Solanum tuberosum L.
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
Tubers are one of the temperate staples, eaten boiled, baked, fried, stewed,
etc. Surplus potatoes are used for fodder and alcohol, and chemurgic
applications. The flour can be used for baking. Potato starch is used to
determine the diastatic value of starch. Boiled with weak sulphuric acid,
potato starch is changed into glucose, fermented into alcohol, to yield
"British Brandy." Ripe potato juice is excellent for cleaning cottons, silks,
and woolens. Root and leaf diffusates of growing potato plants possess
cardiotonic activity. Dried ethanol extracts of above-ground parts show marked
hypotensive and myotropic action and a spasmolytic and soothing effect on
intestinal musculature. Ethanol extracts of leaves have antifungal properties,
active against Phytophthora infestans. Leaves, seeds, and tuber
extracts show antimicrobial activity against Gram-positive and Gram-negative
bacteria. US per capita consumption of processed products increased from ca 1
kg in 1940 to ca 10 kg in 1956. Potato chips accounted for 42% of processed
products produced in America during 1964; frozen products, 36%; followed by
dehydrated potatoes, 16%; canned potatoes, 2%; and miscellaneous other
products, 4%. About 30% of the total potato crop was utilized by the American
processing industry during 1964 (C.S.I.R., 19481976).
Reported to be alterative, aperient, bactericide, calmative, diuretic, emetic,
lactagogue, potato is a folk remedy for burns, corns, cough, cystitis, fistula,
prostatitis, scurvy, spasms, tumors, and warts (Duke and Wain, 1981; Hartwell,
19671971). The mealy flour of baked potato is oiled and applied to frostbite
(Grieve, 1931). The tea, made from the peels of the tuber, is said to be a
folk remedy for tumors. The boiled tuber is said to alleviate corns. The
powdered tuber, with copper sulfate, is said to help callused fistulas.
Europeans tie raw potatoes behind the ears for delirium (Duke, 1984b).
Per 100 g, the tubers contain 7682 calories, 77.779.8 g H2O, 1.72.8 g
protein, 0.10.2 g fat, 17.118.9 g total carbohydrate, 0.40.6 g fiber,
0.91.6 g ash, 713 mg Ca, 5053 mg P, 0.61.1 mg Fe, 37 mg Na, 396407 mg K,
traces to 25 mg b-carotene equivalent, 0.70.11 mg thiamine, 0.030.04 mg
riboflavin, 1.31.6 mg niacin, and 1821 mg ascorbic acid (Duke and Atchley,
1984). Mineral elements present are (mg/100 g): Mg, 20; Na, 11.0; K,
247; Cu, 0.21; S, 37.0; and Cl, 16.0; small quantities of iodine (11 ug/kg) Mn
and Zn are also present. Potato is among the richest foods in potassium,
poorest in sodium. The more important sugars are sucrose, glucose, and
fructose; some galactose, melibiose, raffinose, stachyose, planteose,
myoinositol, maltotriose, manninotriose, galactinol, trigalactosyl glycerol,
digalactosyl glycerol, glucosyl myoinositol, ribosyl-glucose, xylosyl-glucose,
arabinosyl-glucose. Non-starch polysaccharides include hemicellulose,
cellulose, and pectic substances. The pectin content varies from 1.8 to 3.3
percent. The pectic substance consists of anhydrogalacturonic acid (51%) and
polysaccharides (49%), composed of rhamnose (6%), fucose (0.6%), arabinose
(5.6%), xylose (1.8%), and galactose (86%). The amino acid composition
follows: arginine, 6.0; histidine 2.2; lysine, 7.7; tryptophan, 1.6;
phenylalanine, 6.6; cystine, 2.1; methionine, 2.3; threonine, 5.9; and valine,
