l8 9 1 -] Bacteria of the Melons. 303 



Bacteria of the Melons. 



1 



BYRON D. IIALSTED. 



Early in July there were many complaints throughout the 

 country that the melon, squash and cucumber vines were 

 either not doing* well or dying from some unknown cause. 

 The first specimens to arrive were from Bangor, Me., followed 

 by others from the central part of New Jersey, a locality 

 famous for its production of cucurbitaceous fruits. 



The attacked vines vary somewhat in their appearance, but 

 generally there is a decay of the stem in proximity to the 

 root, and then the whole plant wilts and fails to grow. Some- 

 times one or more leaves will fall to the ground and rot away 

 before the balance of the plant is seemingly affected. This 

 is particularly true of the cantaloups, while in the case of cu- 

 cumbers the fruit may be the first to show the trouble. Here 

 the half grown cucumbers exhibit from one to a dozen or 

 more specks looking like " water cores," which increase in size, 

 until the whole of the fruit becomes a rotten mass, the firm 

 skin still holding the watery interior in shape. 



A microscopic examination of the decaying stems, leaves 

 and fruit showed that the decomposing tissues were teeming 

 with bacteria. This was to be expected, but it remained to 



prove that these germs could be the primary agent in the 



decay. Inoculations of healthy fruits were made in the usual 

 way by means of sterilized platinum wire, taking the germs 

 from the centre of freshly decaying cucumbers. It was found 

 that with no other fungus present these germs were abund- 

 antly able to introduce a rapid decay into cucumbers, melons 

 and squashes. Cucumbers seem to be the favorite, and in 

 them the decay is the most rapid. It will run from one end 

 to the other through the succulent centre of a four inch fruit 

 in a single day. From the placentae the rot spreads towards 

 the surface until all is a noisome pulp inclosed by the skin 

 which may remain unbroken if the inoculation has been made 



at the stem end. 



The next step in the study was the application of these 

 germs to healthy plants in the field. This was done by means 

 of a flamed glass tube one end of which had been drawn out 

 into a long point. By means of this, the germs in liquid, 



_^ „__ !^^^^^^^^m mi m 1 MW iM M ^^-ri j —i n — ^^Ti ■ 1 — ' — ^i^ ^— — ■ h^— ^^^^— ■ 



1 Read before Section F. A. A. A. S.. Washington meeting, August, 1891. 



