Abo El-Abbas,et al
EVALUATION OF COMMERICAL POTATO CULTIVARS
TO EARLY BLIGHT INFECTION IN EGYPT
[8]
Abo El-Abbas, F. M.(1); Afifi, M. A.(2); El-Miniawi, S. M. H. (1)
and Rashed, M. S .S.(3)
1) Faculty of Agriculture, Ain Shams University,Cairo,Egypt. 2) Plant
Pathology Research Institute, Agriculture Research Center. 3) Institute of
Environmental Studies and Research, Ain Shams University,Cairo,Egypt.
ABSTRACT
Potato early blight, caused by Alternaria solani plays an important
role in potato health and can limit tuber yield and quality. Control of this
disease depends primarily on using potato resistant cultivars. This
investigation was carried out to evaluate ten commercial varieties of potato
namely, Draga, Diamont, Picasso, Nicola, Flora, Hermez, Spounta, Lady
Rosetta, Lady Clear and Lady Olumpia for susceptibility to infection by
early blight, under both greenhouse and field conditions. Results indicated
that all tested cultivars were susceptible and differed in their reaction to early
blight pathogen A. solani. The highest susceptible varieties were Lady Rosita,
L. Clear and L. Olumpia. However, Spounta, Hermez, Flora and Nicola, were
moderately susceptible.
Keywords: potato cultivars, early blight disease, Alternaria solani,
susceptibility, resistance.
INTRODUCTION
Potatoes are one of the most popular vegetable crops in Egypt for both
local consumption and exportation. In recent years, the European commission
(EU) has accounted for about 70–90% of Egyptian potato export. Potato is
Vol.20, No.2, june. 2010
41
J. Environ. Sci.
Institute of Environmental Studies and Research – AinShamsUniversity
attacked by several plant pathogens causing serious diseases during the
growing season; such diseases caused about 19% crop losses (Holley et al.,
1984). Early blight caused by Alternaria solani (Ellis & Mart.) Jones and
Grout poses a significant risk to crop productivity in the field and to tuber
quality in storage. This disease can occur over a wide range of climatic
conditions and can be very destructive, sometimes resulting in complete
defoliation of plants. Values in the literature for measured crop losses due to
early blight vary enormously from 5–78% (Waals et al. 2004). In Egypt, early
blight was found in all potato production areas and is a major disease in hot
climate regions (El-Far, 2006). Moreover, the ultimate control of such disease
is by using fungicides and cultivation of resistant varieties (Abd El Rahman,
1977; Ismail, 1987; Lima et al., 1996; Khan, et al., 2001; Raj and Kang, 2003
and Rodriguez et al., 2006). The objective of this study was to screen some
potato cultivars against A. solani, under both greenhouse and field conditions,
as the basic component of suggested integrated pest management (IPM)
program to manage potato early blight disease successfully with optimized
usage of fungicide applications to avoid the human hazards and
environmental pollution.
MATERIALS AND METHODS
Isolation of Alternaria solani
An isolate of Alternaria solani was obtained from infected leaves and
stems samples of potato. Plant samples were thoroughly washed with tap
water, cut into pieces and surface sterilized by immersing in a 0.3 % sodium
42
Vol.20, No.2, june. 2010
Abo El-Abbas,et al
hypochlorite solution for one minute, then passed through three changes of
sterilized water and dried with sterilized filter papers. Samples were
aseptically transferred to sterilized Petri dishes containing potato dextrose
agar PDA and incubated at 27oc for 7 days. The growing fungus was hyphal
tipped and transferred to PDA slants.
(Keitt, 1915 and Brown, 1924).
Identification of obtained isolate was kindly done by the Mycology
Department, Plant Pathology Research Institute, ARC, Giza.
The obtained isolate was considered as highly aggressive and causing a
severe early blight disease on potato plants, following pathogenesity tests
under greenhouse experiments.
