INVESTIGATIONS 0N _ ‘_ “ BLOTCHY IIIPEIIINO'j' _. - — OF GREENHOUSE TOMATOES _ THISISIIOII THE IIIIIIIIOII IIIIII s. . ' H L SEATON 1933 INVJSTIGATIONS ON "BLOTCHY RIPENING" OF GREENHO SE TOMATOES Thesis Submitted to the Faculty of the Michigan State College of Agriculture and Applied Sci- ence in partial fulfillment of the requirements for the degree of master of Science by H. L. Seaton M WMZé’ /f33' _ Vii/‘77. £4 ‘7' z THEE?!“ CONTI‘ITS Introduction Review of Literature Ripening Disorders of Greenhouse Tomatoes Streak or "Stripe" 1 "Green Back" or "Hard Back" True "Blotchy Ripening" or"Green Spot" Methods Seasonal Occurrence Varietal and Strain Susceptibility Area of Fruit Envolved in Blotchy Spots Size of Fruit and Blotchy Ripening Naturation Period and Green Spot Position of Fruit and Green Spot Location of Plants and Green Spot Date of Planting and Green Spot Effects of Fertilizers Temperature and Green Spot Transpiration Studies Effects of Shade Study of Water Movements Discussion Summary Acknowledgements Literature Cited 126135 QOONH 10 12 13 16 17 18 19 22 24 25 29 31 35 36 37 43 46 46 l. Investigations on "Blotchy Ripening" of Greenhouse Tomatoes Introduction Greenhouse vegetable production in Michigan centers around Grand Rapids with smaller producing areas near other cities. For years the Grand Rapids area produced a large portion of the greenhouse leaf lettuce grown in the middle western states. However, the severe competition of the western grown head lettuce with the leaf lettuce during the past decade has forced the growers to change to a more profitable crOp and in most cases this has been greenhouse tomatoes. According to the Fifteenth Census of the United States 1,299,545 square feet were devoted to greenhouse tomatoes in Michigan in 1950 with a gross return of approximately $259,909.00. The change from leaf lettuce to tomatoes, however, has been accompanied by a number of serious problems. In the first place, greenhouse tomatoes are sold on the markets in competition with field grown tomatoes from Florida, Cali- fornia, Mexico, Cuba and other southern sections, where the fruit is harvested green and ripened artificially. The vine- ripened greenhouse tomatoes command a higher market price due to their better quality. Secondly, the greenhouses were con- structed primarily for the production of lettuce, a cool season crop, and in many cases were not equipped to maintain the higher temperatures required for tomatoes, nor were they equipped for adequate ventilation. Lettuce will produce satisfactory crops under the poor sunlight conditions prevailing during Michigan winters, but this is not usually true with tomatoes. The tomato plant requires a different soil fertilization system than that required by lettuce and is therefore not a satis- factory companion or succession crop for the latter. Leaf mold (Cladosporium fulvum, Cke.), mosaic, fusarium wilt (Fusarium lycopersici, Sacc.), blossomeend rot and other diseases as well as injury caused by nematodes (Heterodera- radicola), white fly (Trileurodes vaporariorum), red spider (Tetranychus bimaculatus), and other insects, the controls of which have been formulated, all result in reduced yields where they are not adequately controlled. But, during the past decade, one of the most baffling problems of Michigan greenhouse tomato growers has been the "blotchy ripening" or "green spot" of the fruits, which often greatly reduced the quality of the finished product. It is the purpose of this thesis to present experimental data bearing upon this problem. Review of Literature Blotchy ripening has not been reported, to the writer's knowledge, as a disorder of greenhouse tomatoes in the United States. Bewley and White (4) consider blotchy ripening a rather serious disorder of glasshouse tomatoes in England and from their descriptions and color plates it is to all appearances the same condition that prevails in this section. They report that in many cases the percentage of blotchy fruits is as low as 0.5 or 1 per cent., but under unfavorable conditions it may rise as high as 50 per cent. Under conditions in England they found the disorder was most prevalent during late May, June, and July and less prevalent or completely absent during the remaining months of the year. Their results over a five year period (1921-19z5) indicate that blotchy ripening is connected with an insufficient supply of available potassium and nitro- genous nutrients, particularly the former, whereas phosphate deficiency appeared to be unimportant. The feeding of affected plants with potassium and nitrogen fertilizers resulted in a corresponding reduction in the quantity of affected fruits. Applications of sulphate of potash at the rate of 500 pounds per acre were sufficient to correct blotchy ripening on average soils. However, they report cases where it was necessary to apply three tons of sulphate of potash in order to reduce blotchy ripening to negligible proportions. Under the most favorable manurial conditions, however, they found small quantities of blotchy fruits were invariably produced, and they state that "apparently other factors, probably climatic in nature, are operative." Root invading fungi, such as Colletotrichum tabificmm, interfere with the feeding of the plant and indirectly result in blotchiness of the fruit, according to these writers. In several cases, they also traced blotchy ripening to the dryness of the soil below the surface six inches. They further report that exposure of fruits to excessive sunlight when the potash and nitrogen supply is in- adequate causes a type of uneven ripening known as "green back" or "hard back." Hoffman (7) states that nitrogen deficiency affects the size and number of fruits more than it does their shape. He found that fruits on nitrogen-deficient plants usually were 4. smooth, solid, and well colored, if adequate amounts of the other nutrients are present, but they were much smaller and fewer than when adequate amounts of nitrogen were available. His results also indicate that the ripening of the fruits was delayed on nitrogen-deficient plants after the first two or three clusters were matured. Fruits in the upner clusters were greatly retarded in growth and slow in ripening. He recommends the use of ammonium sulphate as a side dressing at the rate of 250 pounds per acre each week after the third cluster has set fruit for eight applications,in order to over— come any nitrogen deficiency. Bewley and Corbett (3) have shown that the period between the opening of the flower and the picking of the fruit varies considerably and that this maturation period lengthens as the plant