460 Journal of Agricultural Research voi. xxii. no. 9 



growth started earlier and proceeded more rapidly on the agar than on the 

 peaches. The fungus finally made a slow growth on the agar at 5°, but 

 on peaches it made no growth at this temperature and with the exception 

 of a few overripe peaches none at 7K°- 



These contrasts in the behavior of the two fungi can probably be partly 

 explained by the fact that Monilia is a parasite and adapted to growth on 

 living material, while Rhizopus is a saprophyte and suited to growth on 

 dead material, like the agar or inactive living material such as overripe 

 fruit. It is interesting to note that with both fungi unfavorable 

 food material and unfavorable temperatures work together in delaying 

 growth, one unfavorable factor adding to the other in delaying or inhibit- 

 ing activity. 



A study of figures 3, 4, 5, 6, 18, and 20 gives a detailed idea of what 

 can be expected of Monilia rot at any transportation or storage tempera- 

 ture. The results in the last two figures have been obtained by averag- 

 ing those of the first four figures and therefore stand as a summary of 

 the various experiments. With fruit that is infected with brown rot 

 (Monilia) 3 days at 15° C. would result in heavy losses, 3 days at 10° 

 would mean badly specked fruit that would go down rapidly at that 

 temperature and that would be entirely destroyed by a day at "a higher 

 temperature. Brown rot cannot get started in 3 days' time at 7K°. but 

 by the end of the fourth day fruit at that temperature may be specked with 

 rot. In 6 days the fruit at 5° may be spotted, in 9 to 12 days growth 

 may be evident at 2}4°, and at the end of 3 weeks rots may have started 

 at 0°. Brown rot does not develop rapidly at the lower temperatures 

 even when well started, yet its later growth is inhibited far less than its 

 initial stages. 



A study of figures 8, 10, 12, 14, 15, 16, 17, 19, and 21 shows that 

 Rhizopus has more decided temperature limitations than those that 

 have been pointed out for Monilia. The results in the last two figures 

 have been obtained by averaging those of the first seven and therefore 

 stand as a summary of the various Rhizopus experiments. At 15° and 

 20° C. the growth rate of Rhizopus rot is practically the same as that of 

 Monilia rot, Rhizopus being a trifle more rapid at 20° and Monilia just a 

 little more rapid at 15°. At 10° Monilia rot develops more than twice 

 as fast as Rhizopus rot, and at 7^° Rhizopus is practically eliminated. 



Whether Rhizopus could make any start whatever at 7^° C. seemed 

 to be determined mainly by the maturity of the fruit. The curves of 

 figure 15 show that Rhizopus had not made a start at 7^2° in 11 days. 

 The peaches at that temperature were still free from rot at the end of 14 

 days, were removed to a warm room at that time, and were entirely 

 rotted with Rhizopus 2 days later. The results show that the fungus 

 was held completely in check at j}4° but was alive and ready for rapid 

 development when given a more favorable temperature. With the ex- 

 periments reported in figure 17, Rhizopus had produced evident rotting 

 at 7^° in 6 days. At that time only the ripest peaches were affected, 

 but at the end of 12 days rots began to develop on the greener peaches. 

 When once started at this temperature Rhizopus rot made a fairly rapid 

 growth. The results as a whole show that with the usual number of 

 days in transit for most peach shipments Rhizopus can produce little or 

 no damage at 10° and none at 7/^°. 



Figures 3 to 21, inclusive, show the development of the rots when the 

 fruit is stored at the given temperatures immediately after inoculation. 

 Figures 22, 23, and 24 show the effect of i day's delay at a higher tem- 



