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I .-__ f. _-.-b|_ I ._-_ _ THE IJFLUENCE OF MALE C DRAZIDE CH TTE BLOSSCE KG AND FRUITIKG OF STRAWBERRIES AND THE FORIATIVE EFFECTS PRODUCED A THESIS Submitted to the School of Graduate Studies of Kichigen State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of EASTER OF SCIENCE Department of Horticulture 195C J‘HEEES new 9;; scanners Acknowledgements . . Introduction . . . . Review of Literature . Greenhouse Experiment Plant Materiel . Environment . . . Design of EIperhment ‘Records . . . . . Results . . . . . Field.Experinent . . Plant Materiel . Environment . . . Design of ExPeriment Records . . . . . Result! 0 o e e e 5 Miscellaneous ExPerinents . Effect on Mature Plants . Effect of Temperature . ; . . . . . . . . . . Mcvenent of Maleic Hydrazide through.Runners Inhibition of Runner Formation Germination of Seeds 0 O O 0 Influence on Peaches, Cherries, Inhibition of Lawn Grasses . Influence on Lily-of-the-Valley Sun-any . Literature Cited . . 244554 0 Pears & Apples. Q 11 11 11 13 14 20 21 22 24 25 36 36 36 37 38 88 43 n3 "037.213 .-ENT I wish to eXpress my sincere appr Ml tion to Dr. Charles L. Hammer for guiding this re- search, for help_in he writing, and for encour- agement at all times. I thank Dr. James Ioulton and Kr. Robert Ca_rlson for many sug C,estions, for plants for the greenhouse studies, for saving the plots from pilferers, and reviewing the manuscript, Dr. Sylvan Wittwer for reviewing the manuscript, and Er. A. E. Kitchell for reviewin the eXperiments on the tree fruits. I am grate— ful for tr e chemicals recieved from NaubutucA Che emi al Division, United States Rubber Company, Ifaugutuck, Connecticut. Lastly, I am indebted to hr. Otto Silberstein and Irs. Dorothy Keuther for assistance in collecting the data, and to my entire family and wife for help throughout. Paul Rood -2.- INTRODUCTION Many practical applications have been found for growth regulating substances in recent years. They have been used for rooting cuttings, and for the setting of fruit. They can be used to thin the fruit on a tree, and later in the season, the pro-harvest drcp of fruit and the formation of an abscission layer can be prevented by applications of the same substance at the same concentra- tion. Growth regulating substances at higher concentrations are used as selective herbicides and in some instances for completely killing all weeds. They are also used to prevent sprouting of stored produce such as potatoes. The buds on potato tubers are vegetative, but growth regulating substances have been used to inhibit flower buds as well. The emperiments reported in this thesis were conducted primarily to determine if early spring applications of maleic hydrazide would inhibit or retard the developement of the flower buds of strawberry plants, and then after a short period allow the plant to resume normal growth and developeaent, and blossom. Naylor (15) suggests that maleic hydrazide affects plant metabolism through a disruption in sugar breakdown and utilization, and Kraus and Kraybill (B), and many other workers have determined that carbohydrates are essential for flower production. If maleic hydrazide would disrupt the sugar supply to -3- the flowers for a short period and delay developement it would be important commercially. If the time of blossoming could be delayed, many disastrous spring frosts could.be avoided. It might mean that fruits could be grown outside the relatively frost free areas in which they are now grown, or be grown in areas nearer to their*markets or in areas where the other factors of fruit production were more favorable. If the time of blossoming and subsequent fruiting could be controlled, the big demand for labor at harvest time could be lessened. This would also mean fruit from certain areas could be marketed over a longer period, perhaps at a time when the price was higher. The major’part of the work was done on strawberries because they were available, could be treated and harvested at a convenient time and were readily adapted to green- house experimentation. The study was limited to the macroscopically visible effects. In order to make the experiments as clear to the reader as possible, they have been divided into three groups. The main greenhouse experiment was conducted early in the spring to serve as a preliminary guide to determine the best rates and time of application of maleic hydraside sprays for the field experiment and to provide an Opportunity to observe any effects caused by the treatments under greenhouse conditions. The field -4- experiment was conducted to test the practicability under field conditions. The miscellaneous experiments were conducted to explore some other hypothesis but were not conducted on a large enough scale to be conclusive. -5- REVIEW‘Q§_LITERATURE Maleic hydraxide was first tested.for growth