444 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



determine. The ideal time would be to 

 spray before the first fall rains. In prac- 

 tically all sections of the Northwest 

 where this disease occurs this would be 

 before the fruit is picked, and it is found 

 somewhat objectionable to use Bordeaux 

 mixture before the fruit is picked because 

 of the slight deposit on the fruit. 



In many of the older orchards where 

 the trees are close and it is found neces- 

 sary to use props in case of a heavy 

 crop, it is often impossible to get 

 through the orchard with a spray ma- 

 chine before the crop is picked without 

 knocking off considerable fruit. On the 

 other hand many growers complain that, 

 on account of unfavorable weather con- 

 ditions which frequently prevail follow- 

 ing picking, they are often unable to 

 spray in the fall as recommended — until 

 it is too late to be of any value — if the 

 spraying is delayed until after picking 

 is done. Others complain that on ac- 

 count of the press of work incident to 

 picking and packing a large crop even 

 in seasons of favorable weather condi- 

 tions, they have not time to spray until 

 the proper season is past. On the other 

 hand it is evident that trees must be 

 protected with a fungicide during the 

 fall of the year in order to prevent in- 

 fection. 



Experiments which have been conduct- 

 ed to date indicate that good results are 

 obtained by spraying once with Bor- 

 deaux mixture 4-4-50 before the first fall 

 rains, or about the middle of September, 

 following by another application, using 

 Bordeaux mixture G-6-50, after the fruit 

 is picked. 



It is possible that where growers give 

 a late spray for codling moth that a 

 combination spray could be applied, using 

 Bordeaux mixture 4-4-50 and arsenate of 

 lead, two pounds to 50 gallons, in the 

 latter part of August. This would be 

 used to take the place of the spraying 

 suggested in the middle of September. 

 It has not been fully demonstrated 

 whether this suggestion will prove satis- 

 factory in general practice. It is worthy 

 of trial, however, by interested growers, 

 and may prove to be the most satis- 



factory solution of the problem for the 

 grower who wishes to keep a compara- 

 tively clean orchard protected from in- 

 fection by this disease. 



In orchards where the disease has ob- 

 tained a foothold, however, the recom- 

 mendations as given under the sum- 

 mary should be followed. For other 

 supplementary methods of control see 

 Summary of Recommendations. 



SUMMARY 



Life History Investigations 



1. A disease known throughout the 

 Northwest as Apple Tree Anthracnose 

 or Black Spot Canker is caused by a 

 fungus which, in the conidial stage, is 

 a parasite causing cankers on the 

 branches of apple and pear trees. 



2. The cankers caused by this fungus 

 cause the death of the tissue of the bark 

 in which it develops and of the cam- 

 bium, and spreads to some extent to the 

 sapwood beneath. 



3. Infection occurs in the fall and 

 early winter and the cankers develop 

 slowly during the early part of the 

 dormant season and spread rapidly in 

 the early siiring. reaching their full size 

 when the cambium resumes activity in 

 the spring. 



4. The fungus matures slowly during 

 the summer in the dead bark of the 

 cankei's thus formed. Spores are pro- 

 duced in acervuli characteristic of the 

 genera Oloeosporium or Myxosporiiim of 

 the Fungi Imperfecti. 



5. This conidial form has been named 

 by Cordley, Oloeosporium maUcorticis. 



6. The fungus continues to develop 

 in the dead bark of old cankers as a 

 saprophyte and produces in the late 

 summer or fall, one year after the ma- 

 turity of the conidial stage, an ascosporic 

 form having the characteristics of the 

 family Mollisiaceae of the Discomycetes. 



7. The connection of this Ascomycete 

 with the conidial stage has been proved 

 by inoculation experiments. 



S. This has been made the type of a 

 suggested new genus called Neofahraea. 

 The proper scientific name for the 



