770 YEARBOOK OF AGRICULTURE 1953 healthy plants, is referred to as wet feet. The symptoms are best described as a general decline in plant growth. On affected plants the lateral branches produced in the spring on the fruiting Diseases of canes often are less than 12 inches long; normally they are at least 36 inches. The leaves are smaller, bronzed Berries in or yellow, and lack the bright green of healthy leaves. Usually all the canes in a hill are affected. The plants may the West die in dry hot weather or may linger on and produce a few weak canes, about 2 to 4 feet long, for the next Folke Johnson season's crop. They remain unthrifty and finally succumb. A healthy plant Raspberries and blackberries bring annually produces 8 to 12 or more in about lo million dollars a year to young, vigorous canes 8 to 10 feet or growers in the Pacific Coast States of more high. Sometimes when the root California, Oregon, and Washington. system has been killed during the rainy Diseases often are of great impor- season, only weak, short laterals an tance in so large an industry. They dif- inch or two long are produced with fer somewhat, according to locality and small, undeveloped leaves, which soon crop. California is concerned mosdy wither and die. New canes fail to with the trailing blackberries, Boysen, develop and the plant succumbs. The Logan, Nectar, and Young. Black and fruit from affected hills is greatly re- red raspberries are more important in duced in size, number, and quality. Oregon. In Washington the leaders If the plants are dying when the fruit are red raspberries and the Cutleaf is ripening, it shrivels up, turns a dark Evergreen blackberry. red, and has little flavor. The fruit is The varieties of red raspberries pro- crumbly and hard to pick. duced commercially in Oregon and Root suffocation is noticed mostly in Washington are somewhat different. late spring or early summer in the Production in Washington is almost lowest places in the field. All plants in limited to the Washington variety, but such locations are thus affected and a there are a few fields of Tahoma and field may be spotted with dead or Willamette. Oregon has a large acre- weakened plants, while in the higher age in Guthbert in addition to Wash- levels the canes are normal. Symptoms ington and Willamette raspberries. of root suffocation do not generally ap- A well-drained soil is needed for pear until the second or third summer growing red raspberries. Silt loam or after planting, although older plants silty clay-loam soils even on moderate may also become affected, partic- slopes are avoided because their water- ularly after an unusually wet season. holding capacity is often great enough The only known control is to provide to sufiPocate the roots. Sandy or porous better drainage. Replanting with new soils with fairly heavy subsoil, where stock is not practical, because the new free water during the rainy season re- plants also will become affected. All mains in the root zone for long periods, commercially grown raspberries, such have the same effect. The choice soils as Washington, Willamette, and Cuth- are those of good texture, as loams or bert, arc susceptible. Newburgh tol- sandy loams, where excess water drains erates the condition but is not grown ofT or percolates away from the roots. extensively in the West. There is indi- Root suffocation by water, one of the cation of tolerance or resistance among severest of problems in maintaining new hybrids, but they require further DISEASES OF BERRIES IN THE WEST 771 testing for other qualities before they so that no great damage results before can be recommended. the crop is harvested. Of the newer varieties, Willamette and Tahoma are WHEN FIRST INTRODUCED in 1938, the resistant. Prompt removal and burning Washington was resistant to western of the old fruiting canes in the fall aids yellow rust, caused by Pkragmidium in reducing the spore load for infections rubi-idaei, which had plagued other the following year. varieties. In 1944, however, a new strain of the rast fungus infected the ANTHRACNOSE, caused by the fungus Washington variety, ft has since be- Elsino'é véneta, is present to some extent come widespread in Washington and each season. It is worse on black rasp- Oregon. berries than on the commercially The most obvious symptom is the grown red varieties. The disease is yellow flecks or pustules on the upper recognized in early spring on the surface of the leaves in early spring. lower parts of young canes by the Light-orange pustules break out 2 or 3 appearance of round to elliptic sunken weeks later on the under leaf surface, spots, one-eighth to one-fourth inch or on the canes, or on leaf petioles. Some- more in diameter. Those lesions have times they almost cover the leaves and light-gray centers with purple margins, cause them to die prematurely. The are somewhat depressed in the centers, yellow or light-orange pustules contain and may become so numerous as to numerous spores, which are carried impair the movement of water and about by wind currents or splashing nutrients through the canes. Similar raindrops. New infections arise all spots, but smaller, may be present on summer. In favorable weather all the the leaves and even on the fruit. plants in a field become infected. Se- The spray schedule against yellow vere infection means defoliation, and rust will usually suffice to hold in check lesions produced on the canes weaken anthracnose on red raspberries. Often them so they break easily during subse- an additional spray is required, espe- quent cultural practices. The pustules cially in the black varieties. Several and