reg- ulating properties at the Naugatuck Chemical Division of United States Rubber Company, Naugatuck, Connecticut. Schoene and.Hoffnann (18) reported that concentrations of 500, 1,000 and 2,000 ppm of ammonium salt of maleic hydraside caused an inhibition of growth of tomato plants in direct proportion to the concentration used. They also found that lawn grasses were inhibited and corn seedlings retarded. Baylor and Davis (15) found that concentrations of 600, 1,000, 2,000 and 4,000 ppm maleic hydrazide stunted sunflowers, tomatoes, peanuts, tObacco, cocklebur, corn, peas, barley, oats, wheat, and red top grass. However, in general, the stunting was not proportional to the concentration used. Shoene and Hoffmann (18) noted that growth of their / tomato plants was retarded for (bout two months. When terminal growth was resumed, some leaves with formative effects were produced. Most of the new growth on the tomato was from lateral buds. Naylor and Davis (15) found.500 ppm of maleic hydraside generally produced a loss of apical dominance, and a developament of the axillary sheets on representative monocots and dicots while 2,000 and 4,000 ppm usually caused death. Baylor and Davis (15) also state that the respira- tion of root tips was inhibited in proportion to the —6- proportion to the concentration of maleic hydrazide in the solution at pH 4.0 but not at pH 6.0. Other inves- tigations (ll) indicate concentrations as low as 5 ppm maleic hydrazide caused root inhibition on plants grown in Hoagland's solution. Observing that treated corn plants exuded viscous droplets containing sucrose from their leaves, and these leaves accumulated a tremendous amount of anthocyanin pigments, laylor (15) suggested that maleic hydrazide affects plant metabolism.primarily through a disruption in sugar breakdown and utilization. Another explanation of the action of maleic hydraaide is suggested by Andrew (1) who noticed that concentrations of 10,000 ppm maleic hydrazide caused the chromosomes in onion root tips to be shorter and abnormally shaped, and that no metaphase plate was formed during mitosis. The possibility of using maleic hydrazide to delay the blossoming of strawberries was proposed by White (19). He applied 1,000 ppm maleic hydraside to second year Premier strawberry plants which had formed flowers‘but had not blossomed yet. The plants began blossoming at the normal time but one month after treatment they ceased blossoming for a week and then resumed normal blossoming. The vegetative growth was retarded but no specific in- Jury was observed. Unfortunately these experiments were plowed under. Black raspberries were also sprayed and -7. blossoming was delayed r... 24 to as days, and fruiting was delayed from 16 to 23 days. The fruit produced was normal. Golden Delicious apple trees were sprayed in the early pink stage which caused an early abscission of the fruit but no vegetative or floral retardation was produced. Fillmore (4) reported that 3,000 ppm maleic hydraside inhibited vegetative growth and flowering of blueberries grown in the greenhouse. The treated plants began flowering 14 days later than those not treated, however no fruit was set. A concentration of 5,000 ppm of maleic hydrazide applied soon after clipping a Pyracantha hedge complete- ly inhibited new sheet growth for a month and retarded growth for a second month (7). littwer (21) applied maleic hydrazide at concentra- tions of 500 to 2,500 ppm as pro-harvest foliage sprays on onions and carrots and found that it completely in- hibited sprouting in storage. Nelson (16) used maleic hydrazide on apple cuttings and found it either prevented rooting or killed the cut-- ting. Fillmore (4) found that by treating dormant rose bushes with maleic hydraside soon before taking cuttings, that growth of the cutting was inhibited on some varieties. Lungs persica, g. sargenti, and g. zedoensis cuttings taken from dormant plants which had Just been treated with maleic hydraside were inhibited by 3,000 ppm but ~8- resumed growth later. Dormant sweet cherry seedlings were killed by 6,000 ppm maleic hydraside. McIntosh apple scions which were treated with 6,000 ppm maleic hydrazide and then granted upon ordinary seedlings, produced some callus formation and a fair union, but shoot growth was inhibited. Langer (10) used concentrations of about 500 ppm to thin peaches. Miller and.Erskine (13) found 1,000 ppm smaleic hydraside sprayed on Gingko trees prevented fruiting. Currier and Crafts (3) found that 2,000 ppm.maleic hydraside acted as a selective herbicide in that it killed barley plants but had little effect upon cotton. The effect of maleic hydraside varied with the species and stage of development of the plant. Harris and Leonard (5) report that wild onion can be controlled with maleic hydrazide sprays. Unpublished investigations done at the University of