THE MENACE OF FIREBLIGHT

Nelson Evening Mail, Volume LXI, 11 August 1928, Page 3

THE MENACE OF FIREBLIGHT

EXPEDIENCE IN CANADA AND UNITED STATES

VALUABLE REPORTS RECEIVED

keHlicS TO INQUIRIES Bt PROFESSOR EASTERFIEtD

On behalf of the institute Trust Board, the director, Professor Easterfield, recently addressed an enquiry to the Departments of Agriculture in Canada and the United States, asking (1) for any literature on the subject.of .fireblight; (2) for a statement as to the relative,amount,of damage by fireblight in apple and pear districts; (3) a statement of any experience with the hawthorn hedge as a carrier or host; and (4) any additional information that might, be of, use. . Valuable reports have been received in reply which are published below.

The,report .from the Bureau of Plant Industry in Washington is as follows: Experts in the. Bureau of: Plant.. Industry have investigated this • disease very thoroughly, though most .of the investigation was carried out. many years ago and our Department publications on the subject are now out of print. With.regard to your first item, you will find ah article by Dr. ,M. B, ( Wftite, entitled, “The Cause and.Prevention-.of Pear. Blight”; in the Yearbook of the Department of Agriculture for ,1895, pages 295-300. There is also an article by the same author entitled. ‘‘Commercial Pear Culture”. 1 in the. Yearbook,for 1900, pages 369-396. There .are, many other articles in .American .literature on this disease, some ; ,of; which, have been written by the Department investigator. The best one of these-is in the Annual Report of the State Horticultui’al Commissioner for IQOS, a. paper read before the ..Thirty-Firsti Fruit . Growers’ Convention, at Safita Rosa, .Calif., entitled, “Pear Blight Work .and Its Control in California,”, by M, B. Waite. We hope you will have access to these reports, as, : we have np .available separates for distribution now. •

As to your second item,, pear blight, or, as.it is sometimes called, ; fire, blight, has. d6no;;a -vast amount ,of damago on both apples. and pears and to some ,extent on quince and other pomacqous fruits in the United States. This varies enormously from year to year. The disease breaks out in epidemic form either in new regions recently planted or in old established districts and may be very severe for a period of two or three years, during which it is a major disease and extremely destructive, and then it may gradually subside for a varying period of three to five years or even inore. In. these-outbreaks the pear suffers distinctly more than the apple, and whole pear districts which may be shipping a trainload' of fruit a day have befeh wiped,out of existence. iJPbe disease is much more serious in eiu ll Southern States, especially viear the Gulf- Coast, than it, is in the,Northern States along the Canadian border. In Now England it scarcely extends into Maine or tHo northern part of Massachusetts, especially near the sea, but it has been very injurious west of Now/England, in Michigan, even in the relatively cool districts around the. Great Lakes; but here it lias been serious only on the more susceptible varieties like the Bartlett or' Clapp’s Favorite. In California and even in southern Oregon, Utah and Colorado it has at times been very destructive, especially injuring the Bartlett pear orchards, which are rather susceptible. While it has exterminated these orchards in parts of the San Joaquin Valley and some of the warmer valleys of California and they have usually not been refuted, it has been fought out in the main pear districts of California and Oregon so that the industry is still flourishing. . The apple suffers much less as to the destruction of the tree and of the orchards. Certain varieties, however, are very susceptible to this bacterial blight at the collar of the tree just above or just below the ground line, and have been almost- wiped out in regions where the top blight has not been serious enough ordinarily to cripple the industry. The Grimes Golden and the Esopus Spitzenburg are the two most important varieties badly affected by collar blight, and our experts have developed a method of growing these varieties on iesistant stocks and bodies so as to overcome entirely this particular phase' of the trouble. In the Eastern States the Grimes Golden is propagated as follows: A resistant commercial variety, such as Paragon or'Mammoth Black Twig or Northwestern Greening is propagated by using a. long scion and a short piece root. The one-year tree is successfully grown to three- feet or inore and is then budded about twenty-; four inches from the ground with the Grimes Golden. During the second year the top is grown from this bud, the result being, that the collar and body pf the tree is of a- satisfactory resistant Sort. Orchards fifteen to twenty years old propagated by this method are now doing well. Some varieties of apples, such as Yellow Transparent and at times Maiden Blush, Esopus Spitzenburg, and even York Imperial, are badly injured by the blighting, of the twigs and larger tranches. However, if these are properly cut out and disinfected the trees may recover without serious difficulty, and if the outbreak passes over, the orchard may get along for several years without : any trouble. ' ,

Ifi some, of our. bad outbreaks!'of peijr '/blight,, like, that: which', occurred Jin»the Eastern States; about 1912-1914, the; blospom blight form on-the apple was especially destructive. Thousands of acres of orchards from Pennsylvania to Virginia and westward to Missouri • and Arkansas and Kansas had a large frac-> tion of their blossom clusters and fruit spurs killed enough to reduce the crop Seriously for the current year and for a year or two following. Such outbreaks have been repeated in the Eastern United States at intervals of seven to ten years for at least fifty to sixty years if hot longer. This blossom cluster and twig destruction, however, while temporarily serious, usually does not impair the future of the apple orchard, .especially if the trees are twelve to fif- ; teen vears old or older. The outbreaks • usually pass over and the orchard again resumes production. Item 3. Pear blight is a disease native to the Eastern United States on species of wild crabapple, several species ■of native Hawthorn, and probably some ■other related pomaceous fruits on which if is frequently found. When cultivated Hawthorns from Europe and other parts of the world ar? planted tliev also suffer in varying degrees from this disease. As a matter of fact, this statement applies to most of the species of the family Pomaceae of rosaceous fruits. In a clean-up campaign, when the pear blight is being cleared out of an orchard, any host, plant attacked by the disease or any potential host plant in the innnejdiate vicinity becomes an element, of ■danger. Of course, it may or may ■not,- be in such a condition of vigorous growth, or in blossom, for instance, as tb support an outbreak of the disease. 'But practically all tho Hawthorns when ‘grown in the Eastern United States in the vicinity of bearing orchards and fruit gardens have at times, along with our natives, been found attacked by this disease. They will need either to be cleaned up and treated as is done with the pears and apples or else to, be. eliminated for safety. Item 4. Tt. is assumed that you are

well posted about the methods of control of peur blight, particularly cutting out the hold-over blight during the dormant season, or you can get this information from the Yearbook articles to which reference has been made. In California in -the great clean-up campaign in 1905-6-7, in a few cases a wild crabapple native to California, not one of the original native hosts, was found attacked, . and the growers voluntarily out these out in the vicinity of the pear orchards,, In the same way the so-called California Holly, species of Heteromeles, with red berries resembling the Mountain Ash, was. found attacked, this being a new host plant which caught the disease from the pears and carried it along like, one of the original eastern native host plants. The result is we look •vvjth suspicion on any garden forms or garden cultivated trees and shrubs belonging to the family Pomaceae. Among the unusual hosts have been species of Cotoneaster, Mespilus, Sorbus, and the Mountain Ash.