107 283 AR EVALUA?!GN 0!- 735 RAW 09 REPROE‘L‘CfiOE r3? TfiE TWO $993750 SHEER MW?” I§”RA.NYC§*%U§ TELARE’QS {2.}, REARED ON G§BEERELL§N TREATED BEAN PLAETS Thai: for 510 Mae 6‘ M. S. MECREGAE STATE UNE‘V'ERSETY Jack Aibar‘a" Eéchmoior 1958. "(u o-‘ ...... ‘TIII: ill: .IIII uflrLlls . .Hiiliu Ally AN h'ALU.TICN C? THE FATE OF KEFECL3CTION OF THE TWJ SPOTTED SPIDER MITE, Tetranxchua telariue (1.), R?&RFD ON GIBBERELLIN TREATED BEAN PLANTS by JACK ALBERT EICHMEIER AN ABSTRACT Submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Entomology Year 1958 APPYOVOd /Qi:;f' €/}{;}12:;%;,‘ as, h.r..._n:.l Lam 3., . n warlike. ABSTRACT Experiments were conducted to determine if mite populations on‘ plants were affected when these plants were treated with gibberellin. Five different treatments of gibberellin were evaluated. The plants used in this study were the Tendergreen variety of snap beans. The mites used were two-spotted spider mites, Igtrgnxghug tglarigs (L.). Mite reproduction was studied on attached leaves and on excised leaf discs floated in.a 2 per cent sucrose solution. iMites were placed on leaf discs in the following arrangements for each treatment: 1. Mites raised on control plants were placed on leaf discs from control plants. 2. Mites raised on control plants were placed on leaf discs from treated plants. 3. Mites raised on treated plants were placed on leaf discs from control plants. ‘4. Mites raised on treated plants were placed on leaf discs from treated plants. Mites were left on the leaves or leaf discs for ten days. The leaves or discs were then frozen and the mites and eggs counted. The results of these tests are outlined as follows: 1. There were significant reductions in mite populations on plants treated with certain gibberellin applications. 2. Some of these reductions were probably caused by the response of the plant to the gibberellin treatment. 3. There appeared to be differences resulting from factors other than direct plant growth (nutritive). 4. The low rate of reproduction of mites on treated plants rose rapidly to nearly normal when these mites were returned to control plants. 5. Mites raised on control plants and transferred to treated plants showed a drop in the rate of reproduction.within one generation. "I" ._.u__.-._4—aa. AN EVALUATION OF THE RATE OF REPRODUCTION OF THE'THO SPOTTED SPIDER MITE, Tetranychus telarius (L.), REARED 0N GIBBERELLIN'TREATED BEAN PLANTS by JACK ALBERT 310mm A THESIS Submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department.of Entomology 1958 ACKNOWLEDGMENTS Grateful acknowledgment is made to Professor Ray Hutson, Haad of the Entomology Department, for his continuing interest and for procur- ing the assistantship which made this thesis possible. To Dr. Gordon Guyer, the author expresses his sincere thanks for his constant interest and assistance. The author wishes to express his appreciation to Dr. Julius Hoffman for providing the mites used in this work and for his con- sultation during the study. He wishes to than]: 11'. J. Fredrick Davis for his assistance with the statistical analysis of the data. Grateful acknowledgment is made to Merck Chemical Company for materials and financial aid which made this study of gibberellin possible. The author also wishes to thank the other members of his graduate committee, Drs. Herman King, B. H. Grigsby and G. P. Steinbauer, for their criticism and review of the thesis. r «we! I. II. III. V. VI. TABLE OF CONTENTS INPRODUCT I ON 0 O O O O O O O O O O O 0 LITERATURE REVIEW . . . . . . . . . . The Effect of MRneral Concentrations in Plants on Mite Populations. . . . . The Effect of Gibberellin on Plants The Effects of Gibberellin on Plant PROCEDURE . . . . . . . . . . . . . . EXperiment A. . . . . . . . . . . . Experiment B. . . . . . . . . . . . PRESENTATION AND DISCUSSION OF RESULTS SUMMARY . . . . . . . . . . . . . . . LITERATURE CITED . . . . . . . . . . . Diseases. 