Northern Nut Growers Association Report of the Proceedings at the 41st Annual Meeting Part 19

As Dr. Waite told us one time in Was.h.i.+ngton--you will probably remember the remark he made about the pecan trees in an orchard which were absolutely fruitless year after year. He went through that orchard, and he saw a pecan here and a pecan there that had a good, big crop right among the empty trees. He examined them and found signs driven into the trees, and some of the signs were put up with zinc covered nails. Those signs that had the steel covered nails had no nuts on, but those that had zinc in had a huge crop. It excited the growth of the female blossom.

Now, we have got an awful lot to discover, as you gentlemen say in this nut culture, way beyond the imagination of the human mind.

DR. MacDANIELS: We had better limit discussion to this particular problem. Is there more comment?

MR. McDANIEL: On that problem, I have observed the brooming in the heartnut seedlings about three years old, which were seedlings of the Fodermaier variety growing at Norris in the late 30's. Brooming developed in some of them in either the second or third year from seed.

DR. MacDANIELS: That answers their remark about the young trees.

MR. SLATE: A plant that is well fed and making very vigorous growth may be more attractive to the insect vector. Therefore, a healthy tree might take it.

MR. McDANIEL: These trees were very vigorous.

DR. MacDANIELS: How many growers of nut trees have this bunch disease on their property?

MR. KINTZEL: Black walnuts?

DR. MacDANIELS: On anything at all. (Showing of hands.) There are at least a dozen.

When Mr. Burgart up in Michigan finds out that the limiting factor practically cleans him out, there is this question of bunch disease with witches'-broom resulting from ground deficiency. I know in the Wright plantings in the vicinity of Westfield they had brooming trees of the j.a.panese walnut which apparently recovered after treatment with zinc.

And, of course, we know on the West Coast you get witches'-broom in the Persian walnut which cannot be cured by zinc.

Is there any other discussion on this point?

(No response.)

We will go on to the next paper.

MR. CORSAN: Anybody pa.s.sing through Toronto can drop in and see my j.a.panese walnuts with 24 to the cl.u.s.ter and not a sign of bunch disease.

DR. MacDANIELS: Yes, you may not have the bunch disease near you. We hope you haven't.

The next paper is by J. A. Adams, who is from the Experiment Station here at Poughkeepsie. This experiment station is a branch of the Geneva Agricultural Experiment Station. I believe that's right, isn't it, Mr.

Adams?

MR. ADAMS: That's right, and it is concerned primarily with the fruits down here in this region.

DR. MacDANIELS: His subject is "Some Observations on the j.a.panese Beetle on Nut Trees." Let me say Mr. Adams would like to show some slides, but it didn't seem feasible to close this window down.

The j.a.panese Beetle and Nut Growing

J. A. ADAMS

a.s.sociate Professor of Entomology, New York State Agricultural Experiment Station, Geneva and Poughkeepsie, New York

It is a pleasure to attend this meeting of the Northern Nut Growers.

a.s.sociation and to take part in your program. I shall discuss the j.a.panese beetle as it seems to affect nut culture, and outline our methods of control.

The j.a.panese beetle evidently came into this country in the soil about some roots of plants imported to a nursery near Philadelphia nearly 40 years ago. Since 1916, its distribution, habits, and control have been closely studied by the federal j.a.panese Beetle Laboratory at Moorestown, New Jersey. The insect has become generally distributed in the coastal area, as far north as Ma.s.sachusetts, as far south as Virginia, and as far west as West Virginia. Beyond these limits, it has established local colonies in New Hamps.h.i.+re, Vermont, Western New York, Ohio, Michigan, and North Carolina. In most of the states affected there is an investigator who, like myself, carries on local studies, more or less in cooperation with the federal laboratory. In New York we now have, in addition to the generally infested areas on Long Island and in the Hudson Valley, about 50 isolated infestations in the central and western parts of the state.

Might I have a showing of hands by those who have j.a.panese beetle already? (Showing of hands.) There is quite a sprinkling of you who have them. Many of you do not have them yet, but, since the insect is spreading every year, you can expect them some day, especially if you live in the Northeast. It is expected that this pest will not thrive in the drier central States, but it might become established in the Pacific States some day, unless prevented.