ages and the truss lengthens. according to Duggar (6) the characteristic color of ripe tomato fruits is due to the presence of two carotinoid substances, lycopersicin, the red pigment, and carotin. These carotinoids develop in the fruits as they approach maturity whether on or off the plant. Smith and Smith (21) bagged small fruits of several varieties grown under both outside and green- house conditions with manilla bags lined with heavy black paper. They found that "during the ripening of tomato fruits in total darkness no chlorophyll developed. The fruits were pure white and gradually shaded into the yellow or red as they approached maturity. When mature, the bagged and unbagged fruits of red varieties were the same color." Duggar (6) found that green tomatoes stored at 35°C. were ripe in 6 days but yellowish in 5. color, due to the failure of lycoperiscin to develop at that high temperature; at 20 to 25°C. and 12 to 2600. normal red developed. He suggests that failure of lycopersicin to develop at high temperatures is probably due to a lack of oxygen, the limited supply being used in respiratory activities. That oxygen is essential for lycopersicin develOpment was also shown by Duggar, as tomatoes stored in hydrogen and nitrogen did not redden. Sando (l9),using fruit of known age, determined, by tagging the blossoms and chemical analyses, that in general throughout the ripening period there was an increase in moisture, acids and sugars, and a decrease in solids, total nitrogen, starch, pentosans, crude fiber, and ash. Miller (14) grew tomato plants in sealed containers at Manhattan, Kansas, and kept the soil in good moisture tilth by the daily addition to it of the water that had been removed by the plants during that time. A single plant, of the Louisiana Pink variety pruned to a single stem, transpired 34 gallons of water during the growing season from May 19 to September 2, 1924. He also presents stomatal count data secured over a three-year period on several varieties of tomatoes. He found that there was an average of 131,000 stomata per square inch on the lower surface of tomato leaves and 62,000 per square inch on the upper surface, giving a total of 193,000 stomata per square inch. Mac Dougal (12) by the use of an auxograph studied the daily accretion in size of tomato fruits in connection with temperature and water relations. as the temperature of the fruit, attached to the plant, rose from 12° to 14°C. to 266to sin,“ II 28°C. the volume increased to a point where the increased temperature caused an excessive water loss by transpiration which overbalanced the gain by hydration. The mid-day shrinkage could not be prevented by watering the plants abundantly. His data show that a water deficit may exist in the fruits because of excessive transpiration regardless of the moisture content of the soil. Newhall and Wilson (15) in their studies of Cladosporium leaf mold state that "transpiration is found to be the greatest factor responsible for high humidities in greenhouses. As many as 400 gallons of water an hour have been computed to be given off by an acre of greenhouse tomatoes under normal conditions in June." Ripening Disorders of Greenhouse Tomatoeg. Several ripening disorders have been confused with blotchy ripening and in order to distinguish between them two are described. strmk or stripe. Streak has been known as a greenhouse trouble for many years. All parts of the plant may aiow symptoms of streak. 0n the fruits, according to Ramsey and Link (18) "the disease is characterized by more or less extensive brown discolorations of the surface, which may result in a great diversity of pattern, such as circular spots, blotches, 100ps, and streaks. These areas are somewhat sunken, and on green fruit the brown color may be absent, in which case the disease manifests itself as variations in the intensity of the green color. Immature fruits do not ripen. The brownish surface discolorations of the 7. ripening fruits sometimes penetrate the inner tissues and entirely destroy the marketability of the fruits." During recent years it has been shown that certain viruses alone and some virus mixtures will produce streak when introduced into tomato plants. ‘ZGreen Back" or "Hard Back." Another condition which is often confused with blotchy ripening is "green back" or "hard back." Hard green areas are apparent around the cavity, while the rest of the fruit softens and turns red. As the ripening processes continue, the affected areas may either remain green or become orange in color, but in- variably they remain hard, even though the remainder of the fruit becomes over-ripe. The flesh immediately below the hard green area is opaque, hard and green, whereas other tissues are clear, soft and red. The vascular bundles within the hard flesh are usually green in color and necrosis of the bundles has not been observed. Frequently the wall of the fruit is thinner than in the riper areas. The cause of this disorder is unknown but it seems to be more prevalent when the sunlight is intense and appears to be more serious on certain'varieties than others. The Blair and Lloyd varieties were found to be highly susceptible to this condition. Bewley and White (4) express the opinion that the injury may be reduced by applying sufficient potash and nitrogen. True Blotchy Ripening, Blotchy ripening is referred to locally as green spot, green spotting, green back,and Grand Rapids disease. The two latter terms are confusing, since green back as described above Figure 1. Greenhouse tomatoes affected with blotchy ripening showing the location and ex- tent of the blotchy areas. These fruits are typical of the condition found during June and July. Figure 2. A type of blotchy ripening occasionally observed in the Blair variety. Small colorless areas appear at the stylar scar region. 