\/ol. III. No. 28. 



JUNE I908. 



^im5H OARDENINO 



A Monthly Educational Journal devoted to 

 the Advancement of Horticulture in Ireland 



Club-root Disease. 



CLUB-ROOT is a very troublesome disease 

 in cabbag-e, turnip, and other cruciferous 

 crops. It begins with tiny swelHngs on 

 the roots of the young- 

 plants, and as the plants, 

 g-row bigg-er and big-g-er 

 the swelling's enlarge 

 more and more. At last, 

 when the affected parts 

 of the roots have attained 

 an enormous size, they 

 gradually die, and then 

 rapidly pass into a 

 mass of soft, putrescent 

 matter. 



What is the cause of 

 all this? What excites 

 the root to such extra- 

 ordinary growth, and 

 why does it all end in 

 the early and rapid 

 decay of the affected 

 parts ? The cause is a 

 particular kind of fungus 

 that enters the plant 

 through its young and 

 delicate roots, estab- 

 lishes itself in the living' 

 cells of the softer tissues, 

 feeds upon the nutritive 

 sap of its host, and 

 causes intense local ir- 

 ritation. The fungus is 

 not of the usual 

 thready type ; it consists 

 simply of a slimy sub- 

 stance, and this, after it 

 has run its brief life in 

 the cells of the root, 

 gets transformed into 

 spores. The spores are 

 formed when the ex- 



/ 





Once the tissues die, decaj' rapidly sets in ; hence 

 the offensive condition of the attacked root in an 

 advanced state of the disease. 



Let us consider these 

 briefly told incidents in 

 the life of the clubbing 

 fungus with a view to 

 the better protection of 

 our cruciferous crops 

 against the attack of 

 this dreaded enemy. In 

 the first place, we must 

 remember that the cause 

 of the disease is this 

 particular fungus, that if 

 there is no attacking 

 parasite there is no club- 

 bing. In the second 

 place we know that the 

 infection comes from the 

 soil — always from the 

 soil. How does the soil 

 get infected with the 

 spores ? That is easily 

 answered. The soft, 

 rotten roots containing 

 such enormous numbers 

 of spores readily break 

 up and mix with the soil, 

 and so it becomes 

 peculiarly unhealthy for 

 any cruciferous crop. In 

 such a soil no crop of cab- 

 bage, cauliflower, Brus- 

 sels sprouts or turnip 

 can be expected to escape 

 clubbing. The spores 

 mav lie dormant for 

 months or years, but 

 sooner or later the living 

 content will become 

 active, burst the spore 



Club-root disease in a plant of Brussels Sprouts. 



The rounded swellings at the base of the stem have no connection 

 with the fungoid disease ; they are due to the attacks of a beetl-. 



hausted cells of the sorely harassed root die ; case, creep out, and enter the root of any 



they are almost inconceivably minute, so that cruciferous plant within its reach. And so 



even in a small piece of the rotten material the the trouble is passed on. From this the 



number of these spores must be many millions. reasoning gardener w411 see how very important 



