170 Report of the Botanist of the 



duce dealers who were accordingly suspicious of all onions coming 

 from Orange Co. The same rot was also common in the onion 

 fields of Madison Co., but the losses from it there were not nearly 

 so great as in Orange Co. 



Thie rot was of two kinds: (1) One which starts at the bottom 

 of the onion, and (2) One which starts at the top or " neck." 

 The latter kind of rot was much the more common, constituting 

 perhaps eighty per ct. of the total amount of rot. Where the rot 

 had started at the top the bulbs were frequently sound in ap- 

 pearance, but rotten within. Oftentimes it was difficult to deter- 

 mine, before cutting, whether or not a bulb was rotten. In sort- 

 ing, the customary test for soundness was to press down with the 

 thumbs close about the " neck " of the onion. If it was hard the 

 bulb was sound, but if soft it was usually rotten inside. Onion 

 growers speak of such onions as being " weak in the neck." Upon 

 cutting open the affected bulbs it was generally found that two or 

 three of the outer scales were perfectly sound while the remainder 

 of the bulb was a rotten mass. Frequently a single scale would 

 be entirely rotten from top to bottom and clear around the bulb, 

 while the remaining scales upon both sides of it, were perfectly 

 sound. Such specimens cut crosswise showed the rotten part in 

 the form of a ring. (See Plate X.) Again, a perfectly sound 

 scale would be found between two rotten ones. (See Plate XI.) 

 The rot appears never to spread from one scale to another later- 

 ally, and this peculiarity furnishes the most reliable means for the 

 identification of this rot. The organism causing it is unable to 

 pass through the uninjured epidermis of the scale. The passage 

 from one fleshy layer to another is effected at the base of the bulb 

 where they unite. Upon reaching the base of the scale in which 

 it is working th,e rot commonly stops, and this accounts for the 

 large number of cases in which one or two scales are rotten while 

 the remainder of the bulb continues sound. Under certain con- 

 ditions the rot does not stop at the base, but works its way into the 

 bases of other scales which it then follows upward destroying the 

 whole bulb. 



