GILBERT L. SMITH, Wassaic, New York
In the spring of 1935 we purchased from the Wisconsin Horticultural Society two pounds of the nuts which Rev. Paul Crath had imported from Poland. We planted these nuts in the nursery row. Sixty-two seedlings resulted. We assigned a number of each of these seedlings and transplanted them when they were two years old. Here we made our first mistake. We selected what proved to be a very poor site for them, adjacent to and nearly surrounded by woodland, in which were a goodly supply of butternut curculios which we have found to be by far the worst insect enemy of the Persian walnut. It attacks the terminal growth doing some damage by feeding but principally by laying eggs in the terminals and the fleshy base of the leaf stems. From these eggs grub-like larvae hatch which bore into the terminal and the leaf bases, greatly dwarfing the terminal growth. We have found as many as six larvae in a single terminal. Of course they also like to lay their eggs in the young nuts which then drop from the tree in mid-summer.
In the spring of 1937 we started to graft from these seedlings on black walnut stocks, giving each the same number as that of the seedling from which the wood was taken. It is too bad that we did not start this work sooner as we lost a few of the seedlings, largely through the ravages of the curculio, but possibly some of them were just not rugged enough to stand our climate. We still have 49 of these varieties living, either as grafts or the original trees. To this collection we have added a few varieties, securing wood from seedlings being grown by others. We have had living grafts of some of the named Crath varieties which we suppose developed from some of the wood imported from Poland by Rev. Crath. All of these have failed with us except one, Carpathian D. Apparently they were not hardy enough for our climate.
So far we have had only one severe test of our Crath seedlings, as to hardiness. This was on February 16th, 1943, when the temperature at Mr. Benton's farm was thirty-four degrees below zero. This was not official but was registered by two thermometers which Mr. Benton knew to be very accurate. Many of our Crath seedlings showed no injury at all on this occasion while others showed varying degrees of injury. Our grafts of Broadview were damaged quite severely, Carpathian D to just about the same extent. One other named Crath variety, Crath No. 1, was killed outright. Only one of our seedling varieties showed as severe injury as did Broadview. This was S 12. This tree has now fully recovered but we will not grow any trees from it except for more southern latitudes and then only if it shows exceptional merit when it begins to bear. Therefore, according to our experience so far, there is quite definite evidence that these Crath seedlings are hardier than Broadview. McDermid was killed outright.
We have found that practically all Persian walnut trees, when young, will bear pistillate blossoms for several years before they bear staminate blossoms (catkins). This fact has delayed us in securing nuts from these seedling varieties and has compelled us to resort to hand pollination. However, they are now beginning to produce both kinds of blossoms.
The first one to bear was in 1944, when one tree bore twelve nuts which had resulted from hand pollination with pollen sent us by Mr. Reed. This variety appears to be the most promising one that has borne so far. We have named it Littlepage and have had a booklet printed which describes it fully. We will be glad to mail a copy to anyone who wishes. We have now found a good pollinizer for Littlepage, our No. S22 seedling. This variety produces pollen at just the right time, some of which I used this spring to hand pollenize the Littlepage tree. A fine crop of nuts is now on this tree as the result of this pollination.
Last year (1946) we had a few nuts from each of five other seedling varieties. While we did not consider any of them equal to Littlepage, they were all worth growing and compare quite favorably with English walnuts as found in our markets. This year we have nuts on each of eleven varieties, five of them and the same ones that bore last year and six new ones. Now that these seedlings are beginning to bear we are able to cull out any that prove to be very inferior. As our facilities are far too limited to thoroughly test the promising varieties, we have started to propagate them and offer them in many parts of the country and subject them to many different conditions. Thus it should be only a matter of time until the truly worthy varieties will prove themselves. If we were wealthy we could propagate them and distribute them free of charge but I doubt if it would prove as satisfactory as it is to charge for them, as it seems to be a trait of human nature to take better care of that which costs us something. We will not name these new varieties at present but will put them out under their test numbers. Later the ones that prove best can be named.
To facilitate the distribution of these new varieties we are getting out a folder showing natural size pictures of the nuts of the six varieties which were produced last year, with a brief description of each. I am very sorry that I was unable to get these folders from the printer before coming to this convention. However we will have them very soon and will be glad to mail a copy to anyone who requests it.
As stated before we have found that the butternut curculio is a very bad pest with the Persian walnuts, also heartnuts and butternuts. It does not injure the black walnut at all. There are also several other insects which feed on the Persian walnut, most of these chewing insects that simply injure the foliage more or less severely. Last winter I was advised by Dr. Dean of our experiment station staff, to try benzene hexachloride (hexachlorocyclohexane) for control of the curculio. He stated that in California they have found out that the Persian walnut is quite susceptible to arsenical injury when a spray containing arsenate of lead is used on it. Also tests so far indicate that D.D.T. is not very effective against the apple and plum curculio, therefore not likely to be effective against the butternut curculio. So last spring we secured a supply of benzene hexachloride. Just as we were about to spray the trees I discovered a swarm of orange colored insects with black wing covers, feeding on them. So I checked the compatibility chart in the February issue of the American Fruit Grower and found that benzene hexachloride and D.D.T. were compatible when used together in the spray mixture. I thought it would be well to use a double barreled dose. So we made up a spray of four pounds of benzene hexachloride, four pounds of D.D.T., 50% wettable powder, and 6 pounds of wettable sulfur to 100 gallons of water. This first spray showed a slight burning of the leaves, which I suspected was due to the sulfur. We omitted sulfur from the later sprays and did not note any more burning. We put on three sprays at about two week intervals and a fourth spray about the middle of July. The result of these sprays appears to be excellent. I have found only one nut showing any insect injury and this one was only slightly injured, whereas last summer we lost a considerable percentage of the nuts from curculio injury. A day or two after applying the first spray, I wanted to secure a specimen of the orange-colored insects with black wing covers, but I could not find a single specimen.
We did not apply our first spray quite soon enough and curculio larvae had already invaded a few of the terminals. The first spray should be applied about as soon as the leaf buds separate and quite likely should be followed by the second spray in about a week, as new growth is very rapid at this time and the scant foliage at the time of the first spray would hardly hold enough of the chemicals to give control for more than a few days.