STYLAR-END BREAKDOWN IN PERSIAN LIMES INFLUENCED

Transcription

1 344 FLORIDA STATE HORTICULTURAL SOCIETY, 1968 Figure 5. Sugar apple infested with a mealybug (Thailand). for introduced predaceous or parasitic species from similar areas. Uniform or constant tem peratures may be another explanation for favor able media in an islandic society, whereas on the wide land areas of continental expanses more variation occurs over day- and night-time hours. STYLAR-END BREAKDOWN IN PERSIAN LIMES INFLUENCED BY TEMPERATURE AND BRUISING T. T. Hatton, Jr.1 and W. F. Reeder Market Quality Research Division Agricultural Research Service U. S. Department of Agriculture Miami lpresent address is Market Quality Research Division, Agricultural Research Service, U. S. Department of Agri culture, Orlando, Florida. Abstract Significant amounts of stylar-end breakdown in Persian limes were induced by exposure to elevated temperatures such as 100 and 110 F. or by the intentional bruising of the fruit on the stylar end. The two treatments combined re sulted in a comulative effect with significantly

2 HATTON AND REEDER: STYLAR-END BREAKDOWN 345 Table 1. Picking dates, treatment temperatures, and days of inspec tion of limes tested for stylar-end breakdown. Test No. Picking dates Treatment temperatures Inspection D S 1 Oct. 29, , 70, 100, 110 3, 6 Nov. 12, , 70, 90, 100 5, 8 3b June 8, I , 70, 110 3, A, U Oct. 30, , 70, 90, 110 3, 7, 10 Limes vere not bruised but vere subjected to temperature treat ments only. Stylar-end breakdown of limes vas prevalent in groves and pack inghouses at the time of all tests except No* 3, when little or none could be found. climes vere more than 2 inches but less than 2 1/4 inches in diam eter; limes in the other tests vere 2 1/4 through 2 3/8 inches in diameter. more of the disorder developing than with either Introduction of the treatments alone Most of the disorder Styiar.end breakdown of Persian limes is a developed within 1 or 2 days. physiological disorder which causes heavy losses When stylar-end breakdown of limes was not in Florida, especially in large and mature fruit prevalent in groves and packinghouses at the during late summer and early fall. Its presence, time of testing, significant amounts of the dis- however, can be extremely variable. The dis order could not be induced either by holding at order has previously been described and illuselevated temperatures or by intentional bruising. trated (3, 9, 10).

3 346 FLORIDA STATE HORTICULTURAL SOCIETY, 1968 Table 2. Effect of temperature and bruising on the development of stylar-end breakdown in Persian limes (Test 1, 1963)^ Temperature Affected fruit after and bruising x treatments 1 d*y 2 da^a 3 da*a 6 days 50 F. Unbruised 70 F. 100 F. 2b 65bc 58b 93c 68b 95c 75b 98c 110 F. Unbruised 100c 100c 1/ Data are cumulative and are based on a total of 40 limes per treatment. Data followed by different letters are significantly different at the 5% level (2). Using room temperature and an oven set at eral materials, after various storage times. 95 F., in conjunction with wrapping the fruit Stylar-end breakdown can be increased by in plastic, Conover (1) reported that increasing rough handling (5, 8, 11) and can be initiated the temperature or humidity increased the per- by injecting sufficient water into the center of centage of stylar-end breakdown. The greatest a fruit to distort the stylar-end U). When styamount of the disorder occurred when both tern- lar-end breakdown was not prevalent, bruising perature and humidity were elevated. had little or no effect on the incidence of the dis- Mustard (7) recorded the accurrence of sty- order, which varied widely with limes from diflar-end breakdown in limes packaged with sev- ferent groves (5).

4 HATTON AND REEDER: STYLAR-END BREAKDOWN 347 Table 3. Effect of temperature on the development of stylar-end break down in Persian limes (Test 2, 1963)^/ Treatment temperature ( F.) 1 day Affected fruit after 2 days 5 days 8 days Aa 42b 44b 44b 1/ Data are cumulative and are based on a total of 50 limes per treatment. Data followed by different letters are significantly different at the 5% level ( }. The purpose of this investigation was to gain insight into the rate and extent of development of stylar-end breakdown in limes subjected to increasing temperatures and the effect of con trolled stylar-end bruising. Materials and Methods Persian limes were harvested from groves in the Homestead, Fla., area. Controlled bruising was accomplished by pressing the surface of a wooden block against the stylar end of each lime with a pressure of 30 lbs., as measured by a pressure tester (6). Replicated samples of limes were placed in several chambers ranging from 50 to 110 F. Relative humidity in the chambers ranged from 80 to 95% as measured by an electric hygrograph. Fruit were inspected at various intervals from 1 to 14 days. Table 1 gives the details of the 4 tests. Results and Discussion Test 1. High temperatures accelerated the development of stylar-end breakdown in Persian limes (Table 2). Limes developed 100 percent stylar-end breakdown after 1 day at 110 F, with and without bruising. Conversely, stylarend breakdown did not develop in limes until the sixth day at 50, and then in only the bruised fruit. At 70 limes had slightly more stylar-end breakdown than at 50, but the difference was not significant; at 100 breakdown was significantly higher than at 70. The cumulative effect of bruising was also apparent and was significant in limes held at 100 for more than 2 days. Test 2. Table 3 shows the relationship be tween holding temperature and stylar-end break down, using limes selected a month later than those used in Test 1. Significantly more stylarend breakdown developed in limes held at 100

