0034-7744 0034-7744 S0034-77442000000100001 Nigeria 00 03 2000 00 03 2000 48 1 01 05

Frequency and pathogenicity of fusarium wilts (Fusarium solani and
Fusarium equiseti) of cotton (Gossypium hirsutum) in Adamawa in Nigeria

I. B.Chimbekujwo. 1

Received 2-VII-1998. Corrected 19-VIII-1999. Accepted 27-VIII-1999.
Abstract

Cotton fungi were surveyed in Ngurore, Adamawa, Nigeria in 1992 and 1993 by counting the number of isolates in each 100 infested plants per plot. Approximately 90% of the isolated fungi were Fusariumsolani and Fusarium equiseti, both pathogenic; F. solani isolates were more virulent and frequent than F. equiseti. The high frequency and virulence of both fungi make them important pathogens of cotton in the area.

 

Key words

Cotton, Fungi, Fusarium, Gossypium, ecology.

]]> Upland cotton (Gossypium. hirsutum L.) is an important cash crop and food in the world (Prentice 1972). Seedling disease in cotton is a worldwide problem, particularly the wilt and root rot disease causing loss to farmers (Hillocks 1992). The most common fungi associated with cotton disease are Fusarium spp., Colletotrichum gossippi, Rhizopus spp., Thielavispsisbasicola and Pythium (King and Presley 1942; Roy and Bourland 1982; Johnson et al. 1978, Mauk and Hine 1988 and Hillocks 1992).
 
The studies of Fusarium wilt of cotton are well advanced in some regions of the world, but are still limited elsewhere. Fusarium wilt of cotton was first isolated as a root rot pathogen of cotton plant (Woodroof 1927, Colyer 1988); delay boll formation (Sparnicht and Roncadoni 1972); The seeds and seedling diseases have been reported by Simpson et al. (1973), Watkins (1981), Roy and Bourland (1982), Klich (1986), Kerbabaeva Frolovi (1986) and Sharma and Sandhu (1986), Katan and Katan (1988), Melero-vara 1990 Mousa et al. (1990), and Pizzinatto et al, (1991), Soleymani et al. (1993), Asssigbetse et al. (1994). Nelson et al. (1981), Minton and Garber (1983) and Hillocks (1992). Fusarium wilt is blamed on failure of the infected xylem to meet the water requirements of the plant (Hillocks 1992).
Similar reports on wilt and seedling rots in Nigeria caused by Fusarium spp. exist (Adeoti 1990, Adeoti et al. 1992).
Although Fusarium is known to be associated with seedling disease of cotton, species have not been defined for cotton grown in Ngurore area of Adamawa Sate.The results presented in this paper were from the survey carried out to determine the incidence and severity of seedling disease and to identify the causative fungi.

Materials and Methods
 
Disease survey: Systematic disease surveys were conducted in the cotton growing plots between May and July 1992 and 1993. The number of isolates in each 100 infested plants from two plots were counted and expressed in percent (%).
 

Isolation and identification: Seedlings of GH 216 with wilting were sampled. The soil around the wilted plants (rhizosphere) was also collected. Roots were washed with distilled water and cutt into 5-10 mm long sections with a sterilized sharp blade. The pieces were surface disinfected for two minutes in 0.1% sodium hypochlorite and rinsed in several changes of distilled water before plating on potato dextrose agar (PDA) containing 0.2% streptomycin and incubated at 30C. Fungi grown from the root pieces were subcultured.
]]> Single spore isolates were obtained by using the technique of Manandhar et al (1995). Petri dish containing fungi were flooded with distilled water and serial dilution was made. Five ml of suspension (100 spores/ml) were added to water agar (2gm of agar in 100ml) and marked out using a grid drawn on the base of each Petri dish. The plate was incubated for 12 hours and single spores were subcultured onto fresh PDA. The two isolates were identified to the genus level using a microscope. The microscopic characteristics, and cultural characteristics were compared to the description in Booth, 1971. Also pure slants of two representative but different organisms were prepared and sent to international mycological institute (IMI) for confirmation.
 
