Northern Nut Growers Association Report of the Proceedings at the 41st Annual Meeting Part 20

Rotenone, which, I believe, is one of your main insecticides in nut culture, is fairly effective on j.a.panese beetles. It kills the beetles. .h.i.t with the spray and gives protection for several days thereafter. If you apply it often enough, rotenone can take care of the plants so that they don't become disfigured by the beetles. Using cube powder, you may apply five ounces of 4% rotenone in 10 gallons of water. Of course, in many cases there is no objection to using DDT wetable powder or dusts, unless you are afraid of a mite problem arising after DDT is used. If DDT can be sprayed on the plants, it needs to be applied only about three times during a summer, or sometimes only twice. For plants that are growing very fast, the new growth, of course, has to be kept treated. You may prefer to spray once heavily over all the plants in July and then, after that, keep the beetles off by spraying or dusting the new growth, during August. For more directions see U.S.D.A. Farmers Bulletin No. 2004.

Now, there are new chemicals that will kill j.a.panese beetles very quickly. Parathion will kill them, but its toxicity necessitates great care in handling and, on peaches, we find it protects the plants for only a few days. Chlordane, which has a very important use in connection with these insects in the grub stage, is not recommended above ground; it is too brief in its action. Methoxychlor may be used instead of DDT.

It is less effective, but much less poisonous, and should be applied more frequently.

Now, the other aspect of control is to try to reduce beetle production over the whole area so that you don't have so many beetles flying in to the plants during the summer and you don't have to spray so frequently, if at all. This is the phase to which I wish to give particular attention, after we consider the life history.

~Life history:~ The j.a.panese beetles in the adult stage are in evidence here from late June to late September, or, roughly, for the summer season. The adults lay their eggs in the soil, mostly in lawns, mowed gra.s.sy fields and pastures. The adults die but the eggs give rise to tiny, bluish-gray larvae which feed chiefly on gra.s.s roots. The larvae grow through the fall and spring, and, if more numerous than about 40 to the square foot in September, or about 25 in April and May, can cause severe lawn damage.

MR. CORSAN: That's the stage when the pheasants and starlings eat them.

DR. ADAMS: Yes, in the grub stage.

MR. CORSAN: I see thousands of starlings gorging themselves.

DR. ADAMS: Yes, scratching birds, crows and skunks can take them out; the starlings make a hole the size of a pencil point to do so. In our survey areas grub populations sometimes seem to drop rapidly in May, when the birds are feeding their nestlings. In June, the surviving larvae mostly change into pupae, and by July they are appearing as beetles. From the lawns and gra.s.sy fields they readily fly to weeds, shrubs, grapevines and trees. They fly at least a few hundred yards, if need be, to find their host plants. Well kept, sunny, lawns with good, moist soil, which carry 40 grubs to the square foot in the fall may still have plenty at transformation time in early summer. A lawn of 5,000 square feet could thus produce 100,000 beetles. Yards, roadways and pastures commonly produce as many as six beetles to the square foot, which means a quarter million to the acre.

~Chemical control in the grub stage:~ In New York we suggest that on a home property the more valuable sections of permanent lawn be grub-proofed with chemicals as soon as there are 5 to 10 grubs to the square foot. This grub-proofing has two effects: (a) it stops beetle production from that lawn, and (b) it prevents the lawn gra.s.s being damaged by the grubs of this and other annual grub species and by the birds and animals, including moles, which damage grubby turf. For grub-proofing I prefer to use chlordane. It may be applied in a spray, at 8 ounces of 50% wettable powder to 1,000 square feet, or it may be purchased in the more bulky 5% form and applied dry with a two-wheeled lawn fertilizer spreader. For each 1,000 square feet I take 5 pounds of 5% chlordane and, since it tends to clog the spreader, I mix it in a cardboard drum with 5 pounds of a dry, granular material such as the activated-sludge fertilizer known as "Milorganite." The ten pounds of mixture is then spread on the 1,000 square feet, half east and west, half north and south.

