Compendium of Potato Diseases - (PDF, 101 mb) - USAID

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3) Avoid contamination of clean fields by inoculum transfer Verticillium Wilt through infested soil or diseased tubers and plant refuse. The disease apparently occurs wherever potatoes are grown, Selected References although it may be confused with other diseases that cause early maturity. GOSS, R.W. 1923. Relation of environment and other Iactors to potato wilt caused by I..oarint oxi.vorinn. Neb. Agric. Exp. in. Res. Symptoms Bull. 23. 84 pp. Verticillium wilt causes early senescence of plants. Leaves, GOSS, R. W. 1924. Potato wilt and stem-end rot caused by I usariumn which become pale green or yellow and die prematurely, are eumartii Neb. Agric. Exp. Sin. Res. Bull. 27. 83 pp. described as "early dying" or having "early maturity." GOSS, R. W. 1940. A dry rot of potato steins caused by Ihusariwn l)uring the ,,rowing season, plants may lose their turgor and solani. Phytopathology 30:160-165. wilt, especially on hot, sunny days (Plate 50). Single stems or Mcl.EAN. J. G., and .1.C. WAI.KER. 1941. A comparison of Fusarito, leaves on one ide ofthe stem may wilt first. Vascular tissue of avenaceawn. ' oxirsporui,and 1. ,olani var. e'u artiiinrelation to s potato wilt in Wisconsin. I. Agric. Res. 63:495-525. stems becomes a light brown, best observed if the stem issevered RADTKE. W., and A. ESCANI)E. 1975. Verglcichendc Unter- at about ground level with a long slanting cut. Externally visible suchungen Uiber verschiedene Methoden tur Inokulation von Kar- necrotic stem streaking occurs in certain cultivars when soil toffelsiimlingen mit I.uvariun solani (Mart.) Sace. f. sp. cnm' ariii moisture and fertility are high. (Carp.) Snyder et Hansen. Potato Res. 18:243-255. Tubers from infected plants, but not necessarily all tubers, SNYDER, W. C., and I|. N. HANSEN. 1941). 1941, 1945. The species usually develop a light brown discoloration in the vascular ring concept in Flsarium.Am .J. Bot. 27:64-67; 28:738-742; 32:657-666. (Plate 5I, Fig. 68A); severe vascular discoloration may extend UPSIONE, caused by M. IPusariumo.i-sporuni. E. 1970. A corky rot plant of ,Jersey Pathol. Royal 19:165-167.ovrhlwytouhheue.Caiesmydeopnie potato tubers ay through the tuber. Cavities may develop inside severely affected tubers. Pinkish or tan discoloration (see pink (Prepared by J. E. Huguelet and W. J. Hooker) bA eye) may develop around the eyes oras irregular blotches on the surface of affected tubers. This may be confused with mild late blight infection. Causal Organisms V'erlicillium alho-airum Reinke & Berth. develops septate, resting dark mycelium on stems in the field and also in culture, in contrast to 1'. dahliae Kleb., which forms dark mycelial strands with black, thick-walled pseudosclerotia (Fig. 69), also called microsclerotia, 30-60(lm in diameter. Vegetative hyphac of both are similar (2-4 pm in dia meter and colorless). Conidiophores are septate with side branches (Fig. 6813), swollen at the base, and arranged in a whorl. First-formed conidia of I'.alhoairtim ;,re (T-12 X 2.5-3 p in. Those of 1'. dlalijot are 3-5.5 X 1.5-2 pin. Conidia produced later, particularly those in culture, may be considerably smaller, 3--6 x 2-3 pm. Conidia arc usually single celled but may he one-septate (Fig. 68C and )). Both types may be present within a single potato plant. Disease Cycle Infection is through root hairs, wounds (including those at points of emergence of adventitious roots), and through sprout and leaf surfaces. Hyphae progress intracellularly and intercellularly to the xylem (Fig. 68D). Transport of conidia within vessels of potato is probable. Conidia are short-lived and Fig. 68. A, Verticillium vascular discoloration in tuber. B, Verticillium albo-atrumin culture: a, "ater droplets surrounding Fig. 69. Verticillium isolates from potato. A,Dark mycelial type in conidia on tips of conidiophores; b, a single conidium (bar one-month culture, at X100 and X375 approximately. B, Pseudorepresents 50 mm). C, Conidia from culture; D, fungus mycelium sclerotial isolate in cne-month culture, x175 and x200. (Courtesy in discolored xylem of tuber tissue (bar represents 10 pm). D. B. Robinson et a. 1957) 62
