64 Tin-: APPLK LEAF HOPPER 



cf gall or in the soil for some time, several years — just how long is 

 not known. 



We quote Dr. He(lgecock'.s summary of his recent work with 

 this organism puhlished in bulletin Xo. 131. LUireau of Plant Industry, 

 Aug. 17, 1908: 



■'The soft galls from the almond. a])ricot, blackberry, cherry, 

 peach, plum, prune, and ras])berr},' have been transferred easilv to seed- 

 lings of the almond, apricot, peach, and raspberr}' ; less readilv to those 

 of the blackberry, cherry, plum, prune, and pear; and with great dif- 

 ficulty to seedlings of the a])ple, chestnut, walnut, and rose. 



"Th.e soft galls of the ap]:)le, chestnut, walnut, rose, and ])ear. as 

 a rule have not been transferred readily to any of the plants mentioned. 

 Evidence has been obtained of a wide range of susceptibility in dif- 

 ferent varieties of the same plant. This has been noted in varieties 

 of the apple, blackberry, cherry, chestnut, pear, and rose." 



Fpon the raspberry Crow-n Gall occurs as bunches near or at the 

 crown (see Plate), but may appear on parts above the ground, and 

 eventually weakens and kills the plant. Delaware has lost 40 per cent 

 or more of her vines through Crown Gall, and the raising of berries 

 there has consequently received a serious check. As evidence of the 

 contagious nature of this disease it may be said that scientific and 

 practical workers have demonstrated that healthy vines planted in 

 sterilized soil, ard bits of Crown Gall placed about them, develop the 

 disease. It is evident, too. that rain could easily wash the germs or 

 reproductive bodies on the surface of the galls to other plants. This, 

 too. has been demonstrated in practice by the facts that plants found 

 on a hillside, or in a hollow below infested plants, also contract the 

 disease. An inspector finding diseased crowns on raspberry vines on 

 the higher ])ortions of a field can generally safely ])redict the occur- 

 rence of the disease lower down where the wash of the rains has 

 brought the germ down from the higher ground, if sufficient time has 

 elapsed to allow of growth of gall resulting from the contamination. 



Crown Gall is apparently on the increase in Minnesota nurseries, 

 and so destructive is it to vines, and so insidious in its method of 

 spreading that we deem it necessary to call special attention to it at 

 this time. The increase 01 this disease has been brought about large- 

 ly by infested nurseries sending vines intf) widely separated regions. 

 It is very evident that one nursery may infect an entire state or sev- 

 eral states. Although undoubtedly existing here for a number of 

 years, the first complaint reached us less than a year ago. In this 

 case ras])l)erries were suffermg. We had a vear before founfl this on 