6.1%. The protein is somewhat deficient in sulphur amino acids and probably
also histidine. It is rich in lysine. Potato contains also g-aminobutyric
acid, a-aminobutryic acid, b-alanine, and methionine sulphoxide. Other
nitrogen compounds include: glutathione, choline, acetyl choline, trigonelline,
cadaverine, adenine, hypoxanthine, and allantoin. Potato contains a phenolase,
also called phenol oxidase, polyphenol oxidase, catecholase, and tyrosinase,
which oxidizes phenols. The vitamins present in potato are per 100 g edible
material; vitamin A, 40 IU; thiamine, 0.1 mg; riboflavin, 0.01 mg; nicotinic
acid, 1.2 mg; vitamin C, 17 mg; and choline, 100 mg. A small quantity of folic
acid (total, 7.4 mg/100 g; free acid, 3.0 mg/100 g) is also present. Linoleic
acid is the predominant (41.3% of the total) acid in potato fat; other acids
present are: palmitic, 24.9; linolenic, 19.4; oleic, 6.4; stearic, 5.4; and
myristic, 0.6%; two unidentified acids, and a few hydroxylated fatty acids are
also reported to be present. Cholesterol, sigmasterol, and b-sitosterol are
present in the unsaponifiable fraction. Organic acids present in the tuber
(excluding ascorbic acid, amino acids, and fatty acids) are: tactic, succinic,
oxalic, malic, tartaric, hydroxymalonic, citric, isocitric, aconitic,
a-ketoglutaric, phytic, caffeic, quinic, and chlorogenic acids. Citric
acid is present also in the stems and leaves. Tannins are localized in the
suberized tissue of potato and are also present in leaves (c. 3.2%). Potato
seeds contain 2 flavonol glycosides, kaempferol-3-diglucoside-7-rhamnoside and
the kaempferol-3-triglucoside-7-rhamnoside. The flavonols, myricetin and
quercitin are also present. Volatiles from cooked potatoes include: hydrogen
sulphide, acetaldehyde, methanethiol, acrolein, acetone, ethanethiol,
dimethylsulphide, iso- and n-butyraldehyde, isovaleraldehyde,
methylisopropylketone, etc. Fresh potato tops are said to serve as feed for
cattle and sheep. Analysis gave (dry-matter basis): total N, 1.822.30; EE,
3.064.65; CF, 15.3623.67; NFE, 40.4650.51; and ash, 15.9722.28 (C.S.I.R.,
Although the foliage is considered poisonous, some African tribes used the tip
as a potherb, while others, like Mauritians extract the.green parts as a
narcotic. Solanine is one toxic ingredient in the green tuber and sprouts.
The "green fruit has caused fatalities"..."potato with a green discoloration as
a result of exposure to the sun, contains solanine and has been known to cause
fatal poisonings." (Watt and Breyer-Brandwijk, 1962). There are records of
severe solanine poisoning in 60 persons in Cyprus, with one death, from eating
green potato shoots collected about the time of flowering and boiled ca 1/2
hour before eating. The shoots contained ca 2749 mg solanine per 100 g.
Animals fed large residues of raw or cooked potato or "distiller's slop"
develop a disorder known as potato eruption. Symptoms in mild intoxications
include a slight rise in temperature, anorexy, constipation, stiff gait,
salivation, lacrymation, all preceding a vesicular inflammation on the lower
part of the limbs (Watt and Bryer-Brandwijk, 1962). Persons harvesting,
handling, or peeling potatoes may develop allergy or urticaria (Mitchell and
Rook, 1979). Sir Walter Raleigh is said to be the first to plant the potato,
near Cork, UK, but knowing little about it, he ate the berries. Discovering
their narcotic nature, he ordered his plants uprooted (Grieve, 1931).
