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.
Observations on Hardiness of the Carpathian Walnuts at Poughkeepsie, New York
STEPHEN BERNATH
In our section we have very good Persian walnut varieties of Carpathian and other European sources. I have planted some of all strains and varieties. My place faces northwest on a good elevation. My experience with trees there is that we have no winter injury. We can grow trees there that cannot be grown on some place which is situated low, and therefore does not have enough air circulation. Damage is done after heavy frosts when the sun comes out suddenly. That is what damages the trees—not the cold.
If you take trees and put them in a temperature of 35 to 40 degrees below zero and bring them out to thaw gradually no harm is done. Most people buy trees and plant them in low places; that is the error. We have planted trees where the wind is very heavy throughout the winter and in the spring I found that these trees stood up wonderfully well; whereas, we have European walnut trees with a trunk diameter of about 12 to 14 inches that in one year froze two to six feet—about three to four years growth. If you plant your trees on a fairly good elevation you can be assured of a good nut crop. In planting nut trees I do not know what kind of fertilizer you use, but I always use well decayed cow manure and put a little right around the root system. I never use fresh manure and never use poultry, sheep, or horse manure. They are bad for trees as they are very high in ammonia and this does damage to the trees.
Discussion after Graham, Smith, and Bernath Persian walnut papers.
Corsan: "Is using lime a good idea? I always use a lot of wood ashes."
Stoke: "Use ground agricultural limestone. Burned lime may cause injury."