was taken to follow the spraying schedule exactly throughout the season. The experimental orchards were placed immediately in charge of employees of the Horticultural Department, the employee in charge remaining at the orchard throughout the entire season to conduct the experiment and make the records. Thus the preparation and application of the spray mixtures was attended to directly by expert men. Good fresh chemicals were used each season and the mixtures applied were prepared in accordance with the most approved spray- ing practice. In this way the chances for error in this direction were reduced to a minimum. But in spite of all precautions disappointments were more fre- quent than were complete successes in the results which were ob- tained during the four seasons of 1901, 1902, 1903, and 1904. Small crops in some of the orchards, failure of bitter rot to appear in some orchards, and, in spite of the large plats and the careful choice of orchards, the very uneven distribution of the infection in others, were responsible for the inconclusive results which were obtained from several of the experiments. In a number of orchards, however, conditions proved very favorable for the performance of the experiments, and uniform and satisfactory data were obtained 490 BULLETIN No. 117. [August, therefrom which appear sufficiently significant to be used as a basis for certain definite recommendations for the prevention and control of bitter rot of apples. 1902 The work for 1902, which from this time to the conclusion of the experiments was carried on independent of the Federal authori- ties, was carefully planned with a view of determining the following points : 1. The value of early sprayings repeated at intervals of ten days up to the time of the appearance of the disease. 2. The value of spraying shortly before the appearance of the disease. 3. The value of three applications of spraying material at in- tervals of ten days, beginning after the appearance of the disease. 4. The value of five applications of spraying material, at inter- vals of ten days, beginning after the appearance of the disease. 5. The value of making applications after every rain, beginning after the appearance of the disease. Three orchards were selected in which it seemed probable from past records that the rot would surely develop. These orchards were located near Tonti, Tamaroa, and Flora. In order that the operations might be carried" forward on a sufficiently large scale to render the results of practical value and leave no uncertainty regarding the conclusions, it was decided to undertake the investiga- tion of only a part of the above enumerated points in each orchard. Accordingly the operations at Tonti were carried on with a view of determining the first two points; the operations at Tamaroa, the third and fourth points ; and those at Flora, the fourth and fifth points. In all of the orchards check plats were left unsprayed for purposes of comparison* The material used in all of the spraying was Bordeaux mixture of the usual strength — four pounds lime, four pounds copper sul- phate, and fifty gallons water. ORCHARD OF J. B. BROKAW, TONTI, MARION COUNTY, 1902 Three plats consisting of fifteen or more trees each were laid out in this orchard, all the trees in each plat being Ben Davis with the exception of two Huntsman located at one end of the block, in all six trees of the Huntsman equally divided among the three plats. Plat I was sprayed with Bordeaux mixture May I5th, 28th, June 7th, and I7th. The spraying designed for June 27th was abandoned on account of the soft ground resulting from almost con- tinuous rains, and July 2d, when the Ben Davis trees were sprayed, 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 491 it was impossible to reach the Huntsman which were located on somewhat lower ground than the rest of the plat. Thus the Hunts- man were not sprayed until July gth. Plat II was sprayed with Bordeaux mixture May I5th, July 2d, 9th, and I2th, excepting the Huntsman which received their first application July 9th and the second one July I3th. Plat III was not sprayed. On account of the somewhat different treatment of the Ben Davis and the Huntsman trees in this experiment, and on account of the greater susceptibility of the latter to bitter rot fungus, the results of the work in the Tonti orchard will be given in separate tables. Records of fallen apples were made July 9th, 28th, 3 ist, August 8th, 1 3th, 2oth, 28th, September 9th, 2Oth, 3Oth, and Octo- ber ist. All infected apples were counted as were also those free from rot at each picking. September 3Oth and October ist the apples were picked from the trees, examined and counted, and rec- ord made of the number of specimens showing bitter rot and of the total number of specimens in the crop. The results are shown in Table 2. While the results of the experiment in the Brokaw orchard as shown in the above tabulation are not conclusive, there is consider- able evidence to show that spraying may be effective in checking bitter rot. 44.95 percent of all the fruit on the Ben Davis trees which were not sprayed was attacked by bitter rot, whereas only 3.93 percent was affected in the early sprayed plat, a saving of 91.26 percent of the fruit liable to attack by bitter rot, where the trees were sprayed five times before any rot appeared. Spraying once shortly before the rot appeared and twice afterwards also checked the disease, effecting a saving over the check plat of 63.00 percent of the fruit liable to bitter rot. In this respect, however, the earlier sprayings proved considerably the more effective. In the Huntsman the percentage of rot in all plats was very much higher than in the Ben Davis. It will be remembered, how- ever, that in the case of the early sprayed plat two very important applications of Bordeaux had to be omitted on account of difficulty in getting to the trees, those of June 27th and July 2d, leaving a period of twenty-two days between sprayings in the case of Plat I of the Huntsman, so that when the spray was finally applied the bit- ter rot infection was already quite general. Even then there was effected a saving of 38.66 percent over the check plat and of 34.45 percent over the plat sprayed after the rot appeared. The discour- aging part about the Huntsman experiment is the very small number of apples which remained on the tree until picking time. Such -apples as did remain, however, were all found on the sprayed plats. 492 BULLETIN No. 117. [August, »!*« co co»o co •* r- t-m IM • 5 9 Q * 03 ^ co co •«* T^ CO OS 1C OO XI •2 "o CO - O CD 05 rH O •* « *^ -2 *J 10 oo c^i 00 CD -H -* Tl *"" U »o t- oo m co co ^ * os 13 o oooo *O *£? co ** m CD O3 rooo H «•* •* O5 O ** •«* o "ft c r*« in r-CD OS OSOO ^7* Qt oo in r- CO rH MH <* nj (M CO -- 6 «*KS c "^ O 4J rt • cc 0 G C o •g £ rt rt e "-1 g* S ^ OH 1 C rt cc rt -I-1 rt g «*H & S « 2 a) S IH )H EH 5 ^ <" CH o g] ^ QJ ^ CD (Uro W *J (D S^ MH >) • a> rt rt q m ^ ^'S 8i« u<§^ * "" > O * *J O fe ^ -4-> ^ £ n> ® >*-! ^ -M O ^ T3 ^ (y 4J qj -rH „ flj *-> (L) - rt rt rt -^ <-> rt rt rt ^ R K V s- l-> Z '-4J M ° '- O 1 £ > fN PC; ^
  • ^1 00 O3 00 CD 4> cu K. >> Si "5 5 O I s o 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 495 It will be seen from Table 4 that bitter rot developed to a considerably greater extent in the Tamaroa orchard than in the Tonti orchard, the check plat in the former showing an infection of 68.54 percent and the latter an infection of 44.95 percent for the Ben Davis. So far as the effect of the spray in controlling the dis- ease is concerned the results only indicate that it was markedly in- effective. Even five applications failed to save any large amount of the crop, 48.26 percent of the entire crop being affected with the disease, as compared with 68.54 percent for the check plat. The results for the picked fruit alone are somewhat more favorable to both the sprayed plats, only 20.37 percent of the picked fruit on Plat I and 28.09 percent on Plat II being infected, as compared with 49.20 percent on the check plat. The following table shows the saving in percentages effected by each treatment : TABLE 5. — SAVING IN PERCENTAGES EFFECTED BY SPRAYING IN THE TAMAROA ORCHARD IN 1902 NO; of plat. Treatment. Saving over plat II. Saving over check III. I Sprayed five times after disease was fully es- tablished Percent- age 19.51 Percent- age 29 59 II Sprayed three times after disease was fully established 12 52 Conclusions: — Late spraying had some effect in decreasing the amount of injury done by bitter rot. Five late sprayings effected a saving over three sprayings, of 19.51 percent, and over the check plat, of 29.59 percent of possible infection of bitter rot, but as com- pared with the early spraying in the Tonti orchard, it was much less effective in