Part 20 (2/2)
DR. ADAMS: I would be for that, but we have to find other methods for a lot of people. Besides, we need something that will intercept some of the grubs in the fall, before they get big. After all, by the time the quail are interested in them, they have already done some damage in the ground. In the ground the grubs can do two kinds of damage. They can make turf loose so it can be rolled back like a rug. Second, if you should plow up a piece of sod that has many grubs in it and try to plant row crops or nursery stock, they may eat the roots off the planting in the spring.
DR. McKAY: I'd like to ask what effect low temperature has on them and how far north you think will be their limit?
DR. ADAMS: The soil temperature at which the grubs begin to die in hibernation is 15 degrees, and I have never seen the soil temperature that low here under turf. (I operate a soil thermograph on my lawn.)
A MEMBER: How far down do they go?
DR. ADAMS: They hibernate at 4 to 8 inches in the ground. It's rare to have it drop below 27 degrees at these depths.
MR. STERLING SMITH: What do you mean, Fahrenheit?
DR. ADAMS: That is Fahrenheit.
A MEMBER: That's frozen solid. That's at 32 degrees.
DR. ADAMS: The deeper soil will drop only a few degrees below freezing.
The soil here usually remains no lower than 32 degrees, except within an inch or two of the top.
A MEMBER: Do you think soil temperature is going to be a limiting factor?
DR. ADAMS: I think the limiting factor northward is the coolness of the summers. In Northern j.a.pan their life history gets altered because of the shortness of the summer, and I think in the Adirondack area they won't be serious for that reason.
MR. WEBER: Will this spore powder kill other kinds of grubs that are in the sod?
DR. ADAMS: Not to any practical extent. It does not control the grubs of the ”June bugs,” or brown June beetles, or what are called ”white grubs.”
MR. LOWERRE: Would the DDT kill the parasitic wasps?
DR. ADAMS: Turf treated with chlordane or DDT is grub-proofed and is not of any use to the flying parasites as a place to lay eggs, or for bacteria to multiply. So we don't want to put chemicals on top of biological control plots. For instance, on an average home property I would treat the front lawn, the more valuable piece, with chemicals so that it would be 100% grub-proofed to protect the turf and to take that much turf out of beetle production. Then on the back lawns or gra.s.sy fields adjoining, I would apply at least a half-pound of this milky disease material, and in that way provide a complete treatment; the parasites can be added on some large public turf area nearby. And don't think you are going to stamp the j.a.panese beetle out just by spraying all the adult beetles you see each summer on the cultivated plants, because there are lots more on the shade trees, weeds and vines.
A new book, ”The Insect Enemies of Eastern Forests,” contains a great deal of information on the insects feeding on nut trees. Unfortunately, it isn't indexed to crops, so you can't look up ”walnut” and find what insects bother you. You have to know what the insect is, and you will find it with its insect family. That is U. S. Department of Agriculture Miscellaneous Publication 657, by George E. Craighead. Price $2.50, from the Superintendent of Doc.u.ments, Was.h.i.+ngton, D. C.
MR. CORSAN: What in the world has become of the black walnut caterpillar, that big, black fellow with the grey hairs?
DR. ADAMS: Maybe they are at a low point in a cycle. Mr. Bernath will show you a few of them.
MR. CORSAN: He might show me a few of them, but I have been pestered with them for years, and this year I haven't got any.
DR. ADAMS: I suppose natural conditions have taken care of them for a while, but they will come back again.
(Applause.)
DR. MacDANIELS: Thank you, very much, sir. We will take a few minutes recess now.
(Whereupon, a short recess was taken.)
Editor's Note: The following paper which was delayed, was originally scheduled for our 1949 Report.
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