8. is considered to be a condition distinct from true blotchy ripening and bacterial canker (Aplanobacter Michiganense Smith) has been referred to as the Grand Rapids disease by various investigators. The writer's opinion is that the terms "blotchy ripening" and "green spot" are the more descriptive of the various names offered and since the condition was first described under the former by Bewley and hhite there seems to be no need of changing it. Throughout this paper blotchy ripening and green spot will be used to refer to the same condition. In fruits affected by blotchy ripening, areas of the outer wall, or pericarp, fail to develop and color normally. These areas are not confined to the cavity region and may appear in any portion of the outer wall of the fruit, but are usually more numerous near and radiating from the cavity. Figure 1 shows blotchy fruits in which all portions of the fruits are affected. Figure 2 illustrates an unusual condition of the stylar region, occasionally observed only in the Blair variety. There is no sharp line of demarcation between the green or white and the normal red areas; the colors merge gradually. as the fruit approaches maturity these areas remain hard and green and as ripening proceeds further they assume a waxy or glassy appearance. The vascular bundles lying beneath these clear, glassy areas are almost invariably brown and necrotic, as may be observed from the outside. The area may be confined along one of the furrows formed above the inner walls of the fruit which separate it into carpels and have been found occasionally immediately above the main bundle of the carpel. Figures 5 and 4 show cross and longitudinal sections through Figure 3. Cross sections of blotchy fruits. Note the necrotfc vascular tissues in the blotchy areas of the pericarp which are not present in the unaffected areas. Figure 4. Longitudinal sections through blotchy areas. The ne- crotic bundles extend throughout the affected areas and are not apparent in the healthy portions. affected areas which show the relative positions of the necrotic vascular bundles. When viewed under low power these sections almost invariably show the presence of gaps or canals in the parenchyma tissues adjacent to the bundles. The walls of the parenchyma cells of these canals are usually brown and necrotic. Bewley and White (4) adopted a clearing method con- sisting of carefully removing the epidermis and clearing in xylol following alcohol. Observing bundles by this method they found that the veins radiate from the point of peduncle attach- ment, and that in the upper half of the fruit there are few cross connections, while in the lower half the veins anastomose to form an intricate net work. Their examinations of healthy and blotchy fruits by this method show that there were differences between the bundles. The bundles in blotchy areas were somewhat thicker than those in the healthy fruits, owing to the spongy nature of the cells surrounding them. Necrosis of the bundles were frequently observed and the necrotic bundles they found were directly beneath the blotchy areas. They further observed that groups of corky cells adjacent to the affected bundles frequently occurred. The disorder is apparently entirely confined to practically _ mature fruits. Several hundred fruits of all stages of develop- ment were dissected and examined for evidences of blotchiness. Not one of the immature fruits were found to show indications of developing into a blotchy fruit. The first evidences of blotchi- ness were observed only after the fruit had begun to develop a light pink color which was usually from three to five days before the fruit was ripe enough to harvest. Blotchy ripening is distinctly a disorder of the fruit} 10. no other parts of the plant are apparently affected. The blotchy fruits occur on plants that appear normal in every respect. in occasional blotchy fruit has been observed on plants with symptoms of fusarium wilt, mosaic, and nematode injury, but even under these conditions other fruits on the plant ripened normally. Methods The plants from which the data reported in the following experiments were secured were, except where noted, all grown from seed of a pure line of the Grand Rapids Forcing variety. The greenhouse used has been devoted almost exclusively to tomatoes for the past eight years, two crops being grow1 annually; a fall crop bedded in August or early September and removed in January or early February, and a spring crop bedded in February or early March and removed in August. The house is divided into two ground beds by an eighteen inch concrete walk which extends around the ends and sides of the beds. The soil of the ground beds was originally a sandy loam to which approximately thirty tone of well rotted manure per acre has been applied annually and is in a high state of fertility. A permanent hollow tile system of steam sterilization underlies each bed and it has been necessary to give the soil an annual sterilization in August. The soil management system followed has been a manure application after sterilization.supplemented with from 1000 to 1500 pounds of commercial fertilizer high in phosphorus and potassium. Before the fall crop of 1951 an application of 1500 pounds per acre of an 0-20-20 analysis fertilizer was given and an additional 1000 pounds of the same :material was applied before the spring crop in 1932. After the 11. third cluster had set fruit, applications of 200 pounds per acre of sulphate of ammonia were made every ten days until three weeks before the last picking. At present the soil has a reaction of pH. 7.8. The planting system followed consisted of six rows in each of the beds. The distance between the rows was 28 inches and the plants were set 20 inches apart in the rows. The plants were trained to the single stem system and the usual methods of insect and disease control were followed. Watering during the cloudy weather of late winter and early spring was done with the hose at the base of the plants and after May 15 the over- head Sprinkler system of irrigation was used. A night tempera- ture of 58°F. was maintained early in the season and increased as the outside temperatures increased during late May, June and July. A day temperature of 60° to 65°F. on cloudy days and from 700 to 750 F. on sunny days was maintained early in the season. During late May, June and July efforts were made to keep the temperature as near 75° to 800 as was possible by ventilation. Early in the growing period only the ridge ventilators were opened but later both ridge and side ventilators were opened. Continuous temperature and humidity records were kept through- out the season. The hygrothermograph was housed in a standard type of shelter centrally located in the greenhouse. Records were kept on each plant under test and on the individual fruits of each of the plants. These records included the date the fruit set; the date it was harvested; the weight of the fruit in grams; the location as to cluster and position on the duster; the number of fruits per cluster; and the estimated per cent. of the surface of each fruit that was affected by 12. blotchy ripening. (Records of this type were kept on approxi- mately 30,000 fruits or between two and one-half and three tons of fruit in 1932. Only a part of which are given under the following headings, as several of the varieties used produced a high percentage of "hard back" fruits which