0 PAGE N \ooooux 13 16 38 INTRODUCTION For many years workers in the Orient studied the odd growth ex- hibited by rice when it was attacked by a fungus disease called “Butane." In 1932, workers in Formosa isolated a growth regulator from rice infected with this disease (Kurosawa, 1932). This growth regulator was gibberellin. For many years it was simply a curiosity. During recent years, however, more information about the effect of gibberellin has become available. Its effects when applied to certain plants are startling. Increased total growth, more rapid growth, the overcoming of inherent dwarfism, and increased crop yields have re- sulted when gibberellin was applied to responsive plants. These results have created increased interest in gibberellin and many ex- periments have been established both here and abroad to study its effects on plant growth. Gibberellin is still new and most of these experiments have been established to study its direct effects on different kinds of plants. The effects on fruit yield, nutritional value, vigor and physical strength have been evaluated. The purpose of this experiment we to determine if mite popula- tions on plants were affected when these plants were treated with gibberellin. In this experiment the plants used were the Tendergreen variety of snap beans, chosen by the author for their high level of response to gibberellin. The mites used were two-spotted spider mites, Titragzchus glaring (L.). “ev- urmwga REVIEW The Effect of Mineral Concentrations in Plants on Mite Populations Rodriguez and Neiswander (191.9) found a possible relationship between the mineral constituents of a soil and mite populations in- festing plants growing in that soil. Their work was conducted in Ohio during 1946, 191.7 and 1948. This work was the result of an investi- gation to determine why there were recurring outbreaks of mites in greenhouses. One of the contributing factors to this investigation was the work of Page (191.6) who found that most Ohio greenhouse operators were over-fertilizing their soil. During the first year of the study, there was found to be a positive correlation between the concentration of the soluble salts in the soil and mite populations. This relationship was not found during 1947 and 191.8, but both salt concentrations and mite populations dropped during these two years. Apparently this was due to a decrease in the amount of fertilizer used following the report by Page (1946). There was no attempt made to investigate the effects of each of the individual ions constituting the soluble salts and no analysis was made of plants for their mineral content. German and Kennedy (1949) also found a correlation between soil fertilization and rate of reproduction of the two-spotted spider mite. They carried out a series of tests in which they confined single adult female mites to small leaf areas of bean plants. These bean plants were then subjected to varying rates of fertilizer application. At the end of two weeks, and again at three weeks, counts were made of the mites in each leaf area. These counts showed a difference between 2 mite populations on fertilized and unfertilized beans at the end of two weeks and a great difference at the end of three weeks. later, ' similar results were obtained using peach.as the host plant. Rodriguez (1951) conducted experiments to determine which single mineral or combination of minerals in plants would affect mite develop- ment. He used tomato plants which had been grown in a standard nut- rient solution. This nutrient solution could be modified as desired, either increasing or decreasing the percentage of each of its mineral components. The major elements that were tested were nitrogen, phosphorus, sulfur, magnesium, potassium, and calcium. In addition to the evaluation of the minerals, four concentrations of the nutrient solution were tested. The results of this experiment showed the following: 1. Mite populations were doubled by a doubling of the concentra- tion of the major elements in the nutrient solution. 2. Nitrogen absorption was negatively correlated with the mdte population. There were three times as many mites on the low nitrogen plants as on the high nitrogen plants. 3. Mite populations were positively correlated with absorbed phosphorus up to approximately 0.30 per cent of the dry weight of foliage. Above that point, the populations dropped. 4. Mite pepulations seemed to be correlated with sulfur ap- plication levels, there being a sharp rise at the lower rates of application. However, the sulfur absorption rate did not show such a correlation. 5. There was a positive correlation between potassium applica- tion and mite populations but potassium absorption at differ- ent times showed both a positive and negative correlation. 6. Both magnesium supply and absorption showed signs of being positively correlated with mite populations. 