controlling the disease. ORCHARD OF DALE MANN, FLORA, CLAY COUNTY, 1902 In this orchard but one variety was under treatment, the Willow Twig. The block, excepting the check plat, was sprayed just after the petals fell and again two weeks later, by the owner of the or' chard. This was for scab and codling moth and not a part of the regular experimental work. As in the Tonti and Tamaroa orchards three plats of fifteen trees each were laid out, the object being a comparison of the value of spraying at regular intervals of ten days 496 BULLETIN No. 117. [August, after the appearance of the rot with spraying after every rain after the appearance of the rot. It happened, however, that rain fell just previous to the regular time for spraying throughout the entire sea- son and hence the two sprayed plats received the same treatments. The plats were sprayed as follows : Plat I — This plat was to be treated after the bitter rot became established and all subsequent applications were to be governed by weather conditions. Following out this program applications were made July I4th, 25th, August 5th, I5th, and 25th. On the date of the first application infection of bitter rot was found to be general throughout the orchard. Rains occurred just before each of the applications above referred to. Plat II — Sprayed with Bordeaux mixture every ten days re- gardless of rain, July I4th, 24th, August 5th, I5th, and 25th. Plat III — Check plat, not sprayed. Records on the fallen apples were made July 25th, 3Oth, August 5th, 1 5th, 2 ist, 25th, September ist, 8th, i/th, 24th, and Octo- ber 1 5th. The fruit was picked from the trees October i4th and I5th, the apples were counted, and the records completed. The results of the experiments in this orchard are tabulated in Table 6. The average percentage of bitter rot for the two sprayed plats is 59.89 percent. This shows that an average of 23.43 percent of the entire crop was saved by spraying five times after the appearance of the disease; that is, the percentage of the crop saved was about the same as in the case of the Ben Davis receiving similar treatment at Tamaroa. The percentage of rot in the check plat, 83.32, shows that the Willow Twig at Flora was attacked worse than the Ben Davis at Tamaroa or Tonti, and nearly as bad as the Huntsman at the latter place. In this table the most interesting results from the orchardists' view point appear in the column of picked fruits. The saving effected by the spraying in the case of the two sprayed plats was, taking the average for Plats I and II, 36.85 percent of the fruit picked, and at the same time, the total proportion of fruit remaining upon the sprayed trees was almost four times greater than that remaining upon the unsprayed trees. 1907.] BITTER ROT OP APPLES, HORTICULTURAL INVESTIGATIONS. 497 u ^j Vc . n 10 , '- . oja^-M OS •<* OS t— "* CD r- 10 •^ (M OS 00 CO C o 0) a 2 en Cy rt OJ QJ X CO q=S'rO x ri 55 3, IH H >H IH _. CU > 4jM-l cy dj „ tuD M-i . °6S ^ P< ^S 0 0 © © © 0 0 © © © 0 0 © © O 0 © © © 0 0 0 © 0 O 0 0 © 0 © 0 0 © © © 0 0 © © © 0 0 © © 0 0 0 © © © 0 0 0 © © 0 © © © © e © © © © © © © © © © © © © © w PL, o 3 C S \i O d © 498 BULLETIN No. 117. [August, The saving in percentages of the crop liable to bitter rot effected by the spraying is as follows : TABLE 7.— SAVING EFFECTED BY FIVE SPRAYINGS AFTER THE APPEAR- ANCE OF THE DISEASE No. of plat. Treatment. Saving over plat II. Saving over check III. Average, sprayed five times after the disease 28.12 Of the picked crop an apparent saving in apples liable to infec- tion of 70.46 percent was effected. Conclusions: — Owing to the peculiar weather conditions which prevailed during the season of 1902 this experiment failed to an- swer the question as to whether spraying at regular intervals after the appearance of the rot, regardless of weather conditions, was more or less efficient than spraying after every rain. It did, however, show that spraying after the appearance of the rot would check the disease, though in this instance not completely enough to be recom- mended commercially. The results of the experimental work in 1902 are briefly summed up in Table 8, page 499. CONCLUSIONS FOR 1902 1. In every instance spraying reduced the damage done by bit- ter rot. 2. The saving effected by spraying varied from 91.26 percent of the total infection possible, as shown by the check plats, to 6.42 percent. 3. Spraying five times before the rot appeared and once after- wards proved by far the most efficacious preventive of the disease. 4. Spraying after the disease appeared prevented fresh infections but did not save the fruits already attacked. 5. Huntsman and Willow Twig- apples were more susceptible to bitter rot than Ben Davis. 6. The securing of a thorough coating of Bordeaux mixture on the apples before the first appearance of the disease was more im- portant than spraying at stated intervals with reference to time and rains. 7. Since the bitter rot appeared earlier than usual in 1902, the first and most general infection occurring between June 26th and July 2d, it would seem that the early spraying should be done be- tween June ist and 25th, and, if necessary, the coating of Bordeaux mixture be maintained by later applications. 1907.} BITTER ROT OP APPLES, HORTICULTURAL INVESTIGATIONS. 499 IH CU 4J > rt he* CO O CM O CO CM OS CM • • CM . CD '^f • «O tO • ••!—!• .S-Q i-H CO OS CO OO CD - OS CM OO CO • CM rH • CM rt jg CO 0 ^s In *"" CO CO 1C CD •** 1— CO CD^t* CM 1C OS CM o £ OS COOS t- 1C CM CM OS 1C OOCOOOCO *"* 4J C" CO •«* co os oc ) OS OO t— CM OS CO fcg rH -^ O OO OO ^ i 1C CO to CD «O OO ^-i co 'o ft O CO-* rH 03 00 rH OS CM O —1 CO CO rH OS CM CD •** rH r . Q^ a CD CT r— Tt< r^ ^ CD 1C CO OS rH r- "* CO "^ r— CD CM CM CM rH CM 'o ^ O CO OS r- OT*H OO 1~-CM OSTt co oo b£ bun bo b£ £*> '> > > cu rt rt b "> "> fe fe fe te +-i R • Cw cd rt ctf • tu £— i i~ C— j ^_i PQQ»»» Q_QQ &&fe& oi P C C P C fl c C G PH ^H ^H ^H f> cu cucu 333 cu cucu r^^r^r^ PQ pQpQ H |ij y PQ PQCQ fer^r^!^ CO CD 0) o •g a 00 a 0 • rt cu rt >*> cu 2i 13 ft 1 •^ 3 g 2 IH rt cu a! cu M-i **"* ft S4 CU 4J ° ft (C 00 p, ft ft o B ft T3 rt ri rt ™ ft IH ™ rt cu ^ ^ rti CU Treatment. Tonti Orchard Lmes before any rot a a shortly before any soon after its appear •avprl . o IH C rt cu O ^ ° CO ). ) cu n r eg 2 'H > 'r3 |f CU OJ *> S IH M MH 5- (U CU ^ ~ ^ ^ S ^ ^ "rt oJ a « s s * •& a a cu : i~ •+j ^ cu 2 "^ fa C CJ CU ft IH ^ CU J2 O O 4 , , jj 5 •* CUr^ g- « « i -fl ja ** > > ft X TJ ^ ' T3 ** P ^ j > ^ o 2 4 i -^ co O cfl c« o J 73 ^H fl T3 ^3 CU C &H ! >c 4, i £'i >, -S >,? i CU •& " CU CU bfl ! >-, rt -M f>> >> rt 4d rt ^ i rt ^* ^« 1 - rt ^" * fti O rt 4- ' rt *J u nj nj ^ o hi IH U > IH J- OJ J^ ft ' ft pt rj pj ft rO ft ft > ^j CO CO 6 CO CO Q CO CO O CO CO 1 — 1 W M eg M ga 500 | BULLETIN No. 117. [August, 1903 The work for 1903 was planned along lines similar to that for the preceding year; plats being laid out as before at Olney, Flora, and Tamaroa. This season, however, was a most unfortunate one, very few apples setting in any of the orchards and consequently work was abandoned at Flora, while in the Olney and Tamaroa or- chards work was carried through, hoping that the scattered fruit might develop a sufficient amount of the disease to warrant the drawing of some conclusions. When it was found that these re- sults were not likely to be of a very definite character, orchards were selected at Carbondale and New Burnside, where it was known that there was considerable bitter rot in preceding years and where the rot for this particular season was very promising. It was designed to answer the following problems by means of these experiments : 1. The value of spraying dormant wood in the fall with a cop- per sulphate solution containing one pound of the sulphate to fifteen gallons of water. 2. The value of spraying dormant wood in the spring with a copper sulphate solution containing one pound of the sulphate to fifteen gallons of water. 3. The value of spraying three times in July with Bordeaux mixture. 4. The value of spraying at intervals of ten days after the first three sprayings until after July ist with Bordeaux mixture. 5. The value of spraying four times in June at weekly intervals with Bordeaux mixture. 