were recorded with the blotchy fruits. The amount of green spot or blotchy fruits given in the following tables and graphs is eXpressed as the per cent. of the total number of fruits harvested of which more than one per cent. of their surfaces were blotchy. Seasonal Occurrence Observations of blotchy ripening, made in the Experiment Station greenhouses at East Lansing and in a number of commercial greenhouses at Grand Rapids during.the 1930, 1931 and 1932 seasons, have shown that blotchiness is a serious disorder of the spring crop ripening during late May, June, July and August and is not a trouble of noticeable consequence on the fall crop ripening from October to January. Cases have been observed in commercial ranges where as high as fifty per cent. of the fruits harvested during June and July were so severely affected that they could be sold only as culls, while in the same ranges less than one per cent. or a complete absence of the disorder was found on the fruits ripening from October 1 to February 1. In the Experiment Station greenhouses blotchiness has been observed only occasionally on fruits ripening from October 1 to February 1 and the past three years less than 0.5 per cent. of the fruits ripening during this period have been affected. The fruits affected in these cases were invariably from plants 13. located in the outer rows of the beds nearest to the heating pipes, where the temperature is approximately 50F. higher than other parts of the house and where the soil is exposed to greater fluctuations in its moisture content. However, on the spring crop both the percentage of fruits affected with green spot and the area of the individual fruits that is affected in- creases materially as the season advances and the outside temperatures become higher, as is shown by data from the 1932 spring crOp given in Table I. Table I - Seasonal occurrence of green spot, 205 plants of the Grand Rapids variety spring_crop 1932. _:gotalyield 3Blotchy fruits Harvesting Number weight in Number of Per cent Average per period fruits kilograms fruits of total cent of sur- number face blotchyg May 1-31 203 21.77 14 6.89 7.71 July 1-31 4677 456.20 1314 28.11 15.05 Blotchy ripening was observed to be more serious in commercial ranges during the harvesting periods of the spring crop in 1930 and 1931 than in 1932. Meterological records show that in 1930 and 1931 temperatures above normal, accompanied by long periods with little or no precipitation, prevailed during June and July. The 1932 season more nearly approaches the normal prevailing climatic conditions for this section. Varietal and Strain Susceptibility A certain amount of varietal and strain susceptibility to the conditions resulting in blotchy ripening undoubtedly exists. No variety or strain has been observed to remain consistently free from the disorder. A variety test at this Station in the spring of 1931 (20) in which most of the varieties grown commercially were included, showed that some varieties are more susceptible to the disorder than others. Based on obser- vations on the varieties in this test and on those grown in commercial houses, the varieties may be arranged in order of heir decreasing susceptibility as follows: Blair Forcing, Lloyd Forcing, Bonny Best, John Baer, Grand Rapids Forcing, Best of All, Alsia Craig,Ideal Forcing, Comet Forcing, Lorillard Forcing, Marglobe, and Globe. Seed from various American and European sources were used with several of the varieties. The Blair and Lloyd Forcing, though highly productive, had such a high percentage of blotchy fruits, that they have been discarded by the better growers. In the spring of 1931 individual plant selections were made in the Grand Rapids Forcing variety from plants which at that time were little affected by blotchy ripening and were producing a heavy crop of desirable fruits on the basis of size, shape, and quality. These selections were planted in 1932 and records kept on twelve plants from each selection. The results are given in Table II along with similar data for the Blair Forcing and Alsia Craig varieties. 15. Table II - Comparison of the susceptibility of varieties and strains grown in spring, 1932, to blotchy ripening. Avg. yield per g“ gplant Per cent of Strain or Variety Number Weight in total fruits fruits _pounds blotchy Grand Rapids Sel. 123-31 43 9.38 42.91 " " " 18-31 46 8.79 42.74 " " " 12-31 36 8.81 38.61 " " " 17-31 47 8.61 31.57 " " " 128-31 31 7.79 24.80 " " " 209-31' 34 O 7.18 18.33 " " " 225-31 32 6.72 13.88 " " commercial seed 34 7.84 28.32 Blair Forcing 46 11.72 79.06* Alsia Craig 45 6.56 24.19 * Includes blotchy and "green back” fruits. As is indicated in Table II, no selection was found which produced a reasonably low per centage of blotchy fruits and at the same time maintained a high production per plant. The selections varied considerably but even these variations were around the mean of the variety, as is indicated by the plants grown from commercial seed. In another test seeds were saved from blotchy fruits of several varieties. From 75 to 90 per cent. of the surfaces of these fruits were involved in the blotchy areas. Plants grown from these fruit selections did not produce any significant variations either higher or lower than the average percentage of blotchy fruits for the respective varieties. L0. Area of Fruit Involved in the Blotchy Spots In order to determine the average extent of the injury, as the blotchy fruits were harvested, the affected areas were esti- mated and recorded separately for each fruit. Data were secured on 1515 blotchy fruits of the Grand Rapids variety in 1932. The classified data are given in Table III and shown graphically in Figure 5. Approximately 70 per cent. of the fruits affected with green spot fall within the range from 0.1 to 20 per cent; 87 per cent. less than 30; 91 per cent. less than 40; and 93 per cent. less than 50 per cent. Under commercial annditions fruits with less than 10 per cent of the surface affected are usually packed with the fancy or choice grades and those with more than 10 per cent with the second and cull grades. Table III - Area of fruit involved in the blotchy spots of 1515 blotchy fruits of the Grand Rapids variety in springgof 1932. Per cent of number of Per cent. of surface blotchy blotchy fruits total number blotchy 0.1 - 9 546 36.04 10 - 19 535 35.31 20 - 29 267 17.62 30 - 39 73 4.81 40 - 49 35 2.31 50 - 59 15 .99 60 - 69 15 .99 70 - 79 '16 1.05 80 - 89 8 I .52 90 - 99 5 .33 F\ 3w“: '5 Avea °S Frau SKOVMWCb watchmen Fr u\t$ \3 (.0 O N 0 Per Cent 61$ Toca\ Butch E 0 20 '40 60 80 (00 Per C eat. 03 Stu Secs. 6\0tLV\\s 17. Fruit size and Blotchy Ripening It was thought that some relation may exist between the size of the fruit and the conditions which underlie blotchy ripening. In order to determine any relation of this nature, each fruit was weighed separately on a small gram scales when it was harvested. The data from 36ZLfruits of the Grand Rapids variety, of which 2633 fruits ripened normally and 1003 were blotchy are given in Table IV and the distribution curves for both the normal ripening and the affected fruits are shown in Figure 6. It is evident that no relation between fruit size and green spot existed during the 1932 season as the distribution curve of the affected fruits slows little, if any, variation from that of the nnrmally ripened fruits. Table IV - Showing the relation of size of fruits and blotchy ripening for 3621 fruits of the Grand Rapids variety in the spring of 1932 weight of fruits Number of Number of in grams normal fruits blotchy fruits 9e . 