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Fusarium species of the Liseola section associated with stalk and ear rot of maize in Southern Italy, and their ability to produce moniliformin
[ 215 ] Tra ns. B r. my col. S oc. 90 (2), 215-21 9 ( 1988)
Prim ed in Great Britain
FUSARIUM SPECIES OF THE LISEOLA SECTION ASSOCIATED WITH STALK AND EAR ROT OF MAIZE IN SOUTHERN ITALY, AND THEIR ABILITY TO PRODUCE MONILIFORMIN By A. LOGRIECO AND A. BOTTALICO Istituto tossine e micotossine da para ssiti vegetali del Consiglio Nazionale delle Ricerche, V ia G. Amendola 197/ F, 7 0126 Bari, Italy Fu sarium species of the Liseola section, isolated from infected maize (stalks, seeds ), and from soil after a maize crop in southern Italy, were identified as belonging to F. moniliforme and F . proliferatum . F. moniliform e was isolated more frequently from stalks and seeds than from soil, while F. proliferatum was mainly present in soil. Moniliformin (up to 1520 mg kg:") was produced by only some isolate s of F. proliferatum from seeds and soil.
According to the nomenclature of Booth (1971), both Fusarium moniliforme Sheldon and Fu sarium moniliforme var . subglutinans Wollenw. & Reink. have often been associated with stalk and ear rot of maize (Kommedahl & Windel s, 1981 ; Marie, 1981). Attempts to identify the Fusar ium isolates of the Lis eola section associated with fusar iosis in southern Ital y have led to th e recogn ition, together with F . moniliforme, of another morphologic group of isolates showing characteristics rather different from those reported for F . moniliform e var . subglutinans (Bottalico, Visconti & Solfr izzo, 1984). ' In recent taxonomic investigations of Fusarium species within the Lis eola section increasing importance has been placed on phial ide morphology and microcon idial arrangement, as well as ph ysiological Table
* Table
1.
characteristics . Such criteria have necessitated the recognition of other species (Burgess & Liddell, 1983; Nelson, T ou ssoun & Marasas, 1983) and /or varieties (Gerlach & Nirenberg, 1982; Kuhlman, 1982). This encouraged us to reinvestigate th e taxonomic featu res of the isolates from southern Italy, and to assay th eir capability to produce moniliformin. The production of this toxin by Fusarium isolates of the Liseola section is not universal (Bottalico et al., 1982; Rabie et al ., 1982 ; Marasas et al ., 1986 ). MATERIALS A ND METHODS
Samples were taken in 1984 from three different maize fields in Basilicata (south ern Ital y) wh ich
Per centage of maiz e sta lks inf ected with Fusarium species of the Liseola section
Field
N o. of hybrids examined
1
13
2
11
3
10
Percentage of stalk s infected *
Fusarium spp .
F. moniliform e
F . proliferatum
83'8 97'2 96 '0
47'6 78' 1 58'5
33'6 3'6
11'5
T en stalk cores, sampled in August after anthesis, were examined for each hybrid.
2.
Percentag e of maiz e seeds infected with Fusarium species of the Liseola section
FAO maturity class
N o. of samples examined
Fusarium spp.
F. monilif orme
F . proliferatum
200-300 400-500 600-700
15 19 19
4'1 21·8 5° '3
3'3 20'9 4 8'1
0'4 0'9 1'9
Percentage of seeds infected -
* On e hundred seeds were examined for each sample.
Fusarium spp. of the Liseola section
216
Table 3. Presence of Fu sarium species of the Li seola section in ma iz e fiel d soil, f rom th ree sites, in fo ur months Number of Fusarium colonies* Site -
Fusarium spp. F . moniliforme F . prolifer atum
-
Site
1
- -- -- - - -- -- -
April
May
June
38
42
40
4
16
Jul y 32
Site 3
2
- ----- -
Apr il
May
June
July
Apr il
M ay
Ju ne
Jul y
T otal
70 2 16
50 12 28
30 2 6
4
34
42
16
20
418 16 66
2
4
* Colonies grown on 10 agar-PCNB plate s, each inoculated with 1 ml 1 : 1000 diluted solution from 3 g of soil.
were planted with ten hybrids belonging to two different classes of FAD maturity (60<>-700 and 40<>-5 0 0 ) . In August, after anthesis, ten stalk cores (7 nun diam) were taken for each hybrid per field from the lowest internode of green stalks, using a tool similar to that described by Kommedahl et al, ( 1979) . The cores were brought to the labora tor y in small plastic bags , shaken in 1 % NaOCI for 30 s, placed on pentachloronitrobenzene (PCN B)-peptone-agar medium (N ash & Snyder, 1962), and incubated for 7 d at 23-25 "C . Fifty-three commercial seed samples of different hybrids, belonging to three FAD maturity classes, were examined (T able 2). One hundred seeds per sample were left for 12 h under running water, then surface treated with 0'5 % NaOCI for 1 min, cut in halves, and placed on PCNB medium for 5-7 d.
