UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA CIRCULAR 291 June, 1925. BLACKHEAD AND OTHER CAUSES OF LOSS OF TURKEYS IN CALIFORNIA By H. W. GRAYBILL* INTRODUCTION When turkeys are reared in the same manner as other fowls, serious difficulties and even failure often occur. This has led to the belief that the turkey, by nature, is not well suited to the restrictions of domestica- tion and that it requires a management conforming as nearly as possible to the wild state in order to thrive. However, there is much evidence that there is nothing in the nature of the turkey which unsuits it to domestication. It is well known to those w T ho have reared turkeys by means of artificial brooding that they become tamer than any of the other domestic birds and do well under proper conditions of sani- tation. The relation of disease to failures has not been generally understood. It is evident now that many of the difficulties have been due to disease. The disease which in general is of greatest importance — infectious entero-hepatitis or blackhead — has been studied and the progress made in the control offers opportunities for overcoming former difficulties. Furthermore, the measures which have been worked out for the control of blackhead are also, fortunately, the most effective means known for controlling other infectious diseases of turkeys. In California, climatic and various other conditions are very favorable to turkey rearing. The continuous sunshine and the dry, heated condition of the soil during the dry season, in sections where irrigation is not practiced, are factors that tend to purify the soil and render it free from contamination with disease-producing organisms. Furthermore, the absence of rain and storms simplifies rearing. Under assignment from The Rockefeller Institute for Medical Research. 2 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION The large unirrigated regions are favorable homes for the turkey. On stock ranges in the foothills and on the lower land bordering the valleys, there is an abundance of insect life during the first part of the season and, after harvest, the grain fields, and later in some sections the rice fields, offer an abundance of cheap feed which, if not utilized for turkeys, in a large measure goes to waste. BLACKHEAD Prevalence. — Among the diseases which are responsible for loss of turkeys, blackhead is probably the most important. It has been found in all regions of the United States, Canada, the British Isles, Europe, South Africa and probably occurs to some extent wherever turkeys are raised. The disease has assumed such serious proportions that it has been responsible primarily for turkey raising being abandoned to a very large extent in certain regions where formerly it flourished. Blackhead has long been known to occur in California, and is undoubtedly responsible for severe losses. However, if experience during the season of 1924 may serve as a guide, it is not so prevalent as was supposed. The season, however, on account of a severe drought, was especially unfavorable for blackhead. Observations made in some sections indicate that the disease has not been prevalent to any great extent on well drained unirrigated ranges and grain fields where large bands of turkeys have been running. It is believed that blackhead as a serious disease will be found to be localized to a considerable degree in those sections where the land is low, wet or under irrigation. Birds Susceptible to the Disease. — In addition to the turkey, the disease occurs also occasionally in the chicken, the pea fowl, the guinea fowl, and in pheasants, grouse, quail and possibly other game birds. However, game birds subject to the disease are not sufficiently numer- ous, as a rule, to be a factor in the control of the disease in turkeys. None of the common wild birds are known to be subject to blackhead. Incidence of the Disease. — The degree of prevalence of the disease in flocks varies with the age of the birds and the degree to which the soil is contaminated with blackhead. In young birds on heavily infected soil the number of birds that become affected may approach or even reach 100 per cent. The mortality is very high among young birds reaching in some instances 100 per cent. The proportion of birds that become affected and the mortality become less with age. Chickens are very resistant to the disease and its occurrence among them is represented, as a rule, only by an occasional case. ClRC. 291] BLACKHEAD IN TURKEYS IN CALIFORNIA 3 Symptoms. — The name blackhead is an unfortunate one. The head of the affected bird never turns black but in a certain proportion of the cases takes on a somewhat bluish color. This condition occurs in other diseases and is related to a disturbance of the circulation. A period of about two weeks elapses between the beginning of the disease and the time the affected bird shows symptoms. Birds, espe- cially those but a few weeks old, may die so suddenly that no symptoms of illness have been noticed, but this is rather exceptional. The disease is most serious in birds during the first months of life. As