Pathogenicity test: The method of  Katan (1981) was used for the pathogenicity test. The watered pots were maintained on a bench at 30°C ± 2 and kept under constant observation. Wilting seedlings were removed and the fungi were re-isolated and compared to the one isolated from the field.
Cultural characteristics of the two isolates: The growth characteristics of the two isolates on PDA was observed from day 2 after inoculation. In each isolate, four plates were set up. The observation was on aerial mycelium, the colour of substratum, texture, zonation until the isolate covered the plate.
Conidial measurements: The microconidial and macroconidial were obtained by flooding 7-day old culture of each isolate with distilled water. A slide of spores was prepared and observed under light microscope with Coumasie blue as stain using eye piece and objective lenses fixed with graduated granular slides. The two slides were adjusted so that the line on the eye piece was on the objective lens. The length of the micro- and macroconidial were measured by dividing the length of the eye piece by 2 and multiplying the result by 0.01 to give millimeter (100 x 0.01 = 1mm because each unit of 100 on the granular slide is 0.01). The result was converted to micrometer (µm) by being multiplied by 1000.
Radial growth: The linear mycelium measurement was carried out by cutting a disk of organism on PDA from the outer margin of a 7 day old culture using 6mm cork borer. The disk was placed upside down on solidified 2% agar at the intersection on the transepts drawn at the bottom of 9cm plates (Vakalounakis, 1996). Linear measurements were made every 24 hours with a ruler and the growth per day was obtained from the total diameter by dividing by 2. The experiment was terminated when the plates had been completely covered by the growing organisms.

Results

Two fungi isolated were identified to be F. solani (Mart.) Sacc. Teleomorph; Nectria haematococcca and F. equiseti (Corda)Sacc. The two fungal isolates were confirmed by IMI to be the same organisms with the number IMI 368692 and IMI 368693 respectively.
 

Results of the survey are presented in tables 1 to 5. Table 1 shows the frequency in (%) of F. solani and F. equiseti; Tables 2, 4 and 5 compare the growth characteristics, dry weight and radial growth of the two fungi; and Table 3 states the conodial characteristics of Fusarium isolates.
]]>


TABLE 1
Prevalence of cotton seedling wilts given in terms of Fusarium isolates (%)
 

Year
1992
1993
Plot N°
3
5
 ]]> 3
5
F. solani
60
70
55
65
F. equiseti
30
25
40
30
Others ]]> 10
5
5
5

 

TABLE 2
Growth characteristics of the two isolates on PDA in five days at 30°C ± 1.


]]>
Day
 
F. solani
F. equiseti
2
 Mycelia white. Back of plate yellowish pigments. Mycelia cottony white. Back plate white.
 3 
 Mycelia spread very fast. Spores produced. Yellow pigmentation increased. Zonation. Hyphae branched and septate Mycelia grew slowly.
Macrospores produced. Violet pigments. Zonation. Hyphae septate
4
 
 Three zonations. Pigmentation increased. Sparse mycelia. Woolly mycelium. Pink colour increased.
]]> 5
  		Zones increased. Mycelia scanty and withered. Colour pale. Back yellowish. Radial growth. Zonation not clear. Mycelia yellowish.

 

TABLE 3
The conidial characteristics of Fusarium isolates.


 
 ]]> Microconidia
Macroconidia
 
Length (µm)
Presence
Length (µm)
Septation
Presence
 
F. solani
 ]]> 6.4 ± 0.282
Abundance
2.2 ± 0.141
2-5
Few
 
F. equiseti
2.4 ± 0.070
Few
2.6 ± 0.340
 ]]> 3-5
Abundance

 

 

TABLE 4
The dry weight (g)of mycelia and pH of the two fungi for 30 days incubation grown
in a liquid medium of potato dextrose at 25°C ± 1.


