33 



Remedies. — When the disease first appeared a common practice was 

 to cut out the diseased spots while small and to paint over the result- 

 ing wounds. This was practicable only on the trunks of young trees, 

 and where the spots were few was fairly satisfactory. When, how- 

 ever, a young tree trunk has dozens or even hundreds of such spots 

 the remedy is nearly as bad as the disease, besides being extremely 

 laborious. On the branches of old trees such a method is utterly 

 impracticable. 



From the foregoing account of the disease it is evident that the time 

 when the tree needs protection most is from November 1 to February 1, 

 and perhaps even later; at any rate, this is the period when most of 

 the spots begin. Apparently such a fungicide as Bordeaux mixture 

 should protect the trees during the period. The greatest difficulty 

 arises from the fact that even Bordeaux mixture will not withstand 

 the frequent fall and winter rains which prevail, unless applied several 

 times. An ideal remedy w^ould ben solution as effective as Bordeaux 

 mixture for fungicidal purposes, and which would not wash off as 

 readily. Experiments to discover such a wash if possible are now in 

 progress. 



APPLE SCAB. 



Description. — Scab is without doubt the most destructive fungous 

 disease in the Coast region. It commonly attacks ])oth the leaves and 

 the fruit, and sometimes occurs on 3'oung twigs as well. On the fruit 

 the fungus forms circular spots of a dark smok\^ green or nearl}" l)lack 

 color, usually marked at the edge by a pale line where the skin of the 

 apple is slightly raised. These spots begin to appear when the fruit 

 is half grown, or even earlier. Single spots may reach the size of a 

 dime, but ordinarih' the}^ are smaller. When close together they 

 frequently unite and may thus occupy a considerable area. The effect 

 of the fungous spot is to retard the growth of the apple tissue in its 

 immediate vicinity, and when a number of spots are close together the 

 apple becomes more or less distorted on that side. Where several 

 spots merge together, irregular radiating cracks may appear. 



On the leaves the fungus appears as dark olive green spots which 

 are not sharpl}^ limited. Thev occur mostly on the upper side of the 

 leaf, which may, indeed, be completely covered. The growth of the 

 apple leaf where the spots occur is much hindered, so that the leaves 

 are more or less curled or hummocky. 



Microscopic examination of the fungus either from the leaves or 

 fruit reveals that the part of the fungus seen consists of short upriglit 

 stalks, each of which bears a single oval or spindle-form spore, which 

 may or may not be divided b}^ a cross partition. These spores float 

 about in the air and thus spread the disease. 



In comparatively rare cases where the twigs are attacked, the fungus 

 lives over winter and in early spring again produces spores. Ordi- 

 24228— No. 153—02 3 