already indicated resistance increases with age, especially after the first two or three months. In older birds, the disease is more chronic and the affected bird may be ill for some weeks before it succcumbs or recovers. The first change noticed in a bird affected with blackhead is that it is a trifle slower in its movements and does not feed so ambitiously. Later its movements are much slower and it is found at times standing with the head drawn in. As the disease progresses it stands for long intervals or almost continuously with head drawn in, eyes closed, and the tail and wings drooping. It may bury its head in the feathers of the back. There may be a diarrhea. The droppings are stained a sulfur color. Affected birds sometimes prefer sitting on the ground to standing. There is nothing sufficiently characteristic about the symptoms to make it possible to distinguish blackhead from certain other diseases. A definite diagnosis can be made only by an examination of the organs of birds at autopsy. The changes to be found will be referred to later. Medicinal Treatment. — A great number of drugs and substances have been recommended by investigators and laymen for the preven- tion and cure of blackhead. None of these has been proved to be of value. As in the case of most other infectious diseases of animals, prevention based on sanitation is more reliable than curative measures. The best that can be done for diseased birds is to isolate them, give them good care, and feed properly — providing sour milk if possible. The results may be far from satisfying but they will be quite as much so as with any medicinal treatment and there will be no expense for drugs. To try, one after another, various drugs and substances recom- mended to the turkey raiser is productive of much harm. Some of the substances used are poisonous or irritating to the intestinal tract and other organs. The drinking water is frequently rendered dis- tasteful by the addition of medicines which prevents the birds from taking a proper amount of water. When disease appears in a flock the first matter of importance is to determine definitely its nature by an examination of dead birds. If the owner finds himself unable to 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION do this, he should call a competent veterinarian or seek the assistance of a veterinary laboratory in making a diagnosis. When the nature of the trouble is discovered, competent advice should be relied on for its control. Nature of the Organism of Blackhead. — The "germ" or micro- organism of blackhead belongs to the protozoa — the lowest forms of animal life. Originally the organism was classed as an amoeba and named Amoeba meleagridis, but two investigators, Jowett in South Africa and Tyzzer in this country, have found evidence which has led them to believe it belongs to the flagellates, and the latter author has named it Histomonas meleagridis. The organism has been well studied within the tissues affected but nothing is known concerning its nature and occurrence elsewhere. Fortunately, however, measures of control, are not dependent on this knowledge. Changes in the Organs. — The main changes in the organs in black- head are confined to the ceca and liver, and these are the only organs as a rule invaded by the blackhead parasite. The ceca are a pair of long pouches communicating with the back part of the intestine a few inches from the vent. The disease of blackhead originates in these, one or both being affected (fig. 1). The blackhead parasite gains entrance to the inner lining (mucosa) where it multiplies very rapidly. It extends its invasion well into the depths of the wall of the cecum, sometimes occupying the entire thickness of the wall, causing it to become thickened. As a result of injury to the tissues and a weakening of the blood vessels, blood and fluids may escape into the cavity of the cecum and there, becoming more or less mixed with the contents, undergo solidification into a cheesy core. A core is not always present. According to the extent of the wall invaded by the organisms, the thickening may be general or localized to one or more areas. Enlarge- ment of the cecum, a thickened wall and the possible presence of a yellowish cheesy core are the gross changes to be noted in this organ. In the wall of the cecum the organism gains entrance to the portal circulation and by this route reaches the liver, where it sets up a serious disturbance. The liver is much enlarged and permeated with dark red, grayish or yellowish spots where the blackhead parasite has lodged and multiplied, bringing about changes in the liver tissue (fig. 2). At times instead of the changes occurring as spots, they may have a diffuse nature, giving a cloudy appearance to considerable areas of the liver. Transmission. — In studies on this phase of the disease at the Rocke- feller Institute for Medical Research, it was found that the disease is Circ.291] BLACKHEAD IN TURKEYS IN CALIFORNIA J Fig. 1— Oeca of a turkey affected with blackhead. One ceccum shows a discolored diseased area near the tip and two near the middle. The other shows only one located below the middle. b UNIVERSITY OF CALIFORNIA EXPERIMENT STATION not readily, if at all, transmitted directly from sick to healthy birds but that healthy turkeys and chickens could render soil, after a time, dangerous to poults.