California at Davis, California (1?) indicate that concentrations of 2,000 ppm.maleic hydraside caused in- Jury to most vegetable crops, however, asparagus seemed resistant. In some other experiments it was apparent that plants treated with.maleic hydraside on various soil types showed.marked differences in response, but this response could not be correlated with clay content, moisture content, pH, or fertility level. The maleic hydrazide broke down in the soil quite rapidly and seemed -9- to result in greater fertility. Other growth regulators have been used in attempts to delay blossoming with inconsistent or impractical results. Winklepleck (20) reported that 125 mg. of naphthaleneacetic acid applied in a peach orchard before blossoming caused the treated trees to reach full bloom eleven days later than control trees. The petals of the flowers on treated trees were smaller, and the rate of maturation of fruit was delayed but the final size of the fruit was not affected. After conducting a series of branch experiments in the greenhouse, Mitchell and Cullinan (14) concluded that napthaleneacetic acid did not retard the blossoming of peach fruit buds but did retard the growth of vegetative buds on detached peach twigs. In a later experiment napthaleneacetic acid applied to detached peach branches caused the buds to cpen earlier than buds on control twigs. Indoleacetic, indolebutyric and naphthalene acet- amide were also tested. Indoleacetic acid caused the blossoms on detached peach twigs to open earlier when it was applied repeatedly. Hitchcock and Zimmerman (6) applied sprays of 200, 400, and 800 mg. per liter of potassium a-napthalene- acetate on July 21, August 20, and September 17, to apple, cherry, and peach.trees and reported that the opening of flower buds was delayed from a few to 14 days. Vegetative buds were delayed up to 19 days. Concentrations .- 10- of 200 mg. per liter applied in July were about as effec- tive as 400 mg. per liter in August, and as effective as 800 mg. per liter in September in retarding the date of blossoming in cherries. Peaches and plums were more sensitive to a given concentration of potassium a-naptha- leneacetate than cherries, and apples were less sensitive. The cherries on treated trees were normal. Earth, Havis, and BatJer (12) conducted orchard experiments for three years using sodium and potassium salts of a-naphthaleneacetic acid at concentrations of 200 to 800 ppm in August, September, October, November, and January. They found that although there was a slight delay in blossoming the following spring, it was only about two days long. The treatments caused moderate to severe injury to leaves and leaf buds and frequently flower buds and entire branches.’ A.similar delay in blossoming , was produced by mechanically removing the leaves in the fall at the same time the treatments were applied. The sprays applied in January were not effective and the high concentration sprays applied in August killed the branches. Krishnamurthi (9) found that 100 ppm 2,4-D and 50 ppm napthaleneacetic acid applied to sweet and sour cherries in September caused some delay and considerable irregula- rities in the opening of floral and vegetative buds the next spring. However these treatments caused such severe killing of both kinds of buds and formative effects on leaves and fruit that it is impractical. -11.. GWEOUSE EXPERIMENTS Plant Materigl - Premier strawberry plants were obtained which had been dug as rooted runner plants from beds on the college farms in the fall of 1949, and stored in peat moss in a cold storage at about 32°F. The plants were removed from storage, sorted, and planted larch 1 and 2, 1950. Some of the plants had green leaves from the previous season and nearly all had put out new leaves by March 5, 1950. Environment - These plants were grown in pets on benches in the Plant Science Greenhouse. The day temper- ature was about 50°! at the beginning of the experiment but gradually rose with the onset of summer. ' _ A white wash shade was applied to the greenhouse June 16 and maintained. The plants were watered im- mediately after planting and regularly thereafter with tap water. One plant was planted in each five inch clay pot in a soil mixture of one-half Brookston clay loam, one- quarter washed sand, and one-quarter much. The lower leaves of the more vigorously growing plants, which were the check, and low concentration treatments, were turn- ing red and dying so it was thought to be a nutritional factor. The soil was tested in the soil science lab- oratory on lay 19, and was found to contain 50 pounds .9 ~12- of available nitrogen, 84 pounds of phosphorus, and 184 pounds of potassium, per acre, by the Spurway reserve test, which should be more than ample supplies of these major elements. Since the soil was very alkaline and 'some minor elements might be unavailable, an