in.vtf 
 
 Issued April 30 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 I'.l REATJ OF PLANT I NDl'STKY-- Cinular No. 4. 
 1(. r. GALl 0\\ IlV, Chief of Bureau. 
 
 THE TREATMENT OF DAMPING-OFF 
 IX CONIFEROUS SEEDLINGS. 
 
 PERLEY SPAULDING, 
 
 Scientific Assistant, Laboratori <>f Foresi Pathology. 
 
 38045 rir. 4— 08 
 
 WASHINGTON ; GOVERNMENT MINTING OFFICE : 190« 
 
 
BUREAU OF PLANT INDUSTRY. 
 
 Pathologist and Physiologist, and chief <if Bureau, Beverly T. Galloway. 
 
 Pathologist and Physiologist, and Assistant Chief of Hun ait, Albert F. Woods. 
 
 Laboratory of Plant Pathology, Erwin F. Smith, Pathologist in Charge. 
 
 Investigations of Diseases of Fruits, Merton B. Waite, Pathologist in Charge. 
 
 Laboratory of Forest Pathology, Haven Metcalf, Pathologist in Charge. 
 
 Truck Crop Diseases and Plant Disease Survey, William A. Orton, Pathologist in Charge. 
 
 Plant Life History Investigations, Walter T. Swingle, Physiologist in Charge. 
 
 Cotton Breeding Investigations, Archibald D. Shame] and Daniel N. Shoemaker, Physiolo- 
 gists in Charge. 
 
 Tobacco Investigations, Archibald I). Sbamel, Wightman W. Garner, and Ernest H. 
 Mathewson, in Charge 
 
 Coin Investigations, Charles P. Hartley. Physiologist in Charge. 
 
 Alkali and Drought Resistant Plant Breeding Investigations, Thomas II. Kearney, Physi- 
 ologist in Charge. 
 
 Soil Bacteriology and Water Purification Investigations, Karl F. Kellerman, Physiologist 
 in Charge. 
 
 Bionomic Investigations of Tropical and Subtropical Plants, Orator F. Cook, Bionomist 
 in Charge. 
 
 Drug and Poisonous Plant Investigations and Tea Culture Investigations, Rodney H. 
 True, Physiologist in Charge. 
 
 Physical Laboratory, Lyman J. Briggs, Physicist in Charge. 
 
 Crop Technology and Fiber Plant Investigations, Nathan A. Cobb, Crop Technologist in 
 Charge. 
 
 Taxonomic and Range Investigation*, Frederick V. Coville, Botanist in Charge 
 
 Farm Management Investigations, William ,T. Spillman, Agriculturist in Charge. 
 
 Grain Investigations, Mark Alfred Carleton, Cerealist in Charge. 
 
 Arlington Experimental Farm, Lee ('. Corbett, Horticulturist in Charge. 
 
 I egetable Testing Guldens, William W. Tracy, sr., Superintendent. 
 
 Sugar-Beet Investigations, Charles O. Townsend, Pathologist in Charge. 
 
 Western Agricultural Extension Investigations, Carl S. Scofield, Agriculturist in Charge. 
 
 Dry-Land Agriculture Investigations, B. Channing Chilcott, Agriculturist in Charge. 
 
 Pomological Collections, Gustavus B. Braekett, Pomologist in Charge. 
 
 Field Investigations in Pomology, William A. Taylor and (J. Harold Powell, Pomologists 
 in Charge. 
 
 Experimental Gardens ami Grounds, Edward M. Byrnes, Superintendent. 
 
 Foreign Seed and Riant Introduction, David Fairchild, Agricultural Explorer in Charge. 
 
 Forage Crop Investigations, Charles V. Piper, Agrostologist in Charge. 
 
 Seed Laboratory, Edgar Brown, Botanist in Charge. 
 
 Grain Standardization, John D. Shanahan, Crop Technologist in Charge. 
 
 Subtropical Laboratory and Garden, Miami. Fin.. Ernsl A. Bessey, Pathologist in Charge 
 
 Plant Introduction Garden, Chico, Cat., August Mayer, Expert in Charge. 
 
 South Texas Garden, Brownsville, Tex., Edward C. Green, Pomologist in Charge. 
 
 Formeis' Cooperative Demonstration 11 ork, Seaman A. Knapp, Special Agent in Charge. 
 
 Seed Distribution (Directed by chief of Bureau), Lisle Morrison, Assistant in General 
 Charge. 
 
 Fditov, .1. E. Rockwell. 
 Chief Clerk, James E. Jones. 
 