4o - 59 570 105 13 60 - 79 559 199 37’ so - 99 595 249 ‘*P”4 100 - 119 442 187 ”'2- . 120 - 159 296 ‘120 *“’** 14o — 159 196 64 32’ 160 - 1'79 90 53 37 180 - 199 54 21 “‘ 200 - 219 25 6 220 - 259 15 o 240 - 259 6 5 260 - 279 4 1 __ 280 - 299 1 c 0 O 0 MVPfljk w a W w M. chyoz w 90 fifstw I .0 D e \u 2 m A o. o m\ H OH x We ... \m s r. \ w 0 us A a .. 6 \ h \\ e a \ o v e \\ o a ..\ x ‘ “\U m “““. F a \s. T \\\\\ O F 0..““ z “““‘ I MD \tltlt a a ’ Ru :1 o \ III! B 5 Will ‘0 fl .) -0090997 ”Odo a. m a a a .2 a o w I I. l O musadshr Aizuuora ywfigfiz u, Wax (SW 05 FY \n‘t-eroms 18. Length of Maturation Period and Green Spot It has been observed by the writer that if fruits were delayed in their normal ripening processes they are more likely to be affected by blotchy ripening than are fruits that ripen in a normal length of time. In the spring of 1932, the period from the time the flower was pollinated and the ripening of the resulting fruit was determined by tagging the blossoms. All blossoms which were previously pollinated and the corollas of which were losing their normal deep yellow color were tagged daily late in the afternoon. When the fruits were harvested the date of setting was recorded along with the picking date and the number of days intervening was considered as the maturation period. The maturation period was found to vary considerably. The period of normal fruits setting in March and ripening in May was approximately 60 days and as the season advanced, fruit set in early June and ripening in July required fnlm 40 to 47 days. The mean of the Grand Rapids variety for the entire' spring crop of 1932 was 53 days. Fruits affected with green spot were found in most cases to have a longer maturation period than normal fruits and as this period lengthened the percentage of blotchy or Spotted fruits increased materially, as is shown in Table V and Figure 7. p I.‘ ‘ C O Q - ‘ ‘ Totek Num‘per OS Emacs wauxe. ? L an (6th 0‘5 Meturauovx Pew \ 0A and b1otdmaas cevuncb . ‘3'. --- - - - 0 60 70 80 90 Numbmc 08 “6‘38 to Metuvxub OS Tota\ 6“?th ”8 2'1". G—Vfl. 'Pev C loo 19. Table V - The effect of the Maturation period and the percentage of green spot produced for 3793 fruits in spring of 1932. NUmber of days Total number Number of Per cent of to maturity of fruits spotted fruits total spottedl 40 - 49 585 59 10.08 50 - 59 2003 267 13.33 60 - 69 812 115 14.16 70 - 79 281 41 14.59 80 - 89 61 11 18.03 90 - 99 32 8 25.00 Location of Fruit and Green Spot Blotchy ripening may or may not appear on any of the fruits of a plant. Numerous observations have revealed that an entire cluster of fruits may be affected by the disorder or a single fruit on a cluster may show large blotchy areas while the other fruits ripen normally. The first two clusters may ripen normally while a high percentage of the fruits on the third and fourth clusters may be affected and the fruits in the remaining clusters may show varying amounts or complete absence of the disorder. During the harvesting season of 1932 when the fruits were picked records were taken as to the location of each of the fruits as to cluster and position of the fruit on the cluster. The cluster nearest the base of the plant was considered as the first cluster and the other clusters on the plant were numbered in ascending order. The fruit nearest the main stem was con- 20. sidered as the first fruit on each of the clusters and the others were numbered consectively to the end of the cluster. Where a compound inflorescence occurred the fruits on the two branches were considered from their nearness to the main stem and not in consective order on each of the branches. When the harvesting was completed it was possible to locate each fruit on a given plant. Such data were secured from approximately 500 plants and those for 100 plants of the Grand Rapids variety showing the location of the fruit as to clusters and the corresponding percentages of blotchy fruits are pre- sented in Table VI and the plotted data in Figure 8. Table VI - Position of fruit as to cluster and percentage of green spot produced on 100 plants of Grand Rapids variety in the spring of 1932. Cluster Total number Number spotted Per cent. of number fruits fruits total spotted 1 174 12 6.89 2 416 42 11.22 3 442 77 17.42 4 475 74 15.58 5 691 119 17.22 1 6 503 146 29.02 7 411 175 42.57 8 297 166 55.89 9 190 128 67.36 10 76 50 78.94 11 25 21 84.00 9 3 Iota). Harvested. o S '3' -& Pet-g Cent 0 10 I Fuswre 5 Pcsmcvx 03 FYIA‘VC on Plant and B\otc.\I\L3Rxcevxwx% I z .3 E, 5 e 7 a 7 Classex 5V0“ Base. es Plant I/ ‘t \ ° Peat ° Catt“ 61 «6on 100 90 70 C‘ 0 IO As is shown in Table VI, approximately two-thirds of the fruits were located on the lower five clusters and after the fifth cluster the number of fruits decreased materially with only a small number of fruits setting on the upper clusters. This condition was undoubtedly brought about by high temperature and excessive transpiration during June when these clusters were blossoming. The per cent of blotchy fruits increased materially after the fifth cluster and from this cluster to the eleventh cluster the increase is practically a straight line function. These data would further indicate that as the fruits on the lower clusters are removed from the plant the conditions which underlie blotchiness are greatly intensified. Figure 9 illustrates the location of both the blotchy and normally ripening fruits of one of the plants. This illustration is based on actual data for a single plant of the Grand Rapids varxety and may be considered as typical of the condition as it has been observed for three seasons. The variations in the locations of blotchy fruits as found on a single plant Should be sufficient evidence that the disorder is not the result of any invasion by fungi, bacteria or virus and that it is purely physiological in nature. If green spot increases as the plant ages and the fruits are harvested from it, it is logical to expect the percentage of blotchy fruits to increase as the inflorescence lengthens. However, when fruits in the same position on all clusters were considered collectively, no significant differences were noted, as is shown by the data given in Table VII. L‘ E $€W A . NOWAQ\ RwevxmchYuuts @ B\ 013th Fruuts VIC Pat (amt 05 SMSQQQ B\ot.c.