* The investigations finally led to the belief that another factor might be necessary to start the disease. With this idea in mind, attention was directed to a small thread worm, the cecum worm (Heterakis gallinae\) commonly inhabiting the ceca of turkeys and chickens. It was found that by feeding large numbers of fully developed eggs of this worm to healthy turkeys, blackhead could be produced. In blackhead we therefore have two factors involved in the production of the disease, one the blackhead parasite, a microscopic organism which enters the tissues and produces the characteristic changes, and the other a worm which presumably opens up a way for the blackhead parasite to enter. It is possible that there are other factors that may take the place of the cecum worm in the production of blackhead, but none have been found. At present, measures for the control of blackhead resolve themselves into the control of the cecum worm. Life History of the Cecum Worm. — The cecum worm is a small thread worm about half an inch long. The adult females in the ceca deposit microscopic eggs which pass out in the droppings in an undeveloped condition. When the temperature is favorable, they undergo development and in about a week during warm weather, each contains a minute embryonic worm. In this stage, if taken up in food by a suitable host, such as the turkey or chicken, they pass to the intestine where they hatch and the embryos are liberated. The young worms pass onward with the intestinal contents, and finally enter the ceca where they undergo growth and development to maturity. It is the young microscopic larval worm that acts as a factor in the production of blackhead. The eggs of the cecum worm are affected unfavorably by dryness, but they withstand temperatures of freezing and below. They may remain alive on the soil for months and possibly even for a year or more although no doubt a large proportion perish when exposure has continued for some months. In addition to the turkey and chicken, the guinea fowl, pea fowl, pheasants and grouse are hosts of the cecum worm. Methods of Control of Blackhead. — The importance of rearing young turkeys away from old ones and all other domestic birds and on soil as free as possible from eggs of the cecum worm, is evident. Soil * Graybill, H. W., and Theobald Smith. Jour. Experimental Medicine, 31, p. 647. 1920. t Other names applied to this parasite are H. papillosa and H. vesicularis. Circ. 291] BLACKHEAD IN TURKEYS IN CALIFORNIA not previously used for domestic birds is satisfactory, and that which has been ploughed and been under cultivation for a year during which time all domestic birds have been excluded may be regarded as safe. Wide areas, such as ranges and grain fields, may likewise be regarded as safe because, under such conditions, soil contamination does not tend to become great. From the time turkeys are marketed in the Fig. 2. — Liver of turkey affected with blackhead. winter until the following season, as a rule, few or no turkeys are present on such areas. This period favors the destruction of soil con- tamination, and in the case of grain fields, this is still further pro- moted by ploughing and cultivation. In certain sections of California where dry farming is practiced, the grain fields remain unseeded every other year but are ploughed and subjected to cultivation to keep down weeds. Such fields are usually free from infection because there can be turkeys on them only every other year and soil contamination is given time to die out. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION KEAKING PKACTICES TO CONTROL BLACKHEAD Artificial Rearing. — As the name implies, this method involves the use of incubators and brooders. The popular prejudice that turkeys cannot be reared in this way has been shown to be incorrect. Various investigators working on blackhead have found artificial incubation and brooding applicable to the turkey. For a period of about five years birds were raised in this way for experimental work on blackhead at the Rockefeller Institute for Medical Research. Here and there a poultryman may be found who has been successful. The Division of Poultry Husbandry of the University of California for a period of some years has made observations on artificial rearing and has found it suitable to the turkey. The advantage in artificial brooding, from the standpoint of disease control, is that the young birds do not come into contact with old ones and that the soil on which they are placed, if clean to start with, is not likely to become dangerous. Old birds in addition to being able to contaminate the soil with blackhead may also be the carriers of various other diseases, such as fowl cholera, fowl typhoid, and of coccidia or other intestinal parasites which are a menace to young birds. Natural Bearing. — With this method, control of blackhead is more difficult