Evaluation of potato cultivar for resistance to early blight
The susceptibility of ten most commercial varieties of potato namely,
Draga, Diamont, Picasso, Nicola, Flora, Hermez, Spounta, Lady Rosetta,
Lady Clear and Lady Olumpia (kindly obtained from Vegetable Research
Department, Horticulture Research Institute, ARC, Egypt) were evaluated for
susceptibility to early blight disease under greenhouse and field conditions.
A- Greenhouse Trials:
Potato tubers for each cultivar were sown in sterilized plastic pots (50
cm, diameter) contained mixture of sandy soil and peat moss (3:1 v/v); with 4
tubers per each pot. Four replicate pots were used for each treatment.
Inoculum's suspension of Alternaria solani as spores and hyphal mixture was
sprayed on potato plants, 40 days after tuber planting, with the aid of an
atomizer. At the same time, one group was sprayed with sterilized water to
serve as control. Other 4 pots cultivated with each cultivar were kept without
Vol.20, No.2, june. 2010
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J. Environ. Sci.
Institute of Environmental Studies and Research – AinShamsUniversity
inoculation to serve as check. Plants were inoculated with A. solani (1x105
spores and hyphal fragments/ml) after 20 days from sowing. The inoculated
plants were covered with plastic bags for 24 hours in order to maintain high
relative humidity (Reda et al., 1985) Disease severity was recorded after 15,
30 and 45 days from inoculation as described below.
B- Field Trials:
A field experiment was carried out during Nili season 2006 in El-Kherba
region, Housh-Essa center, El-Behira governorate. This region had a history
of severe early blight infection the experiment was designed as randomized
complete blocks and the area of each plot was12 m2 (3.0 x 4.0 m), and four
replicates were used for each potato cultivar and non-treated plots (sprayed
with water only) served as control. Recommended cultural practices
according to Extension Department of Ministry of Agriculture and Land
Reclamation.
Under natural infection conditions, disease severity was determined after
15, 30 and 45 days from appearance of symptoms.
Assessment of disease severity
The severity of early blight disease infection was calculated using an
improved grading system for measuring plant disease described by Horsfall
and Barratt, (1945) and Basu, (1974). Ten plant leaves were selected
randomly for each particular treatment and were classified to score on 12
point rating scale, representing a percent of surface infected area. The rating
scale and corresponding percentage intervals are show in Table (1).
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Vol.20, No.2, june. 2010
Abo El-Abbas,et al
Disease index percentage was calculated according to the following formula:
Σ (nxr1) – (nxr4)
Disease index (%) = ------------------------- Х 100
4N
n = Number of infected leaves.
r1 – r4 = category number.
N = Total examined leaves.
Table (1): Assessment scheme for necrotic or chlorotic leaf areas of single
leaf after which is based on a semi-logarithm with 50 % infection
as midpoint.
Rating Score
0
1
2
3
4
5
Intervals%
0
0 to >3
3 to >6
6 to >12
12 to >25
25 to >50
Rating Score
6
7
8
9
10
11
Intervals%
50 to >75
75 to >88
88 to >94
94 to >97
97 to >100
100
RESULTS
Ten potato cultivars were tested for their susceptibility to infection with
Alternaria solani under greenhouse and open field conditions. The first
symptoms of early blight appeared on the highly susceptible cultivar was
appeared through 7-10 days from infection.
Data in Table (2) show that, all tested potato cultivars, under greenhouse
conditions, were infected with early blight but the susceptibility of these
cultivars was different. Also, disease severity on all cultivars was recorded at
Vol.20, No.2, june. 2010
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J. Environ. Sci.
Institute of Environmental Studies and Research – AinShamsUniversity
three intervals, and the severity was increased progressively. So total mean of
first record was 22.5 %, second record was 35.6 % and total mean of third
record was 50.4 %.The tested cultivars were arranged descondignly due to
their susceptibility as the following: Lady Rosita, L. Clear and L. Olumpia as
highly susceptible cultivars where mean of disease severity were 65.6 %, 55.6
% and 49.3 % respectively. While, cultivars Spounta, Hermez, Flora and
Nicola, were moderately susceptible cultivars and the mean percentage of
disease severity were 42.9 %, 38.6 %, 34.0 % and 29.6 % respectively.