I ONTENTS. 
 
 Page. 
 
 Introduction 5 
 
 Procedure in experiments 6 
 
 Powders used 6 
 
 Sulphur 6 
 
 Dry Bordeaux mixture 6 
 
 Coppei sulphate and lime 6 
 
 Sol lit inns u-eil 7 
 
 Potassium sulphid and permanganate 7 
 
 Formalin 7 
 
 Sulphuric acid 7 
 
 3 
 
 _ 
 
Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/dampiOOunit 
 
B. P. I.— 304. 
 
 THE TREATMENT OF DAMPING-OFF IX 
 CONIFEROUS SEEDLINGS. 
 
 INTRODUCTION. 
 
 Experiments have been carried on by the writer for several years 
 in testing the effect of various chemicals upon the damping-off elis- 
 or 1 tender coniferous seedlings. These troubles are great obsta- 
 cles to the successful production of such seedlings in large num- 
 bers for use in replanting waste or unoccupied land. They are 
 caused by a number of different fungi which arc being studied and 
 will short ly be described. 
 
 The results of the first experiments, which were carried on entirely 
 in the greenhouse, were taken as indication.- of what might be 
 expected in actual nursery practice. It was felt, however, that the 
 work should be extended to Geld conditions, and upon testing the 
 preliminary results there it was found that they could be taken only 
 as very meager and insufficient indications of the results to be 
 obtained in the field. 
 
 During the season of L907, field experiments were conducted in 
 several nurseries of the New York Forest, Fish, and (lame Commis- 
 sion i (me of which is operated in cooperation with the Forest Service 
 of the United States Department of Agriculture) and of the Ver 
 mont State Forestry Commission, located, respectively, at Saranac 
 Inn. X. V.. and Burlington, Yt. These experiment- yielded very 
 interesting results, but because of their preliminary nature it is felt 
 that without further \ cry rigid tests along similar lines they can not 
 be accepted as furnishing conclusive proof of the comparative value 
 of t he chemicals u-vd. 
 
 The great interest centering about these diseases, however, makes 
 of value every scrap of practical information concerning method- of 
 prevention. Until conclush'e results are obtained the present one- 
 may therefore prove useful to nurserymen, but they should be 
 a.c, •pied with the distincl understanding that they are preliminary 
 and are subject to later modification. 
 
 5 
 
6 TREATMENT OF DAMPING-OFF IN CONIFEROUS SEEDLINGS. 
 
 The tests here outlined are being continued on a more extensive 
 scale, and it is hoped that the present season's work will give such 
 results that there can be no doubt as to the conclusions to be drawn 
 from them. 
 
 PROCEDURE IN EXPERIMENTS. 
 
 The plots used were located in seed beds 12 feet long and 4 feet 
 wide, each bed being divided into three equal parts I feet square. 
 The chemicals were used in fine powders or in solutions, according 
 to their original form and nature. The solutions were applied with 
 an ordinary sprinkling can, while the powders were sifted on the 
 beds with a very simple form of duster having a perforated bottom, 
 through which the powder was shaken. The solutions were applied 
 to the soil before the seeds were sown, and then again about five days 
 after the seedlings had come up. The powders were applied to the 
 beds only after the seedlings had been up for three or four days. 
 They were applied in very light coatings, which were renewed 
 promptly after each rain. This renewal is not necessary except for 
 a period of about tw T o weeks, beginning three or four days after ger- 
 mination, when the seedlings are most susceptible to the attacks of 
 the damping-off fungi. 
 
 POWDERS USED. 
 
 Sulphur. — Sulphur was obtained in three forms: Washed, resub- 
 limed, and precipitated. Favorable results were given by all, but 
 the first led the others slightly. It was noted, too, that a distinct 
 odor of sulphur could be detected at least 8 inches above the surface 
 of the plot treated with washed sulphur, while no perceptible odor 
 could be detected over the other two at a greater distance above the 
 surface than 1 or 2 inches. This difference was as marked several 
 days after the sulphur had been applied as it was immediately after 
 the application was made. 
 
 Dry Bordeaux mixture. — Dry Bordeaux mixture made according 
 to Scott's formula" was also tried, but the method of preparation 
 is too tedious and time consuming to be of use in the case of a disease 
 like damping-off unless the mixture is made up some time in advance. 
 It is seldom practicable for the nurseryman to give the necessary 
 time for its preparation, owing to the pressure of other duties at this 
 period of the year. This powder was accordingly discarded for a 
 copper sulphate and lime mixture which is easily and quickly made 
 up as required and apparently should give as good results as the Bor- 
 deaux preparation. 
 