do not survive drying. Both species are poor competitors and survive poorly in soil in the absence of suitable hosts. Infectious propagules of dark mycelium and pseudosclerotia are usually relatively short-lived, but survival time isinfluenced by soil type and is severely limited by anaerobic soil conditions. Infectious propagules germinate and produce conidia within hours. Epidemiology V allo-airwtnigenerallyappers to be more pathogenic than I. (Iahliae. Warm soil temperatures (22-27' C) favor growth of v daliae. tempeatures. I" a/bo-atrun itsrnge is is relatively more pathogenic reltivlC.moepratoenicatsl at lower r temperatures; its range is 16-27'C. Crop rotation buildup affects of soil inoculum, th and three-year rotations have effectively reduced soilborne inoculum. Inoculum is reduced when cereals, grasses, and legumes are included in the rotation. When potatoes are grown several years in succession or in rotation with susceptible crops, inoculum increases in the soil. Other factors that favor incidence and severity of Verticillium wilt include disconuatinion planting of highly the susceptiblc practice cultivars such of as Kennebec, burning potato tops, and red a u ation the f practice of chemical reuction in the formerly common practice of chemical treatment of seed potatoes. Inoculum in field soil or in soil adhering to the surface of potato tubers is more important in initiating wilt symptoms than is inoculum from seed tubers with vascular discoloration. Paradoxically, seed tubers with vascular discoloration often produce plants as wilt-free and as vigorous as those from comparable seed tubers free from vascular discoloration. hnoculum can he distributed long distances by contaminated soil adhering to seed surfaces and from field to field by contaminated equipment or irrigation water. Inoculum may also be airborne or spread from phint to phint by root contact, Other Hosts Isolations of 1'. albo-atruni, which may have also included I. (/ahlia , havc been made from a very wide range of dicotvle- dotis planits, both wvoody anrd herbaceous. Man of t hese Were sy symtmlss. iptomlcss. I. 1as dahia, athe infects oiver 50 species if nfecort50speesofanhts plants in 23 i 2h families. (rasses aid (ither minocits are nonosts (if both species. Numerous common weeds are suscepts, including ('henopodoMin albiumi, (apsela bIur.sa-iastoris, Tara.'aculn spp., and I:qui.etttn arvcn.e. Resistance Varieties carrying different levels of resistance have been identified within S. tuertostim ssp. titherostim. Certain cultivars etdifferently tc react to varying conditions, including geographic location, abundance of inoculum, and type or strain of the fungus involved, suggesting that pathogenic strains of the causal agent exist. Even highest known levels of resistance break down with high inocultm density in the soil. . lulerostin, ssp. atdigena is reported to have wilt resistance. Control I) Seed tubers contaminated with infested soil should be disinfested before being planted. Liquid seed treatments are more effective than dusts. Organic mercuries are very effective, but their use is generally prohibited. 2) Rotate potatoes with cereals, grasses, or legumes. Avoid rotation with highly susceptible solanaceous crops such as eggplant and most tomato cultivars. 3) Do not plant susceptible cultivars. 4) Control weed suscepts. 5) Systemic fungicides (benomyl or thiophanate-methyl) and nonsysternics (mancozeb, captan, or metiram) applied to seed tubers are reported effective. 