However, the least susceptible varieties were Picasso, Diamont and Draga,
where the mean percentage of disease severity were 24.5 %, 21.2 % and 16.1
% respectively.
Table (2): Response of some commercial potato cultivars to early blight
infection by isolated Alternaria solani isolate, under greenhouse
conditions
Cultivars
Draga
Diamont
Picasso
Nicola
Flora
Hermez
spounta
Lady Olumpia
Lady Clear
Lady Rosita
Mean
46
Disease Severity%
Days after infection
(15days)
(30days)
(45 days)
8.9
14.3
25.1
10.6
20.2
33.0
12.8
23..3
37.6
15.9
28.4
44.7
19.5
33.6
49.1
23.6
37.8
54.4
28.7
42.3
57.9
33.3
49.1
65.7
37.5
56.8
72.5
44.9
66.6
85.3
22.5
35.6
50.4
Vol.20, No.2, june. 2010
Mean
16.1
21.2
24.5
29.6
34.0
38.6
42.9
49.3
55.6
65.6
36.1
Abo El-Abbas,et al
F=3.399
C.V=39.29%
F0.05=2.50
F0.01=3.45
LSD0.05=34.5
LSD0.01=30.66
D.ata presented in Table (3) Show the reaction of different potato
cultivars exposed to natural infection in the field, with the pathogen
Alternaria solani in El-Kherba village, Housh-Essa center, El-Beheira
governorate, during Nili season 2006. Data revealed that cultivars Leady
Rosetta, L. Clear and L. Olumpia were recorded as highly susceptibile to A.
solani; and the mean percentage of disease severity were 56.2 %, 51.5 % and
47.2 % respectively. While cultivars Spounta, Hermez, and Flora were
moderately susceptible, and the percentage of disease severity were 36.6 %,
34.4 % and 28.2 % respectively. The least susceptibility to early blight was
recorded with cultivars Nicola, Picasso, Diamont and Draga; with the mean
percentage of disease severity 24.1 %, 17.8 %, 12.7 % and 10.0 %
respectively.
Vol.20, No.2, june. 2010
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J. Environ. Sci.
Institute of Environmental Studies and Research – AinShamsUniversity
Table (3): Response of different commercial potato cultivars to early blight
disease under open field conditions in Housh-Essa center at Nili
season, 2006.
Cultivars
Draga
Diamont
Ppicasso
Nicola
Flora
Hermez
Spounta
Lady olumpia
Lady clear
Lady Rosita
Mean
Disease Severity%
Days after appearance of natural infection
(15 days)
(30days)
(45 days)
3.5
10.9
15.8
5.4
13.0
19.7
9.1
18.6
25.9
12.6
23.2
36.5
14.1
28.3
42.4
18.8
34.9
49.6
21.5
36.1
52.4
29.3
49.8
62.5
34.6
52.7
67.3
37.3
56.5
74.9
17.7
30.9
42.6
F=4.137
F0.05=2.50
F0.01=3.45
C.V=43%
LSD0.05=31.87
LSD0.01=28.32
Mean
10.0
12.7
17.8
24.1
28.2
34.4
36.6
47.2
51.5
56.2
30.4
DISCUSSION
Early blight is considered one of the most distructive diseases of potato
plants world-wide and poses a real threat to potato growers in Egypt. Control
of such disease relies mainly on using resistant potato cultivars and
application of fungicides (Abd-El-Rahman, 1977; Patel et al, 2004 and
Mustafee et al., 2007). Ten commercial cultivars of potato were screened to
evaluate their reaction against A. solani, the causal pathogen of early blight
disease. Data obtained clearly indicate that all these varities were susceptible
to the disease, although, they differed in their reaction against the aggressive
48
Vol.20, No.2, june. 2010
Abo El-Abbas,et al
A. solani isolate from El-Beheira Governorate. The ten potato cultivars were
arranged descendingly according to their susceptibility as: Lady Rosita, L.
