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Califoruin, with the fungus aiitl ubtniued the tyiiical caukers. During the 

 winter of 1900. D. A. Broilie iinnlucetl the disease on aiiple twigs placed in 

 water in the laboratory by inoculating them with bits of diseased bark 

 collected in the field. Cordley (2) germinated the spores of the fungus in 

 artificial cultures. Later, when the mycelium was developed far enough to 

 be seen by the naked eye. the fungus was transferred to tube cultures. Later 

 inoculations were made in apple twigs with the fungus. The fungus attaclwd 

 the bark and caused small cankers, showing definitely that the fungus is 

 the cause of the disease. Prof. (". V. Piper has done considerable work on 

 the fungus and lias reached similar results. All of the aliove work lias been 

 successfully duplicated l^y the writer and some additiHiuU wnrk has lieen done 

 ou the life history- of the fungus. 



Insects Associated with Blaclcspot Ciiiilicr. 



In some localities where tliis disease exists, two kinds of insects work in 

 or near the wounds caused b,v the fungus. One or both may sometimes be 

 found in the same orchard. 



Tiic Bronze AiJjiic-trec Weevil OUigdidis (pnesccns. Lev.). — The adult 

 females are small bronze or nearly black beetles with long beaks. About the 

 time the cankers are mature in size the.se beetles eat holes in the bark near 

 the margins of the cankers. A single egg is deposited in each hole. A few 

 to several hundred of these eggs may be deposited around a single canker. 

 The work of the beetle and of the larvre retard or prevent the growth of a 

 callus. 



Tiic Woollii Apliis ( Scliizoiiriira htniiieru. Ilausniaiin). — After the cankers 

 are surrounded by a fissure split down the centre, or the diseased bark lias 

 fallen out. the woolly aphis finds its way into tlie wound. The ajihides multi- 

 ply rapidly and soon involve tlie entire callular tissues. The action of these 

 insects on the tissues causes them to become abnormal, forming a thick knotty 

 callus which does not grow enough to close tlie wound. 



General Description. 



The time that new cankers make their appearance during a single season 

 varies considerably with the seasons. Vary rarely new ones start during 

 .Tuly and August. Their appearance at this time is exceiitioual and occurs 

 only when weather conditions are favourable. They are few in numbers and 

 never developed enough to be of economic importance. The first cankers that 

 appear in the fall are usually found about the first week of Noveml)er on the 

 tender twigs of one and two years' growth. Others apjiear on the trunlc and 

 large limbs later in the season. The cankers that do the damage appear from 

 early in November to early in February. The greater number appear during 

 late November and early December. 



When the young cankers have developed enough to be seen D.v the naked 

 eye they are round, somewhat sunken and dark coloured — a colour character- 

 istic of the infested areas. The canker increa.ses very slowly in diameter, 

 but the fungus penetrates through the bark into the sapwood beneath. 

 Having entered the cambium or growing la.ver between the bark and the sap- 

 wood layers it grows rapidly and soon involves a considerable area of it — often 

 many times larger than the outer portion of the canker. With the return of 



