Part 41 (2/2)

Very truly yours,

H. L. CRANE Princ.i.p.al Horticulturist, Division of Fruit and Vegetable Crops and Diseases

U. S. Plant Industry Station.

Beltsville, Maryland

~Editor's Note:~ Dr Crane's experience is exactly similar to my own. The pecans in the grounds at my country home were well loaded with nuts this year, 1950. I doubt if a single nut was half filled.--L. E. T.

Nut Tree Diseases in Europe and Turkey

November 17, 1950

Dr. Lewis E. Theiss Lewisburg, Pennsylvania

Dear Dr. Theiss:

I have only recently returned from three and one-half months spent in Europe, primarily on chestnut problems, as a consultant for the Economic Cooperation Administration. The trip was made at the request and expense of European interests, except while I was up in the Scandinavian countries and at the 7th International Botanical Congress. I gave a paper at the Congress, ent.i.tled ”The world-wide spread of forest diseases,” in which chestnut blight received limited attention.

In Italy, chestnut blight, ~Endothia parasitica~, was first reported at Genoa in 1938, although it started there much earlier. It is now widely distributed here and there as far south as the Naples area. No confirmed infections have been reported from Sicily, Sardinia, or French Corsica, though inspection work has been very, very limited. In all the places where I saw it, the disease was increasing rapidly, with numerous recently-blighted trees. It is expected that the disease will ultimately kill the 988,000 acres of coppice growth, which produces few nuts, and the 1,111,500 acres of grafted orchards. The time of death of isolated stands like the two islands and many other areas can be materially decreased by careful inspection and removal of the earliest infections, just as we have held the disease under control in the European chestnut orchards in California. It is doubtful if this will be done however, in spite of their large unemployment problem.

As the blight continues its rapid spread over Italy, the production of nuts will steadily decrease. The Italian exports to this country will decrease, and the market for the rapidly expanding production of Chinese chestnuts in the eastern United States will improve. The Italian foresters are growing large quant.i.ties of Chinese chestnuts which they purchased in this country, but the difficulties of quickly reestablis.h.i.+ng a large nut industry are very great. This Bureau, including Dr. Graves, has been sending pollen, scions, and plants of our selections to help with this work. It is of vital importance to have a sound economy in Italy to help prevent the Communists from taking over, and loss of their forest and nut orchards and part of their oaks from the blight will be a sad blow to their economy.

The chestnut blight fungus in Italy is attacking three important European oaks, ~Quercus ilex~, ~Q. p.u.b.escens~, and ~Q. sessiliflora~. These are more important in some countries than chestnuts. For instance, Spain has 3,705,000 acres of ~Q. ilex~ orchards, grown largely for acorn hog feed. This will interest Dr. Smith. Possibly the disease may be less destructive to oaks in other countries than I fear, my opinion being based on the examination of only a limited number of diseased oaks in Italy.

I a.s.sume you have heard that Mr. Bretz of our Division has found that the oak wilt fungus has attacked some of our Chinese chestnuts in Missouri. What it will amount to, no one knows. The oak wilt continues to spread southward and eastward, and this year one infection was reported by the State authorities on oaks in your own Pennsylvania.

In Switzerland, in Tessin province, which is along the Italian border, the blight is spreading rapidly. The disease undoubtedly is in Yugoslavia, as there is so much infection in nearby Italy, but I was not in Yugoslavia. In Spain, there are several infections of blight that came in on the original importations of chestnuts directly from j.a.pan. I made two trips into Spain and the authorities there have promised to do everything possible to eradicate these small spot infections.

In Denmark, England, France, Germany, Portugal, and Turkey no blight had been reported by the authorities with whom I conferred, but in most of these countries very little inspection work has been conducted. Any inspection for blight in southern Europe is complicated by the presence of the ink root rot disease, which from a distance looks like the blight. I remember one grafted orchard planting, in the Asia Minor part of Turkey, where a large proportion of the trees were dead or dying, with yellow leaves hanging, resembling the blight. Incidentally, here, as at a number of other places in different countries, orchards, forest, and nearby agricultural land was owned by the village itself.

In southern France I was impressed by a most serious and widely distributed disease of Persian walnuts. Vigorously growing trees start to decline and within a year or two they are dead. The French authorities had no satisfactory explanation of the trouble. I informed them that it looked a lot like trees killed by ~Phytophthora cinnamomi~, the cause of the chestnut root and ink disease in America and Europe.

This fungus also attacks both Persian and black walnuts and other trees (including apples) under certain conditions.

Sincerely, G. F. GRAVATT Senior Pathologist, Division of Forest Pathology

U. S. Plant Industry Station, Beltsville, Md.

Nut Work of the Minnesota Experiment Station

March 27, 1950

Mr. Gilbert Becker, Climax, Michigan

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