cane lesions turn dark and become proprietary materials have given good black in late summer and early fall. results if applied when the current sea- Another kind of spore remains over son's canes are 8 to 12 inches tall. winter on the canes, fallen leaves, plant debris, fence posts, soil—any- GREEN MOSAIC, a virus disease, is thing. Those spores do not germinate most prevalent on the Cuthbert rasp- until early the next spring, when new berry. The effect on the plants is a infections arise on the young unfolding gradual loss of vigor, reduced yields, leaves in the form of inconspicuous, and lower quality of fruit. Such plants pin-point, orange blisters. Those are are more easily winter-killed than are followed by the yellow stage on the healthy ones. The outstanding symp- upper leaf surface and the life cycle has tom is a mottling of dark- and light- been completed. green areas on the foliage; the dark- Experiments by E. K. Vaughan, of green blisters are intermingled with Oregon State College, and me, demon- the light-green areas near the veins. strated that a delayed dormant spray Such leaves are deformed and smaller application to the canes when the buds than healthy foliage. Mottling is more have begun to unfold, usually in late evident on the young leaves near the March or early April, will check the cane tips. It is more pronounced in disease. Several fungicides, such as early summer than later in the season, bordeaux mixture, lime-sulfur, ferbam, when the symptoms become masked. Phygon-XL, Elgctol, and Cop-O-Zinc, Mosaic may be introduced into a have given effective control. They do field by planting diseased nursery not eradicate the disease but reduce it stock. Once established, it spreads 772 YEARBOOK OF AGRICULTURE 1953 rapidly by the feeding activities of ance of water-soaked areas or streaks aphids, Amphorophora ruhi, which move at the tips of the new canes. The about from diseased to healthy plants. streaks later become purple, and the Studies by L. K. Jones and Karl Baur, tips bend downward and usually die. formerly of the State College of Wash- The lateral branches also show this ington, showed that in one held the discoloration, foilow^ed by tip die- number of infected plants increased back. Sometimes during high temper- from 9.5 percent to 51 percent in atures, when the cane tips have not 2 years. They also show^ed that careful been killed, growth is retarded and roguing was an important means of there is produced a rosette of branches holding the disease in check. and leaves, followed by near-normal The Washington, Tahoma, and growth. Leaf mottle, characterized by Willamette varieties have shown symp- light- and dark-green areas scattered toms of being infected with a virus over the leaves, is associated with cane disease called ring spot. The disease tip necrosis. As in red raspberries, the has closely followed the appearance in mottle becomes masked with high tem- 1947 of aphids on those varieties. Ring peratures but reappears on the same spot was present throughout w^estern plants during cool w^eather. Growth of Oregon and Washington in 1953. The afíectecl plants is greatly retarded, and main characteristic is the presence of the fruiting laterals are shorter than circular, light-green rings l:)ordering on healthy canes. nearly normal green tissue. The rings The virus has been recovered from are about one-fourth to one-half inch six red varieties, Antwerp, Cuthbert, in diameter. It is not unusual to find Latham, Lloyd George, Marlboro, and ring spot and a mosaic mottle on the Newburgh, but not from Washington same canes, in which the former symp- or Tahoma. Of 11 black raspberry toms are present on the young leaves varieties (besides the wild species and mosaic on the older. Thus far no Ruhiis leucodermis) tested for suscepti- apparent stunting or loss of vigor has bility by using aphids as vectors, all been associated with the disease. were found susceptible by showing Another symptom often observed on typical symptoms of cane tip, dieback, Cuthbert and other red varieties is a and mosaic. mild mottle, or flecking, of small, light- yellow areas scattered over the leaves. THE TERM BLACKBERRIES includes the The flecks are more abundant on the trailing forms that often are referred to older leaves of new growth. The symp- as dewl^erries. In California dew- toms disappear in hot weather and re- berries are growm on about 6,000 acres. appear when low^er temperatures pre- Most extensively grown are Boysen, vail. Experiments conducted by G. H. Logan, Nectar, and Young, all be- H über, formerly of the Western Wash- lieved to be derived at least in part ington Experiment Station, demon- from the wild Pacific coast dewberry, strated the virus nature of the symp- Rubus ursi?ius. Some of those varieties toms. He refers to the disease as mild are grown in western Oregon but are mosaic. of minor importance in Washington. The virus may be transmitted by In Oregon and Washington the Cut- grafting tissue from diseased to healthy leaf Evergreen blackberry, R, lacini- plants, and the large raspberry aphid, aius, is important. Recently introduced Amphorophora ruhi, is the natural vector varieties from Oregon are Cascade, in the fields. Chehalcm, and Pacific, which also are W^hen the virus is transmitted from dérivâtes oíR, ursinus. red raspl^erries to Cumberland and Verticillium wdlt is one of the worst other varieties of black raspberry, by diseases of trailing blackberries in grafting or aphids, severe symptoms California and Oregon. Stephen Wil- develop. The first efí'ect is the appear- helm and H. Earl Thomas, of the DISEASES OF BERRIES IN THE WEST 773 