than with artificial rearing. The principle of control is to subject the young birds as little as possible to soil contamination result- ing from the presence of the mother birds. It is therefore important that hatching and brooding be done in different locations and that clean ground for brooding be provided each season. It is wise to plan a year in advance for brooding ground. As soon as practicable the hens with their broods should be given their freedom on clean ground. The best chance for success is where large areas are available, for there soil contamination is least likely to become serious. However, a failure to apply the principles underlying control may result in prac- tices neutralizing the natural advantages of ranges and fields and bring about serious and unnecessary losses. Soil tends to become dangerous in places where turkeys congregate repeatedly. In the case of large bands, the flock should be kept on the move and feeding and roosting places changed frequently to keep the flock on soil as little contaminated as possible. The adoption of the artificial method of rearing will go far in the direction of solving the blackhead problem. When the natural method is pursued, practices based on principles of control will greatly reduce losses. ClRC. 291] BLACKHEAD IN TURKEYS IX CALIFORNIA 9 FIELD TRIALS IN THE ARTIFICIAL BEAEING OF TURKEYS IN THE SAN JOAQUIN VALLEY* Early in the season of 1924 two cooperators who were willing to undertake the artificial rearing of turkeys were located in Merced County, through the assistance of Mr. William II. Alison, Jr., of the Agriculture Extension Service of the University. The purposes of the trials made were : first, to test the suitability of the method in practice under farm conditions in California ; second, to determine whether there were any practical problems in the way of rearing artificially on a large scale; and third, to arouse popular interest in this method of rearing as a means of avoiding disease. Rearing was done on soil that had not been previously used for turkeys or other poultry and the birds were not permitted to come into contact with other turkeys or with chickens. One of the trials was made in the vicinity of Planada, California, in cooperation with a breeder of fine birds who had experienced con- siderable loss from disease during previous seasons. Brooding was conducted in a well constructed, movable brooder house. A large canopy hover, heated by means of an oil burner, was used. Two hundred and twenty-five poults were hatched in two lots during the latter part of April. Losses occurred from natural weakness, crowding, chilling and accidents during the first three weeks. After May 15 there was practically no loss until September when thirty were killed by dogs. The birds were kept more or less confined during the first part of the season, but after August 25 were given free range. One hundred were reared. Had the loss from dogs not occurred, the number reared would have been approximately 60 per cent. The second trial involved two flocks located in the region of Gustine, California. The cooperator's home place had become so con- taminated with disease that he was no longer able to raise turkeys successfully. This made it necessary to rear elsewhere and for this purpose he leased a location on new soil some miles away. He raised two flocks in separate places, several miles apart. The same type of brooder was used for both. This was homemade and rather crude, and not to be recommended for general use. It consisted of a series of low, covered compartments (2'x3') with the ground serving as a floor. There-was a common, centrally situated source of heat located in a subterranean fire box provided with an oil burner. * The writer is indebted to Dr. J. R. Beach for advice 1 and assistance in conducting the investigations presented in this circular. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The heat was conducted through two 6-inch galvanized pipes running in opposite directions from the fire box and lying centrally beneath the soil of the compartments. The pipes were two to three inches beneath the surface at the fire box and gradually approached to within half an inch of the surface at the outer end where they turned upward and emerged from the soil. The heat was transmitted through the soil to the compartments. There was no automatic means of regulating the heat. The birds at all times were given a wide range. m Fig. 3. — Band of about 2000 artificially brooded turkeys. On account of a shortage of feed in Merced County, the flocks were, after a time, moved in crates by truck to grain and rice fields in Sutter County in the region of Yuba City, where they remained until the close of the season. In the larger of the two flocks, 3450 birds were hatched during the first half of May. They were hatched in two lots about two weeks apart, and consequently were handled in different brooders. On July 26, when the flock was moved to Sutter County, it numbered 2230. Most of the losses up to that time occurred during the first two weeks. Only a few birds died after June 5. During a period of