7. Neither calcium supply nor absorption showed a connection with mite populations in the specific calcium tests. However, when increasing amounts of calcium were absorbed along with larger amounts of nitrogen, a positive correlation was indicated. The following year, Rodriguez and Rodriguez (1952), again working with tomato plants, investigated the correlation between mite popu- lations and the vitamins riboflavin and niacin. Addition of more nitrogen to the standard nutrient solution used to grow the plants was found to increase the amounts of both of these vitamins in the plant tissues. By adding phosphorus to the nutrient solution only the amount of niacin was increased. The relationship of these two substances to mite populations was not clearly shown by this experi- ment. Riboflavin was not significantly correlated with population in the nitrogen series of tests while niacin had a negative correlation. Niacin in the phosphorus tests showed a positive correlation. Hamstead and Gould (1957) found that mite populations were direct- 1y associated with leaf nitrogen. Mite populations were studied on trees that had been fertilized with one, two and three pounds of nitrogen. Mite populations on trees receiving three pounds of nitro- gen.were found to be more than twice as high as populations on trees receiving one pound. Rodriguez, in 1958, continued his work with mite nutrition using .apples as the host plant. In this study he found that nitrogen was .31.. ,z’ \‘V positively correlated with mite pOpulations. Phosphorus was positive- ly correlated with mite pepulations as long as it was below 0.20 per cent of the dry weight of the foliage. Above that point, it became negatively correlated. The difference in the reaction of mites to nitrogen in this study and their reaction in a previous study using tomato plants is probably caused by the difference in the nitrogen- phosphorus relationships in the two plants. In apple foliage, nit- rogen and phosphorus show antagonism. When the nitrogen level is raised, the phosphorus level drops. In tomato plants, phosphorus and nitrogen show concommitant absorption. When the level of one goes up, so does the other. In raising the nitrogen level in tomatoes, you quickly reach.a point where the phosphorus level is high enough to become inhibitory to the mites. Evidently this is stronger than the increased nitrogen's tendency to stimulate mite populations. Therefore, mite population drops. The Effect of Gibberellin on Plants External effect. Plants react in many different ways to applications of gibberellin. Marth gt,gl. (1956) studied the reactions of forty- nine kinds of plants and found that they varied markedly. In this experiment gibberellin was applied to the plants as a lanolin paste or as a spray or dip. All of these methods seemed to be equally effective. The most obvious reaction to the gibberellin was greater stem growth. However, this varied with the different plant groups. Some groups, such as conifers, responded little, if at all, while others such as Pinto beans, increased their size up to 300 per cent. Greatest growth in most of the plants tested occurred when gibber- ellin was applied to young plants. Growth rates and final size also depended on the concentration of gibberellin applied. Usually, heavier applications caused greater response. . Morgan and Mess (1956) did experimental work on the response of grasses to gibberellin. They applied gibberellin to four plots of grass at the rate of two ounces per acre. Four to ten weeks later the grass was cut, weighed, and the dry weight and nitrogen content determined. The dry weight was found to be from 16 to 43 per cent more than that from control plots. However, if the grass was allowed to grow again, with no further gibberellin treatments, a second cutting showed a decrease in dry weight as compared to the controls. Because of this decrease there was no significant difference between the total yield from the controls and from the treated plants. With other plants it was found that an increase in the aerial parts of plants was not necessarily accompanied by an increase in crop production. Tomatoes, peas, runner beans, and black currants, while showing a marked increase in vegetative growth, gave no higher crop yields. In the case of root crops, total yield was decreased. This occurred in potatoes, turnips, and carrots. Further work on grasses was done by Wittwer 23 51. in 1957 with Kentucky bluegrass. Gibberellin applied at the rate of two ounces per acre resulted in faster growth, increased wet weight, and lighter colored grass. However, the dry weight was not significantly differ- ent from that of the controls. The plots of grass in this experiment had been well fertilized