256 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



cooperation Avith the Florida State Plant Board. This materially 

 aids in the eradication of the weevil without interfering with the 

 production of potatoes, since the contracts provide for clean culture 

 and a fallow period of six weeks prior to planting, together with other 

 repressive measures. It is believed that as the result of this work 

 the end of the growing season will find this locality practicall}^, if not 

 completely, Aveevil free. 



In Alabama, the infestation was found to be confined to a single 

 well-defined locality in Baldwin County, and excellent cooperation 

 has been secured with growers toward the application of all necessary 

 j-epressive measures. It is believed that this isolated outbreak will be 

 entirely cleaned up in another season. 



In Mississippi the passage of a drastic crop-pest law materially 

 aided in the eradication measures, the establishment of a quarantine 

 rendering complete control of intercounty shipments possible. The 

 comparatively light infestation in this State has been mapped, and 

 a material reduction of the area infested has been secured. 



In Louisiana survey work has been continued, and growers have 

 been visited and urged to apply methods devised by the bureau. 

 Reinspection recently indicates that gratifying results have been 

 reached in the majority of cases. A careful study has been made in 

 this State as well as in Mississippi of the other food plants of the 

 morning-glory group, especially the large-rooted perennial morning- 

 glories, and a number of chemicals have been tested as weed killers, 

 to be used against these wild food plants. 



In Texas, 85 counties have been found infested with the weevil, 

 which has been. distributed apparently largely through commercial 

 growers of slips shipping from the Gulf and south-central portions of 

 the State. There is no law in Texas controlling the shipment of 

 infested plant material, whicli is a serious clraAvback to the control 

 of the weevil in that State. The fact that salable sweet potatoes can 

 not be produced in some of the coast counties has helped the wide- 

 spread distribution of the weevil, as draws grown from unsalable 

 stock often prove more profitable than the growing of tubers. Life- 

 history studies at Kingsville, Tex., showed at least six generations of 

 the w^eevils annually, indicating an enormous rate of increase. 

 Spraying experiments at this point have reduced infestation from 

 44.51 per cent to from 2.88 to 12.18 per cent. 



INSECTS AFFECTING POTATO, TOMATO, AND ALLIED CROPS. 



The potato aphis, an unexpected pest which made its appearance 

 in 1917 and again in the early summer of 1918, was experimented 

 with on into July, 1919. The use of nicotine sprays at increased 

 strengths demonstrated practical control in Maryland, New Jersey, 

 and Maine. 



The spinach aphis, which has during recent years become trouble- 

 some as a potato pest, and which also affects cabbage, beets, lettuce, 

 and other staple vegetable crops over a still wider range of territory, 

 has been the subject of continued investigations along the Atlantic 

 coast. A new station in the Aroostook region in Maine, a great 

 potato center, has been established for the study of the Colorado 

 potato beetle, the potato flea-beetle, and other potato pests. An in- 

 vestigation of the spread of the Colorado potato beetle on the Pacific 