a few days, beginning almost immediately after brooding started, there was a loss of 600. The cause of this loss was not determined. The cooperator was inclined to believe it was due to impurities in the buttermilk fed, Circ. 291] BLACKHEAD IN TURKEYS IN CALIFORNIA 11 but the only evidence in support of this view was that the trouble stopped when the feeding of buttermilk was discontinued. Other losses occurred a few birds at a time, from natural weakness, chilling, crowding and accidents. Feed conditions on grain stubble to which the flock was moved on July 26 were bad. As a result, the condition of the birds became poor and their vitality so lowered that exposure to the first rains in October caused a loss of about 300 by chilling. The flock was then moved to pasture land on October 5 and on the 20th to rice stubble where it remained. It continued to do well with practically no further losses. The number of birds raised was 1930 or 56 percent (fig. 3). Fig. 4. — Band of about 1000 artificially brooded turkeys. The smaller flock, consisting of 1200 birds, was hatched in two lots, toward the end of June and early in July. One hundred and fifty birds were lost during the first four or five days from natural weakness. On October 16 the flock was moved to rice stubble in Sutter County. It then numbered 1013. Eleven birds at this time were lost by accident. The number of birds raised was 996 — 83 per cent (fig. 4). The results of these three trials in artificial rearing of turkeys to control disease are gratifying. The inexperience of the cooperators in artificial rearing and the lack of satisfactory equipment in the case of one led to losses that are avoidable, so the percentage of birds reared is not what it should have been. But the results attained by the cooperators were far superior to those of previous years. Experience is certain to reduce losses. 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION A difficulty experienced in rearing large flocks artificially is that the tameness of the birds makes it difficult to drive them. However, the birds readily follow a herdsman and the flocks were handled suc- cessfully in this way. The flock of 1200 discussed above was managed in this way with great ease by a man without any previous experience with turkeys. CAUSES OF LOSSES IN CALIFORNIA OTHER THAN BLACKHEAD During 1924 an effort was made to obtain a better knowledge of the turkey industry in California, the practices followed, the causes of loss and the relationship of natural conditions to disease. A survey to ascertain the exact extent of the losses was not found practicable but observations and inquiries made in a number of turkey growing sections indicate that the annual loss is not far from 50 per cent. One fact brought out by the investigations is of special importance. It has been found that very serious losses result from causes other them blackhead. In some sections, these losses appear to predominate. Faulty Management. — A considerable loss is due to causes other than disease. Crowding and chilling are sources of loss and predatory animals in some sections levy a considerable toll. Insufficient and improper feeding lead to losses which are at times attributed by the turkey raiser to infectious diseases. In the matter of feeding, it is important, especially in the case of the large bands of birds raised on the ranges and grain fields, that the turkey raiser give attention to supplementing natural feeds so that the turkey may have a ration that is properly balanced. A suitable grain feed should supplement that on the ranges where insect (protein) food predominates and some animal protein should supplement that on the grain fields where the carbonaceous feeds predominate when insect life is not abundant. Attention to supplementing properly the feed that turkeys find for themselves will no doubt lead to better results. Furthermore, a certain amount of green feed is essential to the growth and health of the turkey. Investigation of a roup -like disease (nutri- tional roup) of chickens and turkeys in California has shown it to be due to vitamin A deficiency resulting from a lack of green feed.* The long dry season during the summer in California makes the problem of providing green feed one requiring special attention. Losses may occur directly or indirectly from exposure during heavy rains in the fall. They are most likely to occur in flocks that are in * Beach, J. R. Studies on a nutritional disease of poultry caused by vitamin A deficiency. Calif. Sta. Bull. No. 378:1-24. 