clear, L. Olumpia, Spounta, Hermez, Flora, Nicola, Picasso, Diamont and
Draga, respectively. The variability of varietal reaction among potato
cultivars may be attributed to the tuber age plant growth stage, cultivar and
locality (Kuczynska 1992) and breeding program (Gonzalez et al.1998). We
conclude that potato varieties are varying in their reaction to early blight
disease was previously proved by various investigators (Abd El Rahman
1977: Holley et al. 1984: Ismail 1987: Lima et al 1996: Khan et al. 2001: Raj
and kang 2003: El-Far 2006 and Rodriguez et al, 2006).The results obtained
in present study may be help potato growers to use the least susceptible
cultivars in areas with high disease pressure or to integrate cultivar resistance
with minimum fungicides applications or doses to achieve high level of
disease control.
REFERENCES
Abd El-Rahman, M. (1977): Evaluation of the interaction between cultivars
of potatoes and different fungicides and programs of application
on early blight control. Plant Disease Reporter 61:473-476.
Basu, P. K. (1974): Measuring early blight, its progress and influence on fruit
losses in nine tomato cultivars. Canadian Plant Disease Survey 54:
45-51
Brown, W. (1924): Two mycelial methods of isolating single strains of fungi
by cutting out a hypheal tip. Annual Botany,38:402-404.
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J. Environ. Sci.
Institute of Environmental Studies and Research – AinShamsUniversity
El-Far, E.M.M. (2006): Studies on Early Blight Disease of Potato in Egypt.
Ph.D. Thesis, Faculty of Agriculture, Suez Canal Univ.,
Egypt.157pp.
Gonzalez, M. E.; A. Estevez; Castillo, & E. Ortiz (1998): Screening potato
germplasm and parent selection for breeding. Cultivos Tropicales
19:41-44.
Holley, J. D.; R. Hall & G. Hofstra (1984): Identification of rate reducing
resistance to early blight in potato .Canadian Journal of Plant
Pathology 5:111-114.
Horsfall, J.G., & Barratt, R.W. (1945): An improved grading system for
measuring plant diseases. Phytopathology 35:655.
Ismail, M. (1987): Evaluation of some potato varieties and clones for field
resistance to early blight .Pakistan Journal of Agriculture Research
8:356-358.
Keitt, G.W. (1915): Single technique for isolating single spore strains of
certain types of fungi. Phytopathology, 5: 266- 269.
Khan, M. A.; Abdul Hafeez & Khalid Farooq.(2001):.Screening of potato
varieties/lines against early blight disease caused by Alternaria
solani (Ellis & Mart) Jones & Grout. Pakistan Journal of
Phytopathology. 13(2): 124-126.
Kuczynska, J. (1992): The role and importance of the fungi from the genus
Alternaria in early blight elicitation or potato leaves and tubers.
Biuletyn Instytutu Ziemniaka, 41:57-72.
Lima , M.F.; J.A., Buso. & A.C., Torres (1996): Reaction in vitro of potato
plant lets to Alternaria solani. Fito Patologia Brisileira 21:13-18.
Mustafee, T.P.; A. Devnath & A. Chowdhury (2007): Efficacy of
dimethomorph and dithianon against blight diseases of potato.
Journal of Mycopathological-Research. 45(1):85-89.
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Patel , H. R.; A. M. Shekh; J. G. Patel; A. Mishra; G. B. Valand ; G. C. Patel
; R. N. Pandey & D. S. Mistry (2004): Early blight management
and its effects on tuber yield of two potato cultivars under varied
environmental condition. Journal of Agrometeorology. India,
6(2):229-233.
Raj, K. & G. S. Kang (2003): Genetic analysis of early blight (Alternaria
solani) resistance in potato (Solanum tuberosum L.). Advances in
Horticultural Science. 17(4):192-195.
Reda, F. M.; O. Mousa; J. S. Mansour & S. L. Nawar ( 1985): Response of
tomato cultivars to infection with Alternaria solani in relation to
growth and chemical composition of their fruits. Egypt Journal of
Phytopathology 17:83-93.
