ANNUAL REPORT, 193p 37 



by these results, it seems probable that 50 pounds of 4 percent rotenone derris 

 (without an activator or wetter) an acre will be very effective, but this remains 

 to be tried. 



Extensive commercial control of this leafhopper began in 1933. Observations 

 of the results obtained since then indicate that, once control is established, 

 treatment is not necessary on most Massachusetts bogs oftener than once in 

 three years if it is thorough when it is applied. Evidently the hoppers do not 

 travel far en masse and come onto bogs of average size from surrounding uplands 

 very slowly. An infestation of over three hoppers to 50 sweeps of an insect net 

 calls for treatment at any time. Because of the rising cost of pyrethrum products 

 and the falling cost of rotenone dusts and the blanket effectiveness of the latter 

 on the fruit worm, the black-headed fireworm, and this leafhopper, the time for 

 treatment may shift in many cases from the last week in June to around July 10. 



Pyrethrum Dusts. There have been many puzzling failures of these materials 

 to control cranberry pests. Checkings of stated pyrethrin content lead to the 

 conclusion that these have probably nearly always been due to inferior quality 

 of the material used. The purchase of pyrethrum from large local distributors 

 who can have the pyrethrin content of the dust they are handling determined 

 is a protection here. 



Prevalence of Cranberry Pests. The relative general abundance of cranberry 

 pests in Massachusetts in the 1939 season was as follows: 



1. Gypsy moth more abundant in Plymouth county than in 1938, being 

 quite troublesome in some localities; extremely destructive on the middle and 

 outer Cape, even more so than in 1938. 



2. Blunt-nosed leafhopper (Ophiola) even scarcer than last year, due to 

 general treatment. 



3. Cranberry fruit worm (Mineola) generally less prevalent than normal, 

 less so than in 1938. 



4. Black-headed fireworm more prevalent than last year but widely con- 

 trolled by disease. 



5. Firebeetle somewhat reduced from 1938 (see above). 



6. Green and brown spanworms slightly increased from 1938. 



7. Cutworms definitely less than last year and less than usual. 



8. Cranberry girdler (Crambus) and Spittle insect (Clastoptera) about the 

 same as in 1938 and rather less than normal. 



9. Cranberry root grub (Amphicoma). There seems to be a slow general 

 increase of this pest from year to year in spite of effective treatments. 



10. Weevil (Anthonomus) about as last year, more prevalent than normal. 



11. Tipworm {Dasyneura) widely prevalent. 



Control of Cranberry Bog Weeds. (Chester E. Cross.) During the months 

 of June to September, inclusive, 730 weed control plots were treated. Of these, 

 410 were treated variously with water-white kerosene and the rest with the 

 following, alone and in some combination: Sodium chloride, calcium chloride, 

 sodium chlorate, sodium arsenate, copper sulfate, ferrous sulfate, ferric sulfate, 

 cyanamid, and ocean water. Results of 1938 work were also examined. The 

 following findings from all this are of particular interest. 



1. Water-white kerosene, 800 gallons an acre, applied in early November with 

 a watering can, eradicated a thick lot of rice cut-grass (Leersia) nicely. 



2. A large number of plots was used to compare the weed control values 

 of the kerosenes of the following producers: Atlantic Refining Co., Cities Service 

 Refining Co., Colonial Beacon Oil Co., Gulf Oil Corp., Shell Oil Co., Socony- 

 Vacuum Oil Co., and Texas Co. These concerns very kindly loaned the Cran- 

 berry Station drums to hold the kerosenes. No definite relation was found 