\t\\\ ‘ r J I i 9 J”; Loce’oo“ 0’3 b\0tfi\\\§ mes 22. Table VII - Position of fruit on the cluster and amounts of green spot produced on 100 plants of the Grand Ra ids variety in s ring of 1932. Position on Total number Number of Per cent of cluster of fruits spotted fruits total spotted l 566 151 26.67 2 539 163 30.24 3 481 138 28.69 4 472 134 28.38 5 411 113 27.49 6 327 67 20.48 7 263 73 27.75 8 207 62 29.95 9 132 36 27.27 10 and over 302 83 27.48 Many commercial greenhouse tomato growers express the opinion that green spot is more prevalent where the fruits are (exposed to direct solar insolation. It was difficult to secure zaccurate data regarding this question but numerous observations (did not reveal that tlis was true with blotchy ripening but may tnave a definite relation with "green back." As many blotchy jfruits were found under completely shaded conditions as were :found where the fruits were exposed to direct solar insolation. Location of Plants and Green Spot Plants located in the rows to the outside and ends of the bends have been observed invariably he produce larger yields than SjJnilar plants in the inner rows and it has been further observed 'Umat the former are usually more severely affected with green 23. spot. is mentioned under the discussion of methods, the eXperi- mental house is divided into two ground beds by an 18 inch con- crete walk which extends around the ends and sides of the beds. Six rows 28 inches apart and the plants set 20 inches apart in these rows is the planting system followed. In the spring of 1932 data were recorded on plants in 20 rows across the east bed of the house, that is, 20 plants in each of the six rows constituted the individual units. The row nearest the center walk was considered as row 1 and the others were numbered in consecutive order across the bed, so that row 6 was the outside row nearest to the heating pipes which are suspended on the outer wall of the house and also nearest to the side ventilators. The average yield per plant along with the percentages of blotchy fruits produced in each of the rows are given in Table VIII and are presented graphically in Figure 10. Table VIII - Amounts of green spot produced on plants in different locations in the bed in spring of 1932. k I Row Yield per Total number Number of Per cent of number plant in of fruits spotted total spotted pounds fruits 1 7.40 763 207 27.12 2 6.30 601 158 26.28 3 5.44 637 110 17.26 4 5.38 615 100 16.26 5 6.85 671 175 26.08 6 8.67 764 .256 33.50 F\%\LV‘€. (O L. ocetwvx 03 9\evu.s \\ Bea and 6\etc.\ms R\ YQYMWA 7 i) .5 ,J 9' 5. 6 c‘i :' 7) t, ’2 i 5 f 99 s‘ .1 ‘ KB 7 \\)’; a ’0’ l )3 ‘s ,(E I ‘\ I9 O ’ \ .0 K ’ J ‘ ’9 o ’ \(‘t T \ I \ I \ c \ . \ --..J \5 2. 6 ‘f . J . Row \vx Badrvest. to fleet. 6 Per Cont?" $1. stakes" N o 157 24. Date of Planting and Green Spot Various investigators in this and neighboring states, as well as observations in commercial ranges, have shown that a direct relation exists between the date of planting of the Spring crOp and the resulting yields. In general the later the seed is sown after December 15, the smaller are the yields from the respective plantings. Three plantings approximately one month apart were made in 1932 in order that any effects of size and age of plant as well as climatic conditions prevail— ing during ripening could be studied in their relation to blotchy ripening. The seedling was made in each case from six to seven weeks before the plants were bedded. The seed was sown in flats and the young seedlings were grown in three-inch clay pots until they were set in the permanent beds. No effort was made in any case to harden the plants and as a whohe they were in excellent condition when bedded on February 12, March 10, and April 15. Thirty-five plants constituted a plot and all plant- ings were grown as nearly as passible under the same conditions. The first ripe fruit were picked from the plants bedded February 12 on May 5 and the peak of the first fruiting cycle was reached between June 6 and 12 with a second peak nearly equal to the first between July 11 and 17. Those bedded March 10 ripened their first fruit May 20 with the first peak between ripe fruits were picked from the last planted plot on June 9. The first peak from this plot was from June 20 to 26 and the second between July 25 and 31. At the end of the harvesting season the plants of the first two plantings were practically the same size while those of the April 15 planting were can- siderably smaller. T‘r yield per plant in pounds, the total 25. number of fruits and the number and percentages of spotted fruits from the different plots are given in Table IX. Table IX - Yield per plant, number of fruits, number and percentage of blotchy fruits from plants bedded at different intervals. Date set Average yield Total number Number of Per cent of I in bed per plant in of fruits blotchy total fruits pounds per plot fruits per blotchy plot Feb. 12 10.72 1683 363 21.56 Mar. 10 9.38 ' 1616 186 11.51 Apr. 15 9.02 1215 107 8.80 The data given in Table IX and the plotted data in Figure XI show that the earlier planting made February 12 gave the largest yield per plant and the April 15 planting the lowest while the planting made March 10 was intermediate. The same re- lationship was found between the different plantings when the per cent of blotchy fruits were considered. 'The weekly variations in the per cent of spotted fruits along with the prevailing temperature conditions are given for the various plantings in Table XI and in Figures 12, 13 and 14. Effects of Fertilizers Before the fall crOp was bedded in 1931 a series of ferti- lizer plots were established for the purpose of studying any effects of applications of nitrogen,phosphorus and potassium alone and in combination on the amounts of blotchy fruits pro- duced. One of the ground beds was divided into six plots each, 14.5 ft. by 8.33 ft. in size by inserting boards two inches Y\ 216" Vownds Vex ?