University of California, found symp- troL Susceptible crops should not be toms first appearing when the new planted in Verticillium-iniestGd soil. shoots produced in the spring are i to Only disease-free stock should be used 2 feet tall. The canes droop and wilt, in establishing new fields and any and the lower foliage becomes yellow. plants that subsequently show the wilt The yellowed areas begin at the distal symptoms should be removed promptly parts of leaflets and progress inward with the root systems and burned. That between the veins. Later they turn is practical only when fewer than 5 per- brown and become necrotic. The cent of the plants are diseased. lowest leaves of severely affected plants Blackberries are also subject to other fall off in early spring, leaving only a disorders of fungus origin. One, leaf tuft of small, green leaves at the tips of and cane spot, caused by Septoria rubi, the canes. Leaf killing is aggravated by is mostly present on the dewberries in an abrupt onset of hot weather follow- the Willamette Valley of Oregon and ing a cool spell. All young shoots in a in parts of Idaho. Sometimes it is se- hill are not usually affected, as those rious in the commercial berry-growing produced in warm weather escape in- regions of coastal California. The fun- fection and grow normally as long as gus spores are spread from diseased to such v/eather lasts. They may show healthy tissue primarily by splashing light symptoms in autumn. After the water. dormant season, some of these appar- A major symptom on the leaves is ently healthy canes die; the necrosis small, light-colored spots, bordered progresses from the tips downward to with red or purple, about one-eighth the roots. The following year others inch in diameter. The spots also are may produce normal leaves and fruit. present on the canes and may become If prolonged high temperatures follow so numerous as to cause premature cool weather, entire plants may be defoliation and death of the fruiting killed at harvesttime. canes. The plants are not killed but Verticillium wilt is caused by the continue to produce new shoots, which fungus Verticillium albo-atrum^ which is become infected later in the season. present in the soil. Dr. Wilhelm found The overwintering lesions on the canes that the organism tolerates both heavy become brown. In Oregon a spray of clay loams and sandy loams and can lime-sulfur in February or March is exist either in an alkaline soil with a recommended for control. In Califor- reaction of pH 8.5 or one as acid as nia a second application with zineb is PH4.5. required in the early-blossom stage. Certain clones of the wild Pacific A closely related and serious disease coast trailing blackberry, R. ursinus, and is found on Cutleaf Evergreen black- the commercial dewberry varieties, berries in western Washington. Only Boysen, Young, and Nectar, are highly the fruiting canes show symptoms of susceptible to infection by Verticillium. small, black, circular spots, which be- Varieties of black and red raspberries gin to appear in December. They en- also become infected with the organ- large, several lesions coalesce, and it is ism. The late Dr. S. M. Zeller, of Ore- not unusual to find the base of the gon State College, however, discovered canes discolored black for several feet. that in the latter group the Cuthbert The fruiting canes become girdled, and variety is tolerant of the disease even by March the entire cane growth may though infected. Other resistant or be killed. The new spring shoots show immune species and varieties include no symptoms until the following win- clones of the wild trailing blackberry, ter. In Washington the best control is a Logan, Mammoth, Ghehalem, Hima- spray application with ferbam or Phy- laya, and the Cutleaf Evergreen. gon-XL in m id-June or early July. At Once established in a field verticil- that time the young shoots are trellised, lium wilt is hard to eradicate or con- usually beneath the fruiting canes, and 774 YEARBOOK OF AGRICULTURE 1953 the spray thoroughly covers this new Two bacterial diseases of black- growth, protecting it from infection. berries are important in the West— The Cutleaf Evergreen blackberry cane gall and crown gall, caused by in the Pacific Northwest is also affected Agrohacierium ruhi and A. tumefaciens, with cane and leaf rust caused by respectively. In symptoms they are Kuehneola uredinis, George W. Fischer somewhat alike with the appearance and I found the disease widespread in of rough, warty outgrowths. In the western Washington in 1949. Cane former the enlargements are primarily and leaf rust makes its first appear- present on the canes, which are split ance in late spring or early summer, open. The knobby outgrowths in when large, lemon-yellow lesions are crown gall are confined mostly in the produced. They split open the bark of crowns and on the roots. A. ruhi infects the overwintered canes. Later in the plants of the genus Ruhus; while A, summer, minute, yellow pustules are tumefaciens also infects fruit trees, vege- present on the lower leaf surfaces and tables, and ornamentals. sometimes on the fruit. In autumn the Experiments by L. C. Coleman, of leaf pustules become buif-colored from the Dominion Laboratory of Plant the formation of another spore form. Pathology, Saanichton, B. C, showed How the rust overwinters has not been that the horsebean, Vicia Jaba, could determined definitely. Susceptible va- be used as a difí*erential host, for it is rieties include also the Broadleaf form, susceptible to infection by the cane two unnamed hybrids, and Chehalem. gall organism but not by the crown Some clones