You can see these beetles anywhere in and around Poughkeepsie. From Poughkeepsie I have watched them spread in the past few years to Pleasant Valley and eastward. This morning as I parked my vehicle by this building I picked these specimens from the smartweed, ~Polygonum persicaria~. (Pa.s.sing of specimens.) These insects also feed on the flowers and foliage of purple loosestrife, ~Lythrum salicifolia~, so plentiful and showy in our swampy fields. The most conspicuous damage is done to the foliage of wild grape vines. You will observe this when you visit Mr. Stephen Bernath's nut plantation. You will note the conspicuous defoliation of the vines on the fence rows. Willow is another host heavily attacked. I believe you have the beetles at your plantation at Wa.s.saic, Mr. Smith?

MR. GILBERT SMITH: Plenty of them.

DR. ADAMS: You will also observe the damage at Mr. Smith's place. You will see that it is strictly a matter of skeletonization of the leaves.

A MEMBER: They eat the fruit, too.

DR. MacDANIELS: You have damage on fruit.

A MEMBER: They eat berries.

DR. ADAMS: Yes, but on nut plants the damage above ground is confined to leaf skeletonization. It varies widely, depending on the kind of nut plant. Before visiting Mr. Bernath's planting, I sought out the botanical names of the commoner nut plants in Dr. MacDaniels' Cornell Extension Bulletin No. 701, on "Nut Growing." Of the ~Juglans~ species, the black walnut, ~J. nigra~, is sometimes heavily attacked. There are large black walnut trees near one of our peach orchards. I have seen hordes of beetles gather in these trees in July and August, skeletonizing the leaves until the defoliation reached 40% or more. Late in August the beetles seemed to leave the walnut foliage and descend upon the ripening peaches. The heart nut, ~J. sieboldiana~ var.

~cordiformis~, was moderately fed upon at Mr. Bernath's nursery. The b.u.t.ternut, ~J. cinerea~, is only lightly attacked, as a rule.

The hickories and pecans are not attacked to any appreciable extent, but at least some of the chestnuts are very attractive to this pest. I have seen shoots of ~Castanea dentata~ with their foliage reduced to lace. Some of the small Chinese chestnuts, ~C. mollissima~, at Mr. Bernath's place, were about one-fourth defoliated in mid-August.

The hazels seem to be attractive to these beetles. When the j.a.panese beetle spreads to Prof. Slate's plantings of ~Corylus~ at Geneva, we may get more information on varietal preferences. I find that exposed foliage of ~C. americana~, the common wild hazel here, is sometimes fairly heavily fed upon. I am holding up to the window a portion of a hazel bush; you can see that the leaves along one side are skeletonized. It is probable that the species, hybrids, and varieties of ~Corylus~ will show the same marked variation in susceptibility that is shown in so many other genera of plants.

Among the oaks, the pin oak, ~Quercus Pal.u.s.tris~, and the English oak, ~Q.

robur~, are commonly one-third defoliated while the common white and red oaks are almost immune. Among the maples--to go farther afield from nuts--the Norway, ~Acer platanoides~, and the j.a.panese, ~A. palmatum~, are often severely injured, where the sugar maple, ~A. saccharum~, is only lightly injured and the delicate-leaved red maple and silver maple, ~A.

rubrum~ and ~A. saccharinum~, remain untouched.

Since the j.a.panese beetle is here to stay, and to spread, these differences are worth considering where plant materials are being selected for new ornamental plantings. In our bulletin on j.a.panese beetle (Cornell Extension Bulletin 770) we have to warn the reader that planting chestnuts may bring him trouble with the j.a.panese beetle, trouble which he would not have with flowering dogwood, ~Cornus florida~, or the common lilacs, ~Syringa vulgaris~, which are immune to this pest.

It may be, however, that some of the chestnuts carry immunity factors.