attempt Was made to correct it by watering each.pot with about a quart of 1/50 normal sulphuric acid. Since this did not completely remedy the reddening of the bottom leaves, the pots were watered on May 22 with about 1/6 gram of ammonium sulphate per plant. . Bees were observed to be pollinating the flowers on May 4 and later days. Sprays of parathion were ap- plied to control red spiders. Design 2£_Experiment - On March 9, 100 of the best plants were graded by eye into two groups, one containing 50 large sized vigorous plants, and the other containing 50 smaller sized, less vigorous plants. The treatments were replicated on five of the large plants and five of the small plants. This was done to be sure similar plants were used for all of the treatments. This division was found to be of little importance at the time records were taken so it was omitted. The treatments consisted of sprays of 0, 100, 250, 500, 750, 1,000, 1,250, 1,500, 2,000, and 5,000 ppm of an aqueous solution of maleic hydrazide. The entire experiment was randomized as to position -15— on the bench. The solutions were prepared in the lab- oratory using the diethanol.amine salt of maleic hydrazide which contains 50% actual maleic hydrazide by weight. The same atomizer was used for all treatments starting with the low and ending with the high concentrations. The atomizer was emptied but not cleaned between treat- ments. The pctted.plants were removed from the bench for spraying so that there was no drift. The plants were all sprayed between 4:00 and 7:00 p.m. on.larch 9, except for the distilled water on the check treatment and the 100 ppm maleic hydrazide treatments which were applied at 1:00 p.m. on the following day, larch 10. At this time the plants had.formed two to four leaves and were Just beginning to grow after their dormant period. The plants were well watered prior to the treatment and.were not watered for four days after treatment so none of the spray was washed off for at least four days. On April 25, the 750 and 1,250 ppm treatments were sprayed again with 1,000 ppm maleic hydraside to see if any delay in blossoming might be obtained. Records - When the flower buds became macroscopically visible they were counted for each plant at about six day intervals. The opened blossoms and set fruit were also counted. Later the number of runners was also counted. -14- Results - None of the treatments caused a signifi- cant delay in the time of visible appearance of flower buds, time of blossoming or time of ripening of fruit. Generally, as the concentration of maleic hydrazide was increased, the number of flower buds (table 1), flowers (table 2), mature fruit, and runners (table 5) produced by a plant decreased. The higher concentrations of maleic hydrazide caused many abnormalities in the growth and developement of the strawberry plants. .After treatment those plants receiv- ing over 500 ppm maleic hydraaide generally ceased.form- ing new leaves and those that were out failed to expand ‘normally and.their petioles did not elongate. They were somewhat lighter in color than the new leaves of the check plants. The bud scales of the plant which received high concentrations of maleic hydrazide generally opened more, leaving a plant which.appeared to have an Open center. The flowers produced.by these plants had such short peduncles that the flower was often inside the bud scales. The petals on many of the flowers were only about 5 mm wide and 5 mm long and did not overlap as they do on normal flowers, (Figure 6 A.). The anthers of some flowers developed.brown centers and appeared dead. 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N can—an. -17. .nm .naamd 6.2"er vacancy» .IAA 000..." a H o .snc coo.» .mqq 000:0. .lnn can...“ c.aoa ooo.H e oo~.H .ann 08.." sand ocean a. one 4-59 con .55 com .sna ooH moznoon cocor-IHooo NH OH OH V'NCOOOOOOO NHOOOHOOOO O .5” h 300.80 :4 nH awe» om ease a one» on new. «nauseous s-I oz c2 Jowmdonmooo Hepoa .aonpomoa Godunov one 38.33233.» no» .34 .33 meveeoeam on» do 63:53 anemone no menus: one hope ensues... a." 3.0935 acne» an» omeuoanea sandman enema flag—Hag Hmbomzmfima 2H4: Hun. IH amHMHb HdQOHmoomomodfl 30mm on max—um kHz ho Ema! .mfifia -13- However, the base of the recfitical which contains no achenes expanded and elongated and formed a reddish conical tissue with the tip of brown dead achenes. The petal and sepal bases were also thickened (Fig. 5 A, B, a 0). Some fairly normal appearing blossoms on plants receiving the higher concentrations of maleic hydraside had a gummy fluid in their floral envelope at the time of full bloom. The higher concentrations of maleic hydrazide caused definite formative effects on leaves developing from the treated plants. Many leaflets were lobed, deeply crinkled, and generally more elongated.than leaves from normal check plants. The lobes occurred on any part of the