187 



Goss-\KD (H. A.). Is the Hive a Center for distributing Fire Blight? 

 Is Aphid Honey Dew a Medium for spreading Blight? — Jl. Econ. 

 Entom., Concord, ix, no. 1, February 1916, pp. 59-64, 2 plates. 



Examination of cultures made from old honey, taken from hives 

 early in the spring, failed to show the presence of the organism of fire- 

 blight. Cultures made during the apple-blooming period from fresh 

 apple honey, which had been carried from orchards blighted during 

 the previous year, were also negative. When bacilli were inoculated 

 into sterilised honey, and the culture, after a varying period, was 

 introduced into the growing tips of apple shoots, it was found that 

 the organism can remain virulent in honey for 47 hours and then 

 produce infection. No infection was obtained after a certain limit 

 of incubation ; hence it may be supposed that the bacteria survive 

 for some time without multiplication. It is possible that multiplication 

 may take place in the nectar in the state in which it is carried into the 

 hive. If this is so, the bees which work on the nectar at night carry 

 virulent bacteria to the blossoms on the next or the following day. 

 This would explain to a great extent the rapid infection which occurs 

 in the latter part of the blooming period. 



Drops of Aphid honey-dew, a substance similar in composition to 

 nectar, were placed on leaves of infected apple trees. At the end of 

 20| hours, 43 hours, and 71 hours respectively, this culture was 

 inoculated into clean apple shoots. Inoculations resulted in 66*6, 

 83-3, and 100 per cent, of infection respectively. The habit of ants 

 of visiting colonies of woolly Aphids present in spring in old but living 

 blight cankers, and then of visiting green Aphids on the expanding 

 buds, which in turn are visited by bees and flies in quest of honey-dew, 

 may be of significance in blight control. 



In the discussion following the paper, Mr. J. H. Merrill stated that 

 in Kansas, in 1913, a contact insecticide was used against green aphis 

 on unopened apple buds. Later in the season, the sprayed orchards 

 were practically free from blight, while in unsprayed orchards the 

 disease was prevalent. In 1914, both Aphids and blight were rare, 

 while in 1915, conditions were similar to those of 1913. The speaker 

 therefore concluded that Aphids were one of the chief distributors of 

 blight. Mr. T. J. Headlee believed that the type of cultivation was 

 an important factor in the prevalence of blight, the damage caused 

 by the disease being greater in neglected orchards in which a rainy 

 season had induced greater succulence of the trees. Failure to spray 

 might be followed by abundance of Aphids and fire-blight without 

 there being any essential connection between them. 



Paddock (F. B.), Observations on the Turnip Louse. — Jl. Econ, 

 Entom., Concord, ix, no. 1, February 1916, pp. 67-71. 



Observations on Aphis pseudobrassicae, sp. n. (turnip louse) were 

 begun in Texas in 1913, at which date the insect was becoming 

 destructive over the entire State. The following plants, in order 

 of importance, were attacked : — turnip, radish, mustard, rape, cabbage, 

 kale, kohl-rabi, bean and lettuce. The reproduction of this insect in 

 Texas appears to be entirely asexual and is continuous throughout 

 the year. A winter temperature of from 15° to 20° F. is common and 



(C259) c2 