in late 1956. Brian and Hemming (1955) treated 11 varieties of peas with different concentrations of gibberellin in a lanolin paste. They found that the slower maturing and dwarf varieties had more response than the fast growing varieties to gibberellin treatment. With suit- able doses of gibberellin it was possible to eliminate differences in size and in growth rates between short and tall varieties. The length of time in which the plant continued to respond to a dose of gibber- ellin was found to vary directly with the dosage. Approximately the same results were observed by Wittwer and Bukovac (1957), in an extended series of tests performed at Michigan State University. Celery treated with 2 to 100 micrograms of gibber- ellin per plant showed thickened petioles, increased length, and a large increase in fresh and dry weights. A 10 to 25 microgram appli- cation of gibberellin to bush beans caused earlier flowering and seed setting. Broccoli heads developed up to two weeks earlier with weekly applications of 100 micrograms of gibberellin. Endive, mustard, and lettuce grew taller than the controls and flowered earlier, following gibberellin application. According to Wittwer and Bukovac (1957) gibberellin seemed to have an adverse effect on peppers. Flowering and fruiting in these plants were delayed by single or repeated doses. Internal 213.2230 A large part of the research done on the internal effects of gibberellin has taken place in China and Japan and has been published in Chinese and Japanese literature. This was unavailable to the author. There has been, however, a review of this literature by Stowe and Yamaki (1957). According to this review, observations made by Kurosawa, Shimada, and Imura tend toward the theory that the major part of a plant's growth when treated with gibberellin comes from cell enlargement rather than from cell division. In certain cases however the rate of cell division may also be increased. Lona found that in one plant the total length of the shoot increased over thirty times while the average cell length only increased four times. -The review also reported that Yabuta gt,3l. found that gibberellin treatment may lower the chlorophyll level in the plant. In an experiment with Kentucky bluegrass, Wittwer‘gt,gl. (1957) found that treatment with two ounces per acre of gibberellin signifi- cantly reduced the total sugar content but did not affect the mineral and dry matter content. Their findings were in agreement with those of Yabuta gt_gl. (1951) who worked with rice, as reported by Stowe and Yamaki (1957). However, they did not agree with the results of Brian gt_gl. (1954) who found that total sugar was increased in wheat plants treated with gibberellin. Morgan and Mass (1956) found that gibberellin treatment lowered the nitrogen content of grass about 2 per cent. The Effects of Gibberellin on Plant Diseases Barton and Fine (1957) found in preliminary tests that gibber- ellin could be used with either Captan or Manzate for control of blight on tomatoes and did not seem to decrease the effectiveness of either. Furthermore, gibberellin itself seemed to act as s disease inhibitor. PROCEDURE Experiment A 23;; I. Eighteen pots of Tendergreen beans were used in this part of Experiment A. The pots were standard five-inch clay flowerpots. After they had been filled with dirt they were sterilized in an autoclave. Following the autoclaving six Tendergreen bean seeds were planted in each pot. This experiment was carried out during January and February of 1958. Because of the cold weather prevailing, the decision was made to rear the beans in.a room in the Natural Science Building instead of the Michigan State University Greenhouse. This eliminated the possible danger of temperature changes affecting plants or materials as they were moved from the greenhouse to the Natural Science Building where it was necessary to do part of the work. Adequate lighting for the growth of the beans was obtained with two banks of lights, each consisting of nine lOO-watt incandescent bulbs and four fluorescent tubes. These lights when placed four and one—half feet above the beans illuminated them with approximately 450 foot candles at the plant level. The temperature in the growing room remained relatively constant, at 72° 1 2° F, throughout the experiment. Six days after planting the beans had broken ground and were from one-half to three inches tall. At this time, nine of the pots were selected at random and the beans given an application of gibberellinl. An