The pecan growing heat units, pecan units they may be called for short, for Evansville, Ind., in 1914 were 143.9. From this we might conclude that a place where the pecan units for 1914 would figure out 143.9 would be likely (as far as climatic conditions are concerned) to grow pecans as well as Evansville, that is, of course if other years should show similar figures.
With the idea of seeing if the experience of those who were growing pecans would be anything like what might be calculated from the Weather Bureau Records, letters were written to all members of the National Nut Growers' Association to find out if pecans grew and bore well in their sections and if so which varieties. From the replies received it has been in a number of instances difficult to judge just how well pecans grow in some sections. For this reason I have interpreted the replies somewhat on the basis of my own knowledge and on certain facts told me by Mr. C. A. Reed. Apparently at least 175 pecan units are to be found in most places where the southern pecan is successful commercially. This corresponds to a line through Augusta, Milledgeville, Macon and Columbus, Georgia and Montgomery, Alabama. There seems little question but that pecans can be grown north of this line but until I get more positive information than I now have I shall doubt if the planting of southern varieties of pecans much north of this line is nearly as advisable as it is south of it.
When we come to compare this figure with the pecan units for Ocean Springs and Pascagoula, Miss., where a number of the fine southern pecans originated which are now being propagated we find an average of about 222 pecan units. To reduce this to a percentage we find that many of the standard southern pecans grow and bear well when the pecan units are as low as 79% of those of the place of their origin. In other words the adaptability of the southern pecan is 79%, that is it will grow and bear well where the pecan units are as low as 79% of those of the place of its origin or to use rough figures, 80%.
When we come to ascertain the pecan units of the locations where the northern pecan grows and bears well we will consider Evansville and Vincennes, Ind., as places where it bears well; Burlington, Ia., as a place where it does quite well, but not as well, as in Evansville; Clinton, Ia., as a place where trees are growing well but where they bear a large crop only once in several years; and Charles City, Ia., as a place where the pecan does not mature its nuts. The pecan units are also shown for several important places outside of the native pecan area.
| Highest | Lowest | Average | |||
|---|---|---|---|---|---|
| Evansville, Ind. | (1919) | 147.5 | (1917) | 116.4 | 135.7 |
| Vincennes, Ind. | (1914) | 144.7 | (1918) | 123.1 | 130.8 |
| Burlington, Ia. | (1914) | 125.8 | (1917) | 90.2 | 108.4 |
| Clinton, Ia. | (1914) | 109.2 | (1917) | 75.3 | 94.9 |
| Charles City, Ia. | (1914) | 91.2 | (1915) | 65.4 | 78.5 |
| New York City | (1914) | 101.2 | (1917) | 85.2 | 94.3 |
| Lancaster, Penn. | (1919) | 108.7 | (1917) | 84.9 | 98.4 |
| Gettysburg, Penn. | (1919) | 108.4 | (1916) | 89.4 | 100.7 |
| Cincinnati, O. | (1914) | 131.7 | (1917) | 88.9 | 109.5 |
| Baltimore, Md. | (1919) | 127.2 | (1917) | 106.7 | 121.0 |
| Washington, Md. | (1918) | 126.8 | (1917) | 104.7 | 119.3 |
| Hartford, Conn. | (1919) | 88.9 | (1917) | 74.8 | 85.1 |
If we consider that Evansville and Vincennes are the center of the pecan district near which most varieties have originated and that a place should have 80% as many pecan units as in this Evansville district in order to have the northern pecan do well, a place should have 105 pecan units in order for one to feel reasonably certain that the northern pecan will do well there. It will be both interesting and instructive to see how well the applications that may be made from the conclusions compare with observed facts.
We know that there are large numbers of pecan trees at Burlington, Ia., and that the trees grow and bear well. Its pecan units are 108.4. We should conclude that at Baltimore and Washington with pecan units at 121.0 and 119.3 respectively that pecans would grow and bear well. There are pecan trees over 100 years old at Marietta, Md., which is half way between Baltimore and Washington. These trees bear nuts and although it has not been possible to get bearing records it is evident that they bear considerably for on the roads of that vicinity are hundreds of young pecan trees which evidently came up from nuts borne by these old trees. We should expect the pecan to do well at Cincinnati, O. In fact I have been expecting to find it native there, but, so far all inquiries have failed to do so. At Fayetteville, however, which is about 40 miles east of Cincinnati and somewhat north of it, are bearing pecan trees raised from seed brought from Shawneetown, Ill., which is in the Evansville district. Seed from these Fayetteville trees planted at Baldwin have shown nearly 100% germination.
There is some question as to how well pecans should bear at Gettysburg, and Lancaster, Penn., and at New York City where the pecan units are much like those at Clinton, Ia., where, on forest pecan trees, we get a fair crop but once in several years. Perhaps with our present knowledge these places should be considered on the borderland between the country where the pecan is likely to do well and that where it will not mature its nuts. We know that pecan trees have borne nuts at Aspers, Pa., near Gettysburg, at Lancaster, Pa., and at Westbury and Glen Cove, Long Island, near New York City but so far it has not been possible to make sufficient observations to form definite conclusions as to what to expect. It seems quite likely that fertilization and care may help materially the maturing of crops in those sections which in our present knowledge we must consider on the borderland.
Probably we should not expect pecan nuts to be borne at Charles City, Ia., where pecan units are but 60% of those at Vincennes, and pecan units at Hartford, Conn., are not so very different. There are northern pecan trees at Charles City, Ia., which many years ago were brought there, but the information I have about them is that they have never borne. There is a large pecan tree at Hartford, Conn., but I have never been able to learn of its bearing nuts.
As the northern pecan trees now being planted get to bearing age we shall have actual experimental data as to what they will do in the different sections. Until that time by the method outlined herein and with the Weather Bureau Records for several years at hand inquiries regarding its probable adaptability for a given section can be answered with far more confidence than was possible heretofore.