]]>
 

 
Weight (g)
Weight (g)
Day
 
F. solani
F. equiseti
3
 ]]> 0.332 ± 0.008
0.249 ± 0.011
6
0.421 ± 0.047
0.379 ± 0.096
9
0.671 ± 0.041
0.633 ± 0.131
12
0.755 ± 0.100
 ]]> 0.761 ± 0.233
15
0.645 ± 0.026
0.801 ± 0.013

 

Discussion

The role of Fusarium spp. as a pathogen of cotton seedlings, and other crops is well known. But Johnson and Doyle (1986) reported that Fusarium spp. were not important pathogens in cotton seedling disease complex, even though Fusarium spp. were the most frequently isolated fungi. The species involved were not identified by them.
 

The observed symptoms of this disease on the affected seedlings in Adamawa Nigeria (Table 2) are similar to those earlier reported from other countries (Melero-vara 1990, Colyer 1988, Schrender et al. 1995).
In this study, F.solani and F. equiseti approximated 60% and 30% of all fungi isolated from diseased seedlings. These values agree with that reported by Pizzinatto and Menten (1991). Colyer (1988) reported that Fusarium solani was more frequent and virulent than Fusarium equiseti. The high virulence of these species to cotton agree with the works of Johnson et al (1977), Klich (1986), Sharma and Sandhu (1986), Mousa et al. (1990) and Solymani et al.(1993). ]]>  
 


 
 

The observed morphological and cultural characteristics of F. solani and F. equiseti was the same as that reported by Booth (1971) and Joffe (1986), except that the growth rate differed. The growth rates of F. solani and F. equiseti were 3.2cm and 5.8cm, while the average growth rates observed were 1.3cm and 0.3cm for the two fungi, respectively. The differences in the growth rates may be due to the growth medium and the incubation condition.
 

The differences observed in pathogenicity and virulence between this study and others may have resulted from differing pathogenicity testing conditions used. The high level of virulence and frequency of isolation indicate Fusarium spp. as an important cause in the etiology of cotton seedling disease in Adamawa area of Nigeria.
]]> References

Abbas, H.K., T Tanako & S. O.Duke. 1995. Pathogenicity of Alternariaalternata and Fusarium moniliforme and pathogenicity of AA1-toxin and Fumonism B1 tomato cultivars. J. Phytopathol. 143: 329-334.         [ Links ]
 

Adeoti, A.A., A. M. Emechebe, M. D.Alegbejo & M.A.T. Posdroal. 1992. Cropping scheme meeting: Report on fibre research programme, Institute research for Agricultural Samaru, Ahmadu Bello University, Zaria, Nigeria. 59-62p.
        [ Links ]
Adeoti, A.A. 1990. Cropping scheme meeting: Report on fibre research programme, Institute for. Agricultural Research Samaru, Ahamadu Bello University, Zaria, Nigeria. Pg. 40-44, 68-69.
        [ Links ]Assigbetse, K.B., D.Fernandez, M.P. Dubois & J Geiger. 1994. Differentiation of Fusarium oxsysporum f. sp. vasinfectum races on cotton by random amplified polymorphic DNA (RAPD) analysis. Phytopathology 84: 622 - 626.         [ Links ]

Ben-Yephet, Y. M. Reuven & A. Genizi. 1994. Effects of inoculum depth and density on Fusarium wilt in carnations. Phytopathology 84: 1393-1398.         [ Links ]

Bollenbacker, K. & N.D. Fulton. 1970. Disease susceptibility of cotton seedling from artificially deteriorated seeds. Pl. Dis. Rep. 59: 222-227.         [ Links ]

Booth, C.1971. The genus Fusarium. CAB, CMI. England.46-49, 157-159p         [ Links ]

Colyer, P.D. 1988. Frequency and pathogenicity of Fusarium spp. associated with seeding diseases of cotton in Louisiana. Pl. Dis. 72: 400-402.         [ Links ]