Erect or clambering succulent herb to more than 1 m tall, the stems sometimes
quadrangular or even winged, with tuberiferous stalens just at or below the
soil surface. Leaves alternate, imparipinnate, short-stalked, 1030 cm long,
515 cm wide, the leaflets opposite or alternate, very unequal in size and
shape, the larger often petiolulate, ovate to ovate-oblong, enequilateral,
apically acuminate to acute, basally subcordate, 210 cm long, 16 cm wide, the
smaller more blunt apically, more cordate basally, broadly ovate to orbicular,
215 mm in diameter, thinly to densely pubescent. Flowers white or blue,
pedunculate in lateral, many flowered cymes, the hairy peduncle 515 cm long,
the jointed hairy pedicels 335 mm long. Calyx campanulate, 5-lobate, 1.52 cm
in diameter, the lobes acute or acuminate. Corolla twice as long as calyx,
3.54 cm in diameter. Anthers free, erect, poricidal, yellow. Fruit a globose
2-celled berry, many-seeded, yellowish green (Ochse, 1931; Vilmorin-Andrieux,
Reported from the South American, and secondarily, the Middle American and
Eurosiberian Centers of Diversity, potato, or cvs thereof, is reported to
tolerate aluminum, bacteria, fungi, hydrogen fluoride, high pH, laterites, low
pH, nematodes, photoperiod, slope, SO2, ultraviolet, viruses, and weeds, potato
sometimes becoming a weed itself in potato fields. Vilmorin-Andrieux (1885)
depicts 28 cvs in a rather extensive discussion of some of the older
"varieties", some of them long gone. Smith (1981) states that more than 100
varieties are grown in the US, with the leading ones, in acreage, being Russet
Burbank, Norchip, Kennebec, Katahdin, and Superior. In Peru clones are being
tested to derive from their wide genetic diversity the ability to adapt to
extreme temperature conditions. Crossing genetically diverse parents,
previously selected for adaptation, might yield heterozygosity to maximize the
performance of the hybrids. Mendoza (1977) reports a screening of 6000 clones
for germplasm adapted to high temperatures and humidity. Hybrids of
tuberosum x neotuberosum and tuberosum x phureja
showed promise given the short growing season and the stress imposed not only
by the weather but also by weeds, insects, and diseases. Many Andean peasants
plant small insurance crops of wild-type potatoes, of poor quality, but good
frost resistance. Potato breeders are charged to combine frost resistance with
quality and yield potential of Solanum tuberosum. Solanum demissum
Lindl. and S. commersonii Dunal ex Poir. are among the frost-resistant
species. Richardson and Weiser (1972) list S. acaule Bitter, S.
chromatophilum, S. commersonii Dunal ex Poir., S. X
juzepczukii Bukas., and S. multidissectum Hawkes as highly
resistant; S. ajanhuiri Fozepczuk and Bukasov, S. X
curtilobum Juz. and Buk., S. demissum Lindl., S.
megistacrolobum Bitter, S. microdontum Bitter, and S. vernei
Bitter and Wittm. as very resistant. S. acaule has been reported to
tolerate -3 to -9°C. S. brevicaule Bitt. x S. phureja Juz.
and Buk. hybrids have survived -4 to -9°C. Frost resistance, like heat
resistance, of potatoes can be improved. Solanum megistacrolobum Bitter
is an effective donor of frost tolerance. Among tolerances reported are
'Dakota Chief', 'Fillmore', 'Rili', and 'Viking' tolerant to drought;
'Belchip', to fluctuating temperatures; 'Sebago', to frost; 'Alpha', 'Arka',
and 'Up-to-Date', to hail; 'Superior' and 'Virgil', to heat; 'Kasota' and
'Yampa', to heavy soil; 'Cherokee' and 'Osage', to muck; 'York', to organic
soils; 'Mesaba' and 'Waseca', to peat; 'Atlantic', 'Red Lasoda', and 'Red
Pontiac', to photoperiod; 'Yampa', to sand; and 'Osseo', to short season.
Cultivars differ in Al tolerance (Duke, 1982a). The potato, a tetraploid
species, arose in the Andes. Various species have been postulated as the
diploid progenitor, e.g. one source has proposed S. stenotomum
introgressed with S. sparsipilum, while another source has proposed
S. vernei as one parent. S. stenotomum and S. vernei are
similar to S. tuberosum spp. andigena in their cytoplasmic
factors and either could have given rise to it with minor (if any) cytoplasmic
changes. Results of a study of variation in Fraction 1 protein were consistent
with an origin of spp. andigena from chromosome doubling of S.