aerosol formulation of gibberellin was used in this experiment and 1“Gibrel" was supplied by Merck and Company Inc., Chemical Eivision, Rahway, New Jersey ill, seslen; I“ 10 each plant received a three-second application. This is the equiva- lent of a fifteen p.p.m. aqueous solution sprayed to run-off. The other nine pots of beans were maintained as controls. Five days later a second application was put on the treated beans. On the succeeding day five pots of beans were selected from the nine control pots and five pots from the nine that had been treated with gibberellin. Each of these ten pots of beans was then infested with mites from.a culture at the Michigan State University Greenhouse. A strand of tanglefoot was applied to the stem of each plant in the pots to prevent migration of the mites. Four days after infestation of the beans with mites the third and final gibberellin application was made on the nine pots of beans previously treated. This included the five pots that were infested with mites. On the following day the final part of the experiment was begun. At this time there was a definite difference in size between the treated and control beans. The treated beans were over twice as tall and were much lighter in color than the un- treated ones. Ten leaf discs seven-eighths inch in diameter were out from the treated plants in the four pots not infested with mites. Ten more seven-eighths inch leaf discs were cut from plants in the four control pots not infested witn mites. The leaf discs were cut with a sevenseighths inch cork borer and were all taken from leaflets in the let and 2nd trifoliate leaves on the plants. As there were six plants in each of the pots, a random selection was made of leaves from which to cut discs. As the discs were cut, each one was fastened to (a small piece of pencil eraser with a pin and floated in.a petri dish containing a 2 per cent sucrose solution (Fig. l). The piece of eraser acted as an anchor to keep the disc in the middle of the petri "we 11 dish. After the discs were floating in the petri dishes each one was infested with five female mites. These mites came from the plants infested five days earlier and were placed on the discs according to the following arrangements: 1. Mites from control plants were put on five leaf discs from control plants. 2. Mites from control plants were placed on five leaf discs from treated plants. 3. Mites from treated plants were placed on five leaf discs from control plants. 4. Mites from treated plants were placed on five leaf discs from treated plants. The petri dishes containing the discs were then placed under the lights and left for ten days. Voter was added to the dishes daily to replace that lost by evaporation and to keep the leaf discs floating. At the end of ten days the dishes were frozen and the mites and eggs on each disc counted. The above method of studying mites on detached leaf discs was taken with slight modifications from Rodriguez (1953). Immediately after the cutting and infesting of discs Part II of Experiment A was started. All but two of the bean plants were re- moved from each pot of the eight pots of uninfested control and treated plants. Then, one leaf on each plant was sealed off with tanglefoot. Five female mites from the infested plants were then placed on each leaf. The same arrangements for placing mites were followed as on the discs: Control mites on control leaves, control mites on treated leaves, treated mites on control leaves and finally treated mites on ’- _N t—~-—- #- ---."‘ ’ " , ‘r r ’ / [‘PAI'VI‘VM‘w' ’ , ,— ‘ ., AUG 0 58 Q If ”J‘— J‘fv/‘VWVV VVWV‘V qu‘x/‘V AN Wv'w\_ ‘x'MM ‘ w.~~‘-~“\—-‘ 'V Fig. 1. leaf disc floating in a petri dish containing a two per cent sucrose solution. 13 treated leaves. The only difference was that there were five repli- cations on the discs and only four on the leaves. At the end of ten days these leaves were picked from the plants and frozen. The mites and eggs were then counted and their numbers recorded. Two factors that may have affected the outcome of this experiment were: 1. Light - The author does not believe that there was sufficient light for the normal growth of the beans in this experiment. The control beans grew taller and more spindly than was normal for bush beans. 