6) Several soil treatments show promise; sodium methyldithiocarbamatc, benomyl, and systemic insecticides (aldicarb, acephate) have delayed symptoms and increased some yields, 7) Several nematodes increase incidence and severity of Verticillium wilt. Soil fumigation with nenaticides alone (tri- chloronitromethane or 1,3-dichloropropene and related compounds) or with chemicals that control both fungi and nematodes is effective. Selected References AYERS, G. W. 1974. Potato seed treatment for the control of verticillium wilt and Fusarium seed piece decay. Can. Plant Dis. Surv. 54:74-76. BIEHN, W. L. 1970. Control of Verticillium wilt of potato by soil treatment with benomyl. Plant Dis. Rep. 54:171-173. BUSCH, I.. V. 1966. Susceptibility'of pcotato\arieti,:sto Ontario isolates of Verticilliumalto-atruni. Am. Potato J. 43:439-442. EASTON, G. D., M. E. NAGI., and D. effect I.. BAII.EY. of soil fumigation 1975. with Residual vine bt ning on control of Verticillium wilt of potato. Phytopathology 65:1419-1422. ENGEI.HARD, A. W. 1957. Host index of Verticillium alho-atrun? Reinkeand Berth. (including I'erticillium dahliae Kleh.). Plant t)is. Rep. Suppl. 244:23-49. FRANK, .. A., R. E.WEBB, and I). R.WILSON. 1975. The effect of inoculum levels on field evaluations of potatoes for Verticillium wilt resistance. Phytopathology 65:225-228. I).G. A.. and 1). C. M. CORItArI. 1973. Controlling potatoes caused early death by Ilhterodera of rostochiensis and I'erticillium dahliae.Ann. Appl. Biol. 75:461-462. HOYMAN, W.G. 1974. Consequence of'planting Norgold Russet seed infected with Verticillium a bo-atrioo. Am. Potato J. 51:22-25. KHEW, K. .., and .. V. BUSCH. 1968. Soil temperature affects infection of potato and tomato by mixtures of DM and MS strains of 1'erti'illitot al'o-atruti. Ant. Potato .1.45:419-413. KRAUSE, R. A...1. P).HUETIIER, P. SATIROPOULOS, and L. E. ADAMS. Verticillium 1975. wilt. Systemic Plant insecticide control Dis. of aphids and potato Rep. MORSINK, 59:159-163. F., and A. E. RICH. 1968. Interactions between Vertiillium albo-airtm oand I'rat hInchus /lnetrans in the Verticillium wilt of potatoes. phytopathology 58:401 (Abstr.). POWEI.SON. R. I., and G. E. CARTER. 1973. Efficacy of soil fumigants for control of Verticillium wilt of potatoes. Am. Potato J. 50:162-167. RICHl, Potatoes: A. F. 1968. Production. Potato Storing, diseases. Pages Processing. 397-437 Avi in: Publ. 0. Smith, Co., Inc., ed. Westport, CT. ROBINSON, 1). B., and G. W. AYERS. 1953. The cillium control wilt of potatoes of Verti by seed treatment. Can. J. Agric. Sci. 33:147-152. ROBINSON. 1). B.. R. H. LARSON, and J. C. WALKER. 1957. Verticillium wilt of potato in relation to symptoms, epidemiology, and variability ofthe pathogen. Wis. Agric. Exp. Sin. Res. Bull. 202. 49 pp. SMITH, H. C. 1965. The morphology of Verticilliun albo-atrum, V' dahliae, and I. tri.orl.%. N.Z. .. Agric. TIANASSOIJI.OPOULI.OS, Res. 8:450-487. C. C., and W. J. and HOOKER. sprout infection 1970. Leaf of potato by i'erticillium alho-atrua. Phytopathology 60:196-2(13. WOOI..IAMS, G. E. 1966. Host range and symptomatology of Verticillim dahliac in economic, weed, and native plants in interior British Columbia. Can .1.Plant Sci. 46:661-669. (Prepared by A. E. Rich) Thecaphora Smut Thecaphora smut is found in northern Central America (Mexico) and the northern regions of South America (Bolivia, Chile, Colombia, Ecuador, Peru, and Venezuela). Loss up to 80% is known. Symptoms Usually no aboveground symptoms are found. Affected tubers have wartyswellings on the surface (Fig. 70A) and, when sectioned, reveal dark brown, !ocular sori pervading the interior (Fig. 71 A and B, Plate 52). Galls resembling deformed tubers form directly from infections on the sprouts, stems (Fig. 70B), or stolons and, less frequently, on the tubers. Rootsare not known to become infected. 63
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, ,. ,o . ; , . o , . r. , -' .L ,
Page 3 and 4:
Compendium of Potato Diseases W. J.