If applied in the fall or early spring there will be no beetles coming out in July and no grubs for several years. DDT at 6 pounds of 10% DDT to 1,000 square feet will give an even longer grub-proofing effect. Our plots so treated in 1944 are still grub-free. The possible trouble with DDT is that it is too nearly permanent, and if you should plow up a piece of lawn treated with it and try to raise tomatoes or strawberries, you might find the soil too toxic.

~Biological control in the grub stage:~ The chemical grub-proofing of the sunny parts of the front or main lawn on a property is desirable for the reasons stated, but it does not usually stop more than a fifth of the beetle production around the property, because there are usually plenty of neighbors' lawns, pastures, public grounds, and other beetle-producing turf areas nearby. How are you to reduce the beetle crop on these places, mostly on ground you don't control? Here is where biological control comes in, something which I feel will appeal to you in this group. The parasitic insects known as spring Tiphia, imported from the Orient and well established on hundreds of estates, golf courses, and cemeteries around Philadelphia and New York, may be introduced in your vicinity when grubs reach about 5 to the square foot.

The parasites, which are like flying ants, appear above ground in spring and feed on honey-dew. The female burrows in the soil and attaches her eggs singly to j.a.panese beetle grubs. A maggot hatches and consumes the grub. I have charge of the distribution of these parasites in New York.

I like to liberate at least one colony in each village or town division.

Some of you may help me plan the liberation for your vicinity, possibly on a cemetery near your place. The colonies enlarge to about a square mile in 10 years, and may cut beetle production by 50%.

Another biological agent which can be added to grub-carrying turf is the bacterium causing j.a.panese beetle grubs to turn milky white and die. A powder is made from diseased grubs and talc and this milky disease spore inoculum is applied with a teaspoon in dots or spots over the turf. The important point is that the spore powder must be used on a plot where there are grubs to get the disease, and not on chemically grub-proofed soil. Milky disease spore powder is sold under three brand names, "j.a.pidemic," "j.a.ponex" and "Sawco-j.a.py." One-half pound, suitably applied, will cost you about $2.50 and be an act of good citizens.h.i.+p, for the disease slowly spreads to any grubby soil in surrounding properties. I can supply addresses of the producers and detailed reprints of my studies.

Discussion

MR. McDANIEL: Does this disease affect any other beetles we have in America, besides the j.a.panese?

MR. ADAMS: Yes, one other species; it causes some sickness in the grubs of the turf pest known as the Oriental beetle.

MR. McDANIEL: How about the green June beetle?

DR. ADAMS: No, unfortunately, it doesn't work on that beetle, which is a pest on Long Island and in the South.

A MEMBER: How much area would a (1/2-pound) can like that treat?

DR. ADAMS: It depends. You can apply a half-pound to a quarter acre, or any smaller s.p.a.ce you want to put it on. If you want to put spots down closer together, say every three feet, it will treat about 1,000 square feet. It suggests on the label that you do. But if you treat a plot on a large field, I'd recommend you put it out at about a teaspoonful every ten feet. In other words, I wouldn't put less than a half-pound on the plot set aside for it on my place. The application is just a starter to introduce the disease in the area, and it doesn't matter too much whether you spot it at 10-foot intervals on a pasture or put it at fairly close intervals on an area about the size of this room. The point is that it mustn't be broadcast, because that spreads the spores too thin. Grubs don't get the disease if they eat only a few spores. We a.s.sume that where you put the spots down on the ground the grubs under those spots will get the disease and wander off and die. When a grub dies, it multiplies the number of spores up to many millions. That portion of soil becomes infective, and more grubs going through the infective portions carry the disease to intervening areas until the whole piece of turf is unhealthful to these grubs. Droppings of birds feeding on sick grubs spread the disease.

MR. FRYE: One application is all that's needed?

DR. ADAMS: One application is all that's needed. Control is slight at first, but increases with the pa.s.sage of the years.

MR. CORSAN: Quail feed on them. Why can't we have quail around the farms instead of shooting them?

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.