In the U. S. Department of Agriculture Circular No. 547, published in 1940, "Feeding Habits of the j.a.panese Beetle," by I. M. Hawley and F. W.

Metzger, ~Castanea crenata~, the j.a.panese chestnut, is listed with beech and chestnut oak as "generally lightly injured." I understand you consider the nut of this species poor, but if resistance factors are in the genus, there can be hope of finding or developing a chestnut resistant to j.a.panese beetle.

We might be able to do with chestnuts what has been done with poplars.

The common poplars range from the Lombardy, ~Populus nigra italica~, which is heavily damaged by the beetle, to the white, ~P. alba~, which is immune. The forest geneticist, E. J. Schreiner, has written an article, "Poplars can be bred to order," which appears on pages 153 to 157 in "Trees," the Yearbook of Agriculture for 1949, published by the U. S.

Department of Agriculture. Schreiner provides an interesting diagram of random planting of 102 poplar hybrids, in plots of 50 trees each, representing 30 parentages. He writes, "j.a.panese beetle infestation was heavy in ~1947~; as late as September 9 beetles were as numerous as 10 to 12 per leaf on the most susceptible plants. Although the insects were feeding everywhere on the spa.r.s.ely scattered weeds growing under the hybrids, beetle feeding was found on only nine hybrids, representing four parentages. Three of these parentages include hybrids that were entirely free of beetle feeding during the entire infestation." Among five hybrids of ~P. charkowiensis~ and ~P. caudina~, three were highly susceptible, one moderately susceptible and one was non-susceptible.

j.a.panese beetles, when infesting rows of plants of the same variety, usually occur unevenly on the individual plants. Some of the factors have to do with the vigor or color of the tree. In my observation on peach, I have repeatedly seen a sickly, yellow and half-wilted tree with thousands of beetles in it, while other similar but healthy trees in the same row averaged only a few hundred beetles. You can make one branch of a tree more attractive to the insects than the rest of the branches by partly girdling it or permitting borers or cankers to damage the base of the branch. This observation suggests that the increased sugar content raises the attractiveness of the leaf. It coincides with what is already known that extracts of plants preferred by the j.a.panese beetle have, in general, a higher sugar content, or more of a fruit-like odor than those not attacked. (Metzger et al, Jour. Agric. Research, ~49~ (11): 1001-1008.

1934. Was.h.i.+ngton, D. C.)

There are other observations you can easily make yourselves. The j.a.panese beetle avoids shade, except on the hottest days, and its feeding in dense trees shows up most in the tops; its feeding on uniform plantings tends to show up most in the edge rows. Nursery-size trees are more extensively defoliated than larger ones. At this point we must consider that the insect usually has to fly into a planting from the outside, for it breeds chiefly in lawns and meadows. If the foliage ma.s.s of the nut planting is small and the gra.s.s areas nearby are large, the beetles are likely to do heavier damage than where the planting is very large and gra.s.s areas negligible. A small planting in a suburban area, beside a large golf course, cemetery or dairy farm, is going to be more heavily attacked than a large one set in a clearing in the woods.

~Control of the adult:~ The safest, most direct measure is to pick or knock the beetles off the plants, preferably in the early morning, when they are cool. They may be dropped in a pail with a little kerosene in it. Some plants can be s.h.i.+elded with thin nets which can be placed on them by day. We do not recommend j.a.panese beetle traps. These yellow traps, which are baited with geranoil and other essential oils, can draw beetles in from a considerable distance but we have found that, possibly because many beetles miss the trap, the population of beetles remains high near the trap, in spite of heavy daily catches. Although the use of one trap to the acre on a block 10 miles square would probably get results, the use of a few traps on a small nut planting is likely to be disappointing.

A MEMBER: Will birds or any kind of poultry eat them?

DR. ADAMS: Yes, poultry will eat them, as far as they can reach. Certain birds, of course, will feed on them to some extent, but birds, in summer, seem to have plenty of other things to eat, and they certainly leave plenty of beetles in plain sight uneaten. We can see that the birds are a fairly constant helpful factor, but are not to be relied upon to prevent injury occurring in a beetle outbreak.