Page 5 and 6:
In memory ofimy respected colleague
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Acknowledgments Planning Committee
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Introduction 1 Potato Disease 1 The
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A potato disease is an interaction
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Fig. 1.A, Lower portion of young po
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+q I B Fig 4. Natural openings in a
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Part I. Disease in the Absence of I
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more heavily in the vascular region
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the air temperature when tubers are
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iiO A B 'D C Fiq. 14 Second growth:
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identifying tissue bruised by black
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Internal Sprouting multiple sprouts
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conditions permits normal leaf deve
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Epidemiology Oxidant injury is pres
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sevritof stnting, chiorosis. loss o
Page 35 and 36:
Selected Reference brown to bronze
Page 37 and 38: Part II. Disease in the Presence of
Page 39 and 40: should be planted on land with at l
Page 41 and 42: Control I) Use disease-free tubers
Page 43 and 44: FOI-SO M. D, and I. A. FRIEDMAN. )9
Page 45 and 46: Fungi Powdery Scab liberating powde
Page 47 and 48: Histopathology Sort of sporangia de
Page 49 and 50: any time but generally occurs late
Page 51 and 52: '40 ff .. . '1 f . ."L', . '1 .,. "
Page 53 and 54: A \, 2) Powdery mildew is rarely a
Page 55 and 56: R., Inst.. Kew. Surrey. ngland. 609
Page 57 and 58: TORRES, H.. E. R. FRENCH, and I.. W
Page 59 and 60: d AC D A 0 Fig 53 Gray mold. A, Bot
Page 61 and 62: strands of pigmented hyphae. Sclero
Page 63 and 64: tuber malformation. Roots are also
Page 65 and 66: 1. Giant-hill plants, taller than n
Page 67 and 68: 13. Bacterial soft rot. Erwinia car
Page 69 and 70: 24. Wart. Synchytrium endobioticum
Page 71 and 72: 34. Pleospora herbarum (Stemphylium
Page 73 and 74: 44. Charcoal rot. Macrophomina phas
Page 75 and 76: 55. Leafroll virus. Current season
Page 77 and 78: 67. Mop-top virus. Primary tuber 68
Page 79 and 80: 77. Aster yellows mycoplasma sympto
Page 81 and 82: Symptoms Small, localized, light br
Page 83 and 84: obovoid, and 14-30 X 5-10 pm. Pycni
Page 85 and 86: invaders through the IFusarium lesi
Page 87: necrosis extending into the tuber t
Page 91 and 92: cauisal. Tesis Magister Scientiae e
Page 93 and 94: penetration, and subsequent disease
Page 95 and 96: have been demonstrated, including t
Page 97 and 98: In P..floridana,strains of PVY" and
Page 99 and 100: infects certain comnie,-cial stocks
Page 101 and 102: cytoplasm of infected potato cells
Page 103 and 104: WETTER, C. 1971. Potato virus S. No
Page 105 and 106: 3) Resistance has not been identifi
Page 107 and 108: nm), which do code for coat protein
Page 109 and 110: Symptoms AMV may induce Other predo
Page 111 and 112: Disease Cycle I)escriptions of Plan
Page 113 and 114: Selected References KASSANIS, B. 19
Page 115 and 116: Control 1)Avoid locations in wkhich
Page 117 and 118: The "yellows" types of disease, cha
Page 119 and 120: modifying cultural practices and by
Page 121 and 122: immature females in the white or ye
Page 123 and 124: l.aboratory, Control. and Quarantin
Page 125 and 126: They attack many major crops in the
Page 127 and 128: infested areas of North America sev
Page 129 and 130: antennal tb l tuberce u antenna eye
Page 131 and 132: carbon tetrachloride, applied at th
Page 133 and 134: Diagnostic Microbial Structures Scl
Page 135 and 136: Surface and or interior Shades of g
Page 137 and 138: Equivalent Names of Potato Diseases
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Common Name Causal Factor Other Nam
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Common Name Causal Factor Other Nam
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coalesce-union of similar structure
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many days following removal of the
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Index Abrasions, tuber surfaces. 14
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Irost tolerance in. 9 aniligena. 68
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