6 Journal of Agricultural Research vol. xx, No. i 



FOOTROT 



Careful examination of the underground portions of winter crops early 

 in spring and of spring crops somewhat later in the season shows partial 

 rotting of the roots, the bases, and, in some cases, the interior of the 

 stems just above the bases. Various fungi may be found associated 

 with this condition on the cereal crops, among which Gibberella saubi- 

 netii and species of Fusarium are common. No attempt has been 

 made to obtain definite data on the relative frequency of occurrence of 

 different species of Fusarium on root lesions and discolorations. This, 

 of course, would be necessary before their relative importance as or- 

 ganisms inducing rootrot under field conditions can be determined. 



The first evidence of the pathological condition of the roots of the 

 cereals, whether the source of infection be the seed or the soil, is the same. 

 The organisms first appear on the remnants of the kernel and follow 

 some of the primary roots, causing rotting and browning as described 

 above. When the crown and the crown roots are formed, the primary 

 stem below the crown roots, now quite darkened and in some cases 

 beginning to die, is invaded by the organism from the remnants of the 

 kernel and the primary roots. Soon it, too, becomes brown and shows 

 evidence of rotting. When the invasion reaches the crown it may stop, 

 or, depending perhaps on the condition of the plant, it may continue, 

 invading the central woody portion of the primary stem above the crown 

 as well as the secondary stems and causing a browning of the woody 

 portions. Rotting and browning of the scale leaves and of the sheath 

 may also occur as a result of the invasion. How much of this rotting 

 and discoloration of the underground portion of the cereal crops due to 

 Fusarium species is parasitic and how much is saprophytic is not known. 

 That some of these organisms are parasites is shown conclusively by the 

 rotting of the roots next to the remnants of the kernel or next to the 

 crown while their lower portions continue to be normal. It is shown 

 also by the browning of the interior of the primary stem at and above 

 the crown. The separation of discolorations and rotting of underground 

 portions due to the parasitic and saprophytic action of the organisms 

 concerned is unusually difficult, as large portions of the original under- 

 ground parts of the plants eventually die even without any fungus in- 

 vasion, and the presence of parasitic organisms may have nothing to do 

 with it. Such is the case with the primary roots and the primary stem 

 below the crown, and later with some of the crown roots themselves. 



The amount of damage, if any, due to this invasion of the roots and 

 other underground portions is even more difficult to determine. As a 

 rule, the plants so attacked are at first small and stunted, but with the 

 coming of sunny and warmer weather they usually recover and reach 

 normal development, even when very badly injured. With the coming 

 of favorable weather such plants may send out secondary roots or even 