leaf and although they never out major veins, the veination was often different from normal. Jlore leaves with one, two, or four leaflets were produced than on normal leaves, (Fig. 11). About four and a half months after treatment some of the plants which had been most severly stunted by high concentrations of maleic hydra- zide began developing a tuft of new leaves in the cen- ter of the plant, (Fig. 2). The blades of these leaf- lets were only about one centimeter wide and had.very deep serations along their margins, (Fig. 5). In other respects the leaves were normal, but small. The appear- ance of m... leaves may have been stimulated by the nitrogen treatment for all the plants tended to grow more vigorously. Figure 1. The Right and Left Plants Were Killed by Treatment- of 2,000 ppm Msleic Hydroxide. Center Plant W39 Not Tpegtgq, Figure 2. Plants Showing Small Green Leaves Growing from Cen« r ter of Stunted Plants Four and a Half Months after estment. Left 1500 ppm Center 1250 & 1000 ppm Rignt 750 & 1000 pnm Figure 5. Leaves Which Grew from the Center of Plants Recovering from a Period of Inhibit- ed Growth. -19. The higher concentrations of maleic hydrazide generally killed the plant in four months, (Fig. l) and (table 4). Table‘g. THE PERCENTAGE OF STRAIBERRI PLANTS WHICH DIED WITHIN FOUH.AND ONE HALF MONTHS AFTER RECEIVING THE FOLLOWING MALEIC HYDRAZIDE TREATMENTS: Treatment Percentage of dead plants my. Check 0% 100 ppm. 10% 250 ppm. 0% 500 ppm. of 750 a 1,000 ppm.* ' 50;: 1,000 ppm. 50% 1,250 & 1,000 ppm.* ,_405 1,500 ppm. 60% 2,000 ppm. 60$ 3,000 ppm. , 80% * 1,000 ppm. treatment applied.April 25. - 20.. 2132?. EXPERIMENT ‘glggg Haterial - Pour varieties; Premier, Sparkle, Hidland, and Robinson were available for the experiments in the field. The patch was set out in the spring of 1949, and 1950 was the first year it bore fruit. The Premier plants were of about normal vigor and had pro- duced.plenty of runner plants for a good stand.but they were spotty in their distribution in the row. The Sparkle variety was very vigorous, producing large tall leaves. However, their stand was similar to that of the Premiere. The Midland variety was low in vigor and had produced few runner plants so the stand was quite poor. The Robinsons had produced runner plants profusely which formed a matted bed about 2 to 2% feet wide. The plants were quite vigorous although.they were so thick they were small in some cases. The number of plants per ten feet of row varied from 0 to 155 for the extremes. However, when the number of plants in all sevem replications were added together, the treatment with the lowest number of plants had about 75 per cent as many plants as the treatment with the most plants. uost,treatments contained an equal number of plants. The half of the experimental plots which were sprayed later had been part of a 2,443 emperiment the year be- fore and had received treatments of one-half and one -21... pounds per acre about two weeks after planting. However, no effects were observed on the strawberry plants and since whole rows had been treated the same in the 2,4-D experiment and each of my maleic hydrazide treatments appeared once in each row, any difference due to the 2,4—D experiment should be constant. The entire planting was mulched with straw in the fall of 1949. The mulch was removed from the plots which were to receive the A early treatment on April 27, and from the plots that were to receive the late treatment on April 25. Environment - The experiments were conducted on the college farm at East Lansing, Michigan. The light in- tensity and rainfall were about average for this local- ity. Because of the low spring temperatures, the plants were retarded about two weeks more than normal for the area. The rainfall was about normal and sufficient throughout the harvest season. The soil was a uniform silt loam with about 5 per cent slope toward the west. The pH was 7.5, and the .Spurway reserve test for phosphorus was 29 pounds per acre, and for'potassium it was 192 pounds per acre, which was thought to be sufficient. A soil test for nitrogen is subject to so many variables that it was not made. No attempt was made to control the weeds during the spring of 1950 when this study was made, and there were a great many throughout the plots. -22- Ho attempt was made to control insects and there were some spittle bugs (Philanus lineatus) on the leaves of the plants. Desigg 2f.