Trees require a good supply of plant food materials and water to produce profitable crops. Tho heaviest bearing chestnut trees we have observed were grown in an irrigated orchard in California and in a poultry yard in the East where chicken droppings actually formed a mulch under the trees. However, if you wish to kill a young chestnut tree quickly, just apply a very heavy application of chicken manure; the point is that trees must become adjusted to chicken manure by gradual applications. Another way to damage a tree is to keep it growing late in the fall by cultivation and fertilizers so that it does not harden off properly. Many plantings, representing heavy investments, fail because of lack of organic matter in the soil. This is related to water-holding and water-supplying capacity of the soil, and lack of proper fertilizer. Dr. Harley L. Crane and his assistants, in their work with tung and pecan trees, have shown the vital need for certain elements on some soils. Trees weakened by the lack of these elements are early prey for some diseases. The element most frequently deficient is nitrogen, but sometimes boron, copper, or iron is lacking; or the elements are not in balance, because of the excess of some, or the lack of others. By adjusting the various soil, water, and site factors necessary for a continuous, vigorous growth of trees, many so-called disease conditions are eliminated. Many fungi and viruses, however, will attack trees in the pink of condition; a few of the more important of these are treated in the following sections. +Chestnut Blight+ The destruction by blight of the native stands of the American chestnut, and of the small eastern orchard industry based on European and American chestnuts and their hybrids is almost complete. Blight has been found in the planted European chestnut orchards of the Pacific Coast from time to time, but it has been kept under control by eradication. Chestnut trees or nuts from the eastern States, where blight is common, should not be shipped into the Rocky Mountain or Pacific Coast States.