\ev\t N M Fab 1?. Flame. H Date. P1¢wun and. B\o mk\\R\Y€“\V\% Mar 10 Date. E) edhed '20 a 7999C Cent. :5 Total Blott‘fvz 26. thick across the bed from one concrete walk to the other, to a depth of 18 inches. The boards extended approximately two inches above the surface of the soil to prevent any washing of soil or nutrients between the plots. As pre- viously stated, the soil was a fertile sandy loam which had been used for the preceding seven years for the production of tomatoes and had been manured annually with supplementary applications of chemical fertilizers high in phaephorus and potassium. Before the fall crop was planted in 1931 the soil was sterilized and all plots received an application of approximately 25 tons per acre of well rotted horse manure. The manure and fertilizers were applied to the sur- face and mixed well with the upper ten inches of soil before the plants were set. The following treatments were given: Plot 1.- Nitrogen only - 800 lbs. ammonium sllfate at planting plus 250 lbs. every 10 days after third cluster had set until 3 weeks before final harvest. Plot 2.- Phosphorus only - 2000 lbs. 0-20-0 at planting. No additional fertilizer given. Plot 3.- Potassium only. - 2000 lbs. 0-0-20 as KCL at planting plus 200 lbs. K01 every 10 days after third cluster had set until 3 weeks before final harvest. Plot 4.- Check - no fertilizers applied except manure at time fall crop was bedded. Plot 5.- Phosphorus and Potassium - 2000 lbs. 0-20-20 at planting plus 200 lbs. KCl every 10 days after third cluster had set until 3 weeks before final harvest. Plot 6.- Phosphorus, Potassium and Nitrogen - 2000 lbs. 0-20-20 at planting time plus applications of 250 lbs. Ammonium sulphate every 10 days after third cluster had set until 3 weeks before final harvest. Thirty plants of the Grand Rapids variety were bedded in each plot the first week in September 1931. Because of the de- layed planting and poor light conditions these plants gave only 27. fair yield. Less than 0.5 per cent of the fruits were blotchy and these were uniformly distributed on the various plots. Practically all of these fruits develOped in the outside row nearest to the heating pipes where the temperature averaged 4 to 5 degrees higher and conditions were favorable to more rapid transpiration. This crOp was removed in January and before the spring crop was bedded the following treatments were given: Plot 1 400 lbs. Ammonium sulfate Plot 2 1000 lbs. 0-20-0 Plot 3 . 1000 lbs. 0-0-20 Plot 4 Nothing Plot 5 1000 lbs. 0-20-20 Plot 6 1000 lbs. 0-20-20 The plants for the spring crop were set the last week in February. One half of the plants in each plot were from a pure line of the Grand Rapids variety and the other from a pure line of the Blair Forcing variety. The varieties were so planted that alternate plants were of the same variety. Additional applications of ammonium sulfate and potassium chloride at intervals of 10 days were given, as outlined for the fall crop. The harvesting period extended fnem the last week of May to August 1. The Blair Forcing variety on all plots produced a high percentage of "hard back" fruits and as these were included in the records as blotchy fruits the data for this variety are not given. A negligible quantity of "hard back" fruits appeared on the plants of the Grand Rapids variety and the percentages of spotted fruits for the different fertilizer plots are given in Table X. 28. Table X - Effects of fertilizers on the percentage of blotchy ripening in spring_of 1932 Per cent of Fertilizer treatment blotchy fruits Check (4)* 18.55 P - alone (2) 17.96 N - alone (1) 16.92 K - alone (3) 14.22 P plus K (5) 15.93 PK plus N (6) 8.28 * Indicates the number of the plot The data presented in Table X, though for a single season and from a limited number of plants, would indicate that on this particular soil heavy applications of nitrogen, phosphorus and potassium alone and phosphorus and potassium in combination had little, if any, effect on the percentage oftflotchy fruits produced. 'However, where a combination of phosphorus and potassium in equal quantities applied before planting and supplemented with top dressings of ammonium sulfate during the development of the fruits, the system how followed by the better growers, reduced the injury by approximately one-half. The data would further indicate that factors other than those of a rultritional nature are Operative in bringing about the conditions :resulting in blotchiness. No data are available as to what results may be expected 111 this section on a less fertile soil or a soil deficient in one (I? all of these nutrients. Observations in commercial ranges vfllere the soil types and fertilizer treatments vary widely have rust given any indications that applications of fertilizers are 29. the solution to this particular problem. Temperature and Green Spot The seasonal variations in the severity of green spot in- dicate that temperature may be one of the important seasonal factors involved. Greenhouse temperatures on bright sunshiny days are from 15° to 25°F. higher than outside temperatures, even when the ventilators are open and no artificial heat is used and, as the mean daily outside temperatures, as well as the length of day and the number of clear days, increase materially during the maturation and ripening of the spring cr0p, a relationship between temperature and severity of green spot undoubtedly exists- It is not an uncommon occurrence during June, July and August for greenhouse temperatures from 10 A.M. to 5 P.M. to be above 100°F. while the corresponding night temperatures may fall to between 60° and 70°F. Hybro- thermographic records from February 1 to August 1, 1932, as well as records of weekly variations in the per cent of green spot, were available for studying this phase of the problem. In order to reduce the temperature data to a workable basis for comparison, 70°F. was chosen as an optimum temperature for'the plants during the daylight hours. Weekly variations in immnperature were calculated from this basis; that is, the tenmerature in excess of 700 was multiplied by the number of incurs the excess existed. AS an example, if an average tempera- Inxre of 80°F. prevailed for two hours, the excess would be 10 x 2 OI' 20; if an average of 85° for the next two hours, the excess WCHJld be 30 or the total for the four hours would be 50. Thus thug sum of the hourly excesses for the daylight hours was taken €18 'the weekly accumulated excess and compared with the weekly 30. variations in the percentages of blotchy fruits from the three plantings of 35 plants each in the date of planting test and also from 100 plants grown in another test. These datacre given in Table XI and the plotted data