§§perimen - Seven adjacent rows of each variety were chosen and each of the seven treatments were applied to a ten foot plot in each row. Treating seven rows of each variety resulted in seven replica, tions of each treatment. This pattern was laid out on adjacent blocks of the four varieties. A.design of all four varieties was laid out next to the first design of plots. One design of plots was to be treated early in the season, and the other design of plots was to be treated later. The pattern used is shown in table 5. The treatments were: a check, which was not treated, 50, 500, 1,000, 2,000, 5,000 and 5,000 ppm of an aqueous solution of maleic hydrazide. The treatments in the field were applied with a knapsack sprayer with a fine fan nozzle which covered the plants very nicely. The solution was applied at the rate of about 150 gallons per acre. One part was treated.between 2:00 and 7:00 p.m. on April 28, which was as early in the season as it was thought safe to remove the mulch. The other part was sprayed between 8:00 and 10:00 a.m. 0n.lay 15 and 16, which was about as late in the season as was expected -23— Table ’5 - PLOT DESIGN FOR FIELD EXPERIMENT. Pattern of treatments applied to each variety. Row 1 Row 2 Row 5 Row 4 Row 5 Row 6 ng 7 Check 5,000 1,000 50 5,000 Check 500 50 5,000 Check 500 2,000 5 ,000 1,000 500 2,000 5,000 1,000 50 5,000 Check 1 , 000 50 5 , 000 011001: 500 2 , 000 5, 000 2,000 - 500 2,000 5,000 1,000 50 5,000 5,000 1,000 50 5,000 Check 500 2,000 5,000 Check 500 2,000 5,000 1,000 50 3229.9. .gremier §parkle Midland ' Robinson . 1'L‘reated on April 28. Treated on May 15 and 16. -24- to have any results. The first‘bloesoms had just appeared and it was about two weeks before full bloom. These particular times were chosen because there was no wind to cause the spray material to drift. Records - The records taken on this experiment were the approximate time and number of blossoms on the part which was treated early and the time and total yeild of fruits on both.parts. The number of blossoms were deter- mined by counting all the blossoms with open petals until the petals fell, in a sample area. Little pollen- ation could take place before the petals opened.and the ,stigmas and pollen turned brown and died at about the same time the petals fell. About three to five days elapsed for an individual flower between these two stages and so the presence of petals was used as an index of time of blossoming. .A difference of much more than three days between treatments would‘be necessary before the maleic hydrazide would have any commercial use in delay- ing blossoming. The sample areas chosen to count the blossoms in were: the ten foot area of the check.plot in the first row for the check treatment; the 50 ppm plot in the second row for that treatment, and so forth to all the blossoms in the 5,000 ppm plot in the seventh row. This was done for each of the four varieties on the part of the experiment treated early. Both normal and abnormal blossoms were counted together because it was -25. impossible to separate the gradations between extremely abnormal and normal blossoms. Because the number of plants in ten feet of row varied, the total number of blossoms counted was divided by the number of plants in the plot to get comparable data. The blossoms on the part that was treated late were not counted because until the later part of the blossoming season no difference in the number of blossoms with.peta1s were 0bserved.between the treat- ments. Results - In the half of the experiments treated April 28, the early date, there was no significant delay in blossoming caused by any of the treatments. (Tables 6 a 7) Generally, the higher the concentration of maleic hydra- zide used, the fewer blossoms there were per plant. (Fig.4 and Tables 6 d 7). Some of the flowers that received concentrations of 1,000 ppm. maleic hydrazide had small petals, short peduncles and pedicels, brown spots on the anthers, dying pistils, and occasionally sticky fluid in the floral envelope. A.1arger percentage of the flowers on the plants receiving 2,000 ppm maleic hydrazide were of this type and in the 5,000 and 5,000 ppm treatments nearly all the flowers had the small petals and other abnormal characteristics. The half of the experiments treated.uay l5 and 16, the late date, showed no noticeable difference between 2,000 ppm Maleic Hydrazide 5,000 ppm.Maleic Hydrazide Figure 4. Representative Areas of Plots 0n Robinson Variety Strawberries at Time of Full Bloom, May 50, Treatments Applied April 28, showing the decrease in number of blossoms as the concentration of Maleic Hydra- zide increased. infill-V III”: \f‘ Elmer IRE lulu]. 1.! .I 'H...‘.‘ “In: ,Hannnfinil‘ nehzmHEF‘HurlHt an HNE:H- U .HIS.1: ha gzaihh‘wfi 3“!“ 19‘ 'H n~.|.s..!l -26— c. ». v. H.H o.H o.H m. H. .soo coo.» c. o.H ».H ».H o.H o.H c. c. .soo coo.» s. H.H o.H s. c. m. m. o. .aoo ccc.~ o.H o.H o.H ».m o.m o.m ». m. .soo coo.H ».m m.» ».c e.» m.» H.» s.m c.m .soo com o.H ».» n.» c.« o.m c.» c.m s.m .soo on s. ».m c.m o.H e.m H.m H.H H.H nacho a oasHon m. H. ». v. v. m. H. c. .soo coco v. v. e. m. o. ». H.. H. .soo coo.» c. o.H o.H H.H H.H a. m. m. .soo ccc.m o.H «.H o.H c. c. c. ». m. .aoo ccc.H o.H m.» c.m o.H o.H s. c. ». .soo coo c.m ». c.m o.H H.« c. e. ». .soo on H.