44 MASS. EXPERIMENT STATION BULLETIN 347 



these tests, it may be said that the impregnated dusts, properly prepared and 

 applied, can probably be relied on to check these pests as effectively as the high- 

 grade pjrethrum dust (0.9 percent pyrethrin content), with a material saving in 

 cost. Those who buy these dusts, however, should realize that they are putting 

 themselves more fully in the hands of the manufacturers than they have been in 

 bu\ing the dust used heretofore. 



Prevalence of Cranberry Pests. Notes on the relative general abundance of 

 pests on Cape Cod cranberry bogs in the season of 1937 follow: 



L Black-headed fireworm (Rhopobota) considerably less prevalent than usual. 



2. Fruitworm (Mineola) much less abundant than usual, doing probably as 

 little harm as in any season during the last 33 years and finishing its work very 

 early. 



3. Weevils (Anthonomus) more prevalent than usual, especially on the outer 

 part of the Cape. 



4. Fire Beetle (Cryptocephalus). See above. 



5. Gypsy moth even more destructive in Plymouth Count\- than in 1936, 

 but less so in Barnstable County than in recent years. 



6. Tipworm (Dasyneura) considerably more prevalent than usual. 



Control of Cranberry Bog Weeds. (Chester E. Cross.) This investigation 

 was carried on in 1935 and 1936 by Dr. William H. Sawyer. In 1937 nearly 800 

 different weed plots were given various treatments with chemicals. Ammonium 

 sulfate, copper sulfate, iron sulfate, kerosene, kerosene emulsions, sodium arsenate, 

 sodium arsenite, sodium chlorate, sodium chloride, and sodium nitrate were 

 tested variously as weed killers. The following were the more important results 

 of this work: 



1. A spray of half a pound of sodium arsenite in 100 gallons of water, applied 

 after mid-July, burns all the foliage and more tender stems of the chokeberry® 

 and does not injure cranberry vines or berries. 



2. A spra>' of 20 pounds of copper sulfate in 100 gallons of water, applied 

 heavily late in July or early in August, destroys nut grass' very effectively. 



'At the same time of year, a stronger solution, 25 pounds in 100 gallons, burns off 

 the tops of Bidens and Aster and the foliage of wild rose and severely burns 

 barnyard grass* and some kinds of Panicum and so keeps them from seeding. 

 It is also considerably effective against loosestrife.^ These sprays do little or no 

 harm to cranberry vines or fruit. Copper sulfate is evidently a very important 

 addition to the list of chemical killers of cranberry bog weeds. It kills some of 

 the same weeds that kerosene kills and at half the cost for materials. 



3. A spray oi \\4, pounds of sodium arsenate in 100 gallons of water, applied 

 early in August at a rate of 100 to 150 gallons an acre, is a satisfactory treatment 

 for wild bean,'" triple-awned grass," and partridge pea.^- It also burns off the 

 foliage of the coarser brambles.'^ 



4. A paddle-mix emulsion of kerosene and water, made with Aresklene or 

 Nopco fish-oil soap as the emulsifier, promises to control horsetail'^ as well as 



^ Pyrus melanocarpa Willd. 



^ Cypertis dentatus Torr. and C. strigosus L. 



^ Echinochloa. 



^ Lysimachia terrestris B S P. 



l** Apios tuberose Moench. 



1^ Aristi'Ja gracilis Ell. 



'^ Cassia Chamaecrisla L. 



1^ Rubus spp. 



^^ Equisetum spp. 



