S. H. GRAHAM, Ithaca, N. Y.
This summer has been a difficult one for black walnuts. A late spring delayed starting and three freezes during the week beginning Sept. 22 prematurely checked development so that poor filling seems to be the rule. The Persian walnuts again demonstrated their ability to ripen their nuts in a short season.
Some of our Persian walnut trees are growing in the partial shade of larger black walnut trees. We prefer to keep these larger trees as they may be valuable stocks to be grafted to the superior varieties that one is always hoping will appear later on. This condition gives a good opportunity to observe the effect of shade. There seems to be no doubt that even light shade is detrimental in our latitude to the Persian walnut and results not only in more spindling and unsymmetrical growth but also interferes with proper ripening of the wood making it more subject to winter injury.
One difficulty with the Persian walnuts in the East is premature falling of the nuts. The female flowers on the young Persian trees that we have seen are usually more numerous than with black walnuts of the same size and age, but even hand pollinating often fails to give a good set of nuts. Last spring we took pollen from eight of our Persian trees to the pomology department of our State College of Agriculture for germinating. The best sample showed 45% viable pollen; the next best 15% and the rest from O to 5%. This had been collected and stored for several weeks according to the methods given by Dr. Cox in the annual report for 1943, page 58. It is possible that this lack of viability may be due to some soil deficiency such as insufficient lime or boron. Prof. Schuster of the Oregon station writes that they find that Persian walnuts readily accept good Persian pollen but not black walnut or butternut pollen. If the viability of the pollen falls below 50% they consider it unsatisfactory. On some of the Oregon soils an application of boron in the form of ordinary borax under the trees in the spring has greatly helped in getting a crop of nuts. This should be well worth trying in the eastern states.
The filbert crop this year is better than usual. Out of over a thousand crosses between Rush and Winkler with European and Pacific Coast varieties, in our estimation, only one has proven worthy of propagation considering size, flavor, abundance of bearing and resistance to filbert blight. Some growers think lightly of blight but our experience in fighting it through the years in cutting out cankered wood has convinced us of the futility of this means of control in infested areas. Control measures may apparently succeed for a time but when conditions of moisture, heat and air movement are just right it can spread like wildfire. Therefore, to us, resistance to this disease (Cryptosporella anomala) seems of paramount importance. The prevalence of blight has been almost universal in the scattered plantings which we have visited in central New York, usually without the owner knowing why his trees were dying. All our European and Coast varieties, as well as most of the hybrids, take blight readily but there is an occasional hybrid that is clearly resistant. Bixby is one of these.
We have always used a knapsack sprayer equipped with a mist nozzle for our trees but this is inadequate as the trees grow taller. This summer a much more satisfactory nozzle was found that may be quickly adjusted to throw a mist for low trees or a far reaching one for the taller trees. This is made by the D. B. Smith Co. of Utica, N. Y.
From time to time articles appear on insects injurious to nut trees. Frequently mentioned are the web worms and the walnut caterpillars. With us, the damage they do is as nothing compared to that caused by the curculios, the strawberry root worm beetles and the leaf hoppers. We are getting the upper hand of the curculios by the use of cryolite spray but the root-worm beetle problem is still unsolved. Until Rev. Crath wrote of leaf hopper damage (Annual Report 1938 p. 111) we had not regarded them as at all serious. Subsequent observation has convinced us that he was right and that they are often the cause of the blackening and dying of the tender young leaves of Persian walnuts and the curling up of older leaves. We were especially impressed during the Wooster, Ohio, field trip last year and, later on, in seeing how Mr. Sherman had overcome this trouble on the Mahoning Co. farm simply by adding DDT to his spray mixture.
In closing, we would like to call the attention of new members to the wealth of information that is to be found in the old Association annual reports.