stenotomum and did not support an involvement of S. sparsipilum;
S. vernei was not included in the study. Solanum tuberosum spp.
andigena was introduced to Europe in the 16th Century and persisted
there until late blight struck in the middle of the 19th Century. It is
suggested that catostrophic selection among the survivors of the blight gave
rise to Solanum tuberosum ssp. tuberosum. Experimental evidence
shows that ssp. tuberosum-like plants can be produced through selection
from ssp. andigena. Heiser (1979) notes Grun proposed that, at the time
of the late blight, ssp. tuberosum was imported to Europe from islands
off the coast of Chile. Heiser also notes in their study of cytoplasmic
factors, Grun et al found that plants of ssp. tuberosum from the
northern hemisphere and coastal Chile shared all or nearly all of the same
plasmon sensitivities, whereas they differed from ssp. andigena in eight
of the nine plasmon sensitivities tested. Thus ssp. tuberosum, now
cultivated in the northern hemisphere, may be derived directly from Chile
rather than through the transformation of ssp. andigena (Heiser, 1979).
(2n = 24, 36, 48)
Originally from Latin America, probably Andean, the potato is now grown in
probably all temperate countries and in tropical uplands. Germplasm
improvement is gradually pushing the potato into the lowland tropics, but it
can scarcely compete with the tropical root crops.
Ranging from Boreal Moist to Wet through Tropical Very Dry to Wet Forest Life
Zones, potato is reported to tolerate annual precipitation of 0.9 to 41.0 dm
(mean of 145 cases = 9.3), annual temperature of 3.6 to 27.8°C (mean of 145
cases 12.9), and pH of 4.2 to 8.2 (mean of 122 cases = 6.2) (Duke, 1978; Smith,
1981). Potatoes are a cool weather crop, the optimal temperature for growth
being 1520°C for most cvs. Growth of tubers is best at soil temperature of
1720°C, with usually no tubers formed above 32°C. They perform well on
a wide variety of soils, sandy loams, silt loams, loams, and peats. Soil
moisture tensions between 40 and 60 centibars seem to produce the best yields.
In the temperate zone, potatoes are usually planted in early spring, the "seed"
tubers being spaced 40120 cm apart. Entire tubers or large slices thereof are
planted "eyes" up, and covered with 1020 cm of well pulverized soil. Since
the potato is highly heterozygous, seedlings, exhibiting wide variability,
rarely come true. Hence, potatoes are vegetatively propagated by so-called
seed potatoes, ca 45 cm in diameter. These are cut up so that each portion
contains 1 or 2 eyes. Sprouting buds, especially if sprouted in sunlight, may
be planted. Freshly harvested potatoes, on the other hand, being dormant,
cannot be planted immediately. Dormancy can be broken by gassing with carbon
bisulphide, or soaking in 1.53% ethylene chlorohydrin. Xanthine and
gibberellic acid are also reported to break dormancy. Cut pieces of
non-dormant seed tubers may yield as well as whole tubers where they are not
subject to rot. Disinfecting the cutting knife and treatment of the cut seed
with Dithane M-45 (1 kg in 450 liters water) is advised in India (C.S.I.R.,
19481976). Timing, to avoid excess cold or drought during sprouting periods,
the "seeds" may be sown in furrows 710 cm deep and then covered, level or
ridged. Or ridge can be made and tubers inserted. Seed rates may be as high
as 23.5 MT/ha. Rows are spaced at 4050 cm, or 60 cm in mechanized fields.
Sprouts usually emerge in 23 weeks, with emergence complete or nearly so after
a month, depending on the maturity of the eye, the cv, and the weather.
According to the Wealth of India, where barnyard and green manures are
prevalent "Organic manures are no substitute for chemical fertilizers supplying
nitrogen, phosphorus, and potassium." An N-deficiency is suggested by stunted
plants with short internodes and pale green foliage. Phosphate deficiency
reduces plant growth and internodal length, resulting in dull green leaves. A
K-deficiency does not reduce growth and vigor in early stages, but the leaves
may be bluish green with marginal scorching, eventually bronzing or yellowing.