6. The value of spraying so as to coat the fruit thoroughly with Bordeaux mixture when bitter rot first appears. J. The value of spraying so as to coat the fruit thoroughly with Bordeaux mixture after bitter rot has become thoroughly estab- lished. The Bordeaux mixture used in spraying for bitter rot in these experiments consisted of four pounds of copper . sulphate and four pounds of lime to fifty gallons of water. Applications of spray made early in the season for scab, canker worm, and codling moth consisted of Bordeaux mixture prepared as for bitter rot to which was added four ounces of Paris green. Plats which were reserved as checks received only the early sprayings for scab, canker worm, and codling moth. ORCHARD OF J. L. ZOOK, OLNEY, RICHLAND COUNTY, 1903 The variety selected in this orchard was Ben Davis. The trees were located on a comparatively level tract in the heart of a large commercial orchard. Nine plats were laid out, all of which con- 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 501 tained fifteen bearing trees with the exception of check plat No. 3, which contained only ten trees. All plats received two applications of spray for scab and codling moth, the first just after the petals had fallen, April 3Oth, and the second, one week later, May 7th and 8th. After this the plats were treated as follows : Plat I — Sprayed with copper sulphate solution, one pound to fifty gallons of water, November 24, 1902. Plat II — Sprayed with copper sulphate solution, one pound to fifty gallons of water, March 28, 1903. Plat III — Check plat, not sprayed for bitter rot. Plat IV — Sprayed with Bordeaux mixture July 2d, nth, and 2 1 st. Plat V — Sprayed with Bordeaux mixture May i8th, 28th, June 6th, 1 8th, 27th, and July 8th. Plat VI — Sprayed with Bordeaux mixture June 5th, nth, i8th, and 25th. Plat VII — Check plat, not sprayed. Plat VIII — This plat was to have been sprayed as soon as rot appeared but, as the disease was almost wholly wanting, this treat- ment was not given. Plat IX — This plat was to have been sprayed when the disease became permanently established but this treatment was withheld as in the case of the treatment for Plat VIII. The disease was first noticed August 7th. Records of fallen apples were made July 27th, August loth, 2Oth, 25th, September 3d, 1 5th, and October I4th. The crop was picked from the trees October I4th. Table 9 shows the amount of bitter rot which de- veloped under each treatment : Nt> conclusions whatever are to be drawn from the work in the Olney orchard for 1903. The very slight fluctuations between plats may easily be the result of slight circumstances of variation impos- sible of control in an orchard experiment, as for example a few more centers of infection in one plat than another, differences in crop, and other conditions more or less difficult of discernment. ORCHARD OF F. L. WILLIAMS & SON, TAMAROA, PERRY COUNTY, 1903 The experiments conducted in the Olney orchard were dupli- cated in the Tamaroa orchard. The same number of plats was used and the time of applying the various treatments was practically the same. Bitter rot first appeared in this orchard July 6th, but, as in the Olney orchard, it proved to be so scarce as to make the results absolutely inconclusive and unreliable. The crop, too, was so light and scattering as to interfere with the work very materially. The data gathered are summarized in Table 10, p. 504. 502 BULLETIN No. 117. [August, v,*, u . oo ic o CN t— t— 1C 1^ rH 0> C w -g CO OS rH (M rH rn I— 1C rH Ss^. d CM d d d d odd in 3 «l QO OS CO CO 1C OS 00 CC CD CM CM | »l OO CM OS OC CO O OS U.O &.J g 2 0 r- CO rH CM CO rH rH O CO rH ^"SS1- „*," . «C • : s 4) c *• 'S co • • • D PH o >— IH * "5. * « •d "S » — »C 1C OS CN os oo r- Tt .»c oc CM O CD CO rH OS S o — CO CM rH CM CM C< rH rH rH o ^ «* 6 •M t>^ *-" O ^ 1> ^ rH • | • *b!2 * : : ScS- OS 1C TO •— •*t* t^ rH CC OS t— CJ CN CO CM -^ OS t- l-H (B ^2 y "S u d co d o o" d odd <2 •0 n "S * — co co oo *o 5 £ t- t— oo CO 1-1 4J CO fl C >. TO* rt rt 'o.+i 3 as ^ ftp 2 j— i t-i fl CO T3 00 cu In t>l M O Rj 0 I*H T3 PQ S c • o CO O o w co O w 5 § § 1 ^MH U ^ rt o 3 J ••— 1 ^4 O - 4J 0) S 3 -S 0 "Q O co 5; -in -3 x 5 ft rt -^ 3 ft> a •-s Treatment -2 ^J ^ 5 ' rt >> --* rS1 5 * * co C *^ cu aj » '£ 1 §• /a 1: 5* ft be cu 3 !« OB >» "^3 - JS^ J3 ft ^ W< six times after early ; and codling moth at inte July 1st with Bordeaux once each week during nrp. . ot sprayed ot sprayed ot sprayed na'S ns'S B TJ^ rrj £> r. T3 •*- c c c ^§ &§ jf S^± rt ,% pj fc o at 3 »H «U )-, cu rt •*-> cu ^ >i o **•; >>"c RJ co re rt *• IH >H 0 O O CD CU CU ft ft *£3 r^H rC W CO O CO CO CO O O O MH . 1 1— 1 HH HH rH I-H 1— 1 > > ^ 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 503 1* • H Tt< •a ? C ro Hi 0 S S o ^ ^^ w £ A o M o t, o QJ N 1- Hi 1-5 X-N. b © ° Q H C "5 5 g § 8 3» o . H 1 g i 55 13 M W cc • 5 J OH 21 & rt o w s S 2S •rl O * o o o o o o o o o o O O 0 O 0 * o o o o o o o o o o o o o o o " O O O O. O 0 O O O O © o o§o o » o o o'o o o o o o © o o o o o * o o o o o o o o o o o o o o •* o o o o o o o o o o o o o o o " o o o o o O 0 O O O ~ o o o o o O O 0 • o o o o H O O O © O o o o o o CO m rO *• P> -R^n -navia r; — ft Seedlings DIAGRAM OF PLATS IN THE ORCHARD OF F. L. WILLIAMS AND SON, TAMAROA, 1903-04 O O O O O o o o o o O O O O 0 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o O O O CD O o o o o o © o o o o o o o o o o o o o o o o o o o o o o o o o o o O O O 0 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 504 BULLETIN No. 117. •-cS- •^ oo S 8 CO I— 1 ro co CM TH O5 CO frSjjS CM rH 1— I * d TH CM d d oi 5 "o J CM O5 •* CO oo CO (M oo CO co co oo O5 t— Oi o 6 a »O O5 00 co CM rH O3 rH 10 O rH rH rH *• x<- co oo J_ 10 CM CM CM 0 00 cu «-2 ^ 1— 1 TH rH CO co TH rH is -a.- 2 • ** a "« O5 CM TH U3 CO a> t- •>* • : 8 (M co "3. (Sag 1 CO CM CM CM : : : d d •d 08 i— 1 t- 4O rH co t— co c§ co lr- rH • r-t TH 10 i— «H it d ex CM CO CM "* CM (M TH CM CO 6 jfjN oo oo 00 rH 1 • * CM rH in £§.52 CM CO r- 10 TH TH rH TH B 0 CM d 05 OO , CO -^- 3 • • rt rt rt _rt p rt 1 3 S •d 3 cu • - IH IH a (U _ Tj . * 0 0 i cu u • rt cu •Q. CU 3s ^ rt o "o coCQ 3 ; \ £ "S 's CD CO H.a di rl I IH >H CU ^ CU o rt o fafi — -4-1 M^ r" ° „, o«s O 0> y )H 5- 5" •^•2 -g.S r§ ii rt •* rt ^ IH IH CU rt IH — CD "o C O cu rayed three times i with Bordeaux m rayed at intervals spraying for appl( after July 1st wit! rayed once each we^ mixture cu rt CD O c o CU ti cu rt IH X -U 0 a cu rt Cu CD O n M o cu &i CU rf] pt O) CU c*{ ^f^ pCj CO CO O CO CO CO Q O o SH . 0 4J r— 1 . rt i [ |_| 1— 1 1— 1 1— 1 rH hH > 1— 1 i— i > H 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 505 ORCHARD OF J. W. HEATON, NEW BURNSIDE, JOHNSON COUNTY, 1903 Experiments in the New Burnside orchard were not begun until after the owner had applied the early sprayings for apple scab and codling moth. The block of trees used was of the Ben Davis variety. The trees were divided into three plats of ten trees each. Rot was discovered June 25th on an Early Harvest tree but did not occur on the Ben Davis variety until September 7th. The windfalls were gathered and examined September 7th, :8th, and October 6th. The fruit was picked from the trees and the records completed October 6th. The plats were treated as follows : Plat I — Check plat, received only the early sprayings for apple scab and codling moth. Plat II — Sprayed once with Bordeaux mixture, June 24tli, be- fore the disease appeared, in addition to the early spraying for scab and codling moth. Plat III — Sprayed once with Bordeaux mixture after the disease appeared, in addition to the early treatment for scab and codling moth. In this orchard again very little bitter rot appeared and the re- sults from all plats were so similar as to afford no conclusive data. Table 1 1 gives the data recorded in the New Burnside orchard. ORCHARD OE CHARLES ALLEN, CARBONDALE, JACKSON COUNTY, 1903 This orchard, like the one at New Burnside, was secured after the early sprayings for apple scab and codling moth had been com- pleted. Three plats of ten trees each were laid out in a block of Ben Davis trees. The treatment of the plats was as follows : Plat I — Received only the early applications for apple scab and codling moth. Plat II — Sprayed once with Bordeaux mixture, June 27th, be- fore bitter rot appeared in addition to the early sprayings for apple scab and codling moth. Plat III — Sprayed once with Bordeaux mixture, August I7th, after the disease appeared. Bitter rot was first discovered on August I7th, the date of the spraying of Plat III. The fallen apples were gathered September 5th and I9th, and the crop was picked from the trees on the lat- ter date. Here again the amount of bitter rot was small, though slightly greater than in the Olney, Tamaroa, and New Burnside orchards. It would not be safe to draw conclusions from the results of this experiment but there is a pretty strong indication that one spraying 506 BULLETIN No. 117. [August, £e2~ i— i CO O 1X8^2 M « ^ rt . «— oo -+< t^ r- Ci h^ Q< 12 oo o H ^ d If! s 1 t— d l-H £ cS« oo CD »f CO CO T a "° d d d rt i-1 tn •rt * U oo co »— 5 H®1* CO ira CM Id 1-1 co o 10 Qt 3 IO CO CO (M 1C £L| $•— £ CO 1— S 5? co ^ oi e) — ^ 1 "°j§ '£ 6 "a co CO CO i-H O 0 O CO CO oo •* o 4>»i; • I— (M CO £ u"0 1; o 1 10 co o o 4J ^3 (M 0 0) a a 3 ha 1-5 .5 tf 4J GC rrt D fO s V 1 S 0 e o nJ i-c <1J rt "rt QJ « 1 «j ™ f^t f^, rt O- IN ca ,D ^ O -4-> l-« O to -> 1- 0 O OJ T3 X! ri 5 CJ CJ id 0 0 C E a 0 0 co "O ^ ^T QJ QJ — H- 1 either shortly before or im- mediately after the appearance of the disease is entirely in- effectual in controlling the dis- ease. The results of the experi- ment in the Charles Allen orch- ard are given in Table 12. ORCHARD OF H. E. ALLEN, CARBONDALE, JACKSON COUNTY, 1903 The only orchard to furnish decisive data during the season of 1903 was that of Mr. H. E. Allen, near Carbondale. Bitter rot developed severely in this orchard and some valuable in- formation was obtained through the experiments conducted therein. The block of trees in this orchard consisted of Jona- than, Winesap, and Ben Davis vareties. Spraying for scab and codling moth had been ac- complished before the Depart- ment began work. Three plats of ten trees each were laid out, each plat containing several trees of each variety mentioned above. The plats received ap- plications of spray as follows, p. 509. 