314 MASS. EXPERIMENT STATION BULLETIN 247 



areas that have been flooded, sprayed and resanded regularly. Evidently, 

 it is killed out directly or indirectly by late spring or summer flooding 

 or by sanding or spraying, for no evidence was found that fall flooding or 

 the winter flood, even when it is held late, aifects it. 



(b) Pyrethwm Soap Spray. Extensive spraying tests were carried out 

 with this material to determine its efl'ectiveness as a control for various 

 cranberry pests. As a general result of these tests, it has been decided that 

 the pyrethrum spray should have an important place in cranberry culture 

 as a treatment for the first brood of the black-headed fireworm and as a 

 control for leafhoppers, but that it will not take the place of nicotine 

 sulfate for most of the other treatments for which that insecticide is used. 



(c) Holly Mite (Paratetranychus ilicis McGregor). The general life 

 history of this mite was worked out and it was discovered that heavy rains 

 during its active season sometimes very nearly achieve its complete control. 



(d) Cranberry Root Grub (Amphicoma vulpina Hentz). Progress was 

 made in develoi)ing new and more satisfactory methods of applying the 

 sodium cyanide solution used as a control for this pest. 



(e) Cranberry White Grub (Phyllophaya anxia Lee.) Considerable at- 

 tention was given to the study of the life history of this species and it 

 was found that it could be controlled best by the treatment used against 

 the cranberry root grub. 



(f) Cranberry Black Buy. This cranberry pest has not heretofore been 

 recognized in literature but it is often so abundant that it drains the vines 

 seriously. Its life history was partially worked out. 



(g) Considerable attention was given to the parasites of cranberry 

 pests and several new forms were reared. 



(h) Cranberry flower pollenation and the relationship of insects to 

 it was studied. 



Cranberry Disease Work. (H. J. Franklin in cooperation with tlie Bu- 

 reau of Plant Industry, U. S. D. A.). Dr. Neil E. Stevens of the Bureau 

 of Plant Industry was at the Cranberry Station during the growing season 

 both years and cooperated very actively in this work. The chief studies 

 were the following: 



(a) Fahe Blossom Disease. The distribution and spread of this disease 

 and the possible relationships of insects and of flooding to it were given 

 very extensive and careful attention. The McFarlin variety was found 

 to be the most immune of all the cultivated varieties and the Early Black 

 variety is generally only moderately alTected by it. On the other hand, 

 the Howes variety, which is the standard late variety, is very susceptible 

 to its attack. This disease has been spreading rapidly in recent years 

 and has become a major cranberry problem. Its effect on the Howes vari- 

 ety is so great that the discovery of a new late variety resistant to it may 

 soon become imperatively necessary. It was found that this disease origin- 

 ated with the cranberry in Wisconsin and was brought from Wisconsin to 

 Massachusetts and New Jersey in diseased vines. Its lines of spread in 

 this State from one bog to another were traced, in some cases through 

 considerable series of bogs. It seems probable that this disease originally 

 afl^ected some other species of plant, probably a plant introduced from 

 abroad and grown extensively in the Middle West and not very much in the 

 East. To discover this other host presents an interesting and probably dif- 

 ficult problem. It was proved experimentally that the disease is carried from 

 diseased to healthy plants by insects and experiments have been started 

 to determine just what species are the carriers. Experiments were also 

 started to determine whether the disease can be carried merely by con- 



