54° Joiinia! of Aiiric/zltiirc . Yictoria. [lo Sept., 1912^ 



roots or stem may have been caused in late autumn or during the winter 

 months, and then, owing to the root action being interfered with in 

 supplying moisture to the active top at a season when moisture is all- 

 essential, symptoms as already described are brought about. Good drainage 

 plays an all-important part in controlling and checking the spread of this 

 pest. Very often the damage done is attributed to root-borers, bad drain- 

 age, or similar conditions, when the true cause is ArmiUaria mellea. Exces- 

 sive moisture in the soil through irrigation or natural causes during hot 

 weather may be the rreans of developing this fungus rapidly. The writer's- 

 experience is that, if introduced upon stocks or trees to a clean locality, this, 

 fungus will remain in a dormant state, or nearly .so, for at least two vears 

 W'ithout the stocks, &:c., .showing signs of attack. As soon as conditions 

 favorable to it are bi-ought about, through irrigation or other causes, its 

 spread is rapid, and death to the trees certain. 



Collar Rot {Fiisnriiini Iniioiiis. /hois.) — l.ouo)! Bark Blotch {Ascocliyta 

 Corticola; McAl[).). — Root Rot of Lemon {P/ionia ommvora. McAlp.). — 

 The worst fungus di.seases that the propagator and grower of citrus trees- 

 have to contend with are those known as Collar Rot, Lemon Bark Blotch, 

 and Root Rot of Lemon. Although the same conditions favour the de^•e- 

 lopment and spread of them all, in appearance they are different. Collar 

 Rot. which is probablv the best known, is no doubt often confounded with 

 Bark Blotch. 



Collar Rot. — The first symptom is the exudation of small i)articles 

 of gum from the bark at the seat of trouble. The bark eventually 

 becomes usualh- deep brown in colour. It is generallv when the bark is 

 changing colour that the physiological coiiditions of the tree is noticed to 

 be undergoing a change. The foliage appears to be sickly and pale- 

 yellowish in colour. Matured trees generally show signs of heavy 

 fruit production. Bark Blotch. — The symptom of attack with this 

 disease is verv similai^ to that of Collar Rot, the difference being that the 

 diseased bark is usually .sooty black in colour, instead of brown, and that 

 gumming is absent. The bark eventually cracks, and peels off. Root 

 Rot. — Generally the first symptom of attack is observed through the foliage 

 becoming unhealthy and pale in colour. Upon the soil being remoAed 

 around and close to the butts, the bark, if attacked, will have an unhealthy 

 appearance, and upon scraping the bark lightlv it will be found to be dead 

 or decaying. Such conditions generally start at the extremity of the roots, 

 working u])wards to the ground level. At times this disease works rapidly 

 in the nursery row if over-irrigation is practised. The leaves then suddenly 

 droop, have the appearance of requiring moisture, and if a tree attacked 

 in the nur.sery row is pulled it will leave the soil, and sometimes the 

 freshly-decayed bark upon the roots will be left behind. 



Trees once attacked Avith Root Rot rarely recover if the attack of 

 the fungus is general upon all the roots. \x\ some instances the attack is 

 confined to the roots upon one side of the tree only. If conditions favor- 

 able for the development and spread of this fungus remain for any length 

 of time, its action is rapid and deadly. Should anything occur to 

 change these conditions, then the trees attacked may linger for years 

 before dying out, and indeed, in rare instances, mav e\'en regain their 

 vigour, particularly those branches upon the side of the tree opposite to 

 that part of the trunk or roots attacked. With Root Rot. if the upward 

 spread of the disease should become checked before too serious harm is- 

 done, very often fresh roots strike out from the health}- basal parts. 