1924. ClRC. 291] BLACKHEAD IN TURKEYS IN CALIFORNIA 13 poor condition. Much can be done to avoid such Josses by keeping the birds in a vigorous condition through proper feeding and care. Late hatched flocks are subject to Losses even though in good condition. Colds and roup are not uncommon and lead to considerable loss. Much can be accomplished in their prevention by keeping the birds in a vigorous, thriving condition through proper feeding and care. Infectious Diseases. — It is known that fowl cholera has in the past led to serious losses among turkeys. This season it has been demon- strated that fowl typhoid also causes serious losses. To what extent this disease occurs has not been determined. It was diagnosed in three counties during the 1924 season. In an outbreak in a band of 2700 birds investigated by the writer, there was a loss of about half the flock. There is reason to believe that improper feeding, exposure and lack of proper care may be predisposing factors in this disease. A Disease from an Undetermined Cause. — A serious loss of an undetermined nature occurred in a flock of 1700, which resulted in the death of 1100 birds. The disease appears to be an intoxication and shows some resemblance to botulism. There was no history, how- ever, indicating botulism. It appeared when the flock was transferred from the farmstead to a camp on grain stubble. About a dozen chickens brought to the camp for table use also contracted the disease and died. The first symptom noticed is a weakness of the legs, which finally become paralyzed. The color of the head is normal. The beak is sometimes held open and at times strings of mucus hang from the mouth. The temperature is normal. The wings do not become paralyzed and the bird when disturbed moves forward slowly by flap- ping its wings. As the disease progresses the bird shows somnolence, the vision is affected, the neck becomes paralyzed, the head rests on the ground, and the bird finally goes into a coma. According to the observation of the owner, the muscles of deglutition are paralyzed. The onset is sudden. Cases of recovery occur. Autopsy examination showed the organs including the brain to be normal. Aerobic cultures from heart 's blood and liver were negative. Supplementing the feed of the turkeys to give them a better balanced ration and supplying some green feed failed to have any influence on the disease. No better results followed the application of sanitary measures and moving to a new location on the stubble. The disease appears to be an intoxication, but further investigation will be required to determine its cause. 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Promiscous Purchases of Stock. — Some raisers in California add to their flocks by purchasing young birds several months old and others acquire entire flocks in this manner. Birds are frequently obtained from two or more sources. Unless great care is exercised to obtain birds only from flocks in which disease is not present, the practice involves great danger. The measures outlined for the control of blackhead are also appli- cable to other infectious diseases. Correct management of flocks will also assist not only in preventing losses from infectious diseases but should, in addition, greatly reduce losses resulting from inadequate diet, exposure and other causes. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BULLETINS No. 253. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. 261. Melaxuma of the Walnut, "Juglans regia." 262. Citrus Diseases of Florida and Cuha Compared with Those of California. 263. Size Grades for Ripe Olives. 268. Growing and Grafting Olive Seedlings. 273. Preliminary Report on Kearney Vine- yard Experimental Drain. 275. The Cultivation of Belladonna in Cali- fornia. 276. The Pomegranate. 277. Sudan Grass 278. Grain Sorghums. 279. Irrigation of Rice in California. 280. Irrigation of Alfalfa in the Sacramento Valley. 283. The Olive Insects of California. 285. The Milk Goat in California. 286. Commercial Fertilizers. 294. Bean Culture in California. 304. A Study of the Effects of Freezes on Citrus in California. 310. Plum Pollination. 312. Mariout Barley. 313. Pruning Young Deciduous Fruit Trees. 319. Caprifigs and Caprification. 324. Storage of Perishable Fruit at Freezing Temperatures. 325. Rice Irrigation Measurements and Ex- periments in Sacramento Valley, 1914-1919. 328. Prune Growing in California. 331. Phylloxera-Resistant Stocks. 334. Preliminary Volume Tables for Second- Growth Redwood. 335. Cocoanut Meal as a Feed for Dairy Cows and Other Livestock. 339. The Relative Cost of Making Logs from Small and Large Timber. 340. Control of the Pocket Gopher in Cali- fornia. 343. Cheese Pests and Their Control. 344. Cold Storage as an Aid to the Market- ing of Plums. 346. Almond Pollination. 347. The Control of Red Spiders in Decidu- ous Orchards. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor Hitches. 350. Agriculture in Cut-over Redwood Lands. 352. Further Experiments in Plum Pollina- tion. No. 353. 354. 357. 358. 359. 361. 362. 363. 364. 365. 366. 367. 368. 369. 370. 371. 372. 374. 375. 376. 377. 379. 380. 381. 382. 383. 384. 385. 386. 387. Bovine Infectious Abortion. Results of Rice Experiments in 1922. A Self-mixing Dusting Machine for Applying Dry Insecticides and Fungicides. Black Measles, Water Berries, and Related Vine Troubles. Fruit Beverage Investigations. Preliminary Yield Tables for Second Growth Redwood. Dust and the Tractor Engine. The Pruning of Citrus Trees in Cali- fornia. Fungicidal Dusts for the Control of Bunt. Avocado Culture in California. Turkish Tobacco Culture, Curing and Marketing. Methods of Harvesting and Irrigation in Relation to Mouldy Walnuts. Bacterial Decomposition of Olives dur- ing Pickling. Comparison of Woods for Butter Boxes. Browning of Yellow Newtown Apples. The Relative Cost of Yarding Small and Large Timber. The Cost of Producing Market Milk and Butterfat on 246 California Dairies. