Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


1. Soggy breakdown, a non-parasitic disease which develops at low temperatures, is described.

2. Soggy breakdown is distinguished from "internal breakdown" and from "physiological decay "or the breakdown which accompanies senescence. The name "mealy breakdown" is suggested for the latter.

3. Grimes and Wealthy apples have been found to be very susceptible to soggy breakdown, while Jonathan, Arkansas, Willow and Northwestern Greening appear immune to the disease.

4. The initial appearance of soggy breakdown on Grimes in cold storage occurred during the early part of December.

5. Differences of 2° or 4° F. in cold storage temperatures markedly affected the development of the disease.

6. No serious amount of soggy breakdown occurred on the fruit stored at 36° F., or on fruit held in common storage. The disease did not appear in common storage.

7. Soggy breakdown developed most seriously at 30° F., as compared to its development at 32 °, 34° and 36° F. The most satisfactory temperature for the storage of Grimes was found to be 36° F.

8. When stored immediately after picking, late picked fruit was more susceptible than early picked.

9. Delayed storage materially increased the susceptibility to soggy breakdown. The influence of delayed storage, however, appears to be linked with the time of picking.

10. Exposure of the fruit to free circulation of the storage room atmosphere prevented the development of soggy breakdown on delayed storage fruit during one storage season, and caused visible shriveling of the fruit.

11. Direct access of the fruit to air during delayed storage did not reduce development of the disease in storage.

12. Evidence obtained suggests that apples become susceptible to soggy breakdown after certain periods of exposure to ordinary temperatures.

13. Soggy breakdown appeared to be more serious some years than others.

14. Grimes from the Wenatchee apple district of Washington and those from central Michigan were as susceptible to soggy breakdown as Grimes from Iowa.

15. Grimes in commercial cold storage developed as much soggy breakdown as those at the same temperature in experimental storage.

16. The quality, condition and attractiveness of Grimes, stored at 36° F., were superior to those stored at the lower temperatures.

17. Grimes stored at 36° F. softened only slightly more than those at lower temperatures.

18. An increase in the tendency to apple-scald in Grimes, due to a slightly higher storage temperature. was successfully averted by the use of oiled paper wraps.

19. With well graded, high quality fruit, the increase in loss due to apple rot fungi at 36° F. was insignificant.



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