Smith (1981), in the US, suggests N-fertilization at ca 160260 kg/ha, P2O5 at
110410, and K2O at 110325 kg/ha. When stems are 1520 cm, potatoes may be
simultaneously weeded and earth up, making small hills, which at once tends to
keep the tubers from greening up (tubers that form near the surface and receive
sunlight may green, an undesirable condition) and fosters their growth closer
to the main axis. Some organic gardeners in the US plant potato seed on top of
composted leaves, then covering the seed potatoes with more compost. This may
completely eliminate the weed problem. Potatoes, frequently considered
exhausting to the soil, are often planted in rotation with such things as
barley, corn, peas, or wheat, or intercropped, with the intercrop in the bottom
or edge of the furrows, the potatoes in the ridge. In India, intercrops of
castor, sugarcane, and wheat may individually have their yields lowered though
the aggregate yield may be favorably improved. Where the golden nematode
prevails, long rotations are recommended, with potatoes only every 3 or 4
years. Early potatoes take 80100 days to mature, medium 100120, and late
more than 120.
Potatoes are usually dug shortly after maturing, when the haulms have yellowed
and died back naturally. In home gardens, potatoes are carefully dug by hand,
while the large mechanized farms in the US usually defoliate chemically. After
lifting, potatoes should be stored to dry and cure in a cool shady place. Seed
potatoes and table stock potatoes keep best near 40°C, while potatoes for
processing are stored at 713°C.
The 1979 world low production yield figure for potatoes was 2,000 kg/ha in
Swaziland, the international production yield figure was 15,503 kg/ha, and the
world high production yield figure was 37,772 kg/ha in the Netherlands (FAO,
1980a). In India, yields average between 7,500 kg to 9,000 kg, with some
states averaging closer to 3,000, others closer to 20,000 kg/ha, with maximum
at 35,000 (C.S.I.R., 19481976). The Wealth of India compares yields for 5
years in 25 countries, West Germany being highest in 1968 with 29 MT/ha,
Bolivia and Peru, near, if not, the centers of origin, being lowest with 5.5
and 6.3 MT respectively, cf 24 MT for the US. These are production figures,
India coming out with 8.4 MT/ha. Indian yields are doubled with appropriate
fertilization from 9 to 16 MT/ha in the Rabi, and from 17 to 36 in the Kharif
(Krishnappa et al, 1980). On Cuban ferralitic soils, tuber yields of 17 cvs
from Europe ranged from 1337 MT/ha (Estevez, 1981). Dibb (1983) compares US
yields of 26,600 kg/ha with 9,100 kg/ha in the developing countries, and a
reported world record of 94,200. Potatoes are grown commercially in every
continent, with 70% of the world's production grown in Eastern Europe and
Russia. Although the US produces only ca 4% of world production, it is
nonetheless an important crop in the US, ranking as the eighth most important
crop; 80% of production occurs in nine states, Idaho, Washington, Maine,
Oregon, North Dakota, California, Wisconsin, Minnesota, and New York. The
total marketed value of potatoes in the US varies between $1.2 to 1.5 billion
annually. Prices received by the farmer averaged between $3.01 and $4.89 per
quintal between 1972 and 1977 (Smith, 1981).