« c.» ».c e.m c.m o.H ».H o.H noonc a comb r each a comb H cash on Hm: mm how mwluflm mmlwflw. aneauwena Hoeaaeb moemHnom Hgd Hun. no mm 4554. GHHAmn: Magda Han—"gag OH§ ho H0352 .9244“ mam naomaoqm no gas: an .0 0.2.39 - .27.. ». m. H. on o.H o.H o. o. .soo coo.» ». e. e. ». o.H v.» ».H H.H .soa coo.» o.H ».H ».H ».m o.H c.» o.H ».H .aoo ooo.m o. ».H ».H o.H o.H H.H o. c. .soo coo.H ».H H.» H.» ».m o.» H.» o.m c.» .soo coo ».H n.» m.o m.» m.e o.v o.» o.e .soo oo o.H m.» ».e o.» v.« m.o o.» o.» Hoooo 3 houses w. o. H. ». e. o. m. H. .soo coo.» c. o. o.H o. H.H o.H c. m. .aoo coo.» ». o. o. o. s. ».H e. m. .aoo ooo.m H.H v.m ».» ».H ».H o. ». m. .soo coo.H o.H c.m o.» m.m o.H ».H o. o. .soo co» o.H H.» o.» c.m o.H ».H o- ». .soo c» o.H c.» c.» ».H ».o ».H e. e. noono o one» a one» n cos» H coco o» now omlwwa on no: on no: possesses Humane» eHMhmmm .Hgm mam alommoqm ho $852 mama: HEB 20 mm AHMmd QHHHQAQ mazgdmma manning 0H3: ho HDZHBHZH Huh. .b 0.279 -23- treatments in the number or type of blossoms until the last of May which was near the end of the normal blossom- ing season. At that time the treatments receiving con- centrations of 1,000 ppm or over of maleic hydrazide had practically ceased blossoming. '. There were a few blossoms in all the plots through- out the picking season and there seemed to be a slight increase in the number of blossoms 0n the plots receiving over 1,000 ppm maleic hydrazide at the end of the harvest season in the middle of July. Some of these blossoms set fruit which matured about the first of August. How- ever these blossoms and fruit never averaged more than one blossom to every four or five plants and the fruit formed was not large enough or thick enough to pay for picking. During the last picking a few plants of the Midland variety which had received higher concentration treatments had some fruit with small green leaves about five milli- meters long growing fron the achenes. Apparently the seeds had germinated in the fruit. This may have been influenced by the treatments. Occasionally on all the varieties, plants treated with concentrations of 1,000 ppm or ever would produce varfitated, green and white, leaf like sepals. (Fig. 7) 'In the strawberry the calyx and corolla develops last in the flower bud, and the maleic hydrazide treatments Figure 5. Mature Strawberries from Plants in the Field Treated with Maleic Hydrazide May 15 and 16 Showing Abnormalities. A. Abnormal fruit from treatments of 1,000 ppm or over of maleic hydrazide. 0. Side view of A. showing conical fleshy tissue at base of torus and dead achenes. E. Normal fruit characteristic of those from treat— ments up to 750 ppm and occasion- ally higher. B. Abnormal fruit showing range in size occurring when compared with A. D. Fruit with rosette of verfigated green and white leaf-like sepals. F. Side view of sepals like D. which occur- red occasionally in 5,000 and 5,000 ppm maleic hydrazide. treatments. Figure 6. Flower and Strawberries from Plants in the Field Treated with Maleic Hydrazide April 28 Showing Abnormalities. A. Abnormal flower with small B. petals and dead stamens. D. Normal fruit characteristic E. of those from treatments up to 750 ppm and occasionally higher. Abnormal fruit from 1,000 ppm. Fruit with rosette 0f vcrfigated green and white leaf- like sepals. Figure 7. Varfigated Leaf-like Sepals from Calyx Shown in Figure 6-E. C. Abnormal fruit show- ing compar- ative size. F. Fruit characteristic of intermediate response result- ing occasionally from treatments over 1,000 ppm. r... .s. . “.‘\ s 6" 3 -.’ y "" vull O 4.54:. film A A... 0 , “Al-L -'-ae"\-' ’T‘n-f‘ " I ”,0 ?t 7.. a... filo“ ,. :_t\ _J I" ,— 'j I . I\ f. r: - I-’ ‘ »- .—. . .- .5. -- ..."’ . . I." n‘ 6 ;.. t". (.‘4 n I .- ... 4 C. v. r I. m m :‘S e ~-e :1- \ f- A', uni In a J. H; QIHHO P... «K V .. a, 3: . 3. [1.8.1.161 f" ‘1(‘ Fr ’fi 4 Q ~ A» 93V .5.-- A . a m.‘ Figure 5. Representative Fruits from Maleic Hydrazide Treatments Applied May 15. Figure 6. Representative Fruits and Flower fro. Maleic Hydrazide Treatments Applied April 28. Figure 7. Varigated Leaf-like Sepals from Calyx Shown in Figure 6-3. Figure 8 Representative Flower Stalks from: A. ' B. p c. - D. Cheek' 50 ppm.' 500 ppm. 1,000 ppm. ‘ .Eb 4 , , Fo,-5 ' ‘ Go_ 2, 000 ppm: .<~5,‘000‘ppm. '.5 5 ,000 ppm. Showing shorter {lover stalks, short pediee1s, abnormal fruit, and dead flowers, on higher concentrations Maleic Hydrazide treatments applied 5e: 15 and l6. Figure 9 ’ Representative Flower Stalks from: "A. B. c. ' - .D. .Checiflg r50 ppm. ”,500 ppm. sl,000 ppm. B. , 7F. ’ 1' G. 2,000 ppm. 5;9009pm. 5,000 ppm. Showing shorter flower stalks, short pedicels, abnormal fruit, dead flowers, and leaf-like calyx,.on higher con- centrationednaleic Hydrazide treatments applied April 28. I'- 01. ...‘r ‘ I; vrv u 1,, 7‘ -, 2 .. , 111..“ . ’ ‘4 o ‘f. ' :‘L - - ’ ‘ . . ‘ .A D. '3[Ac‘ '," 1‘,6' :_g".":' ‘5 . ~,__ ' *5 r-. f '1' C ".c. . ’3' [\i ‘ . . . r.