5 348 FLORIDA STATE HORTICULTURAL SOCIETY, 1968 Table 4. Effect of tenperature and bruising on the development of stylarend breakdown in Persian limes (Test 4, 1967)^ Temperature and bruising Affected fruit after treatments 1 day 2 days 3 days 7 days 10 days 50o F. la 26b la 41b la 43b 51b 52b 70 F. 32bc 90 F. Unbruised 45c 48b 48b 52b ; 52b 110 F. 31bc 69d 49b 72c 56b 81c 58b 82c 58b 82c 1/ Data are cumulative and are based on a total of 100 limes per treatment* Data followed by different letters are significantly different at the 5% level (2). F. than in those held at 50, 70, and 90. At ous findings concerning bruising as a single fac- 100 most of the stylar-end breakdown devel- tor (5). oped within 2 days. Test 4. Bruising had a significant effect on Test 3. Regardless of bruising, no stylar- the extent of stylar-end breakdown (Table 4). end breakdown was present in limes harvested Little or no breakdown was present in unbruised in June 1964 and held at 50 or 70 F., and limes held at 50, 70, and 90 F.; however, only 3 "fruits developed the disorder after 14 bruised fruit developed as much as 52 percent days at' 110. This test indicates that, when of this disorder at these same temperatures, stylar-end breakdown is not prevalent in the Limes held at 110 developed significantly more arfe, neither bruising nor temperature affects stylar-end breakdown than similar ones held at its' incidence. These results ar similar to previ- lower temperatures. Regardless of temperature,

6 STRINGFELLOW AND WOLFENBARGER: CARIBBEAN FRUIT FLY 349 most of the stylar-end breakdown developed within 2 days in bruised fruit. Conclusion Losses from stylar-end breakdown of limes can be minimized by careful handling to avoid bruising and by refregeration as soon as possible after picking. LITERATURE CITED 1. Conover, R. A Studies of stylar-end rot of Tahiti limes. Proc. Fla. State Hort. Soc. 63: Duncan, D. B Multiple range and multiple tests. Biometrics 11: Fawcett, H. S Citrus diseases and their con trol. 2nd Edition, McGraw-Hill Book Company, Inc., New York and London, 650 pp., illus. 4. Grierson, William and E. B. Pantastico The origin and development of stylar-end breakdown in Persian limes (Citrus aurantifolia (Christm.) Swing.). Proc. Trop. Reg. Amer. Soc. Hort. Sci. 11 (In Press) 5. Hatton, T. T., Jr. and W. F. Reeder Effects of source and handling on stylar-end breakdown in Persian limes. The Citrus Industry 48(9): Magness, J. R. and G. F. Taylor An improved type of pressure tester for determination of fruit maturity. U. S. Dept. Agri. Circ. 350, 8 pp. 7. Mustard, M. J Packaging and storage of Per sian limes. Proc. Fla. State Hort. Soc. 63: Pantastico, E. B., W. Grierson, and J. Soule Peel injury and rind color of Persian limes as affected by harvesting and handling methods. Proc. Fla. State Hort. Soc. 79: Pratt, R. M Florida guide to citrus insects, diseases, and nutritional disorders in color. Fla. Agr. Exp. Sta. 191 pp., illus. 10. Rose, Dean H., Charles Brooks, C. O. Bratley, and J. R. Winston Market diseases of fruits and vegeta bles: Citrus and other subtropical fruits. U. S. Dept. Agr. Misc. Pub pp. 11. Salama, S. B., W. Grierson, and M. F. Oberbacher Storage Trials with limes, avocados, and lemons in modified atmospheres. Proc. Fla. State Hort. Soc. 78: EVALUATION OF INSECTICIDES FOR CONTROL OF THE CARIBBEAN FRUIT FLY T. L. STRINGFELLOW Plantation Field Laboratory University of Florida Fort Lauderdale D. 0. WOLFENBARGER Sub-Tropical Experiment Station University of Florida Homestead Abstract Seven insecticides and a number of dosage and application procedures were evaluated for control of the Caribbean fruit fly attacking peaches, Suriam-cherry, and guavas. Applications made with conventional ground spray equip ment showed the most promising insecticides to be malathion, carbaryl, naled, and trichlorfon. Introduction Continued unchecked spread of the Carib bean fruit fly, Anastrepha suspensa (Loew) through more than 28 counties and attacking over 50 host plants in Florida have indicated the urgent necessity for establishment of practical control measures. A research program aimed at controlling this fruit fly for small growers and homeowners was initiated by entomologists of the University of Florida Institute of Food and Agricultural Sci ences early in This effort was an addition to other basic Institute studies and cooperative area control investigations with the Florida Department of Agriculture's Division of Plant Industry and the USDA Plant Pest Control Division. The purpose of these tests was to evaluate various insecticides, dosage rates, and possible intervals of application. Experimental Methods and Materials Tests were planned to include research with three preferred host plants, peaches, Surinamcherry, and guavas. Seven of the more readily available insecticides which might lend them selves to use by the small grower or dooryard fruit enthusiast were selected for evaluation. These proposed materials, rates, and applica tion procedures are summarized in Table..1. The large number of these potential treat ments made a complete evaluation of all treat ments at any one time and place on any one