DR. ROHRBACHER: I am sure your project is interesting, manifested by the questions you have been asked.
FOOTNOTES:
[2] Horticulturist and Principal Horticulturist, respectively. U. S. Department of Agriculture, Bureau Plant Industry, Soils and Agricultural Engineering, Beltsville, Md.
[3] Number in parenthesis refer to literature cited, [p. 25].
The Filbert and Persian Walnut in Indiana
W. B. Ward, Department of Horticulture, Purdue University
The soils and climatic conditions in Indiana are, for the most part, favorable to the growing of nut trees. There are various types of soils, ranging from light sand to heavy clay, soils high and low in organic material and natural fertility. The annual rainfall, 35 to 40 inches, is fairly well distributed throughout the year. The length of the growing season is about 150 frost-free days and, oftentimes, another 20 to 30 days of non-killing temperature. The summer and winter temperatures are average, thus providing good conditions for the development of fruit and growth to the trees.
There are always exceptions to the normal conditions, and a good test season broadens the experience of those who want to go to the extreme in planting nut trees. This past year, 1950-51 season, was a good test year. The temperature early in November was as high as 85°, tomatoes, peppers, beans, and sweet corn were growing in the gardens. During mid-November the temperature quickly dropped to near zero. The cold later went down to -20° and even -35°, as recorded at Greensburg. This cold weather, not only killed much of the tender short growth and pistillate flower possibilities, but destroyed many of the catkins. The filbert and Persian (including Carpathian) walnuts, suffered and in some instances the plants were killed to ground level. All of the damaged plants have survived, and where the top of the tree was killed, new growth came up from the root. As only seedling Persian walnut trees were under observation and included in the Purdue plantation, their sucker growth will be used to form new tops.
The native walnut, hazelnut, hickory, and butternut had little or no winter injury and many trees are very fruitful all over Indiana. The improved strains of filberts and the Persian walnuts have only a few fruits this year. Seedling Persians grafted or budded on native black walnut survived, but there was some damage to the top growth due to immaturity of the wood and bud last fall. Before general planting recommendations can be made, other than for the hobbyist or home-owner with a few trees, further testing will be required.