1907.'] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 507 0 0 O O O O O O O O © O O 0 0 • © 0 0 0 O O 0 0 O 0 © 0 0 O O PLAT I O PLAT II (T) PLAT III e e o © e e o o © e e o o o e o PLAT I (Q)PLAT II (T^PLAT III DIAGRAM OF PLATS IN THE ORCHARD OF J. W. HEATON, NEW BURNSIDE, 1903 508 BULLETIN No. 117. [August, ^ w. lO 1C CM ** = ** o s IO C^J »o CO "* • "3 •* CO co O 5 ^s •^ CD O Pi OO CO CO £ 13 rt t- 0 1— 1 ^.(^V- CO 00 1C ;•• »D ^, •*-" 10 Oi O5 ^•ss2 0 CO i-H in £ c 5^ CD I— 1 § S 1.' feo2u d N co CX o S M o CO V 6 "3. O 2°| C3 "u ^ rt* Tfl •«* (M "5. ^i^u r- •«* ^ ^ " S o oo (M i—i Sa2« i— i a> OS co oo s u^o e 6 "a 00 CO ^i CO CO C^l "5 " rt 6 ^^«« CD -tl oo iS'a-- s i 0 rH "> V 0) a ft ^Q 0 ** ** ^ D li h o O •4^ IM S CD rt to '£^ 3 "S tl "rt 0 o ft rt CD 3 he i« o ^ "*Q ^ rt u CD O •^T O IH Ui S 0) «J cu ->-> 'S 13 Sn3 rt ^ (U 0 ^ IH CU O ^ (•) MH rt 4H (^ tn n~( ^ . CL) cy ^ (U ^ O rt rt rt^rt j_ J3 CU a. Q cc cc **-! . 0 *J 6^3 h- 1 I—I 1— 1 U- 1 1— 1 o O O o o n 0 OS •H (D -® ® s § 3 Q K fc O o o H 0 co a ft O O o H o ® o a u o ® H w o & o o o i 0 p M 5 ^ o o o W o EH p5 o o o w B o °i o o o b o o K O o KJ O M fi o g N o O M CM to 1907.'] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 509 0 O 0 0 O 0 0 o O5 0 o S s" 0 0 o M § * 1 O 0 0 S5 | 0 0 4 • 0 0 / M fa o 0 0 ITHAN RCHARD O H 0 0 6! cc h 0 O fa o O O H § O Q to M 0 P © 6 H W to / — Received only the early sprayings for scab and bitter rot. Plat II — Sprayed with Bordeaux mixture for bitter rot, June 26th and July ist, before the disease appeared. Plat III — Sprayed twice with Bordeaux mixture for bitter rot after the disease appeared, /. e., August 5th and 6th. Bitter rot first appeared August 5th. Records were made on the fallen apples August 1 5th, 1 7th, 28th, September 5th and i8th. The Jonathans were picked from the trees September 5th and the Ben Davis and Winesaps September 2ist. In Table 13 the different varieties are given sepa- rately. In order that the compar- isons between the treatments may be made more readily, the percentages of the fruit liable to bitter rot saved by the early spraying as com- pared with the late spraying and check plats are given in Table 14, p. 511. 510 BULLETIN No. 117. [August, co W o i— _j, t- OS -T CO OS CO 0 U •" 4) • 05 t- CO CM eo o 05 co a? 5 ** o CM -*• m' eo t- ,_i CO rH IO f*u--K CD ** O ^ § OS r- OS t- 05 10 s •IB >*< j. 00 CO CO CO 0 CO • O CO 5^ OJ *^ •*-* *J *o CO OS CO CO CO ft-4 »n .^ 5 rH 05 05 CM CO 0 *-H <1 <»& "* co OO rH CD ^ t3 T3 •a T3 ^ OH OH OH OH OH OH OH OH OH OH OH ^ rt ri rt rt E*J> rt ri C o V CO rt U CO rt 0) CO rt cu CO ri O 0 CO rt cu CO ri pd 4J cu 0) cu f£j a bo QJ ff. .5 MJ 5 +J cu IH .5 "cu 4J -t-i c ^3 s ° o (U 0 e, IH «s w -2 MH £> •3 o O £ cu a cu ri i ^ cu X) rt « 4-> Q o S "ri "rt 1 'a a rt •4J o IH "o IH ^ s O )H o c rt -t-> o "o IH ^ -5 fc 0) -4-1 ^ o o IH 0) >H (^ /o rt IH 0) cu o ^J f—J -4-> o T\ CO 3 3 o ri 3 3 CO 2 3 O M-l IH 0 MH IH O ,0 ri IH O '— IH O O IH O MH IM O •H cu CU O U o to a; o OJ o cu CU O 11 O IH rt IH •4-> -i-j O M-l ^ R C ^ & CO •5 13 CO 13 T3 — , rt B a a o. O ® bo « ri Q .-H * fl cnd H 4J rt J3 a 3 bo a 3 G CD or bitter rot was thoroughly coa ing Bordeaux mixtur 4J 0 IH )-. 4J -*-> 0 a 0 SH H o 01 •*J £. co ja a <» O ^3 O rt o2 §2 O 3 rt" +> O r— rrt "*"* n r~~t -3 ^ ^ n P 0> (U j^ - m+j v bfl'r (U.2 - (U co • rt rt' •— o rt ^ rt*-S 1-3 aj S o (^Cfl O IH 0 0 © CD 0 0 0 O 0 0 © • O 0 0 00 0000 00000 00000 O 0 0 0 0 0 0 0 O © VO m •tf cO 01 ^ 0 0 O 0 0 00000 00000 ® 0 0 0 0 0 0 0 © ® O 0 0 0 ® 0 0 0 0 ® © 0 CD 0 O 0 0 0 0 ® © ® 0 0 ® 0 O 0 0 ® O 0 0 ® ® 0 0 0 0 ® 0 0 '0 O © © ® © ® 0 0 0 0 ® © © © (D rooooo oooo oooo coOOOO oooo 00 00 oo 00 oo 0H0 0"0 00 oo oo o oo oooo -oooo oooo oooo ^oooo oooo oooo oo oo oooo «o ooo oo o oooo oooo "oooo oooo oo 00 00 po bo PoO pHo bo 00 00 00 oo 00 oooo «ooo o oooo oooo Noooo oooo oooo oooo Ho ooo oooo o oo o 516 BULLETIN No. 117. protection afforded the treated plats was due to spray and how much was due to advantages in circumstances of infection. The re- sults of the experiment are, therefore, suggestive rather than con- clusive. ORCHARD OF J. L. ZOOK, OLNEY, RICHLAND COUNTY, 1904 The experimental plats in this orchard consisted, as in the case of the Flora orchard, of nine plats of fifteen trees each. (For plan of plats see p. 503.) The variety was Ben Davis and the treat- ments given each plat were identical with those given in the Flora orchard. Bitter rot appeared in this orchard July 2/th. Rec- ords were made on the fallen apples on July I2th, August I2th, i/th, 26th, September 7th, I5th, 24th, 3Oth, and October 2oth. The crop was picked from the trees October 2Oth and 2ist and the data compiled in Table 16, p. 517. None of the plats in this orchard showed any serious develop- ment of the disease. The percentage of bitter rot, however, runs uniformly less throughout all plats sprayed with Bordeaux mixture than through the check plats and the plats which were treated with Oregon Wash and copper sulphate on the dormant wood early in the spring. Here again the results are suggestive, but not marked enough to be conclusive. ORCHARD OF F. L. WILLIAMS & SON, TAMAROA, PERRY COUNTY, 1904 In this orchard the same schedule of treatments was given as in the Flora and Olney orchards, except in the case of Plat IX, which ' was sprayed with Bordeaux mixture until the fruit was thoroughly coated after the rot had become well established. (For plan of plats see p. 503.) The dates of spraying were nearly the same, varying only a day or so for corresponding applications. The check plats consisted of ten trees each and all other plats of fifteen trees each. The variety was Ben Davis. Bitter rot first appeared July i6th. The fallen fruit was gathered on August ist and 2d, 9th and loth, I7th, 25th, September 2d and 3d, I5th and i6th, 27th and 28th, and October 26th and 3ist. The crop was picked from the trees October 27th, 28th, and 29th. The data secured are tabulated in Table 17, p. 518. 1007.] BITTER ROT OF APPLES, HORTICULTURAL, INVESTIGATIONS. 517 -w u i— i t— CO CO t- CO CO •* CO * C * O IO CO i-H O r-l IM CO yi* d rH rH d d d (M O d m O flj CM 2 OS CM t- 00 rH CO CO CO CO rt i— CO 10 »o — ^ oo CO O 6 U z rt 10 CO rH OS rH 05 O rH 00 a « K^1 O O5 C! ••* t- r- CD 10 CO oo oo 01 OO u n ^ •*-• o CO r- CM rH CM co IO IO to 15 *o rH CM rH d d d «; d d M-l •o fi O QJ 40 CO CO r— (M CO IO oo t- t— iO IO o ^ d 3, O r— 10 (M 03 r- ^ r- CO ^H 0 IO CO CO f- o ^ rt d ni ^^ r— CO OS IM t» IO «* (M (M 13 |?P t- r- rH oo rH rH rH CM 00 rt ^ ^ CO i ^i . i A P* 01 r»l ^ i> • • 4J ' C O p< 04 rt CO -4-1 CQ. ; ^ : 0 pj ^— j TO ^ rn3 o o 0) 7^ • ,-C T3 (L) 1^ ^i j-i * -4-1 CJ ^H O bO «4H 'H c '• 's *j rt bo a 0 «i 3 ; O p. a 'co CO ni QJ ^3 . OJ . O rv Treatment. in spring on dormant wood usi in spring on dormant wood t iate solution "o l-l t-, 1 rt IH o< CO 4J O three times in July at interval Bordeaux-Paris green mixtur at intervals of ten days from for apple scab and codling mot 1st, with Bordeaux mixture. . P bo a 3 a> rO . "2 ™ 3 a;5 •5 o a o o 0 X! "o V 4-1 3 o <4H u a a CO O until fruit was thoroughly eaux mixture when rot first a] 4-> 0 cu 4-1 O m »a > rd h a CO 4-1 O T3 T3 p. a rrj f< 'O uj >> T3 3 a T3 12 a OJ >i~3 ^ , c''^ 0; TO1 Jd" CLJ ^ ;>> Jri rt rt d~ rH I-H 1— I 1— 1 1— 1 I-H rH > p 1— 1 M I-H i— i 518 BULLETIN No. 117. [Auyust, ^ i- CM Tt< OS OS O CM ^ iO CO " c C o IO t- co CD o OS CH^V- 0 OS CO 1— ( CO OS rH r— -H CO 1— 1 OS a "o * OS J* t* rH OS ^ CO I-H Kl ($ O "5, ^? CM rH o OS CM I-H co § OS oo f _ t- rH OS J- CO CO CO p ri rH (M CM C<1 Csl ^7,-s ° o oo 6 -i >>>- . 