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- fornia. Results of Rice Experiments at Cor- tena, 1923. Sun-Drying and Dehydration of Wal- nuts. The Cold Storage of Pears. Walnut Culture in California. Growth of Eucalyptus in California Plantations. Growing and Handling Asparagus Crowns. Pumping for Drainage in the San Joaquin Valley, California. Monilia Blossom Blight (Brown Rot) of Apricot. A Study of the Relative Values of Cer- tain Succulent Feeds and Alfalfa Meal as Sourses of Vitamin A for Poultry. Pollination of the Sweet Cherry. Pruning Bearing Deciduous Fruit Trees. Fig Smut. CIRCULARS No. No. 87. Alfalfa. 157. 113. Correspondence Courses in Agriculture. 160. 117. The Selection and Cost of a Small 164. Pumping Plant. 165. 127. House Fumigation. 129. The Control of Citrus Insects. 166. 136. Melilotus indica as a Green-Manure 167. Crop for California. 170. 144. Oidium or Powdery Mildew of the Vine. 151. Feeding and Management of Hogs. 173. 152. Some Observations on the Bulk Hand- ling of Grain in California. 178. 154. Irrigation Practice in Growing Small 179. Fruit in California. 155. Bovine Tuberculosis. 184. Control of the Pear Scab. Lettuce Growing in California. Small Fruit Culture in California. Fundamentals of Sugar Beet Culture under California Conditions. The County Farm Bureau. Feeding Stuffs of Minor Importance. Fertilizing California Soils for the 1918 Crop. The Construction of the Wood-Hoop Silo. The Packing of Apples in California. Factors of Importance in Producing Milk of Low Bacterial Count. A Flock of Sheep on the Farm. CIRCULARS— (Continued) No. 190. Agriculture Clubs in California. 199. Onion Growing in California. 202. County Organizations for Rural Fire Control. 203. Peat as a Manure Substitute. 208. Summary of the Annual Reports of the Farm Advisors of California. 209. The Function of the Farm Bureau. 210. Suggestions to the Settler in California. 212. Salvaging Rain-Damaged Prunes. 214. Seed Treatment for the Prevention of Cereal Smuts. 215. Feeding Dairy Cows in California. 217. Methods for Marketing Vegetables in California. 220. Unfermented Fruit Juices. 228. Vineyard Irrigation in Arid Climates. 230. Testing Milk, Cream, and Skim Milk for Butterfat. 231. The Home Vineyard. 232. Harvesting and Handling California Cherries for Eastern Shipment. 233. Artificial Incubation. 234. Winter Injury to Young Walnut Trees during 1921-22. 235. Soil Analysis and Soil and Plant Inter- relations. 236. The Common Hawks and Owls of Cali- fornia from the Standpoint of the Rancher. 237. Directions for the Tanning and Dress- of Furs. 238. The Apricot in California. 239. Harvesting and Handling Apricots and Plums for Eastern Shipment. 240. Harvesting and Handling Pears for Eastern Shipment. 241. Harvesting and Handling Peaches for Eastern Shipment. 242. Poultry Feeding. 243. Marmalade Juice and Jelly Juice from Citrus Fruits. 244. Central Wire Bracing for Fruit Trees. 245. Vine Pruning Systems. 247. Colonization and Rural Development. 248. Some Common Errors in Vine Pruning and Their Remedies. 249. Replacing Missing Vines. 250. Measurement of Irrigation Water on the Farm. 251. Recommendations Concerning the Com- mon Diseases and Parasites of Poultry in California. No. 252. 253. 254. 255. 256. 257. 258. 259. 260. 261. 262. 263. 264. 265. 266. 267. 268. 269. 270. 271. 272. 273. 274. 275. 276. 277. 278. 279. 281. 282. 283. 284. Supports for Vines. Vineyard Plans. The Use of Artificial Light to Increase Winter Egg Production. Leguminous Plants as Organic Fertil- izer in California Agriculture. The Control of Wild Morning Glory. The Small-Seeded Horse Bean. Thinning Deciduous Fruits. Pear By-products. A Selected List of References Relating to Irrigation in California. Sewing Grain Sacks. Cabbage Growing in California. Tomato Production in California. Preliminary Essentials to Bovine Tuber- culosis Control. Plant Disease and Pest Control. Analyzing the Citrus Orchard by Means of Simple Tree Records. The Tendency of Tractors to Rise in Front; Causes and Remedies. Inexpensive Lavor-saving Poultry Ap- pliances. An Orchard Brush Burner. A Farm Septic Tank. Brooding Chicks Artificially. California Farm Tenancy and Methods of Leasing. Saving the Gophered Citrus Tree. Fusarium Wilt of Tomato and its Con- trol by Means of Resistant Varieties. Marketable California Decorative Greens. Home Canning. Head, Cane, and Cordon Pruning of Vines. Olive Pickling in Mediterranean Coun- tries. The Preparation and Refining of Olive Oil in Southern Europe. The Results of a Survey to Determine the Cost of Producing Beef in Cali- fornia. Prevention of Insect Attack on Stored Grain. Fertilizing Citrus Trees in California. The Almond in California. Oak Fungus in Orchard Trees. The publications listed above may be had by addressing College of Agriculture, University of California, Berkeley, California. 12w-6,'25