According to the phytomass files (Duke, 1981b), annual productivity is 4 MT/ha
in Bavaria. According to one source, the residue potential is calculated by
multiplying tuber production by 0.2. Processing wastes at factories or at
home, where peels are removed, are calculated by multiplying production by 0.1
to 0.2. Rotten potatoes and the 33 1/3% waste in the potato chip industry can
be converted to butanol with a greater energy content than ethanol. Twenty
percent butanol can be added to regular gas and up to 40% to diesel as
extenders without engine modification (Duke, 1984a). Potato wastes are taken
to be 3/17ths of tuber weight, while the moisture content of the haulms (not
normally gathered) is figured at 77.5% (Palz and Chartier, 1980). Near Twin
Falls, Henry Schutte is tooling up to convert 80,000 tons of cull potatoes a
year into alcohol. Schutte's Western Resource Recovery is building a $20
million plant with a theoretical capacity of 5 million gallons of alcohol per
year and hopes to convert cull potatoes to alcohol at $1.20 per gallon. The
corporation plans to feed its stillage (the material remaining after
distillation) to cattle and use the cattle manure to generate methane to power
its alcohol stills. At the University of Idaho, Gary Kleinschmidt is checking
out potato cvs that may produce more than twice as much as most cvs. These
high yielders have distorted tubers or hollow hearts, but that should not
matter for alcohol production (McGill, 1981). Germans developed the energetic
"Fuselol" from potato alcohol (Watt and Breyer-Brandwijk, 1962). Energy
output/input ratios vary from 0.83 in Idaho with yields of 26.7 MT/ha to 1.64
in California with yields of 36.7 MT/ha. Discounting 62 hours labor, the
energy inputs are roughly in decreasing importance; diesel 3,700,000 kcals,
nitrogen 3,000,000, seeds 1,700,000, herbicides 1,200,000, transportation
800,000, gasoline 770,000, phosphorus 640,000, electricity 610,000,
insecticides 365,000, L.P. gas 325,000, machinery 250,000, potassium 165,000,
and irrigation 135,000, totalling nearly 14 million kcals per ha for the yield
of 36,736 kg/ha (622 kg protein) with an energetic equivalent of ca 22,500,000
kcals. In Australia, Stewart et al (1979) estimated that potatoes would give
104 liters ethanol per ton of production at a raw material cost of $1.06 per
liter compared to 117 liters at $1.11 per liter for grapes, 67 liters at $2.86
per liter for apples, 57 liters at $1.93 per liter for pears, 55 liters at
$3.46 per liter for peaches, 40 liters at $7.53 per liter for apricots, 59
laters at $4.15 per liter for plums, 69 liters at $10.65 per liter for
cherries, 96 liters at $3.04 per liter for bananas, and 71 liters at $1.76 per
liter for pineapple (when cereal grains for alcohol were worth only $0.20 to
$0.23 per liter, and gasoline was retailing for $0.15 to $0.19 per liter).
Comparing crops and conifers, Jarvis (1981) concludes, "the actual annual rate
of production of the tree crops and the majority of the agricultural crops are
very similar." Citing other scientists conclusions that potential production of
C3 crops would be 54 MT/ha/yr for a year round crop (of whatever) and would be
36 for 6 months in the Netherlands, Jarvis tabulates the average yields of DM
production and the maximal rates for temperate climates as shown below:
| ||British |
|Abies sachaliensis || -- || 29 ||0.65|
|Avena sativa || 3.0 ||-- ||--|
|Beta vulgaris ||8.0 ||42 || 0.45|
|Brassica oleracea 'calabrese' || -- ||12 ||0.17|
|Brassica rapa ||4.6 || -- ||--|
|Cryptomeria japonica ||-- || 53 ||0.65|
|Glycine max || -- || 10 ||0.30|
|Hordeum vulgare ||4.7 ||18 ||0.39|
|Larix kaempferi ||3.1 ||8* ||--|
|Lolium perenne ||-- ||26 ||0.85|
|Picea abies ||3.4 ||22 ||0.61|
|Picea sitchensis || 3.5 ||9* || --|
|Pinus contorta ||2.4 ||6* || --|
|Pinus nigra ||3.9 ||25 ||0.46|
|Pinus radiata ||-- ||46 ||0.66|
|Pinus sylvestris ||2.4 ||7* ||--|
|Pseudotsuga menziesii ||-- ||28 ||0.71|
|Solanum tuberosum ||5.3 ||22 ||0.82|
|Thuja plicata ||-- ||20 ||0.68|
|Tsuga heterophylla ||-- ||43 ||0.65|
|Triticum aestivum ||4.7 ||30 ||0.40|
|Vicia faba ||-- ||20 ||0.31|
High rates of 3545 MT aboveground DM have been reported for some conifers
outside Britain, but Jarvis apparently accepts Ovington's (1962) conclusion
that the maximum net rate of current annual production of coniferous forest in
western Europe might be 22 MT/ha (17 MT stems alone) with a maximum mean net of
15 MT/ha/yr (12 MT stems alone) over the life of the crop. With an assumption
that one MT DM is energetically equivalent to 2.5 barrels oil, one can
speculate on the relative importance of these conifers and crops in an energy
Smith (1981) estimates loss from potato pathogens at 19%, or 2.7 million metric
tons, annually in the US. Virus diseases include leaf roll, rugose mosaic,
mild mosaic, and latent mosaic. Late blight, early blight, common scab,
Verticillium wilt, and Rhizoctonia are prevalent fungus diseases. Bacterial
diseases such as blackleg, ring rot, and bacterial soft rot are also common.
