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

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Immature tuber surfaces are easily infected, whereas those of mature tubers are much more resistant. Wounds are generally necessary for infection through mature tuber skins. A period of 3-4 days or more between vine killing and digging considerablv increases tuber resistance. Epidemiology Maximum mycelial growth of*A.so/ani in pure culture occurs at 280C, whereas optimum temperature for formation of conidiophores and conidia is 19-23'C. Conidiophore formation is inhibited, but not irreversibly, at temperatures greater than 320 C. Temperatures above 270 ( stop conidia formation. Conidiophores develop in light, whereas light inhibits conidia formation at temperatures above 150C. Maximum spore production in the field occurs between 3:00 1.O , ' ' !41 I /1 H °A C I D Fig. 48. Early blight: A, leaf lesions with concentric targetlike markings, somewhat limited by the larger veins; B,tuber lesions; C, dormant spores of Alternaria solani with short-beaked A. alternata type near top (bar represents 50 pm); D, germinating spore. 44 a.m. and 9:00 p.m. Spores in water germinate within 35-45 min at the optimum temperature (24-30' C) and within 1-2 hr at 6-34' C. Optimum temperature for tuber infection is 12-16' C but varies with cultivar. Most rapid progress of the disease occurs during periods of alternating wet and dry weather. Early blight can be severe in irrigated desert regions because of prolonged periods of dew. The disease is often more severe when the host has been predisposed by injury, poor nutrition, or other type of stress. Field resistance to foliage infection is associated with plant maturity. Late maturing varieties are usually more resistant. liarly blight does not red uce yields when inlection occurs late in lhe season. Other Hosts The fungus is pathogenic on tomato and other solanaceous crops and has been reported on other genera such as Brassica spp. Control I) Cultivars with levels of field resistance are available, but no cutivars are immune. 2) Protectant fungicides such as the dithiocarbamates, fentin hydroxide, and chlorothalonil effectively control early blight on loliage. 31) Fungicide applications scheduled by spore trapping or other methods so as to coincide with secondary spread of the disease are most effective. Early season applications of .fgicides before secondary inoculum is produced often have little or no effect on the spread permit tubers of the to inature disease. in the ground before digging, and avoid bruising in handling. 5) Avoid disturbing seed tubers until ready to plant. Selected References )OUGLAS, 1). R., and M. I). GROSKOIPIP. 1974. Control of c:arlv blight ineastern and soutlicentral Idaho. Am. Potat .I.51:361-368. I)OtJGL.AS. I I). R., andt i. .t. FPAVE K. 1972. Screening potatoes for field EI.IIS, resistance M. .B., to and early I. A, blight. S. GIBSON, Am. Potato 1975. .1.49:1-6. .lhernariasolani. No. 475 in: Descriptions of Pathogenic Fungi and Bacteria. Comnmonw. Mycol. Inst.. Kcn. Sorrey. Ingland. 2 pp. IIARRISON, M. )., C. II. LIVINGSIION. and N. OSFIIMA. 1965. Control of potato carly blight in Colorado. I. Fungicidal spray schedules in relation to the epidemiology of the disease. Am. Potato J. 42:319-327. IIARRISON, M. I)., C. If. 1IVINGSTON, and N.OSIIIMA. 1965. Control of potatocarly blight in Colorado. 1I.Spore traps asa guide for initiating application%ol VFNETTE, hngicidcs. .1.R., Am. and Potato M. ,I.42:333-340. 1). IIARRISON. 1973. Factors affecting infection of potato tubers by .lhernariasolani in Colorado. Am. Potato .1.50:283-292. WAGGONER, P. E.. and J. G. IIORSFAI.L.. simulator 1969. Epiden. of plant A disease written fora computer. Conn. Agric. Exp. Stn. [lull. 698. 811pp. (Prepared by D. P. Weingartner) lternaria alternata Alernaria ahernata (Fries.) Keissler (syn. A. tenuis Nees.) infects potato and other solanaceous crops, forming lesions on potato leaves similar to those of early blight. Spores x (20-63 9- 18 Mpn) are snialler than those of' . solani,are formed in chains, and lack the typical long beak (Fig. 49A). Their sizeand shape may vary considerably. The fungus is often associated with considered other diseases a and weak isfrequently parasite, isolated. It isgenerally which attacks plants weakened by viruses, deficiencies, stress, or senescence. Selected References EIIIS. M.B. 1971. Dernatiaceous Ilyphomycetes. Commonw. Mycol.
R., Inst.. Kew. Surrey. ngland. 609 pp. RAMACIIANI)RA .".\I. RAO. NI 1973. A virulent ,\\ and I:. R. strain K II of 1R Ahernaria , . Kriinkheitcn ill d alternatacausing leaf and fruit spot of chilli. Indian Phytopathol. Schiid linge der Kartoffel. L.andwirtschaltliche I chrmittelentrale 26:6(-603. Zollikofen. 1501 pp. SREFKANIAII. K. R.. K. S. NAGARAJA RAO. and I. N. (Prepared by L. J. Turkensteen) AMAr GE a., G H Ij Fig. 49. Representative st! uctures for identification of: A,Alternaria alternata, conidia; B, Pleospora herbarum (Stemphylium botryosum), conidia and (C) ascospores in ascus; D, Ulocladhum atrum (Stemphylium atrum), conidia; E,Septoria lycopersici,conidia; F,Phoma andina, spores from plate culture; G-J, Choanephora cucurbitarum, sporanglophores and conidia of two distinct types. Bars represent 20 Mm. (B and C. Courtesy Research Institute for Plant Protection, Wagen rugen; A and D-J, courtesy L. J. Turkensteen and W. J. Hooker) N.2 45
Page 1 and 2:
, ,. ,o . ; , . o , . r. , -' .L ,
Page 3 and 4: Compendium of Potato Diseases W. J.
Page 5 and 6: In memory ofimy respected colleague
Page 7 and 8: Acknowledgments Planning Committee
Page 9 and 10: Introduction 1 Potato Disease 1 The
Page 11 and 12: A potato disease is an interaction
Page 13 and 14: Fig. 1.A, Lower portion of young po
Page 15 and 16: +q I B Fig 4. Natural openings in a
Page 17 and 18: Part I. Disease in the Absence of I
Page 19 and 20: more heavily in the vascular region
Page 21 and 22: the air temperature when tubers are
Page 23 and 24: iiO A B 'D C Fiq. 14 Second growth:
Page 25 and 26: identifying tissue bruised by black
Page 27 and 28: Internal Sprouting multiple sprouts
Page 29 and 30: conditions permits normal leaf deve
Page 31 and 32: Epidemiology Oxidant injury is pres
Page 33 and 34: 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: A \, 2) Powdery mildew is rarely a
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 and 88: necrosis extending into the tuber t
Page 89 and 90: do not survive drying. Both species
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
Page 139 and 140:
Common Name Causal Factor Other Nam
Page 141 and 142:
Common Name Causal Factor Other Nam
Page 143 and 144:
coalesce-union of similar structure
Page 145 and 146:
many days following removal of the
Page 147 and 148:
Index Abrasions, tuber surfaces. 14
Page 149:
Irost tolerance in. 9 aniligena. 68
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