The reduction in the check block July 14 may be due to proximity to the sprayed block which was not true in Eldred. This check was small. Table 8 shows on July 14 an approximate reduction of Lindane 99%, BHC 98%, Dieldrin 98%, and Toxaphene 85%.
From these tests in both places it appears that we have a choice of three very good materials, Lindane, Benzene hexachloride called BHC and Dieldrin, and for that reason we can ignore the less efficient material, toxaphene.
At Eldred, since first brood sprays were applied in a sizeable area records of infestation were made shortly before time to spray for the second brood to determine whether the first brood spraying would eliminate the need for second brood spraying. However, the infestation was found to be practically as great in this area as the unsprayed part of the woods. It appears that the control was not good enough to allow this. In part this was due to failure to reach the tops of the trees. Records were made in the lower parts.
5. Varietal susceptibility.
At Anna where there was a limited number of trees, the orchards were plotted on paper and location of each tree with variety indicated records were made of each tree separately, in hopes that some varietal susceptibility would be shown. There is nothing very clear in this respect except that of the varieties in the Casper orchard, Butterick, Busseron, Indiana, Posey, Stewart, Osburn, Major, Green River, the Indiana and Posey may be a little more heavily infested than the others. At Eldred for the second brood infestation, the variety of each of the 10 record trees was reported, but there were so many varieties and they did not occur often enough in the five plots to make variety infestation data reliable. However, the rather high average on the Indiana variety did seem to corroborate the findings at Anna.
There was some foliage burn in two of the record trees in the Dieldrin plot at Eldred, both being the variety Rockville. Another tree in another part of the plot was also found to be burned and also found to be the same variety, so it appears that this may be particularly susceptible to spraying especially in this concentrated form such as we used. There were no Rockville trees in any of the other plots, so we have no way of knowing whether the Lindane, BHC or Toxaphene would have done the same or not.
PRESIDENT MacDANIELS: The next paper, the last paper of the afternoon, is Control of Insects Injuring Nut Trees, by Howard Baker, U.S.D.A. Bureau of Entomology and Plant Quarantine, Beltsville, Md.
MR. BAKER: Mr. Chairman, members of the Northern Nut Growers Association: It is a great deal of pleasure to be back here speaking before a group of nut growers. Back some years ago my first assignment to a station of which I had charge was an investigation to count insects in Louisiana and Eastern Texas, so it is a pleasure to be back before a group of nut growers.
Insect Enemies of Northern Tree Nuts
HOWARD BAKER, U.S.D.A., Agr. Res. Admin., Bureau of Entomology and
Plant Quarantine