Disease control measures include (1) use of resistant cvs; (2) use of certified
seed; (3) roguing of diseased plants; (4) crop rotation; and (5) use of
pesticides. Fungi and bacteria include Alternaria solani, Armillaria
mellea, Ascochyta lycopersici, Aspergillus niger, Bacillus megatherium, B.
mesentericus, Bacterium polymorphum, Botrytis cinerea, Cercospora concors, C.
solani, Clonostachys araucariae var. rosea, Colletotrichum
atramentarium, Corynebacterium sepedonicum, Cuscuta arvensis, Cylindrocarpon
magnusianum, C. radicicola, Erwinia aroideae, E. phytophthora, Erysiphe
cichoracearum, Fusarium spp., Gliocladium sp., Gloeosporium
sp., Hypomyces ipomoeae, Macrophomina phaseoli, Mycosphaerella solani,
Nectria brassicae, Neocosmospora vasinfecta, Oidium sp., Oospora
pustulans, Papulaspora coprophila, Pellicularia filamentosa, Penicillium
sp., Phoma dulcamarina, P. eupyrena, P. solanicola, P. tuberosa, Phomopsis
tuberivora, Phymatotrichum omnivorum, Phytophthora drechsleri, P.
erythroseptica, P. infestans, P. parasitica, Pseudomonas solanacearum, Pythium
aphanidermatum, P. arrhenomanes, P. debaryanum, P. rostratum, P. ultimum,
Ramularia solani, Rhizoctonia crocorum, R. solani, Rhizopus stolonifer,
Scierotinia sp., S. minor, S. sclerotiorum, Sclerotium rolfsii,
Septomyxa affinis, Spondylocladium atrovirens, Spongospora subterranea,
Streptomyces scabies, Stysanus stemonitis, Synchytrium endobioticum,
Trichothecium roseum, Verticillium albo-atrum, V. cinnabarium, Xylaria
apiculata (Ag. Handbook No. 165, 1960). The many nematodes that attack
potatoes include: Ditylenchus destructor, Globodera pallida, G.
rostochiensis, Meloidogyne spp., Pratylenchus penetrans, and P.
pratensis. In the US, potatoes are injured by more than 100 species of
insects, especially the Colorado potato beetle. It and the flea beetle reduce
yields by feeding on the foliage. The potato aphid attacks the foliage and
also spreads several viral diseases. Potato leaf hoppers cause a destructive
disease-like condition known as hopperburn by sucking juices from the plants.
The tubers are attacked by wireworms, often rendering the potatoes unsuitable
for sale. General pest control is afforded by applications of insecticides to
the foliage or soil (Smith, 1981). Chemicals are important in weed control and
harvesting. Weeds and annual grasses are controlled by cultivation and by
preemergence and/or post-emergence soil application of weedicides such as
premerge, linuron, maloran, eptam, dalapon, paraquat, and metribuzin. Various
dusts and sprays, including dinoseb, endothall, ametryn, and paraquat, are used
to kill the potato vines before harvest. The vines are killed to hasten
setting of the potato skin in order to reduce harvesting damage and to
facilitate the use of harvesting machinery (Smith, 1981).
Complete list of references for Duke, Handbook of Energy Crops
- Agriculture Handbook 165. 1960. Index of plant diseases in the United States.
- C.S.I.R. (Council of Scientific and Industrial Research). 19481976. The wealth
of India. 11 vols. New Delhi.
- Dibb, D.W. 1983. Agronomic systems to feed the next generation. Crops and Soils
- Duke, J.A. 1978. The quest for tolerant germplasm. p. 161. In: ASA Special
Symposium 32, Crop tolerance to suboptimal land conditions. Am. Soc. Agron.
- Duke, J.A. 1981b. The gene revolution. Paper 1. p. 89150. In: Office of
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