0.0 o> -J i-H 00 co CM CO CM CM OS CM r— CM CO oo CM 3) *"' Q CM co CO CO CO D a *j -g >0 OS CD OS o CM i— i 00 oo oo t- OS s 0^^ ^ rH rH I— OS rH rH 05 rH OS eo •o "o S t— OS CO ,*-= g ^ o OJ Cu«^ CO MH -&U CTj'-*J ith Bordeau nixture unt: first appeare ure until frui >t had becom b/i c £* cu a ^ _4J ~*~* il n 'So £ ID IH O SH 1 M CU CO O c u ayed with Bordeaux-Paris green fruit was thoroughly coated whenr ayed with Bordeaux-Paris green mi was thoroughly coated after bitter established IH IH O) IH IH j_i 0) IH jpj Cu 0. J3 CM a a *"l CL, ftt CO CO Q CO CO CO CJ CC CO MH O -M HH 6t I-H 1— 1 HH I-H I-H !> rH I-H X HH 1907. ] BITTER ROT OF APPLES, HORTICULTURAL, INVESTIGATIONS. 519 The data contained in Table 17 are certainly confusing. The treatment with Oregon Wash, which in all other experiments had proven ineffective, appeared the most effective of any of the sprays applied. In the other plats spraying with Bordeaux mixture seemed to have only very slight effects upon the rot, the differences between the sprayed and the check plats being too small to warrant the drawing of any conclusions. ORCHARD OP W. T. STORMENT, KELL, MARION COUNTY, 1904 Nine plats of Ben Davis trees were selected in this orchard, each comprised of from eight to sixteen trees, most of them containing the latter number. The treatment was exactly similar to that given in the Williams orchard at Tamaroa, but late in the season two other plats were added to the experiment, these being designated Plats X and XI, and were treated as follows : Plat X — Sprayed on July 29th with a solution of eight ounces of copper sulphate to fifty gallons of water. Plat XI — Sprayed on July 29th with a solution of ten ounces of copper sulphate to fifty gallons of water. Bitter rot was first observed in the plats of July 22d. The wind- falls were gathered July 3Oth, August 8th, I3th, 24th, September ist, 8th, 22d, and October 3d. The fruit was harvested from Octo- ber 3d to 7th. The results were then tabulated in Table 1 8. The most striking results of the season were secured in the orch- ard at Kell, but unfortunately the infection was light in the center of the orchard where plats V, VI, and VII were located, and the results possibly show a greater saving than would actually have oc- curred had the conditions of infection been different. However, the differences between the various treatments are sufficiently wide to warrant the drawing of some definite conclusions. In every instance spraying before the bitter rot appeared, Plats IV, V, and VI, gave almost perfect control of the disease; spraying after rot appeared greatly reduced the number of infected fruits but did not control the disease so perfectly as did the early spraying ; treatment of the dor- mant wood gave no beneficial results as compared with the check plats, and a similar result followed the treatments with various strengths of copper sulphate solution which were given July 29th to Plats X and XI. Indeed the application of the pure copper sulphate caused considerable foliage injury and could not have been recom- mended even had the treatment been effective in controlling the disease. As corroborative evidence the results of the work in the Kell orchard are most valuable. It will be remembered that all the data thus far obtained point strongly to the advisability of coating the fruit thoroughly with Bordeaux mixture before the first occurrence of bitter rot, as the safest and surest preventive of the disease. More- 520 BULLETIN No. 117. [August, t- rH cc j^ OS OS CD 1C rH »C OO u ** <5 ^3 i-H OO 1—1 l-H OO OS O O OS OS Tl< a! S ** ° 1C OO 0 ,_5 o o oo CD oo co oo o;S * ,u OO 00 lO CO i-H OO OO •* t- 1C CO js^ •** ** rH CM CM ^< O CM OS CO ** ^ 00 CO t- os 00 CM os O OO •* QO O OO CC N CO OO r-i OO •* OS 8 (v « " ° 1-^ O rH o o o ci •<*< co oo r- •5. "S" CM 00 C4 CM CM rH rt <*, " rH t— [^. oo (M t— O OO 1C OS OO O S c~l os W OS rH OO OS CD CO ^ . rH ^t* OO oo os oo ic os eo i— Oi 8 o ft fc £ '5, CM OS I-H CO Sg t~* t~ 1C t-* 1C CD O i-H i-H ic r— oo ^ CO T* i-H •<* OO OO O r? J^S o ^^ os •<«* oo as t- rH 1C CO CO r— CO CO CM OO rH t- OS -l • fe >H a >>Q.« i rrHCU^^ " ** r U c & 0 ft ba o 4J SH SrtS m agci g g M&| S& 3« * ••§• c 0) U O to bo .5 .5 S CD 3 r^ o o 2 o > "o at intervals o green mixture S*| 5 ££ JJ^ 3 3 i-n° •-< 3r-g™ x co rt b^ffl * HJ SO ^-> P rH . TOP X4JX-^W5 .3-^5 S ISIS a a a !• «- 3 a IH o §tri HS CajCO) 0 g ^°< cu_S 5,"^ £ - gl r^rt § ^ 5»±»2 .S g bfircj i-Xro § c Treatme ayed in spring on dormant ayed in spring on dorman sulphate solution .. :ck, not sprayed for bitter i ayed three times in July days with Bordeaux-Paris ^C^l 3 rH .2^ »^ ? § C*U^a rtr^ i'feS^S ,d rC 111! fl 2»l»°l^s a .5 B^% S- S- ^« -«^rd >> >> silS1 §2 slNllflll •0° •£ SS ° ij.-s -=2-S r=s «s oj^JcujH ort -cu3 » r± n >> 3J r* >,rH r^r^OI r>,O r*>C fj I-H &PH rtT3 o rtm rttn|i' rt33 rt03 •~ j- V j^j rH rH OJ rH rH 1-1-1 Clt &i -C Pi cxi o. -d a, &, cu & CO CO O CO CO CO Q CO CO CO CO O -M 6t I-H I-H — M H I-H I-H 1— 1 *-H •— i "— ' M I-H >r^_ r.. KN KJ kJ i-> P* r* i— i PS rS 1907.} BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 521 over it strongly corroborated the data showing the ineffectiveness of treatments of the dormant wood with Oregon Wash and copper sulphate solution, obtained in the Flora and Olney orchards, and indicates that the low percentage of bitter rot appearing in the Wil- liams orchard at Tamaroa on the plat treated with Oregon Wash was due rather to lighter infection or to some other cause than to the treatment itself. The following table shows the percentage saving of the total amount of infection, as shown by the check plats, of the various treatments over the checks. The average of the two check plats, III and VII, is taken as the standard of infection, though as a mat- ter of fact higher infections appeared in three other plats, those in which the dormant wood was treated with Oregon Wash and cop- per sulphate solution, Plats I and II, and the plat which was sprayed with pure copper sulphate solution on July 29th, Plat X. TABLE 19 -SAVING EFFECTED BY VARIOUS TREATMENTS IN THE KELL ORCHARD, 1904 No. of plat. Treatment. Saving over check plats. IV Sprayed three times in July at intervals of ten days with Bordeaux-Paris green mixture . Per- centag-e 94 59 V Sprayed at intervals of ten days until after July 1st with Bordeaux-Paris green mixture 98.20 VI Sprayed once each week during June with Bordeaux- Paris green mixture 95.42 VIII Sprayed with Bordeaux-Paris green mixture until fruit was thoroughly coated after rot first appeared 72.02 IX Sprayed with Bordeaux-Paris green mixture until fruit was thoroughly coated after rot had become established 81.91 From the above figures it appears that spraying with Bordeaux mixture three to five times before ihe appearance of the rot may control from 94.59 to 98.20 percent of the entire loss due to bitter rot. Since the treatments in the various orchards during the year 1904 are all similar, and since in drawing conclusions on experi- mental work of any kind it is well to employ the most available data, providing it has been gathered under equally good conditions of con- trol, a summary of the results from the four orchards under observa- tion is given below. For greater convenience in comparing the re- sults the totals of all the check plats are given and placed at the head of the table ; the other plats are numbered as in the case of the tables preceding, and a column is added showing the percentage gain of the various treated plats in cases where gains resulted. 522 BULLETIN No. 117 [August, -p&g •d -a « i-. , cu en ; ; co o •* CO 1C IS 5-- "o ri > ° Ifl ^5 • • oo OO co O5 CO ^o £ £ o ^ ^'o, ^ CO c,v< ^ O5 I—I oo O5 CO 0 -H 1C CD rt) *^ +•* *"* ^^ CO CO t— CM co CO ^* CO ^"SS2 oo g CM I-H CM O5 CO O5 CO i S oo CM en co eS^' t— t- S CO CO GO CO 1-1 05 1C 1C r- CO CO CO O5 8 -"ft °3 *" oo CO -H i— i -« CM CM CO oo t— ft id SH en o l -H 1C CO CO O CO Oi co •d ^eu CO O5 O2 CO I— CO O5 CD co *$ 6 ft oo CO O5 O5 CO t— t- CT. ** CO CO CM 1C eo CD O ,5 ^ n! CO CM CJ IM ™ 6 "3. co rH CM eo i— 1 CD O5 1C 52 a oo I— OO oo CO T-H co t- T^ SH o ft es CO I— 1 i— i CM CM CM I-H 6 i O j3 CD ^ CO •<*< r- r- oo i— i «* CO r— 1C CD 1-H cS t- co CO S CO rH t— i— t- co CO oo «4*3 •<* i— i T-H CM iH co co CM T-t i Treatment. • O M •1 *J >d tt en O O oT ayed in spring on dormant wood using Oregon Wash ayed 'in spring on dormant wood using copper sulphate solution ayed three times in July at intervals of ten days with Bordeaux-Paris green mixture ayed at intervals of ten days from early spraying for apple scab and codling moth until after July 1st with Bordeaux mixture. ayed once each week during June with Bor- deaux mixture ayed with Bordeaux mixture until fruit was thoroughly coated when rot first appeared. . . ayed with Bordeaux mixture until fruit was thoroughly coated after rot had become established (two orchards) — ayed July 29th with eight-ounce copper sul- phate solution oo ! VH • V • PH .' o o • 0) 0 a . 