263 



could be found since the tissues were well broken down. A few plants 

 which had been badly diseased showed evidences of partial recovery, 

 young branches growing from the lower part of the stem. Such plants 

 yielded unmistakable evidences of the work of Eeterodera. While the 

 lower end of the taproot had rotted away the plant had succeeded in 

 putting out a number of roots near the surface of the ground, which 

 had given it the first impetus for growth. These lateral roots possessed 

 an abundance of the galls, and the peculiar cracked and scabby lateral 

 galls in the upper portion of the taproot showed how thoroughly in- 

 fected the plant had been. But the richest specimens were found in 

 plants which showed the first external signs of the disease. In these 

 specimens not only was there a profuse development of the galls on the 

 lateral roots, but nearly the entire lower portion of the taproot was 

 affected, having large lateral galls, which from age were cracked and 

 scabby in appearance. This is the ai)pearance of the old larger galls on 

 all plants, and lays these parts under contribution to various putrefac- 

 tive bacteria and saprophytic fungi, so that the roots of many plants 

 literally rot off*. The presence of the worm has this effect in the case 

 of the tomato plants that are badly diseased. The taproot is always 

 very freely attacked and rots off below. Tomato plants seldom die out- 

 right as a result of the decay of the lower part of the taproot, for they 

 are capable of quickly sending out numerous lateral roots above the 

 point of injury, and thus tide the plant along. Cotton plants do not 

 have the power of sending out lateral roots so readily near the surface 

 of the ground when the stem becomes rather old, and are therefore more 

 liable to serious injury when badly diseased. 



Mr. Rhodes was not acquainted with the characteristics of Nematode 

 root-galls and was not aware that any plants in his neighborhood were 

 affected by such a disease. I noticed one old peach tree still in the 

 cotton field, and was informed that a peach orchard occupied the ground 

 about 20 years ago. At my request we visited the garden and upon 

 pulling up tomato and okra plants found them very badly diseased. 

 This was sufficient evidence that portions of the ground there were 

 very badly infected. 



The external manifestations of the disease in cotton are strikingly 

 similar to those of the root-rot disease caused by Ozonium as de- 

 scribed by Pammel, the irregular distribution of the spots as well as 

 the tendency to increase in size and sometimes the changing of the 

 spots. Also, as in the case of Ozonium^ the first external sign of the 

 disease is the sudden wilting of a plant on a hot, sunshiny day, espe- 

 cially after rain. This similarity in external appearance is easily ac- 

 counted for from the nature of the disease since the condition of the 

 roots prevents the absorption of water in quantities equal to that 

 transpired by the leaves, though there may be an abundance of water 

 in the soil. From this time the plant rapidly declines. 



The diseased plants begin to die about the time of '' chopping out '^ 