‘ O ”I“ J‘ a K ‘ J" J ‘ ‘1‘ . .. v~ .v .1wfi L .c — p f f‘ f l . r' 1 .’ f ' a , ‘ a ‘ ti 0 ‘fl . - I-r ";,'I‘I :1," F. L 4‘ P'f‘b - r ,, I 1 a I --' ‘ ‘1 K‘ . , a I' W inzH .7 '97? “W '.“ . A..- ‘ .'.‘~ I‘ o o- . r' + p 0 l ’ I '4 3‘ 2.; EL TBWOIE s. ‘— 'uLA ‘ ‘T n. H‘ . » 0 .1} ‘ r_-u.v .4 - :v '0 3 :1 IA: ‘23:”. . 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A f _.‘I\ —L o 'bl" ‘ .1531, 0 3’ -‘~:*( ifi‘.’ JV'QC‘_“r c: .- 0Q H: = “z .21 . .- r- 1.“. r . r .‘ -, "3 -"~- u' t \’ o 52'"va \J'V ‘ ‘ ‘1' .rr ’3 "tin—"1: ‘ r’ - L h ' re , ' . , ' as .' ,-_,Ia.-.—',n 50*} ”1,59 ‘95., ,J 19.9313; 'I'ne’lufiii ‘,~.~.!'-...‘§' .._1 L . , T, , . .. 7|. . ._ ‘ if“ ., ' . .. \ q '_ ‘ ~ gs. '? In- of; x.feo e i!— ref Jae Laqeflal. Lree .u t'. 013313390 3. Flower stalks from; A~eheeh, B~SO, D-l,COO, E-2,000, Fa3,000, G—S,OOO ppm Hvdrazide Treatments Applied May 15. . a ' :3“. Figure 9. Flower stalks from. Aacheck, an\. ‘ x f- , I“ ‘\ I“ I‘m - C- 50‘: ’ h)" .11. 3 {)(J\J ’ E- n ’ 1-4: (3 I») : F- :71 ’ (I’!_r" ’ ’ G '- 5 ’ ‘s”1‘d'0 1.:r‘m UnToin Vvflvnvfifla ”nontmanta dnn11¢4 AnniT 90 -29- apparently interfered with the normal develoPment of the petals and sepals. The flower stalks of plants generally decreased in length as the concentration of maleic hydrazide increased over 1,000 ppm. The pedicels were shorter also, giving these flower stalks a club appearance. The flower stalks from plants treated.April 28 were generally shorter and more severly affected than the flower stalks from plants treated 5a: 15 and 16. The plants treated at this later date often had some flower stalks which were short and ' some which were not, depending on the stage of develop— ment of the flower stalks when the treatment was applied. Concentrations over 500 ppm maleic hydrazide inhibited new vegetative growth. The petioles failed to elongate. The leaflets were somewhat smaller than normal and lighter colored. (Fig. 10) ‘lhen these photographs were taken during the last week in June, the leaves of plants treated at the late and early dates were so similar that separate pictures were not taken. The contrast in the lengths of the petioles of the low and high concentration treatments were nearly twice as great a few weeks before this picture was taken. The leaves which.were already partially develop- ed when the treatments were applied generally had short petioles but did not show formative effects. The leaves which were at an earlier stage of develOpment at the time of treatment and appeared later were the ones which had Figure. 10. Leaves frcm; A-check, B—5Q C 500, D 1,000 E- 2, OCO, F-Z,OOO, G 5 ,000 ppm Maleic Hydrazide Treatments showing Formative Effects and Petiole Lengths. 2" a? 43% Figure 11. Leaves Showing the Formative Effects Caused by Concentrations over 1,000 pom Maleic Hydrazide. -30— the formative effects. The formative effects produced by concentrations over 1,000 ppm Maleic hydrazide include lobing and division of leaves at almost any place, ab- normal leaf veination, crinkling, curling, and the produc- tion of leaves with one, two, four, or five leaflets instead of three. (Fig. 11). The 500 ppm treatment of the half of the eXperiment treated April 28 resumed vegetative growth during the last half of May, the 1,000 and 2,000 ppm treatments during the first half of June, and the plants of the 5,000 and 5,000 ppm treatments which lived, resumed growth during July. The 3,000 and 5,000 ppm concentrations of maleic hydrazide were toxic to some of the plants of all varieties but especially the Midland variety which is generally less vigorous. By the first of August it was noticed that the plants receiving the higher treatments were greener and not nearly as infected with leaf spot as the lower con- centration treatments. The treatments applied May 15 and 16, did not affect the mature leaves and the stage of deve10pment when the developing leaves were treated determined the effect it had on them. This resulted in plants which had all of the different kinds of leaves. The ripe fruit was picked for each plot on the dates shown and the weight recorded in grams. (Tables 8 to 11.) The fresh weight was used as a.measure of quantity in- stead of volume because many of the plots only yielded is]... a fraction of a quart, and that would be hard to estimate. There was no delay of any importance in the time of ripen- ing caused by any treatment, and generally the only effect increasing concentrations of maleic hydrazide had on the yield of strawberries was to decrease the yield. The results for the different varieties and the two times of application were quite similar. (Tables 8 through 11). .Although there seem to be two peaks in the data, these peaks occur in the check and low concentration treatments and can not be attributed to the treatments. 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