Three gram soil samples, obtained by combining three randomly selected samples (3- 15 em deep ), were collected for four months (April, May, June and July) from three different fields where maize was previously grown. Each soil sample was passed through a 2 mm sieve, then successively diluted with water to give a final dilution of 1 : 1000. Aliquots of one ml of final soil dilutions, mixed in a shaker for 30 s, were pipetted into Petri dishes ( 10 dishes per treatment) to which 15 ml of cool PCNB medium were added. Identification Fusarium colonies on PCNB medium were
subsequently transferred to potato-saccharoseagar med ium (P SA), and incubated for 7 d at about 24° under fluorescent lamps for 12 h d- 1 • Singlespore cultures of Fusarium species of the Liseola section were then obtained on PSA plates, and finally they were identified in accordance with the nomenclature of Nelson et al. (1983). Observations were made also using water-agar with sterile soil, or with sterile rice seed, or with sterile carnation leaf (Nelson et al., 1983 ), or using KCI media
prepared by adding 2, 4, 6 or 8 g of KCI to a litre of 1'5 % water-agar (Fisher et al., 1983). Moniliformin analysis
Moniliformin production on autoclaved seeds and analysis of the toxin in dried colonies were carried out using methods described in a previous report (Bottalico et al., 1982). Forty-three isolates of F . monil iform e from stalks (20) , seeds (22) and soil (1), and thirty-three isolates of F . proliferatum from stalks ( 18), seeds (8) and soil (7) were tested for moniliformin production. RESUL TS
On the basis of phialide morphology and microconidial arrangement, the Fusarium isolates of the Liseola section from maize stalks, seeds, and field soil were divided into two groups. One group was characterized by microconidia always borne in chains on monophialides (Figs 1-2), while the other group showed microconidia borne both in false heads and in chains , usually on polyphialides but sometimes also on monophialides (Figs 3-8). According to Nelson et al, (1983) they were identified as F . moniliforme Sheldon and F . proliferatum (Matsushima) Nirenberg, respectively. Some isolates of F . pro liferatum with clavate microconidia also produced some pyriform microconidia, but only on rice seeds and never on wateragar, or on other nutrient-poor media. As reported by Nelson et al. ( 1983), this characteristic was not constant, and the percentage of pyriform microconidia was usually very low (0'5- 1 %). On water-agar, the isolates of F . proliferatum generally produced many false heads and short chains, but the abundance and length of the chains was increased by decreasing th e water potential of the medium, and longer microconidial chains were formed on medium with 4 g I- I KCI. Isolates of F . proliferatum also produced thickened hyphae and conidia on different media. F. moniliforme was isolated more frequently than
A. Logrieco and A. Bottalico
6 r
J, ~
.
...
217
7 ~:
.,
•
~
r
.
-v.
'--- •
y
,
J
Figs 1-2. Fusarium moniliforme, simple phial ides bearing microconidia in chains (x 400). Figs 3-10. Fusarium proliferatum, phialides and polyphialides bearing microconidia in false heads and chains, x 100, Fig. 3; x 250, Figs 4-5; x 400, Figs 6-8; water-agar medium cultures without KCI (Fig. 9) or with 4 g I-I KCI (Fig. 10) and longer chains of microconidia (x 100). 9
MYC 90
Fusarium spp. of the Liseola section
218
Table 4. Production of moniliformin by Fu sarium species of the Liseola section isolated from maize in southern Italy* Fusarium isolates']
F. moniliforme
F. proliferatum
*
t
Sou rce Stalk Seed Soil Stalk Seed Soil
No . of isolates tested
N o . of toxin producing isolates
Amount of moniliformin produced (m g kg" )
3 3
221-1520 467-1213
20 22 1
18 8 7
Isolates were grown on autoclaved corn kernels at 25-2 7 °C for 3 weeks . Identified according to Nelson et al . ( 1983 ).
