EHIZOPUS EOT OF STRAWBERRIES IE" TRANSIT. 13 
and allowed to dry in the shade of the packing house or even in 
the sun. 
SOURCES OF INFECTION BY RHIZOPUS NIGRICANS. 
INFECTION IN THE FIELD. 
Infection with Ehizopus apparently could occur either in the field 
before picking or in the packing shed. Microscopic examination of 
diseased fruits (13), as well as observations and inoculation experi- 
ments in the laboratory, the field, and the packing house, indicates 
that Ehizopus rarely, if ever, enters berries through the uninjured 
epidermis. The proportion of injured or wounded berries in a field 
usually is low. Some fruits, of course, are injured by insects or 
birds, but rapidly growing strawberries have a strong power of 
preventing infection by the quick covering of wounds with an im- 
pervious protective layer. 
This was well illustrated in an inoculation experiment made in 
the field on February 23, 1916. One hundred sound berries of 
various ages from one to seven days before maturity were wounded 
with a sterile needle while still on the vines. One hundred similar 
berries were wounded in the same way, and a small quantity of 
dirt from underneath the plants was forced into each wound. One 
hundred wounded berries in another series were inoculated with 
mycelium from a pure culture of Ehizopus. These berries were 
picked when mature and their condition compared with that of 
100 uninjured berries. No rot was apparent among the fruits 
merely wounded. All but two of the berries into which dirt had 
been introduced matured without showing any signs of infection; 
a callus layer underneath the wound was evident in each case. 
Two exceptions showed at the end of five days soft spots on one 
side of the wounds. All of the berries inoculated with Ehizopus 
mycelium developed into typical leaks in from two to four days, 
most of them before the maturity of the berry. Leaky berries 
are rarely, though occasionally, found in the field. 
Similar experiments were performed with ripe berries at the 
time of picking and the berries shipped in iced containers to Wash- 
ington. In this series some of the fruits were wounded also with 
pine needles from the mulch. Eecords taken after shipment showed 
the following percentages of fruit still sound: Unwounded, 72 per 
cent; wounded with sterile needle, 61 per cent; wounded with pine 
needles, 62 per cent ; dirt introduced into wounds, 42 per cent. Those 
inoculated with Ehizopus mycelium had become a mass of rotten 
berries before reaching destination. Wounding the fruit with pine 
needles gave practically the same result as the use of a sterile needle. 
The introduction of soil into the wounds apparently induced con- 
