LIBRARY STATE PLANT BOARD January 1944 E-611 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine CLOSED FIGS IN RELATION TO INSECT ATTACK AND DISEASE INFECTION By Perez Simmons and Charles K. Fisher, Division of Fruit Insect Investigations The purpose of this brief discussion is to bring together cer- tain facts about the protection afforded by tight eyes in figs against invasion by insects and the various organisms that cause spoilage, and consequent loss to growers, which in some seasons is a serious matter. Producers of figs have been aware of most of these facts in a general way, and the present report can only strengthen the evidence that a valuable improvement would result if the character of tight eyes could be established. The term "closed figs" as used herein refers to figs which are closed at the eye by overlapping scales so that there Is no visible opening, or only a minute opening, to the interior. Figs which are "self— sealed" with hardened syrup are not considered. This type of sealing has been found to be of little value since it appears to be a product of seasonal conditions. Experimental sealing of the eyes of small green figs by repre- sentatives of the California Agricultural Experiment Station, the Bureau of Entomology and Plant Quarantine of the United States De- partment of Agriculture, and others has shown that figs which are kept sealed during development are resistant to infestation by in- sects and to infection by diseases. Sealing figs on a commercial scale does not appear practical, although it can be done by spraying. To obtain a cross— sectional record, figs of the Adriatic and Calimyrna varieties were examined by the writers at a storage plant after the fruit had been graded into 6 sizes Standard, Choice, Extra Choice, Fancy, Extra Fancy, and Jumbo. The figs had not been sorted after receipt from growers. In all grades there were figs of all degrees of closure, from those completely closed to those wide open. From each grade all the closed figs and those with the most widely open eyes were removed. There were no records of the places of origin of the figs, which doubtless were representative of a num- ber of orchards. About 38,000 figs were examined, as shown in table 1, which follows, cocamples of figs of both varieties, of all size -2- grades, and with closed and open eyes are shown in figures 1 and 2. These examples are not necessarily typical, but they represent the run of fruit in the lots examined. For purposes of photography the figs were flattened. Table 1. Occurrence of closed figs in random samples. Adriatic Calimyrna Size Number of Closed figs, Number of Closed figs, grade fig s examined percent figs examined percent Standard 3,202 31.9 4,675 10.0 Choice 2,840 31.4 2,685 7.7 Extra Choice 3,946 13.7 3,866 7.5 Fancy 3,597 10.4 2,841 7.7 Extra Fancy 3,083 8.8 2,373 7.0 Jumbo 2,824 13.3 2,268 5.3 The figures in table 1 show that closed figs were generally dis- tributed among all size grades of both varieties, although more common in the smaller figs, which suggests that it is normal for such figs to be produced as a part of many crops. The writers do not know whether or not there are trees or branches which produce them to the exclusion of open figs. The records for the Calimyrna variety show that these figs, which require caprification, do not need open eyes at any stage of development; in fact, Calimyrna figs usually are closed by scales at the time the caprifyiiig insect forces its way into the small green fruit. Among the Extra Choice grade of Adriatic figs were a few dozen with eyes that were folded or crimped, as illustrated in figure 3. These were well closed, and there is a possibility that they represent a. sport (mutation) which could be reproduced by grafting or by rooted cuttings. Examination of 100 closed and 100 open figs from each grade of the 2 varieties showed clearly the protection afforded by closed eyes. Although some individual figs contained more than 1 type of material causing spoilage for example, insects and souring each unsound fig has been recorded only once, insects taking precedence over diseases, and diseases over dirt, in accordance with established practice. These results are given in table 2, which follows. The figs from which the data were obtained were of the crop of 1937. They are, therefore, not necessarily representative of deliveries of figs of more recent years, but the figures do illustrate the improve- ments in quality that accompany the closed— eye character. Table 2. Extent of spoilage in Adriatic and Calimyrna figs having closed and open eyes, taken from the same storage boxes Nature of spoilage Percent of spoilage in Adriatic figs Calimyrna figs Open Closed Open Closed Infestation Dried— fruit beetle Raisin moth Vinegar fly Miscellaneous Diseases Smut and mold Souring Endosepsis Dirt (inside) Total 1.0 0.2 1.2 0.2 2.3 .8 1.7 .2 .3 .2 9.7 .5 11.7 1.0 5.5 .8 3.3 .3 2.0 .2 3.3 .8 22.1 2.3 20.9 1.9 The percentage of spoilage was consistently greater in figs of the larger sizes, the eyes of which, on the average, are larger. The percentages in the open Adriatic figs ranged from 6 for the Standard size to 39 for the Jumbo ; for the Calimyrna the range was from 7 to 31 percent-. The following observations may be made from table 2: (1) The closed dried figs were remarkably free from spoilage, which would not have been the case had the figs been open at any time during growth and ripening. (2) Closed figs were protected even after falling to the ground and during drying and storage. This is shown by the figures for infes- tation by the raisin moth, an insect which seldom infests figs on trees. During September 1943 the records given above were supplemented by counts of closed figs on the ground in orchards. A 50-fig random sample was examined under 20 trees in each of 14 orchards, a total of 14,000, half of the Adriatic variety and half of the Calimyrna. The plantings were in Tulare, Fresno, and Merced Counties. Closed figs were found in all samples of the Adriatic; the average percentage of closed figs was 17.5. Figs of the Calimyrna variety were closed to an average extent of only 1.5 percent. The indications are that the closed— eye variation occurs gener- ally but that there are differences in this respect between localities and seasons as well as between varieties. The existence of trees or branches bearing closed figs exclusively and year after year is at present a matter for speculation; yet the benefits to the industry through reduction in spoilage would, in time, be great if trees or branches bearing such superior fruit could be found and grafting wood were widely distributed. Growers might well be on the lookout for trees or single branches bearing figs that are closed when dry. 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