THE MONTHLY BULLETIN. 



663 



to avoid including diseased stock in filling their orders. Crown gall 

 disease is prevalent in all parts of the country and is believed to exist 

 in most deciduous fruit nurseries. 



Under the provisions of the original inspection law in Arizona, our 

 work was confined to insect pests, and we had no authority to prevent 

 the delivery of trees or plants infected by plant diseases. Under the 

 amended "Crop Pest law," however, action against diseased plants is 

 authorized. The need for this is strikingly shown by a recently in- 

 spected shipment of nursery stock to Saiford, Arizona, from a nursery 

 in Portland, Oregon. This shipment included 3,000 apple trees, and 

 the inspector's report showed that crown gall affected trees were found 

 in every bundle of trees throughout the lot and that one bundle of ten 

 trees included five infected specimens. Five examples sent to the 

 writer's office showed the disease in a most pronounced and unmistak- 

 able form. The consignees did not need to be informed concerning 

 the worthlessness of the diseased trees, and according to their estimate, 

 one fifth of the entire lot of 3,000 trees were visibly infected. 



The significance of this outrageously large proportion of worthless 

 trees included by the shippers is indicated by the proportion of dis- 

 eased trees normally present in honestly sorted nursery stock shipped 

 into this State. It is admittedly practically impossible to prepare a 

 large shipment of deciduous nursery stock and eliminate all trees 

 visibly infected with crown gall, if the disease is present in the nursery. 

 Nevertheless, the inspection of many carloads of deciduous fruit stock 

 from reliable western nurseries has resulted in finding less than one 

 tenth of one per cent of the trees visibly infected by this disease. A 

 representative of a well known Oregon nursery recently called at the 

 writer's office and upon being shown the five specimens of diseased trees 

 from the Safford shipment, referred to above, stated that he would be 

 willing to guarantee a customer against as many typical crown gall 

 infected trees in an entire car lot. In a car lot of ten thousand trees, 

 this would represent one twentieth of one per cent. At the rate the 

 infection was found in the Safford shipment, however, there would be 

 two thousand visibly infected trees in a car lot of ten thousand. 



If we credit the shippers with having made an honest effort to 

 separate out the worthless diseased trees before shipping the order, we 

 are forced to conclude that the sample of their stock shipped to Safford 

 is quite free from the disease as compared with the average stock in 

 the nursery from which the stock was selected. We must also conclude 

 from the sample sent to this State, that the incipient infection among 

 the trees not visibly diseased is at least 200 times as abundant in pro- 

 portion in shipments such as this, with 20 per cent visibly infected, as 

 in shipments showing only the normal degree of infection, or less than 

 one tenth of one per cent. 



The Arizona law gives specific discretionary powers to the inspectors 

 acting under the directions of the State Entomologist. If crown gall 

 was not known to exist in the State, the writer would not hesitate to 

 insist, that shipments be absolutely free from visible cro\^^l gall infec- 

 tion, and to recommend to the Commission of Agriculture and Horti- 

 culture quarantine regulations which would restrict the danger of 

 importing the disease. Since it already exists here, however, w^e can 