Dunlap, A.A. 1941. A convient soil culture method for obtaining sclerotia of the cotton root rot fungus. Amer. J. Bot. 28: 945-947.         [ Links ]

Haware, M.P. & Y.L. Nene. 1982. Races of Fusarium oxysporum f.sp. cerci. Pl. Dis. 66: 809-810.         [ Links ]
 

Hillocks, R.J. 1992. Cotton diseases. CAB. International, Wallingford, United Kingdom.1-38, 127-160p.
        [ Links ]
Joffe A.Z. 1986. Fusarium species: Their biology and toxicology. John Willey, New York.
        [ Links ]
Johnson, L.F. D.D. Baird, A.Y. Chambers & N.B. Shamiyeh. 1978. Fungi associated with postemergence seedling disease of cotton in the soils. Phytopathology 68: 917-920.
        [ Links ]Johnson, .L.F. & J.H. Doyle. 1983. Relationships of seeding disease of cotton to characteristics of loessial soil in Tennesse. Phytopathology 76:86-290         [ Links ]

Kappelman A.J.JR. 1975. Fusarium wilt resistance in cotton (Gossypiumhirsutum). Pl. Dis. Rep. 59: 803-805.         [ Links ]

Kappelman A.J.JR. 1982. Resistance to Fusarium wilt pathogen in currently used cultivars. Pl. Dis. 66: 837-839.         [ Links ]

Katan, J. 1971. Symptomless carriers of the tomato Fusarium wilt Pathogens Phytopathology 61: 1213-1217.         [ Links ]

Katan, T. & J. Katan. 1988. Vegetative-compatibility grouping of, Fusariumoxysporum f.sp.  vasinfectum from tissues and the rhizosphere of cotton plants. Phytopathology 78: 852- 855.         [ Links ]

Kerbabaeva A.A. & I.P. Frolov. 1986. Fungi of the genus Fusarium isolated from cotton of Tashauz Oblast Turkmen-SSR USSR: IZV Akad Nauk. Turkm SSR SER BIOL NAUK. 6: 60-61

King, C.J. & C Presley. 1942. A root rot of cotton caused by Thielopviopsisbasicola. Phytopathology 32: 752-761.         [ Links ]

Klich M. 1986. Mycoflora of cotton seed from the southern USA a three year study of distribution and frequency. Mycology 78: 706-712         [ Links ]

Lekwa, G. & E.K. Nto. 1982. Cotton soil of Nigeria and their management-proceeding of the first National symposium on cotton production, Samaru-Zaria. Pg. 120-130.         [ Links ]

Manandhar, J.B., G.L. Hartman & T. C. Wang. 1995. Conidial germination and appressorial  formation of Collectotrichum capsici and C. gloeosporioides isolates from pepper. Pl.  Dis. 79:361-366.         [ Links ]

Mauk, P.A. & R.B. Hine. 1988. Infection, colonization of Gossypiumhirsutum and G.  barbadense and development of black root rot caused by Thielaviopsis basicola.  Phytopathology 78: 1662-1667.         [ Links ]

Melero-Vara J.M. & R.M. Jimenez-diaz. 1990. Etiology incidence and distribution of cotton seedling damping-off in southern Spain. Pl. Dis. 74: 597-600         [ Links ]

Minton, B.F. & R.H. Garber. 1983. Controlling the seedling disease complex of cotton. Pl. Dis.  67: 115-118.         [ Links ]

Mousa E.M., A.A. Gaafar & El-Shennawy 1990. The influence of root-knot nematode on  damping-off and wilt fungi of cotton. Nematology 36: 373         [ Links ]

Nelson, P.E., T.A. Toussoun & R.J. Cook. 1981. Fusarium : Disease, Biology and Taxonomy.  Pennsylvania state University, United State of America 29-38p.         [ Links ]