3 O a '• rt P C ^ ^ j_, h IH J-( ;_i (^ kl p. cu a o> &, a, P. PH p. O CO CO CO CO CO CO CO CO CO "O *J w >% JH C r-H g< I-H M 1— 1 I-H t> h-H t—t i— i X 1— 1 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 523 • o 05 CO i? S ~ O 1-1 05 ^ t— r- CO O5 £ a. o* y^ CO rH » *•• CD 3 CO oo t— $ r- 1— 1 l-H 1 05 O i-H oo 0 rH 10 CO «=!« r- ~. o l-H 3 § CM CM CM o CO oo 05 — " o|2 ** CO IO o ^ ^ •^ CM iO ^ _J •5 (M CO *— 4 C^l •o • 0 £ § CM (M 00 5 o CO O5 CM Ui CM CO CO "5 6 "a CO CM t- CO I-H CO O5 t- I-H ^ rt CM i-H I— 1 rH CM -H j—4 •<* o 6 s*Is oo o 1— CD OO t- o 00 s CD 5 05 O co SI? s* CD I-H . co CM O5 «4H r^J ^^ co "rt co CD co ZZ co •— O ^ >H C ™ IH 5 rt nj n CU ^ o '> 'a ^ 'n ^ *-" •4-> 3 rt 13 C 0) a -2.2 v 3~£ '£ 3 g U_I fl — — •«— i ^o B c i-s 0 rayed once each week durin Bordeaux mixture , eck, not sprayed for bitter rot rayed three times at interva July with Bordeaux-Paris gn >* dj 13 _C bO cu 'o'C •^ o rt j£ rt 3 rt J* £ rt'O qj O (H 4-1 CO O -4-> P-5 ^ O co (H rayed once each week during Paris green mixture O l-H > 1— 1 ^ hH I-H I-H l-H M 1907. | BITTER ROT OF APPLES, HORTICULTURAL, INVESTIGATIONS. 527 (For plan of plats see p. 515). . Bitter rot was first discovered in these plats on July 25th. The fallen apples were gathered and recorded August 5th, i6th, 2ist, September 8th, 22d, and October 4th and 5th. On the latter date the crop remaining upon the trees was harvested, and the data tabu- lated below give the results of the experiments. -The results of the experiment in the Flora orchard are strikingly in accord with the results obtained in the Flora, Olney, and Kell orchards in 1904. Plat IV which received three sprayings during July, or as near to the time of the first appearance of the bitter rot as they could be applied in accordance with a plan of spraying at inter- vals of ten days, gave a very perfect degree of control of the disease, and proved somewhat more effective than spraying either during" June or after the appearance of the rot. Spraying both in June and after the appearance of the rot, had a decidedly beneficial effect in preventing the disease. The treatment of the ground with salt pro- duced no apparent diminution in the infection. In fact more bitter rot was found in that plat than in the average of the three check plats. The accompanying table shows the relative saving effected by the various treatments over the average of the check plats. TABLE 23.— PERCENTAGE SAVING SHOWN BY THE TREATED PLATS OVER THE CHECK PLATS No. of plat. Treatment. Percentage gain over .average check plat. I Ground treated with twenty-five pounds of salt per tree None II Sprayed once each week during June with soluble Bordeaux mixture 78.06 IV Sprayed three times at intervals of ten days during July with Bordeaux-Paris green mixture 92.14 V Sprayed at intervals of ten days until July 1st with Bordeaux- Paris green mixture . . . 81.00 VI Sprayed once each week during June with Bordeaux- Paris green mixture 68.42 VIII Sprayed with Bordeaux-Paris green until fruit was thoroughly coated when disease first appeared . . 71.63 The figures given in the above tabulation indicate very clearly the high degree of benefit derived from all the different forms of spraying employed in the experiment and corroborate the results of previous years in which from 70 to 90 percent of all the fruit liable to bitter rot was saved by spraying with Bordeaux mixture. 528 BULLETIN No. 117. [Awjust, ORCHARD OF JOHN BLACKI^DGE;, CLAY CITY, CLAY COUNTY, 1905 A very comprehensive series of eighteen plats was selected in the Ben Davis orchard of Mr. Blackledge, of Clay City, in 1905. There was a promise of a good set of fruit and bitter rot had been prevalent the previous year. Hence it was hoped that some valuable data might be obtained in this orchard. Most of the plats received the first three sprayings for apple scab and codling moth with Bor- deaux-Paris green mixture made up according to the standard form- ula. Plats XIII and XVI, however, were sprayed with the dust Bordeaux-Paris green preparation, Plats VII and XVIII received the first early spray only, while Plats XI and XIV were not sprayed at any time during the season. The early treatments were given April nth to I4th, April 28th and 29th, and May 5th to 9th. The schedule of treatments planned for each plat was as follows : Plat I — Salt, one application; twenty-five pounds to each tree evenly spread on the ground. Plat II — To be sprayed three times at intervals of about ten days beginning about July 1st using Bordeaux-Paris green mixture. Plat III — Check, to receive no spray after first three applications. Plat IV — Commencing after third early application to be sprayed at intervals of ten days until after July ist, using Bordeaux-Paris green mixture. Plat V — To be sprayed four times in June, on or about the 4th, nth, i8th, and 25th, using Bordeaux- Paris green mixture. Plat VI — To be sprayed until the fruit was thoroughly coated as soon as bitter rot first appeared with Bordeaux-Paris green mix- ture. Plat VII — Check, to receive no spray whatever after the first three applications. Plat VIII — To be sprayed until the fruit was completely coated after bitter rot had become thoroughly established, with Bordeaux- Paris green mixture. Plat IX — To be sprayed with copper sulphate solution, three pounds to fifty gallons of water. To be applied ten days after third spraying and then if no foliage injury followed to be repeated every ten days. Plat X — To be sprayed with copper sulphate solution, six pounds to fifty gallons of water. To be applied ten days after third spray- ing and then if no foliage injury followed to be repeated every ten days. Plat XI — Check, to receive no spray whatever. Plat XII — Liquid, to be given three applications of Bordeaux- Paris green mixture at intervals of ten days, beginning ten days after third application. 1907.'] BITTER ROT OP APPLES, HORTICULTURAL INVESTIGATIONS. 529 Plat XIII — Dust, to be applied at the same time the liquid spray was applied to Plat XII. Plat XIV — Check, to receive no spray whatever. Plat XV — Liquid to be given six applications of Bordeaux- Paris green mixture at intervals of ten days beginning ten days after the third spraying for apple scab and codling moth. Plat XVI — Dust, to be applied at the same time the liquid spray was applied to Plat XV. Plat XVII — To be treated with twenty-five pounds of salt to each tree but to receive no early sprayings. Plat XVIII — Check, to receive no treatment whatever. Bitter rot was first noticed July 2ist and occurred rather spas- modically after every rain and warm spell throughout the season. The disease varied considerably in the severity with which it at- tacked various parts of the orchard. There was very little rot on Plats VIII and XVI which were located at the south end of the orchard. Plat X which was located in a low place somewhat isolated from the rest also showed almost no infection, and Plat XVII con- tained only two trees neither of which was much infested. These four plats, then, are left out in the tabulation of data which follows. Windfalls were gathered July 7th to I3th, August yi to 7th, i6th to i Qth, 24th and 25th, September ist to 4th, 7th and 8th and 2Oth to 22d. The crop was harvested September 25th to October 3d, and the records completed as follows, Table 24. In this orchard again plats sprayed several times just previous to the discovery of the disease showed very much less bitter rot than the other plats. Spraying until the fruit was thoroughly coated with Bordeaux mixture either as soon as the disease was discovered or after it had become thoroughly established proved much less effect- ive in combating it than did the same treatment in the Flora orchard. Spraying with pure copper sulphate solution gave no decisive results. In fact there was a larger infection of the disease in Plat IX, which was treated with three pounds of copper sulphate to fifty gallons of water, than in some of the check plats. Dust spraying proved very unsatisfactory. The highest infection occurring in any plat was shown by Plat XIII, which was sprayed three times after the early sprayings with dust Bordeaux-Paris green mixture. The three early sprayings with ordinary Bordeaux mixture for scab and cod- ling moth appear to have exercised a very considerable degree of control over bitter rot. In the check plats which received only the three early treatments the average amount of the total crop affected was 10.86 percent, whereas, in the plats which were not sprayed at all during the entire season, the average amount was 35.59 percent, or nearly three and one-half times as much. Plat XVIII which was sprayed only once during the entire season showed a percentage of 22.17 percent affected by bitter rot, an amount intermediate between 530 BULLETIN No. 117. [August, 4-> u aj|-|I r- •* m •* •* coco co-* co as oo o i— O i-HO in rH 00 1— OO CO O t- m i-lr-i co •* co coo oo oo co ro t- co t- oo e-i i— I i— I 1—1 CO m co t-co oo co •* oo cooo co os co rt»in oo t- 1— i •* m t- os coco m oooo -^ oo i— ' i— i o fc t> <- ^ i— i co co i— i m co * co i— i •* •*!