 Coffer sulphate and lime. — Powdered sulphate of copper was 
 mixed with powdered lime, at the rate of 1 pound of the former to 
 
 ° Waite, M. P.. Fungicides. U. S. Department of Agriculture, Farmers' Bul- 
 letin 24.'',, pp. 11-12, 1906. 
 
I |;i \ i .MIX I OF DAMPING-OF] IN CONIFEROUS SEEDLINGS. i 
 
 in pounds of the latter, in the following way: Fresh stone lime was 
 slaked with a- little water a- would keep the slaking in progress. 
 In this way slaked lime was obtained in the form of a line powder. 
 This was screened and very thoroughly mixed with the powdered 
 copper sulphate, and was then ready to be used. Attention i- called 
 to the need of thoroughly mixing the two ingredients, a- disastrous 
 results air likely to ensue if the coppei sulphate is not properly 
 diluted with the lime. 
 
 This mixture was used very freely after the seedlings had come up. 
 Absolutely no injurious results could be noted, even when the applica- 
 tions were made early in the morning while the seedlings were still 
 wet with dew mi that the powder stuck to them. It may lie said that 
 the better time to apply the powders and also the solutions is late in 
 the afternoon. The powder- will then adhere very slightly to the 
 plant let- and practically all of the powder will fall on the soil, where 
 it i- wanted. 
 
 This copper and lime mixture was used upon the following species: 
 Pinus sylvestris, /'. ponderosa, /'. strobus, /'. sinosa, Picea rubens, 
 !'. . and Pseudotsuga taxifolia. Very good results were ob- 
 
 tained in checking the damping-off with it. and it is believed to be 
 one of the mixture- tested which may prove of value commercially. 
 
 SOLI nONS I -ll>. 
 
 Potassium sulphid and permanganate. A solution of potassium 
 
 Sulphid, made :.! the rate of 1 ounce id' dry chemical to 1 gallon of 
 water and applied to the -oil before sowing the seed, gave no definite 
 results because of the absence of the disease in the experimental plot-. 
 This was also true of a -oh it ion of potassium permanganate, mixed at 
 the rate of 1 gram of chemical to 1 gallon of water and similarly 
 applied. 
 
 Formalin. -Commercial 10 percent formalin, used at the rate of 1 
 ounce- to :; gallons of water, when applied to the -oil before seeding 
 and not afterward repeated, seemed to have no effect whatever upon 
 the disease. Tin' check plot, indeed, was much better, a- were all of 
 the other plot-, both treated and untreated, located in that section of 
 the nursery. When applied a- stated and repeated after the seedlings 
 had come up. the results were poor. It is now believed that formalin 
 i- of little value with the damping-off diseases of coniferous seedlings 
 unless supplemented after the germination of the seed with some other 
 efficienl chemical. The results were disappointing when compared 
 with those obtained w ith some of the other chemicals. 
 
 Sul phuric acid. The best result- were obtained with weak solution- 
 id' sulphuric acid. A solution mixed at the rale of 1 ounce of acid to 
 1 gallon id' water was applied t,» the -oil several days before sowing 
 
8 TREATMENT OF DAMPING-OFF IN CONIFEROUS SEEDLINGS. 
 
 the seed, until it was thoroughly drenched, and the treatment was re- 
 peated about a week after the seedlings came up. The treated plot 
 was in excellent condition in December: there was a very good stand 
 of fine, healthy seedlings and the soil was entirely free from algae and 
 moss. The check plot, on the other hand, had practically no seedlings 
 left, and the soil was green with algae and moss. 
 
 This solution of sulphuric acid was applied to young seedlings of a 
 number of different species, and but one showed any ill effects. This 
 was Norway spruce (Picea excelsa). It is not advisable to use an 
 acid solution as strong as this upon the plants. Kraemer « has shown 
 that a solution of sulphuric acid at the rate of 1 to 500 is as strong as 
 should generally be used upon plant tissues, and this is recommended 
 rather than the much stronger one used in these experiments For 
 soil treatment the stronger solution will probably prove preferable. 
 
 Approved : 
 
 James Wilson, 
 
 Secretary of Agriculture. 
 
 Washington, D. C. April 6\ 1908. 
 
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 "Kraemer, Henry Dilute Sulphuric- Acid as a Fungicide. Proceedings. 
 American Philosophical Society, vol. 45, pp. 157-163, 1906. 
 
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