are shown in figures 12, l3, l4 and 15. That temperature exerts an influence on the quantity of blotchy fruits is well shown in figures l2, l3, l4 and 15 where the per cent of green spotted fruits follows rather closely the variations in the weekly excess temperatures. It is interesting to note that in most cases there is a lag of approximately one week between the influence of temperature and the amount of blotchy fruits, except in the case in figure 15 for the twelfth week where a large picking was made on Saturday of that week. Table XI - The 31. relation of temperatures and green spot for the Grand Rapids variety - Spring, 1932. Ileeks of Accumulative Per Cent 31°t°hy Fruits harvesting temperature 'First* Second7 Third7 lOOplwds season excess 70°F. planting planting planting inlflbed 1 4/25-5/1 88 2 5/2-5/8 552 0 5 5/9-5/15 268 0 4 5/16-5/22 156 7.69 0 5 5/25-5/29 282 14.05 0 6 5/30-6/5 572 12.98 0 7 6/6-6/12 660 12.98 1.97 4.55 0 8 6/13-6/19 1252 19.01 2.98' 2.27 11.00 9 6/20-6/26 1084 16.40 6.29 17.87 15.82 10 6/27-7/5 856 14.90 0 --—-- 11.51 11 7/4-7/10 1528 ------ ---- 7.60 14.91 12 7/11-7/17 1892 10.04 2.56 6.66 15.25 15 7/18-7/24 1498 58.88 18.91 15.27 11.27 14 7/25-7/51 1246 45.52 56.55 5.79 19.12 15 8/1-8/7 ---- ----- 9.09 5.00 ----- Transpiration Studies Since blotchy ripening is apparently closely associated ‘with.the vascular tissues of the fruit and as conditions favoring excessive transpiration have been observed to increase the amount of blotchy fruits, the writer endeavored to study the trans- piration of tomato plants under greenhouse conditions during June and July, 1932. as that described by Marshall (12). The method used was essentially the same The plants used were grown under'conditions as previously described and at the time of the tests were approximately two meters tall and had been topped so d 0 vs QIwnmg hue ‘3 x: O at) O J” 0 N 41 0x mew/dd»? II 4 0,909 W45» 0) 9.01 «a 2 0a a 0 k w a. a. 0 M \.... , 1!..o\\ fifvéflo 99:» . Ao‘,§ww $9 A32090/O 06.0 agave? 5W... .2 d930,» O 3 m Jam'n‘axadeaJ’ i 6 O 9 'Is 3001’ S 633%; 000“ m4 §\\\3101Q\ 1‘?) ABA 8 3 2 'O :- §~ fix «\ mXMWY/II floryunw fluiufiuv 9.01 agoaeoswbwfiua . \.....Il .... Q‘. 000:. c 0 .tt. .... ~ 0 0 kW If. N Q .\W% 0!: _N on. lo a lo. a»: ..... hi 9“ nog’V‘cfim 42.3.00 Ao‘ztuV/Mw flee/330 4‘0 avivofiyiexr 0’ dydfipb pooh § Awe/L 000— ooou a 001 563313 .— ‘3 Jemima; A g 1MB) 6.; the, 9m O h 0 or 41 n4 36,937 limo/yaw $559,961 M a t 9‘ m 0 k w m. 4.9 t... d h. .\~\ 0 .0 to w .omuhd‘ m \Mwo \fi can 0. o .7 .00 |% 0.6.9 Q I Q .8 00. an. QQ 0000 Q as 0.4% \Q ~ s o Q Q Q flezzvrroflw V344) a; at!!! #9540? ’% (fade/0 459. abducvuw 1 NP 4. team .‘ AWE]. O o .3. 5’. 5.0L $62613 —- “annexe i o 8 M awn 101$) awe) ”d s e 5 O ‘0 MV/dl} I. flo/vaw A2360 73.61 inxdatexmokohrnxg Q \ s 6‘6 ’00. U 6Q wed as. cats s .xfiu AWtBV. .v. .6 0 ton“. _ ml. c $9 I, .9. e. o of o c Q o Q 0! QQ o. 00 a o lo a “II _% l . I u ’0 Q I Q o o If u I o . . o 5 o o 00 Q a. 4963 v2.7»). «56$ 00. . . Ao!z.£d?¢ //4Jo/n.v 42,4 dvfivOQOV‘uP m; . dyfiflcf— 8 9 Awe). cook 00.2 ssooxg —- Danna Xe H.0L 32. that practically all of the leaves were fully mature. There were approXimately twenty-five leaves to a plant with a total leaf area of about 10,000 square centimeters. ‘The fruits on the plants had a total weight of between two and three kilograms per plant. Practically all of the above ground portions of the plants were used except a small portion of the main axis which was immediately recut under water when the potometers were connected. All connections were made under water in order to exclude any air pockets. The apparatus consisted of a 100 0.0. burette connected to the, plant by heavy rubber tubing. A11 rubber connections were made air—tight by wrapping and twisting florists' wire around them. 'Because of the angular and ribbed nature of the stems considerable difficulty was experienced in securing air-tight connections. This was overcome by moulding a plastic, water—proof wax preparation around the stem before it was cut and submerged in water. The connection was then made by slipping the rubber tubing over the stem and up over the waxed area where it was wired. Care was exercised to prevent any of the wax from coming in contact with the cut surface. The water was supplied from the burettes located at approximately the same level as the base of the excised plants which were suspended in their normal position from overhead wires. The burettes were filled from another burette so that any error during the filling was eliminated. Burette readings were made every ten minutes and temperature readings were made at the same interval. Immediately after the tests the leaf areas of the plants were determined by measuring their lengths and reading the areas from a curve previously determined by Porter (15). .m.‘ ‘,""- . p..._.'._' "aqua-[pu- ‘ : -.‘ u ‘. 55. Some 30 tests at various hours of the day and under different weather conditions were made. Only the record secured on July 9 is given since it is the most complete of the diurnal trend. This was, however, checked with data secured at various times during the day on similar days and under similar conditions. The plants used on July 9 were set up between 3 A.M. and 4.x.M. and the readings were begun shortly before sunrise and continued throughout the day until 11 P.M. E Three plants, each connected to a separate potometer, were used and the data, given in Table XII and shown graphically in i~d Figure 16, are the means for these plants after corrections E-' for differences in leaf areas were made. ' Excised clusters of fruit, which were representative of the quantity of fruits found on the plants at the time of the tests, were set up by connecting the potometers to the main axis of the inflorescence as described for the excised plants. The areas of the fruits were subsequently determined by . quartering the fruits, tracing around the flattened quarters c>n heavy wrapping paper and measuring the tracings with a 'planimeter. The area of the fruits used on July 9 was 1333 square centimeters and their weight was 1589 grams. fPhe amount of water used by the fruits per hour was calculated on the basis of 10,000 square centimeters in order that it may be comparable to that transpired by the same leaf areas. These data are also given in Table XII and Figure 16. z o 3 u w R .c 0 .A» _ on H O h A \\ ow «\a w W 03 0~ fl/OD no 9501 s w m. r a «£3. .3 t S I. /. IIIJI'l afiflflu.‘ o’. \ l./ \. . . o‘. #14? 'II E a.. . I. o IV D o— f. N: ... a» m... ’1» ‘0 O \\ on 5‘ 0O ‘~III.I I \\\ 00. use I" \\\\ IIIU‘§\ a Q. 0' \\ run)... s «2: n w a)!» ./>9.¥0.7/Vw/>O.flx £6 arc/P /O