30 MASS. EXPERIMENT STATION BULLETIN 327 



THE CRANBERRY STATION 



(East Wareham, Massachusetts) 



H. J. Franklin in Charge 



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



Franklin. ) 



Dust Insecticides. Several thousand acres of cranberry bog were dusted com- 

 mercially during the season of 1935 with mixtures of fine ground pyrethrum 

 and gypsum and pyrethrum and clay, largely for the purpose of controlling tne 

 blunt-nosed leaf hopper (Ophiola) and the blackheaded fireworm (Rhopobota). 

 The season's extensive experience led to the following conclusions: 



1. A mixture with 30 percent of high-grade pyrethrum, 100 pounds to the 

 acre, is entirely satisfactory as a general control for the blunt-nosed leafhopper 

 under Cape Cod conditions. 



2. Results with the 30 percent pyrethrum mixture applied to severe infes- 

 tations of the blackheaded fireworm and blunt-nosed leafhopper varied materi- 

 ally and often failed to be entirely satisfactory. It is not known whether this 

 was due to unknown differences in the materials used, in the method of appli- 

 cation, in the weather, or in the vines, to a combination of these differences, or 

 to some other cause. 



3. Entirely satisfactory control of these pests was obtained when the amount 

 of high-grade pyrethrum in the mixture was increased to 50 percent or more. 

 Unmixed pyrethrum at the rate of 60 pounds to the acre was also entirely 

 effective. 



As pyrethrum for use in 1936 is offered at very low prices, it may be best to 

 use it in these greater amounts against severe infestations. 



4. Adults of the cranberry spittle insect (Clastoptera) were checked effec- 

 tively with 100 pounds of the 30 percent pyrethrum mixture to the acre. This 

 method of control should be used if earlier treatment has been neglected, but 

 this insect should be stopped as soon as the spittle masses appear on the vines. 



5. On the whole, gypsum seemed to be a much more satisfactory diluent 

 for pyrethrum than clay. 



Airplane Dusting. "With the cooperation of some of the cranberry growers 

 and a company offering agricultural air service, extensive tests of the possi- 

 bilities of this method of dusting cranberry bogs were carried out, over a hundred 

 acres being treated. The machine was handled with great skill and showed 

 that airplanes may prove to be useful on bogs of over twenty acres. It was 

 evident, however, that a flying technique for an evener distribution of the dust 

 over a bog area will have to be developed. This will require careful selection 

 of weather and marking off into lanes of areas to be treated. It appeared also 

 that, to be effective, much more pyrethrum must be used than with ground 

 dusters. With the prospective low cost of this material, this may not be an 

 insuperable objection. Airplanes as at present developed can never be used 

 to advantage on small bogs because the maneuvering required is difficult and 

 very extensive in proportion to the area treated, and therefore costly. 



Kerosene Vapor and Pyrethrum Extract. The experience with kerosene in 

 cranberry bog weed control work given below suggested an immediate trial of 

 its use with pyrethrum as a possible cheaper treatment for blunt-nosed leaf- 

 hopper and blackheaded fireworm. Several plots on different bogs were 

 treated with a paint sprayer, water-white kerosene alone being applied on some 

 and kerosene with pyrethrum extract on others. No injury from the treatment 



