Returns indicate that winter injury is not always, nor even usually, the result of low temperatures but, rather, to the condition in which the trees enter the winter. If late excessive growth leaves them with wood not wholly dormant, they suffer. If not, they will stand extraordinary low temperatures with little or no damage. One way to guard against this damage is by preventing late growth. A means of doing this will be found in an important contribution by Mr. H. P. Burgart, of Union City, Michigan. Mr. Burgart says:
"After 21 years of experience with growing, selling and planting nut trees, I have had to have a neighbor show me the best way to care successfully for them. I have studied and practiced Mr. Baad's methods, and in comparing them with my former practice, and with the practice of others who have failed with their trees, I will suggest the following cultural procedure to be given all plantings when possible, and to be continued for at least three years, or even longer for best nut production.
"Nut trees should be given clean cultivation right after being planted (in the spring) and until August 1st. This encourages root growth and conserves moisture. Then sow a cover crop of rye, cow peas or soy beans to take up moisture, slow up growth and prevent the late sappy condition that is often responsible for winter injury. Leave the cover crop over winter and turn it under in the spring for humus. Before turning under, a light application of some kind of manure, along with some superphosphate and potash, should be sprinkled around each tree. Then thorough cultivation again until August, and repeat.
"Soil for nut trees should be tested for acidity, nitrogen, phosphate and potash. It has been determined that most nut trees prefer a pH range of 6.0 to 8.0; but I have frequently found people planting trees on soils of 4.0 and 5.0, where nothing but sickly growth could be expected.
"Where it is not possible to work all of the ground between nut trees, cultivation should begin with a three or four foot circle around each tree, annually increasing this space with the growth of the branches. Cultivation, with attention to humus and fertility, are necessary to proper tree growth and nut production. Sod culture will never do."
Mr. Burgart's method has the advantage not only of guarding the trees from excessive winter injury but at the same time adds an almost immediately available source of humus and nutrients to the soil for spring growth. If followed, it should greatly reduce the number of reports of winter injury, failure to start, and of weak growth afterward.
Excessive summer heat is not so great a problem in most portions of the northern states. The highest expected temperatures range, in our reports, from 86° to 110°; mostly from 90° to 100°. The highest known are reported to be all the way from 95° to 120°, but mostly from 100° to 110°. A method of guarding against heat damage will be found in a communication from Mr. H. F. Stoke, of Roanoke, Va., which appears later in this report.
Drouth and hot, dry winds are more dangerous enemies than either cold or heat. It is somewhat ominous that, out of eighty-three reports, forty-two, originating all the way from Maine to Oregon and from Canada to Tennessee, report the occurrence today of frequent drouths, while forty report hot, dry winds. Surely the need for tree planting is immediate and urgent. Mulching, and the protection of recently planted trees by wrapping their trunks, are preventives of some damage, but can not stand up forever against the longer and longer periods of drouth now being reported, during which the water table is gradually being lowered beyond the reach of tree roots.
The length of the frost-free season has an important bearing upon the production of nuts after the trees are matured. This is true in the south as well as in the north. One of the most frequently reported causes of loss of nut production in southern sections is an early spring, inducing growth of buds and blossoms, followed by a frost. No protection seems to have been found against this damage except by use of heavy smudges. Large orchardists protect themselves, but planters of small groves rarely do so. This explains the autumn scramble, reported by many members, in search of early fallen nuts. We should continue our search for trees which produce nuts of early maturity. Thus far the search has not been too successful among most species, but some progress has been made and the future is more encouraging in this respect than it was a decade or two ago. Some early maturing nuts have been found and pollen from the trees is being used for cross-pollination with better known nut producers. In the northern states, dates of the latest spring frosts range from April 1 to June 1, with the average around May 15. The earliest fall frosts come from Sept. 5 to Oct. 15, with the average about Sept. 15 to 20. Where the frosts fall much outside these limits—too late in the spring or too early in the fall—protective measures will help but will not always prevent damage.
Soil Conditions. There is a slight preponderance of clay soils over loam among the returns from planters. Loams and sandy loams are tied for second place. A smaller number report that these top soils lie shallow over hard-pan or rock. Fewer still report a soil underlaid with sand or gravel.