1772 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



particularly, purple) margins. Fig. 1 

 shows the characteristic appearance on 

 canes of loganberry. The spots may run 

 together, forming long, irregular patches 

 of diseased tissue. On the leaves small 

 spots are produced with pale centers, but 

 with rather broad reddish or purple bor- 

 ders. (Fig. 2.) On some varieties the 

 diseased area may drop out and give 

 more or less of a shot-hole effect. On 

 the fruits the drupelets are found to be 

 affected, the fungus spotting the indi- 

 vidual drupelets. These may be attacked 

 when about half ripe or later. The dis- 

 ease on the fruit has been reported as 

 particularly serious on the Snyder black- 

 berry and on the loganberry. 



Cause 



This disease is due to a fungus, Gloeos- 

 porium venetum, which, growing in the 

 tissues of the plant, produces the spot- 

 ting described above. The fungus is re- 

 produced in the spots by*' the formation 

 of many minute spores. These spores are 

 disseminated most abundantly by wind 

 and rain. Under favorable conditions 

 spores are produced in great numbers 

 and the disease may spread rapidly over 

 the field. No winter st^ge has been re- 

 corded for this fungus, and it is probable 

 that the summer spore stage may live 

 over on the dead leaves or canes, or in 

 the spots on the living canes. 



Prevention 



Experience has shown that proper pre- 

 cautions in regard to sanitation have a 

 very important bearing upon the control 

 of this disease. All fruiting canes should 

 be removed as early as practicable after 

 the fruit is picked. These should be re- 

 moved from the field and burned, prefer- 

 ably before all leaves fall. In trimming 

 out the patch in the fall one should also 

 prune out any seriously affected canes 

 of the current year's growth. The re- 

 moval of the canes of the current year's 

 growth might be delayed till early spring 

 on account of the danger of winter in- 

 jury, but if this is practiced then they 

 should be protected, as suggested below, 

 by a fall application of spray. There 

 seems to be considerable difference in the 



susceptibility of varieties to this disease, 

 and where possible resistant varieties 

 should be grown. The experience of in- 

 vestigators regarding spraying for this 

 disease has not been uniformly success- 

 ful; but it seems probable from experi- 

 ments conducted by Lawrence that three 

 sprayings in the spring will go far to- 

 wards controlling this disease in the 

 Northwest. Bordeaux mixture should be 

 used in the 4-4-50 or 5-5-50 formula. 



Spray first before the leaves appear in 

 the spring, covering the canes thor- 

 oughly; spray again as soon as the leaves 

 are well out and the young shoots are 

 about six inches in height; spray a third 

 time just before the plant blossoms. 

 Where loss due to infection in the fruit 

 is experienced, it may be found desirable 

 to spray when the fruit is half to three- 

 fourths grown. In this case the use of 

 some spray mixture such as the Ammo- 

 niacal Copper Carbonate or Bergundy 

 mixture may be found desirable, since 

 such sprays leave no deposit on the fruit. 

 Where the disease is particularly serious 

 and spring spraying has not been en- 

 tirely successful an application of Bor- 

 deaux mixture about the middle of Au- 

 gust or first of September, before the fall 

 rains begin, might prove advisable, be- 

 cause it would doubtless prevent a large 



Qt'h'^I''^ •^^^'^ 



Fig. 2. Logman berry Leaf Showing Spots 

 Caused by Anthracnose. 



