346 PLANT DISEASES 



into the diseased part, and all plants included should be 

 carefully removed and burned. When a field has once 

 become thoroughly infested, it has been proved that after 

 an interval of twenty years saffron has been attacked at 

 once, the fungus having lived in the meantime on the roots 

 of various weeds. 



Cereals which are not attacked by the Rhizoctinia should 

 be sown on infected ground, and all weeds should be kept 

 down ; by these means alone can the fungus be destroyed. 



Prillieux, Malad. des Plantes Agric., vol. ii. p. 144, figs. 



COTTON ROOT-ROT 



(Ozonium auricomuni) 



Bulletin No. 7 of the Texas Agricultural Experimental 

 Station is devoted to an account of the above disease. 



Ozonium was by the older mycologists considered as a 

 true genus of Fungi; it is now known to consist only of 

 ^sterile mycelium, usually of a brown or orange colour. 

 Opinion differs as to the perfect or fruiting condition of 

 Ozonium mycelium, which is probably a name covering 

 the mycelium of many distinct species. The cotton rot 

 has not yet been connected with any fruiting stage. It 

 attacks the roots, more especially the taproot, which is 

 surrounded by a weft of brown strands of mycelium. 

 When this stage has been reached, the cotton plant wilts, 

 then blackens and dies. The disease travels in the soil, 

 spreading irregularly in all directions from the point first 

 attacked. 



Numerous forest and orchard trees, excepting the genus 

 Primus^ also suffer from root-rot caused by this fungus, as 

 do also the tubers of the sweet potato. Wet seasons, and 



