6 TIMELY HINT 118 



munity and State. According to Dr. A. W. Morrill, all States 

 except New Mexico require now an annual inspection of nurseries. 

 Neither the orchardist nor the nurseryman should grow in orchards 

 or among nursery stock, grapes, cane fruits, including blackberries, 

 raspberries and dewberries or field crops that are subject to crown 

 gall, since these plants may communicate this disease to fruit trees 

 about them. In a small home orchard this would be less serious, as 

 the loss would not be so great. The writer endorses heartily the 

 work of the Arizona Commission of Agriculture and Horticulture in 

 dealing with dangerous plant pests^ though some of the recommen- 

 dations made here go farther in the matter of controlling crown gall. 

 Nurserymen should practice a regular rotation of field crops, 

 such as cereals, grasses, corn, cane and sorrghum, with their 

 nursery tree crops, to prevent one crop of nursery trees from 

 becoming infected from another. Nurserymen should select 

 their plum, peach, apricot, almond, and similar pits for graft- 

 ing and budding stock, from trees that are known to be 

 healthy, rather than to buy such pits in miscellaneous lots from 

 canning factories. They should select scion wood also, for budding 

 and grafting, from healthy plants. Only recently we have come to 

 appreciate the importance of selecting scions for budding and grafting 

 from healthy trees, and it is equally important to select pits for 

 grafting stock from healthy trees. 



At this time no definite remedy is known for crown gall, nor is 

 there much hope for the discovery of one. The blue stone-copperas- 

 lime paste has been used with some success as a treatment. This is 

 recommended only for large trees, however, and is made as follows: 



Bluestone (copper sulphate) 2 parts. 



Copperas (iron sulphate 1 part. 



Unslaked lime 3 parts. 



These ingredients are reduced to a fine powder, after which they 

 are carefully mixed together and enough water added to form a thick 

 paste. This is applied with a small paint brush to wounds made by 

 the removal of galls. In treating trees, the crown is exposed by 

 digging away the soil to a sufficient depth. The galls are then cut 

 away with sterilized pruning tools and the wounds coated over 

 thickly with the paste. The soil is then shoveled back in place. The 

 galls should be put in receptacles and destroyed as soon after as 

 convenient. The crowns of trees thus treated should be examined 

 several times during the season and if fresh galls appear these should 

 be removed and the wounds treated as before. 



It is not recommended that one should treat a large number of 

 orchard treees infected with crown gall with this paste with the 

 idea of eradicating the disease. It may very well be applied to 

 occasional large, heavy-bearing trees, which are removed some- 

 what from orchards, to prolong their lives and thus enable one to get 

 several crops more of fruit while other trees are brought into 

 bearing. Such trees, however, should be destroyed as soon as their 

 usefulness is past, since at best they are a menace to healthy trees. 



J. J. THORNBER, 



Botanist, Agr. Exp. Station. 



