282 Diseases of Truck Crops 



teleutospores (fig. 52 d) axe two celled, thick walled, 

 dark colored, and borne singly on long stalks. The 

 teleutospores must first winter over before they can 

 germinate. In germination each ceU sends out a 

 thick short germ tube which divides at the tip into 

 four parts, each of which produces a side branch 

 which bears secondary spores known as sporidia. 

 The latter break away, and when falling on a fresh 

 green asparagus top germinate by sending out a germ 

 tube which penetrates the host. After proper incu- 

 bation, the cluster cup stage appears, and the same 

 life cycle is repeated over again. 



Control. Asparagus rust may be kept in check by 

 taking advantage of certain cultural conditions. 

 Rust is more abundant in seasons with insufficient 

 rainfall or on lands which dry out rapidly, while 

 soils which have an abundance of moisture harbor 

 little or no rust. In moist soUs, asparagus plants are 

 more vigorous than those grown under dry conditions 

 and vigorous plants are less subject to rust than weak 

 ones. Irrigation, therefore, wherever possible will 

 help to keep the rust in check. Rust infection can 

 never take place unless there is plenty of dew to 

 enable the spores of the fungus to germinate. In 

 low l3ang places, dew formation is heavier and hangs 

 on longer than in more elevated regions. As far as 

 possible, asparagus shotdd be grown on high, well 

 exposed moist lands. In regions subject to rains and 

 heavy dews, spraying is recommended. Sirrine^ has 



' Sirrme, F. A.. N. Y. (Geneva) Agr. Expt. Sta. Bui. l88 : 122- 

 166, 1900. 



