ANNUAL REPORT, 1930 249 



THE CRANBERRY STATION 



(East Wareham, Massachusetts) 



H. J. Franklin in Charge 



The station has enjoyed for tlie first time, during the most active part 

 of the 1930 cranberry season, the effective cooperation of the extension 

 services of Plymouth and Barnstable Counties. These counties togetBer 

 hired a special agent, an experienced cranberry grower of Kingston, Mass., 

 to conduct the cranberry extension work from the middle of May till the 

 middle of August. The work was handled satisfactorily, and more time was 

 available for the station's research work in spite of an increase in the 

 number of extension calls. 



Injurious and Beneficial Insects Affecting the Cranberry. (H. J. Frank- 

 lin). Various samples of pyrethrum soap were tested on different kinds of 

 insects to guide manufacturers of these soaps in improving and standard- 

 izing their products. Bog tests of pyrethrum soap sprays brought out 

 clearly that such sprays are entirely safe to use on cranberry vines when- 

 ever it is safe to spray with nicotine sulfate and soap. They are likely to 

 cause serious loss by blasting blossoms or newly set berries or by stunting 

 small berries if they are applied while the vines are in full bloom or be- 

 fore the berries are well started in growth. Pyrethrum extracts without 

 soap, such as Evergreen, did harm to blossoms and small berry sets in 

 some cases, but were generally much less injurious than pyrethrum soap. 

 The season's experience with pyrethrum soap sprays leads to the conclusion 

 that such sprays are preferable to nicotine sprays for treating the first 

 brood of the black-headed fireworm (Rhopobota vacciniana), for they are 

 fully as effective and kill much more promptly. The prompt kill is a 

 great advantage, especially if it rains soon after the spraying is done. 



Penetrol, used in sprays as directed by the manufacturer, did material 

 injury when applied to cranberry vines during and just after the blossom- 

 ing period. 



Bog tests showed that it takes an application of sodium cyanide solu- 

 tion about sixteen hours to kill a satisfactory percentage of an infestation 

 of the cranberry root grub (Amphicoma vuJpina Hentz.). Tests with her- 

 ring in tubs of water containing samples of treated bog soil showed that 

 the cyanide poison used to treat this grub persists in the soil in consider- 

 able strength at least a week. In treating the soil, six ounces of the cya- 

 nide had been used to a hundred gallons of water, and the solution had 

 been applied at the rate of a gallon to the square foot. This treatment 

 has proved satisfactorily effective in killing these grubs in all their stages 

 including the flaccid stage that comes just before pupation, but it seems 

 to kill the pupae much less readily. It should therefore always be com- 

 pleted before the grubs begin to pupate. 



Submergence tests were conducted with partly grown nymphs of the 

 cranberry black bug (Plagiognathus repetitus) and of the false blossom 

 leaf hopper {Ophiola striatula Fallen). The insects, in tin coffee cans with 

 muslin tied over the tops, were submerged to a depth of about a foot in 

 Spectacle Pond at East Wareham. A complete twelve-hour submergence 

 v.'as not enough to kill all the nymphs of either of these two species; but 



