62 



BACTERIAL DISEASES OF PLANTS 



as follows: Special, January, 1915, $35,000; special, February, 

 1916, $300,000; general, in Department of Agriculture appro- 

 priation bills, 1916-17, $250,000; 1917-18, $430,000; 1918- 

 1919, $250, 000. l This disease occurs also in Japan, China and 

 the Philippines (Water T. Swingle) and was certainly intro- 

 duced into the United States on imported citrus plants. It 



now occurs (or did occur in 1916) 

 in every Gulf State. It should not 

 be confused with the somewhat similar 

 looking Costa Rican pseudo-canker 

 (Figs. 45, 46) which is of non-bacterial 

 origin, nor with the verrucosities -due 

 to Cladosporium citri (Fig. 47). The 

 true bacterial canker is usually sur- 

 rounded by a narrow w r ater-soaked 

 area best seen by holding the leaf up 

 to the light (Fig. 48) and is swarm- 

 ing with bacteria, whereas the pseudo- 

 canker shows no such border and con- 

 tains at most only some fungous 

 threads well corked out. 



Holland and Denmark. In Hol- 

 land the yellow disease of hyacinths 

 will eventually put an end to hyacinth- 

 growing for export if means cannot be 

 had for its control, since the land 

 suited to hyacinths is limited in 

 amount. Black rot of cabbage oc- 

 curs in Holland and Denmark, and is common now also in 

 many parts of the United States. It was probably imported 

 into the United States from Denmark on cabbage seed. 

 Some years in nurseries about Amsterdam the lilac blight has 

 been troublesome. In Denmark Rathay's disease is said to be 

 rather troublesome on orchard grass grown for seed. 



J On April 30, 1918, in the Florida Plant Commissioner's Office, Department 

 of Citrus Canker Eradication, 183 persons were employed, including a divisional 

 inspector, district inspectors, assistant district inspectors, foremen and inspectors. 

 During the year 1918 over 2,000,000 grove trees were inspected and six times as 

 many nursery trees. 



FIG. 44. Cross-section of 

 grape-fruit leaf showing a 

 young canker inoculated by 

 the writer in 1915. Time, 16 

 days. See Fig. 42. 