Rodriguez, M.A.D.; S.H. Brommonschenkel; K. Matsuoka & E.S.G.
Mizubuti (2006): Components of resistance to early blight in four
potato cultivars: effect of leaf position
.Journal of
Phytopathology. 154(4):230-235.
Waals, J.E.; L. Korsten. & B. Slippers (2004): Genetic diversity among Alternaria solani
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Vol.20, No.2, june. 2010
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‫‪J. Environ. Sci.‬‬
‫‪Institute of Environmental Studies and Research – AinShamsUniversity‬‬
‫تقييم األصناف التجارية للبطاطس لإلصابة بالندوة المبكرة في مصر‬
‫[‪]8‬‬
‫فوزى مرسي أبو العباس(‪ -)1‬صالح الدين محمود حسن المنياوى(‪ -)1‬محسن عبد الرزاق عفيفي‬
‫(‪)3‬‬
‫محمد سمير سالم راشد‬
‫‪ )1‬كليةةالزرا زع‪،‬ةةا لجامعةةال‪،‬ةةمسل ةةم ‪.‬ل‪)2‬لمعهةةألرم ةعزنلزر‪ ،‬ةةاز لمعكةةالزر اةةة‪.‬لزراعز‪،‬يةةا‪.‬ل‪)3‬لمعهةةأل‬
‫زرأعزسازلةزر اة‪.‬لزربمئيا لجامعال‪،‬مسل م ‪ .‬ل‬
‫(‪)2‬‬
‫المستخلص‬
‫تعتبع لزر طاط لةزاأة لمس لركثع لمااصمل لزرخضع لفى لمصع لرهميا لرالستهالك لزرمالىل‬
‫ةزرتصأمعل‪،‬لىلاألسةزءلةتهاجملزر طاط لخالللفتعةلاعز‪،‬تهال كثمعلمسلزرمسب ازلزرمعضيالزرتىلتؤثعل‬
‫ارسلبل‪،‬لىلزراارالزر‪ ،‬اتيا لةمسلثمل‪،‬لىلزال‪،‬تاجيالزرماصةريا لةتهأفلهذهلزرأعزسالإرىلتقميمل عنل‬
‫رص‪،‬افلزر طاط لةمأىلقابلمتهالرالصا ال معنلزر‪،‬أةةلزرم كعة لزرمتسببل‪،‬سلزرفطعل ‪Alternaria‬‬
‫‪ solani‬لتملزخت اعل‪ ،‬عةلرص‪،‬افل طاط لفى لكالً لمس لزرصة الةزراقللةةجألرسلرقللزألص‪،‬افلقابليال‬
‫رإلصا ا لهة لص‪،‬ف لأعزجا لةرس لركثعهم لقابليا لرإلصا ا لهة لص‪،‬ف لزرلمأى لعةايتا ل لةتأتى لزألص‪،‬افل‬
‫زرأزيمة‪،‬ز لةزربيكاسة لةزر‪،‬يقةال لةزرفلة زع لةزرهمعما لثم لزالسبة‪،‬تا لةزرلمأى لزةريمبيا لةزرلمأى لكلممع لكأص‪،‬افل‬
‫متةسطالزرقابليالرإلصا ا لفىلزرصة اللةزراقل لةفىل‪،‬هايالزرمطافلالبألرسل‪ ،‬معلرسلاعز‪،‬الزألص‪،‬افل‬
‫زألقل لقابليا لرإلصا ا لتعتبع لراأ لطعق لزرمقاةما لزآلم‪،‬ا لبمئياً لألمعزن لزر طاط لرخفن لزالستهالكل‬
‫زرازئأ لمس لزرمبمأزز لزرفطعيا لةالبأ لمس لزالهتمام لبتلك لزرأعزساز لرتج‪،‬ب لزرمخاطع لزربمئيال‬
‫ةزر عيا‪ .......................................................................‬ل‬
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