—( oco •"•< os t— TO oo os c^ i"^ co co ^* in co in osmco coo ommo i— < •*:» coif CO 1-11— I r-i SO CO O CO »T itment. i 1 fe'Sa,^ |S * S.5 :S.S§ S.5 M • *-1<4~'>ipQ 3 fl MH -— • HH ^ 3 H-i ~- | |j fill 11 1 iijPilitiii 1 11 §||| *j | !J»1!4§!!|]> rt —i m i+ wr "^ a)> ^ ^^u^^uoo,^ o J< ^ S *.£4*tB^« £"3 ^" ^^^^'SSo02^- ^•^^fiBSiS-S.ta ss •?•§.«! jrlsoTS. 2 ?S -4J^CDi-.™oQj'^i-a3<^ . d)> ^-.S > Q< ' fli r3 D.-^ *i JsB-SlJal^lfs «s ll^l§-|lli|| 0) £ ofe^^s^l^-^^ =s6«^.JViL*»SJV»i 2o-C^f^«JS^B^5 '°-R>>5^o^^o'go-Si?«c SM-.2i5JJ>a)_cjrt SD^ o-aa)te^^BCoac2^(Eofe>XJ *^ ^O^HXi-i^X^ oJO> >>*J *-> ^ en C g »^ « c^ „, ^^ 3ra.ti^ c^ 53 g«J£?5«^g 2^-^5'a ?I ^lpl= 51 111^1.2 HS I IS l HS § I *;tHCJ|H u)-i t±> hH E^ u..^ s -> > _ S M^ > f> >S XX X XX X 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 531 © © O O O O O o O 0 O O CO o o o o o 0 © © o o o o in H o o o o o o o © © o o o o 0 O 0 0 0 o o o o c- o o o o o 0 © © o o o o H 000*0 o o 00 o o o o o o o o o 0000 10 o o o o o o © © 0 O O O „ o o o o o o o © © 0 O O O o o o o o o o o o 10 o o 0 o o 0 0 0 O O 0 8T o o S2 o o o o o o o o CO H 0 O 0 O O o o o o „ o o o o o © © o o o o CM H o o o o o © 0 o o o o o o o o o o o o o to o o o o 0 © © o o o o rH o o o o o o o © © o o o o o o O 0 O CM o o o o o o © © o o o o 0 H o o o o o o ©© o o o o o o o o o o o o H O O 0 O O PT © © © o o o Cft o o © © O 0 0 6k/ O O Al g w a H O 532 BULLETIN No. 117. [August, the plats treated three times early and those not treated at all. The following tabulation shows the percentage gain of various plats over the check plats, untreated plats, and dust sprayed plats, etc. The standards taken in the case of the check plats receiving the three early applications of spray for the scab and codling moth are de- rived from the totals of the two plats, respectively, in each case, viz., the totals of the two Plats III and VII in the first case, and Plats XI and XIV in the second case. Plat XIII is taken as the dust- sprayed standard. TABLE 25. — PERCENTAGE GAINS OF VARIOUS TREATED PLATS OVER UN- TREATED AND DUST SPRAYED PLATS IN THE CLAY CITY ORCHARD IN 1905 No. of plat. Treatment. Percent- age gain over early sprayed plats. Percent- age gain over un- treated plats. Percent- age gain over dust sprayed plats. I II Not sprayed for rot but treated with salt Sprayed three times at intervals of ten days in July with Bordeaux-Paris green mixture 44.11 61 88 82.94 88 37 88.50 92 16 IV Sprayed at intervals of ten days until after July 1 with Bordeaux-Paris green mixture 67.40 90.05 93.29 V VI IX Sprayed once each week during June with Bordeaux-Paris green mixture. . . Sprayed until fruit was thoroughly coated when bitter rot first appeared Sprayed twice with weak copper sul- phate solution at intervals of ten days 6.63 18.69 71.51 75.19 63 95 80.79 83.27 75 70 XII Sprayed three times at intervals of ten days with liquid Bordeaux-Paris green 24.05 48.80 XIII Sprayed six times at intervals of ten days with dust Bordeaux-Paris green XV Sprayed six times at intervals of ten days with Bordeaux-Paris green mix- ture 24.95 77.10 84.56 XVIII Sprayed only once during entire season 37.71 58.00 III& VII Sprayed three times early in season for scab and codling' moth 69.49 1907. J BITTER ROT OF APPLES, HORTICULTURAL, INVESTIGATIONS. 533 A remarkable feature of the results obtained in the Blackledge orchard is the demonstration of the effect of the three early spray- ings applied for apple scab and codling moth, in controlling bitter rot. In every instance, as will be seen by comparing columns one and two in the above table, the percentage gain of treated plats over absolutely untreated plats was from 23 percent to as much as 60 percent greater than the gain of treated plats over check plats sprayed three times for apple scab and codling moth. Comparing Plats III and VII, which are given the three early treatments for apple scab and codling moth, with Plats XI and XIV which were not sprayed during the entire season, the two early treated plats show a gain over the two untreated plats of 69.49 percent. CONCLUSIONS FOR 1905 Besides confirming various conclusions already drawn that bitter rot may be almost completely controlled by three to four applica- tions of Bordeaux mixture applied at intervals of ten days just previous to the appearance of bitter rot, and that sprayings after the appearance of the rot are of some benefit, the data obtained in 1905 pointed to the following conclusions : 1. That the spring sprayings for apple scab and codling moth are, in seasons like that of 1905, effective in controlling a very con- siderable percentage of bitter rot. 2. That dust spray is ineffective in combating the disease. 3. That spraying with pure copper sulphate solution is not an effective way of controlling bitter rot. IN GENERAL WEATHKR CONDITIONS FAVORABLY FOR BITTER ROT The spasmodic and erratic occurrence of the disease in different seasons has long been noted and has been more or less generally taken as indicating a relationship between the weather conditions and the development of the fungus. The year 1900 proved to be a year of exceptional severity in the attacks of the disease and it was, in part, the uncommon destructiveness of the pest during that year that led the Horticultural Department of the University of Illinois to inaugurate this line of work looking towards the discovery of a means to control the bitter rot fungus. Yet in the following year, 1901, the experimental work. of the Department was rendered null by the failure of bitter rot to develop in orchards where the disease had been prevalent the year before. In reference to the season of 1901, Mr. A. V. Stubenrauch, who had charge of the field investi- gations that year, says : "The exceedingly dry hot summer seems to have been very unfavorable for the development and spread of bitter rot. Last year, 1900, the disease destroyed practically the 534 BULLETIN No. 117. [August, entire crop wherever it made its appearance. The disease has not been nearly so bad this year. Many orchards badly affected last year were entirely free this season; many were only slightly af- fected and no case of a total failure has come to my notice."* The year 1902 proved favorable again for the rot and in all the orchards under experimentation check plats showed an infection of 44 per- cent to 89 percent of the total crop. In 1903 the bitter rot was present in five orchards under test but in only one of them was there an infection of commercial importance, the infection in the excep- tional case being, however, very serious, and amounting to 63 per- cent of the crop. In 1904 the disease was present again and was apparently more general in its spread. It was more destructive than in 1903 but less so than in 1902, in the orchards which were under observation. In 1905 only two orchards were under experi- mentation, but in both of these the disease was sufficiently serious to destroy from 14 to 35 percent of the crop in the untreated plats. Comparing different seasons in the same orchard it will be seen by reference to the following table in the Tamaroa orchard, where three seasons' work were carried on, there was an infection of 68.54 percent in 1902, 1.27 percent in 1903, and 15.94 percent in 1904. In the Flora orchard there was an infection in 1902 of 83.32 percent, in 1904 of 11.68 percent, and in 1905 of 14.63 percent. A glance at the table of infections which follows will serve to impress still fur- ther the erratic manner in which the disease appears from season to season : TABLE 26.- -PERCENTAGE OP BITTER ROT IN UNTREATED PLATS DURING DIFFERENT SEASONS FROM 1902 to 1905 Year Orchard. Per cent bitter rot. Year Orchard. Per cent bitter rot. 1902 Tonti (Huntsman) 89 27 1904 Flora 11 68 (Ben Davis) . . . 44.95 Olney 1.18 Tamaroa 68 54 Tainaroa 15 94 Flora 83 32 Kell 21 50 1903 Olney • .32 1905 Flora 14.63 Tatnaroa 1 27 Clav Citv 35.59 New Burnside 3.51 Carbondale No 1 7 05 . Carbondale No. 2 (Jonathan ) 62 97 ( Winesap) 23.69 (Ben Davis) 63.09 ^Circular No 43, University of Illinois Experiment Station, 1902-p. 4. 