2. Flies -.At the time of this experiment, there was another experiment involving onion maggot flies, flylegyia antique (Meig.), going on in the same room. Many of these flies escaped and were attracted to the sugar solution around the discs. Here they either walked on the discs or drowned in the water. In their final struggles some of them pushed the discs over to the edge of the petri dish. when the discs touched the edges of the dish, there was nothing to stop the mites from leaving the disc. The fly problem was eventually solved by putting a screen over the petri dishes and by trapping the majority of the lies with fly ribbon. Experiment B This experiment was arranged in the same general manner as Experiment A but with several important changes. One of these was that there were fifteen different arrangements plus a control used instead of the three arrangements plus a control used in each part of é’g— 5p .,.' 14 Experiment A. Gibberellin was applied to plants in the following four ways: 1. As a three-second aerosol spray applied once. 2. As a three-second aerosol spray applied twice at intervals of five days. 3. As a three-second aerosol spray applied three times at . no... "as intervals of five days. 4. As a slurry treatment on seeds using a 1100 p.p.m. slurry of gibberellin. The two applications of a three-second spray were duplicated on two sets of bean plants. From one set, leaf discs were taken from the plant after they had reached full maturity. At that time there was a great difference between treated and control plants. From the second set of beans, leaf discs were taken just after the second spray. The effects of gibberellin on the plants at this time were just beginning to be apparent. This experiment also differed from Experiment A in that it was run during the warm: weather of late spring and the plants were raised in the greenhouse under normal sunlight. When it was time to cut discs from the plants they were removed to the Natural Science Building. The petri dishes containing the leaf discs were kept in the author's office under one of the banks of lights used in the previous experiment. The last variation from Experiment A was that measurements of plant height and average leaf diameter were taken from the plants of each treatment just before the leaf discs were cut (Table 1). Aside from these differences, the experiment was set up like Part I of Experiment A. Discs were out from each group of beans which 15 had received a different application of gibberellin. Female mites were placed on these discs in the same arrangements as those used in Experiment A. They were left on the discs ten days, then frozen and counted. A factor that may have influenced this part of the experiment was the appearance of powdery mildew on the bean plants just prior to the cutting of the leaf discs. Care was taken to cut discs from leaf parts without mildew but it still appeared on the discs after approxi- mately five days. By the end of the experiment some of the leaf discs were almost covered with the mildew. 16 TABLE 1 AVERAGE PLANT HEIGHT AND LEAF MEASURWNI‘S, F OLLOWING GIBBERELLIN TREATMENT OF PLANTS USED IN EXPERIMENT B. mean Mean Mean Type of Treatment Plant Pbight W M None ll" 4.5" 3.25" One Three-Second 28" 5.5“ 3.5" Aerosol Spray Two Three-Second Aerosol Sprays. Discs Cut Nine 30.5" 5.5" 3.75" Days After Second Spray Three Three-Second 30" 5.75" 3.75" Aerosol Sprays Two Three-Second Aerosol Sprays. 15.5" 5." 3.5" Discs Cut Two Days After Second Spray Seeds Treated With A 1100 p.p.m. 16.5" S." 3.5" Gibberellin Slurry PRESENTATION AND DISCUSSION OF RESULTS The data from Part I and Part II of Experiment A and from Experi- xment B were treated separately but in.the same manner. The mites on the replicated discs or leaves of each.mite-disc arrangement were counted and the mean for each arrangement was calculated (Tables 2, 8, and 14). An analysis of the variance (Snedecor, 1957) was then made to determine if there were significant differences between the arrange- ments (Tables 3, 9, and 16). The results of these analyses are pre- sented in multiple range tables, (Tables 4, 10, and 15). The same procedure was followed for the mite eggs in each experiment. Tables 5, 11, and 18 give the number of eggs found on the discs of each arrangement in Parts I and II of Experiment A and in Experiment B. Tables 6, 12, and 17 present the analysis of variance data for the egg counts. The multiple range tables for the egg analyses are pre- sented in Tables 7, 13, and 19. In Part I of Experiment A, the following mite-disc arrangements differed significantly both in mite population and in egg counts: 1. Mites raised on control plants and placed on treated discs, and.mites raised on treated plants and placed on treated discs, showed significantly lower reproduction than mites raised on control plants and placed on discs removed from control plants. 