454 



•carrying infection to several healthy plants after leaving a diseased 

 host. Supposedly non-virus-bearing Aphids were found to cause 

 blight infection when transferred to healthy spinach. Aphids imported 

 from several other States, or the juice crushed from such Aphids, 

 did not cause infections of the disease unless they had previously 

 fed on diseased spinach. Uninfected Aphids must remain on diseased 

 plants for from 5 minutes to 14 hours to become carriers of infection. 

 Infected individuals do not lose their ability to transmit the causal 

 entity of spinach-blight during moulting. Infections were obtained 

 with the offspring of virus-bearing Aphids that had not previously 

 fed and the infectious entity of spinach-blight was found to be trans- 

 mitted by adult Aphids to their offspring. It was also found that 

 when Aphids were reared on lettuce for four consecutive generations, 

 a few of the fourth generation were virus bearers and produced 

 infections when they were transferred to healthy spinach. These 

 results show similarity to certain animal diseases transmitted by 

 insects or ticks. Since the causal factor of the disease may be 

 hereditary with the Aphids, the possibility of its lasting through 

 the summer by this method was indicated. Aphids collected on 

 spinach plants left after the crop had been harvested were found to 

 be possible virus bearers, as also are Aphids collected from weeds 

 growing later in the season in the same fields. Experiments with 

 Aphids from plants other than spinach during the autumn produced 

 spinach-blight in a limited number of cases. The direct offspring 

 of a known Aarus-bearing Aphid reared during the summer in a field 

 cage on pepper and potato plants produced blight when they were 

 transferred to spinach seedlings in August, or about the time early 

 spinach is appearing. Infections were obtained in a few cases with 

 several other species of Rhynchota, but these are probably unimportant 

 as blight transmitters, as they do not occur abundantly at the time 

 bUght is prevalent. The control of the Aphids infesting spinach 

 therefore offers the most immediate possibilities for the control of 

 ■spinach-bhght. 



BiTCHTE (A. H.). Cucumber and Pumpkin Worms. — Jl. Jamaica 

 Agric. Soc, Kingston, xxii, no. 6, June 1918, pp. 240-241. 



The caterpillars of Diaphania hyalinata periodically attack the 

 foliage of cucumbers and related plants. White lime dusted over the 

 the plants acts as a repellent, but if the plants become infested a 

 poison spray must be resorted to. Lead arsenate in the proportion 

 2| lb. to 40 gals, water is recommended ; this should be coated over 

 the under-side of the leaves as soon as the caterpillars make their 

 appearance. 



NowELL (W.). Internal Disease of Cotton Bolls in the West Indies. II. 



• — West Indian Bull., Barbados, xvii, no. 1, 1918, pp. 1-26. 



This paper records the continuation of studies on the internal boll 

 disease of cotton and its connection with plant bugs [see this Review, 

 Ser. A, V, p. 580 & vi, p. 251]. The success of the control measures 

 against Dysdercus spp. (cotton stainers) in St. Vincent in 1917 was 

 found to have reduced the prevalence of the disease to neghgible 

 proportions over large areas. Nezara viridula (green bug) and Edessa 