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 535 This irregularity in the behavior of bitter rot is not confined alone to different seasons. It makes its appearance in different years at very different dates and in different orchards it may occur at more or less widely separated intervals in the same season. Bit- ter rot is a disease which ordinarily develops comparatively late in the season causing the greatest amount of damage when the fruit is fairly well matured and not far from the picking stage in its de- gree of ripeness, but we now know that the destruction is sometimes greatest in July when the late varieties are not half grown. In- fected apples in orchards subject to the disease are found at various dates during the months of June and July. In 1902 the first record of its existence on young apples was made June 28th but the speci- mens showed that the infection must have been at least two weeks earlier, and it has been otherwise sufficiently proved that in numer- ous instances the attack occurs as soon as the middle of June. Some interesting data in this regard appears in the tabulation following : TABLE 27.- -DATE OF FIRST APPEARANCE OF BITTER ROT DURING DIF- FERENT SEASONS Year. Owner of orchard. Location. County. Variety. . Date of first appearance of bitter rot. 1902 1903 1904 1905 J. B. Brokaw F. L. Williams .. ... . and Son Tonti Tamaroa Flora Olney Tamaroa NewBurnside Carbondale Carbondale Flora Olney Tamaroa Kell Flora Clay .City Marion Perry Clay Richland Perry Johnson Jackson Jackson Clay Richland Perry Marion Clay Clay Huntsman Ben Davis WillowTwig Ben Davis Ben Davis Early Harvest Ben Davis Jonathan ) Winesap Ben Davis ) Ben Davis Willow Twig Ben Davis Ben Davis Ben Davis Willow Twig Ben Davis July 8th July 5th July 10th Aug. 7th July 6th June 25th Sept. 7th Aug. 5th Before Aug. 17th July 24th July 27th July 16th July 22d July 24th July 21st Dale Mann J. L. Zook F. L. Williams . . and Son J. W. Heaton .... H E. Allen Charles Allen . . . Dale Mann J L Zook .... F. L. Williams . and Son W. T. Storment . Dale Mann John Blackledge This characteristic irregularity in the behavior of the disease must possess some significance in the history of its development, and this significance must be concerned either with the conditions con- trolling the original infection or the conditions controlling the viru- lence of the disease after infection takes place. In all of the orchards under experimentation enough bitter rot appeared every season to infect the entire crop, under conditions favorable to the growth and 536 BULLETIN No. 117. [August, spread of the fungus, Table 26. The characteristic irregularity of bitter rot must therefore be due to the presence or absence of those conditions which are favorable to its distribution and growth. What then are the circumstances which favor the development of the disease ? In Bulletin No. 77 of this Station it was stated that the rapidity of development depends upon climatic conditions. It is essentially a hot weather disease and moisture is necessary for the distribution and germination of the spores. It is true that the infection of the fruit sometimes becomes apparent and the progress of the disease is abundantly evident when the atmosphere is very dry; but this only happens after the fungus has gained entrance to the apples, which must have occurred during a previous period of rainy weather or heavy dews. Moisture, generally in the form of rain, and high temperature are necessary to start an epidemic. These of course are only favorable conditions for the development of the fungus which is, itself, the direct agent of destruction. Fortunately the fungus is not very resistant to unfavorable conditions and may sometimes die out entirely during one year where it has been previously abundant. This, with its power of enormous multiplication under circumstances well suited to its growth, sufficiently accounts for the marked irregu- larity in the time and virulence of its attack. Scott says, "The predominating conditions that influence the development of bitter rot are temperature and humidity. A few days of hot showery weather may start an epidemic that will destroy the entire crop of certain varieties, provided the fungus is present. "Cold is decidedly unfavorable to the fungus and it rarely does any damage during a cool season. An outbreak may be almost completely checked by a few days of cool weather, especially when the mean temperature remains below 70 degrees F."* Von Schrenk and Spaulding write in regard to this point that "The factors which determine the time of the appearance of the dis- ease are probably (i) the age of the fruits j v (2) the temperature and humidity of the air; (3) the presence of spore distributing centres. "Warm, sultry weather, particularly after a rain, forms the ideal condition for the development of bitter rot. In cool dry sum- mers the bitter rot is usually present but sparingly. A short series of hot, wet days in August may bring about a sudden and very de- structive attack. Nights with a heavy fall of dew alternating with hot days are usually followed by an extensive development of the disease."** *The control of Apple Bitter Rot, \V. M. Scott. U. S. Department of Agriculture, Bureau of Plant Industry — Bulletin No. 93. pp. 12-14. **The Bitter Rot of Apples, Von Schrenk and Spaulding, U. S. Depart- ment of Agriculture, Bureau of Plant Industr3T — Bulletin No. 44. p. 15. 1907.] BITTER ROT OF APPLES, HORTICULTURAL INVESTIGATIONS. 537 If the prevalence of the disease in different seasons be referred to the weather conditions for the corresponding seasons there should be no difficulty in settling the relation between the virulence of the disease and the climatic conditions obtaining during the season. The accompanying tabulation of temperatures and rainfall for various points in southern Illinois is compiled from records in the Agron- omy Department at the University of Illinois. In some cases the readings appear high owing to the class of thermometers used by some observers, but as the readings are merely for relative references in this connection, they are sufficiently accurate to serve the purpose of comparisons, pp. 538-540. It will be noted that in the year 1900 when the bitter rot was so enormously destructive in the southern part of the state the month of June was exceptionally wet, nearly twice the average rainfall for that month being noted at Flora, Mount Vernon, and Centralia, and two inches more than the average at Olney. The mean temperature for the year proved to be one to three degrees lower than the aver- age but still from 2.4 to 4.2 degrees warmer than that mentioned by Scott as being favorable to the growth of the fungus, i. e- 70 degrees F. July also proved unusually wet, considerably more than the average amount of rain falling at all points except Centralia, and the weather, while not exceptionally warm for the district, ranged from 5.5 to 8.2 degrees above 70 degrees F. August proved to be dry, the precipitation falling considerably below the average, but the damage had already been done and the infection was com- plete during the preceding months. The year 1901, which has al- ready been referred to as a season in which little bitter rot occurred, offers an interesting contrast in respect to moisture conditions to the preceding year. In every instance during the months of June and July the rainfall is markedly below the yearly average, and even the precipitation during the month of August, which proved to be a little more than the average for that month, is not excessive, the largest fall recorded being 3.52 inches for the month. The prevail- ing temperatures throughout were higher than their respective aver- ages. The conditions and results of these two seasons bear out very clearly the contention that warm moist conditions are favorable to the spread of the disease and tend to discredit the theory advanced some years ago in certain quarters that it is a hot dry-weather fungus.* The season of 1902 as shown by the results of the work in .the experimental plats, Table 26, proved favorable again to the dis- ease, though reports from commercial quarters did not indicate so *Note reference to this theory by Burrill, Transactions Illinois Horticul- tural Society, 1901, p. 186. 538 BULLETIN No. 117. [August, £_ H Tj •g'M OO — CD O 1C CO •* CO -f I— OO CO OO OO OS t— Tt >C CO OS 1C 03 v H ,5 i— i'CO CO »C CO CO i— i (M CO (M i— 1 r-l CO CO CO CO CO O CO CO •** (M e ri ^-THTf*^ (MO COCO^OSCO CD O ^ oo 30 £ — * as co os i— i CD icmt-cDt~- (MOSr-i^ticDr^ r— c Sic ic icicicicic «c »c ic »c ic »c ic ic ic ic frl X re ^ CO OO r^ CO O OS CD OS O CO «* CO CO OO OS •*+< t- CD 1C OO i— 1 'tzjosoasososas asOooos as <— i as os as as OSI-HOSO • ™rH i— 1 i— ' i— i r-( rHi— 1 • .s. — — CO moorHcooo^o ascoot>co iceoicasr— ^ CDCDCO^ as J3 CO OS CD i— I -- OO (MiCl—iCO COCOCOaOi— I--H OOTjiOCO CO 05' « COOCOT}C O >— ' CO CO "* OrHCOCO-^iC O i— i CO CO • co co co co co co co co co co co co co co co co o co co co • as as os as as as asasasasos osososososos as as as as • tn Place. o S .2 1 § ^ 3 ^~? i-i |—| O rt 'dj ^ O k> ^ S pq O l-i ^-* " S ^ ™ 0 o £, !> ^ «S -4-i CO ^ Si ^ i-i C^ 0 j3 o g rt Pk fl OO i-l OO O r-l t- .(-. v- rt PH*4 CDCOIDCDCOt-CDCDCOCOCDr— j3OiOOSC