2. Mites raised on control plants and placed on treated discs, and mites raised on treated plants and placed on treated discs, also showed a significantly lower rate of reproduction than mites raised on treated plants but placed on discs from 17 18 TABLE 2 NUMBER OF TWO-SPOTTED SPIDER MITE ADUETS ON LEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART I OF EXPERIMENT A Replication M1t°‘D1‘° ‘ I II III Iv v Mean Arrangement 1. Control 32 30 26 27 38 31 2. CM#TD 5 14 6 2 7 7 3. TM-CD 12 17 25 27 108 22 4. TM-TD 7 6 10 6 '7 7 aIn describing mite-disc arrangements, c=control, T=treated, M=mites and D=disc. TABLE 3 ANALYSIS OF VARIANCE DATA FOR THE TWO-SPOTTED SPIDER MITE ADULTS FOUND ON'IEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED THREE TIMES WITH'GIBBERELLIN IN PART I OF EXPERIMENT A Degrees of Sum of Mean "F“ Freedom Squares Square Ratio Total 19 2391 Replications 4 72 18 .75 Treatments 3 2027 676 28.1** Error 12 292 24 TABLE A RANGE TABLE FOR THE TWO-SPOTTED SPIDER MITE ADULTS FOUND ON LEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART I or mmnmwr A Mite-Disc _ _(/+) _(2) -(3) Arrangement‘ x x-7 x-7 x-22 1. Control 31 21.“b 2.4% 9 3. TM-CD 22 15* 15‘ 2. CM—TD 7 o 40 TM'TD 7 a In describing mite-disc arrangements, 0=control, T=treated, M=mites and D=disc. bAll values in the Range Table marked with an asterisk are significantly different at the 5 per cent level. The difference num- ber was calculated by st-(2.2)(4.2)g2;g (Snedecor, 1957). ‘ 20 TABLE 5 NUMBER OF TWO—SPOTTED SPIDER MITE EGGS ON LEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED‘THREE TIMES WITH GIBBERELLIN IN PART I OF EXPERIMENT A Replication fiiigggzzznt. I II III Iv v Mean 1. Control 98 76 75 88 115 90 2. CM—TD 1 18 4 17 11 ’ 1o 3. TM-CD 19 64 77 107 92 72 4. TM-TD 1o 36 30 13 11 20 8In describing mite-disc arrangements, C=control, Tstreated, Memites and D=disc. TABLE 6 ANALYSIS OF VARIANCE DATA FOR THE THO-SPOTTED SPIDER MITE EGGS FOUND ON LEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART I OF EXPERIMENT A Degrees of Sum of Mean ”F" Freedom Squares Square Ratio Total 19 29338 Replications 4 1648 412 l Treatments . 3 22885 7628 l9.l** Error 12 4805 400 21 TABLE 7 RANGE TABLE FOR THE TWO—SPOTTED SPIDER MITE EGGS FOUND ON LEAF DISCS REMOVED FROM BEAN PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART I OF EXPERIMENT A Mite-Disc a _ _(2) _(1.) _(3) Arrangement X xa1o X-ZO X-72 1. Control 90 80*b 70* 18 3. TM-CD 72 62* 52* 1.. TM—TD 20 1o 2. CM-TD 10 8In describing mite-disc arrangements, =control, T-trastsd, M=mitas and Dadiso. bAll values in the Range Table marked with an asterisk are significantly different to the 5 per cent level. The difference number was cal- culated by st.(8.9)(4.2).32.3 (Snedecor, 1957) 22 TABLE 8 NUMBER OF TWO-SPOTTED SPIDER MITE ADULTS ON LEAVES ATTACHED TC PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART II OF EXPERIMENT A Replication Mite-Disc s I II III IV--“- Mean Arrangement 1. Control 79 103 111 87 95 2. CMJTD 22 15 32 23 23 3. TMFCD 102 91 76 99 92 4. TM‘TD 30 61 39 31 40 1‘In describing Mite-disc arrangements, C=control, T=treated, M:mites, and D=disc. TABLE 9 ANALYSIS OF VARIANCE DATA FOR THE TWO-SPOTTED SPIDER MITE ADUETS FOUND ON LEAVES ATTACHED TO PLANTS SPRAYED THREE TIMES WITH.GIBBERELLIN IN PART II OF EXPERIMENT A Degrees of Sum of Mean "F" Freedom Squares Square Ratio Total 15 17742 Replications 3 213 71 .39 Treatments 3 15927 5309 29.8** Error 9 1602 178 23 TABLE 10 RANGE TABLE FOR THE TWO-SPOTTED SPIDER MITE ADULTS FOUND ON LEAVES ATTACHED'TO PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART II 0F EXPERIMENT A Mite-Disc _(2) ,(4) -(3) Arrangementa X X-23 X-40 X992 1. Control 95 72*b 55* 3 3. TMACD 92 69* 52* 4. TM—TD 40 17 aIn describing mite-disc arrangements, Cscontrol, Tatreated, Mamites and D=disc. bA11 values in the Range Table marked with an asterisk are significantly different at the 5 per cent level. The difference number was calculated by st=(6.6) (4.42):§_._l (Snedecor, 1957 . TABLE 11 24 NUMBER OF TWO-SPOTTED SPIDER MITE EGGS ON LEAVES ATTACHED TO PLANTS SPRAYED THREE TIMES WITH GIBBERELLIN IN PART II OF EXPERIMENT A Replication Mite -Disc I —- Amngamnta I II III IV than 1. Control 61 49 56 64 57 2. CM-TD 9 12 15 7 11 3. TM-CD 57 68 45 53 56 4. TM-TD 16 49 19 28 28 “In describing mite-disc arrangements, =control, T=treated, Manites and D=disc. TABLE 12- ANALYSIS OF VARIANCE DATA FOR THE TWO-SPOTTED SPIDER MITE EGGS FOUND 0N LEAVES ATTACHED TO PLANTS SPRAYED THREE TIMES WITH GIBBEIELLIN IN PART II OF EXPERIMENT A Degrees of Freedom Total 15 Replications 3 Treatments 3 Error 9 Sumof Squares 7258 261 615 1 846 Lean 'F" Square Ratio 87 .92 2050 21 . 