of the wild trailing black- gall bacterium. Severe infection devi- berry, R. ursinus, are also infected. talizes the plants. Nine commonly grown varieties of The organisms readily contaminate dewberry, besides Himalaya, and two the soil in which they can persist with- numbered hybrids were found to be out susceptible plants for several years. immune. No definite control program All blackberries and dewberries are has been developed for the disease. susceptible to infection by both organ- Stamen blight, Hapalosphaeria de- isms, as are black and red raspberries, for mans, another disease found mainly but raspberries appear to have more in the Pacific Northwest, can cause resistance than the other brambles. serious losses to the fruit of Boysen, Pruning out and burning infected Young, and Cutleaf Evergreen black- canes as soon as symptoms appear of- berries. Occasionally it has been found fers some degree of control. New plant- on R, ur sinus. Stamen blight is most ings should be established on noncon- easily detected when the flowers open. taminated soil with disease-free stock. Then the anthers of the blooms are Introducing soil from a contaminated transformed into gray, moldy masses field into noninfested areas by cultiva- of spores. The stigmas, which are not tion implements or other means should infected, function normally; when be avoided. some are pollinized by insects with pollen from healthy blossoms, a de- DWARF is the most important virus formed fruit results with only a few disease in the trailing blackberries. It normal drupelets. It is not known defi- generally is present in the three Pacific nitely when infection takes place, but Coast States and is important to the it likely occurs during early spring Loganberry industry. from spores produced in the flowers Plants affected with dwarf take on a the previous year and carried over yellowed hue. The canes are much winter in the buds. No conclusive con- shorter and three or more buds are pro- trol program has been developed, but duced in the leaf axils where only one a lime-sulfur solution with water is normally present. The canes are sprayed on the canes in August has spindly at first and in later years be- resulted in about 60 percent control. come stout, stiff, and unnaturally up- DISEASES OF BERRIES IN THE EAST 775 right. The leaves are mottled with irregular bronzed and light-green splotches and are smaller than healthy foliage. Considerable leaf distortion by crinkling and puckering of the tissue between the veins is noticeable. Diseases of The Phenomenal and Logan varie- ties are most susceptible to dwarf, al- though the thornless Logan is reported Berries in somewhat tolerant to the disease in California. The wild Ruhus ursinus is infected and serves as a reservoir from the East which the virus can spread to com- mercial fields. The aphid Capitophorus: tetrarhodus is a vector of the virus in W, R Jeff er s Oregon, 'but the means whereby the spread is effected in California is un- Growers of raspberries, blackberries, known. Dwarf has not been found oc- and dewberries usually appreciate the curring naturally in the Boysen, Nec- severe losses that diseases may cause tar, and Young varieties. but often they are not aware of the ten An unusual malformation of the percenters—the less severe ailments Thornless Logan, referred to as purple that may make the difference between stunt, has been observed in western a profitable crop and an unprofitable Oregon by E. K. Vaughan, of Oregon crop. State College. The disease is minor, With the present high cost of pro- but it deserves attention because if it duction and premium prices for high- should become generally established in quality berries, it is more essential than the Logan fields great losses may result. ever before that growers follow sound Purple stunt is characterized by severe disease-control practices. Just as they stunting. The canes seldom reach a make careful plans for fertilizing, length of more than a few inches and pruning, and harvesting, they should remain purple throughout the season. take steps to prevent and stop diseases Death of affected plants is the usual before it is too late. The alert grower result. of bramble crops learns to identify the As with most virus diseases in other diseases in order to insure profitable crop plants, there is no control once a production. plant has become infected. If stunt is not too prevalent in a field, dis- MOSAIC is the most widespread and eased plants should be rogued out and common virus disease of raspberries, burned. Disease-free stock should be yet so many symptoms and effects are used when establishing a new planting. associated with mosaic that it is hard Control of the insect carriers is an to describe properly. important and effective method for Apparently several different but re- reducing spread of viruses in the fields. lated viruses can cause mosaic. Plants infected with a mixture of mosaic vi- FoLKE JOHNSON is a plant pathologist at ruses usually show symptoms different the Western Washington Experiment Sta- from those infected with only one. tion of the State College oj Washington^ He Two main types of mosaic diseases was reared in the Pacific Northwest. Dr, occur on raspberry. Green mosaic causes Johnson is a graduate of that institution; a mottled pattern of light and dark before returning there in ig43, he spent 4 green areas in infected leaves. Yellow years investigating virus diseases of plants mosaic causes bright-yellow discolor- at the Rockefeller Institute for Medical ation of part or entire leaves. Both Research and Ohio State University* attack black and red raspberries.