Parkinson, D., T.R.G. Gray. & S.T. Williams. 1971. Methods for studying the ecology of soil  microbiology organisms. 1-16p.         [ Links ]

Pizzinatto M.A. & J. O.M. Menten. 1991. Pathogenicity of eight Fusarium spp isolated from  seeds to cotton seedlings. Sum. Phytopathology 17: 124-134         [ Links ]

Prentice, A.N. 1972. Cotton: with special reference to Africa. Pub. Ltd. London.. 1-20p.         [ Links ]

Ray, W.W. & E. Mclaughline. 1942. Isolation and infection tests with seed and soil borne cotton pathogens. Phytopathology 32:233-238.         [ Links ]

Roy, K.W. & F.M Bourland. 1982. Epidemiological and relationships in cotton seedling disease in Mississippi, Phytopathology 72:868-872.         [ Links ]

Scherger, A.C. & D.J Mitchell. 1993. Influence of mucilage secreted by macroconidia of, Fusarium solani f.sp. phaseoli on spore attachment to roots of vigna radiata in hydroponics nutrient solution. Phytopathology 83: 1162 -1170.         [ Links ]

Sharma Y.R. & B.S. Sandhu. 1986. A new fungus associated with boll rot of arboreum cotton. Cur. Sci. (Bangal).54: 937         [ Links ]

Simpson, M.E., P.B. Marshi, G.V. Merola. R.J. Ferretti. & E.C. Filsinger. 1973. Fungi that infect cotton seeds before harvest. Appl. Microbiol. 26: 608-613.         [ Links ]

Soleymani, M.J., G.A. Hedjaroude. & J. Zad. 1993. Survey on mycoflora of cotton seed in Iran. Iran. J. of Pl. Pathol. 29: 55-56         [ Links ]

Soleymani, M.J., G.A. Hedjaroude. & J. Zad. 1993. Studies on pathogenicity of some seedborn Fusarium species on cotton seedling. Iran. J.of Pl. Pathol. 29:19-20.         [ Links ]

Sparnicht, R.H. & R.W. Roncardori. 1972. Fusarium boll rot of cotton: pathogenicity and histopathology. Phytopathology 62: 1381-1386.         [ Links ]

Watkins, G.M. 1981. Compendium of cotton disease. Pub. By the American Phytopathology society. 1-87p.         [ Links ]

Weindling, R., P.R. Miller. & A.J. Uiistrup. 1941. Fungi associated with disease of cotton seedlings and bolls, with special consideration of Glomerellagosypii. Phytopathology 31: 158-167.         [ Links ]

Woodroof, N.C. 1927. A disease of roots produced by, Fusarium moniliforme sheld. Phytopathology 17: 227-238.         [ Links ]
 

1 Department of  Biological Sciences, Federal University of Technology, Yola.
Adamawa State. Nigeria.
]]> 1995 143 329-334 1992 59-62 1990 40-44, 68-69 1994 . 84: 622 - 626. 1994 . 84: 1393-1398. 1970 . 59: 222-227. 1971 . 46-49, 157-159 1988 . 72: 400-402. 1941 . 28: 945-947. 1982 . 66: 809-810. 1992 . 1-38, 127-160 1986 . 1978 . 68: 917-920. 1983 . 76: 86-290 1975 . 59: 803-805. 1982 . 66: 837-839. 1971 61: 1213-1217. 1988 78: 852- 855. 1986 6: 60-61 1942 32: 752-761 1986 78: 706-712 1982 120-130 1995 79 361-366 1988 78 1662-1667 1990 74 597-600 1983 67 115-118 1990 36 373 1981 29-38 1971 1-16 1991 17 124-134 1972 1-20 1942 32 233-238 1982 72 868-872 1993 83 1162 -1170 1986 54 937 1973 26 608-613 1993 29 55-56 1993 29 19-20 1972 62 1381-1386 1981 1-87 1941 31 158-167 1927 17 227-238