8** 94 25 TABLE 13 RANCE TABLE FOR THE TWO-SPOTTED SPIDER MITE EGGS FOUND 0N LEAVES ATTACI'ED TO PLANTS SPRAYED THREE TIMES WITH GIBBEIELLIN IN PART II OF EXPERIMENT A Mite-Disc -(2) _(4) _(3) Museums 1 x-11 x-28 x-56 1. Control 57 1.6»b 29* 1 3. TM-CD 56 45* 28* 1.. TM—TD 28 17 2. CM—TD 11 ‘In describing mite-disc arrangements, C-control, T-treated, M-mites and D-disc. bAll values in the Range Table marked with an asterisk are significantly different at the 5 per cent level. The difference number was calculated by st:(4.8)(4.42):2_1;2 (Snedecor, 1957). 26 TABLE 14 NUMBER OF TWO-SPOTTED SPIDER MITE ADULTS FOUND ON IEAF DISCS REMOVED FROM BEAN PLANTS TREATED WITH DIFFERENT APPLICATIONS OF CIDBERDLIIN AND FROM VARIOUS MITE-DISC ARRANGEMENTS IN THESE TREATMENTS, IN EXPERIMENT B Replication Treatment Mite-Disc Arrangement‘I I II III IV V man_ 1. CM-TD 92 125 90 65 86 91.6 Gibberellin Slurry 2. TM-CD 67 94 79 81 98 83.8 3. TM-TD 110 115 93 82 75 95 One Three- Second Aerosol 4. CM-TD 89 80 119 82 101 94 Spray. 5. I‘M-CD 98 2 105 89 70 72.8 6. TM-TD 127 113 83 87 26 87.2 Two Three- Second Aerosol 8. TM-CD 108 91 94 117 109 103.8 Sprays. 9. TM-TD 68 76 97 81 83 81 10 . CM-TD 16 4 16 30 21 17 .4 Three Three- Second Aerosol ll. TM-CD 71 59 96 101 105 86.4 Sprays Two Three- 13. CM—TD 7 38 3 15 24 17.4 Second Aerosol Sprays. Cut At 14. TM-CD 91 101 124 101 116 106.6 Half Growth. 15. TM-TD 71 33 31 42 31 41.6 Control 16. CM-CD 123 138 84 132 112 117.8 ‘In describing arrangements, =control, T=treated, M=mites, and maiQCe 27 .«H OHnee :H npaeaomcunue oquuouHa op hogan saunaszo ASS £8883 wufl. Looéfiénxa .3 “.3538 .3 ~35. agenda .5. 28 pa m a: e. 28.88 3.53.:qu 8a €233 a. fin. cats. o2: .95 a... 5 83: SE .He>QH .0395 use mega-.2 68393-9 .HoupnoOIo Jens—omega 03733 mangoes :He m NH 5H 0 NH bH mN mN hm Nv ON mq mq sum No HH Hm tom t©m ewe Mb m OH on sew eqp sou Hm m HH NN N< the eve :05 «N N m MH «N «q :00 two eHm cm H m o «H MN nv son :05 st hm m o w HH 0H om sow sub emv sow Na N b m OH «H HN Nm st 365 :55 saw «a H m m 0 HH «H NN mm emm awn amp :00 «a m 0H NH bH mH ON MN Hm Ne 1N0 ebm ebw eom «OH m NH NH mH ON HN MN 0N fin me. tmo $00 now #NOH 50H HH «H MN «N 0N Hm NM «m on mQ tom :06 eHOH sHOH nanH mHH CHIN .v. HIN mix «mix oak wIN wIN Q..." HIM mIN N we 3 ms “AS was. E Ms 3 m1 $10419 3 .m bang—ea 2H 6.5355: mafia E mg SEAS: 28m; :9: 82 £545.38 .8 $0333.34 ES 59 355a. whim 3m :9: 3:95 moms a 20 858 9229‘ ME: EonmnamEomm 2:. Mae «8 E9; 823 mH Haas NH nH OH m H H (DMQHOHNO‘IAF :3 OS evcoaemaauhd 33.. 3E 28 TABLE 16 ANALYSIS OF VARIANCE DATA FOR THE Two-SPOTTED SPIIER MITE ADULTS FOUND - ON IIAF DISCS RMOVID FROM BEAN PLANTS TREATED WITH DIFFERENT APPLICATIONS OF GIBBERELLIN, AND FROM VARIOUS ARTE-DISC ARRANGEHNTS IN THESE TIEATNENTS, IN EXPERIMENT B. Degrees of Sum of Mean "F" Freedom Squares Square Ratio Total 79 114616 Replications 4 191 48 . 11 Treatments 15 83944 5929 13.9" Error 60 25481 424 TABLE 17 ANALYSIS OF VARIANCE DATA FOR TIE THO-SPOTTED SPIDm MITE EGGS FOUND ON LEAF DISCS IEMOVED FROM BEAN PLANTS TREATED WITH DIFFERENT APPLICATIONS OF GIBBKRELLIN, AND FROM VARIOUS MITE-DISC ARRANEMENTS IN THESE TREATMENTS, IN MMNT B. Domes of Sum of than '1" Freedom Squares Square Ratio Total 79 26900 Replications 4 169 42 .42 Treatments 15 20839 1339 14. 1" Error 60 5892 98 TABLE 18 NUMBER OF TWO SPOTTED SPIDER MITE EGGS FOUND ON LEAF DISCS REMOVED FROM BEAN PLANTS TREATED WITH DIFFERENT APPLICATIONS OF GIBBERELLIN, AND FROM VARIOUS MITE DISC ARRANGENBNTS IN THESE TREATMENTS, IN EXPERIMENT B. Replication Treatment Mite-Disc Arrangement“ I II III IV V Eben 1. CMHTD 17 39 43 27 33 31.8 Gibberellin Slurry 2. TM-CD 41 39 52 36 37 41 3. TM-TD 31 31 42 27 38 33.8 4. CMJTD 35 39 38 24 38 34.8 One Three- Second Aerosol 5. TM—CD 35 25 51 43 36 38 Spray. 6. TM>TD 44 37 39 32 8 32 7. CMHTD 25 30 65 54 65 47.8 Two Three- Second Aerosol 8. TM-CD 53 46 53 47 64 52.6 Sprays. 9. TMHTD 34 33 34 27 33 32.2 Three Three- * Second Aerosol 11. TM-CD 70 39 34 -43 32 43.6 Sprays. ' 12. TMUTD 0 3 0 8 5 3.2 Two Three- 13. CMHTD 12 32 1 9 17 14.2 Second Aerosol Sprays. Out at 14. TM-CD 52 54 47 53 55 52.2 Half Growth. 15. 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