F. proliferatum, both from stalks from each of the three fields (T able 1) and from seeds of different FAO maturity classes (T able 2). In contrast, from soils the ratio was reversed, and F. moniliforme was not found at all in two fields (Table 3). None of the forty-three isolates of F . moniliform e from soil, seeds or stalks was able to produce moniliformin. This toxin was produced by 6 out of 33 isolates of F. proliferatum (up to 1520 mg of toxin per kg of dried colony). All the toxinproducing isolates were obtained from soil or seeds. Isolates from stalks failed to produce moniliformin (T able 4).
1979 ; Allen et al., 1981 ; Rabie et al ., 1982 ; Marasas et al., 1986). Such conflicting data may be related to the geographical or igin of the isolates, as well as to the use of different systems of naming isolates. The ability of F. proliferatum to produce moniliformin appears to be restricted to some isolates, and it is not clear why all isolates from stalks were negative . Marasas et al . (1986) found all strains of F. proliferatum were able to produce moniliformin, but they analysed onl y a few isolates from maize and did not specify their origin. It appears that further studies are necessary to assess the relationship between source and toxigenicity for isolates of th is species.
DISCUSSION
The authors are grateful to Mr V. Ricci and to Mr M. Solfrizzo for their competent technical assistance.
It appears that in southern Italy maize represents an important host for both F. moniliforme Sheldon and F. proliferatum (M atsushima) Nirenberg. However, F . moniliforme is more widely distributed in vegetative parts, while F . proliferatum is more frequently present in soil , and the thickened hyphae formed by F. proliferatum could represent soil survival structures. Some sim ilar taxonomic characteristic could lead to confusion of F. proliferatum with F. subglutinans (Wollenw. & Reink.) Nelson, Toussoun & Marasas, the latter being characterized by microconidia always borne in false heads on polyphialides. As a result of this investigation, we support Fisher et al. (19 83) , who recommend the use of KCI (4 g 1-1) in a wateragar medium for the improved identification of Fusarium species belonging to the section Liseola . Isolates of F. proliferatum, but not of F. moniliforme, were able to synthesize moniliformin . The negative results concerning F . moniliforme are in accordance with our previou s report (Bottalico et al., 1982) and those of others (K riek et al ., 1977; DeLucca et al., 1982; Thiel, Meyer & Marasas, 1982), but there are also reports of positive results (Cole et al., 1973; Burmeister, Ciegler & Vesonder,
REFERENCES ALLEN, N. K., BURMEISTER, H. R ., WEAVER, G. A. & MIROCHA, C. J. (1981). T oxicity of dietary and intravenously administered moniliformin to broiler chickens. Poultry Sc ience 60, 1415-141 7. BOOTH, C . (1971). Th e genu s Fusarium. Commonwealth M ycolog ical Institute, Kew. BOTTALlCO, A ., VISCONTI , A. & SOLFRIZZO, M . (1982). Production of moniliformin by Fusarium species, in Italy. Phytopathologia mediterranea 21 , 105-106. BURGESS, L. W . & LIDDELL, C . M . (1983). Lab oratory Manual f or Fusarium Research . Department of Plant Pathology and Agricultural Entomology, University of Sydney. BURMEISTER, H. R., CIEGLER, A . & VESONDER, R. F . (1979). Moniliformin, a metabolite of Fusarium monilif orme NRRL 6322 : purification and toxicity . Applied and Environmental M icrobiology 37, 11-13 · COLE, R. J., KIRKSEY, J. W ., CUTLER, H. G., DOUPNIK, B. L. & PECKHAM, J. C. (1973). Toxin from Fusarium moniliforme : effects on plants and animals. Sc ience 179,
1324-13 26. DELUCCA, A.
J., DUNN, J. J., CIEGLER,
A . & KUHLMAN,
A . Logrieco and A . Bottalico E . G. ( 1982). The inability of Fusarium species extracts to induce dieback in pines . M y copathologia 79,105-108. FISHER, N . L., MARASAS, W. F . O. & TOUSSOUN, T . A. (1983). Taxonomic importanc e of microconid ia I cha ins in Fusarium sectio n Liseola and effect s of water potential on their form ation . My cologia 75, 693-{)98. GERLACH, W . & NIRENBERG, H. (1982). T he Genus Fusarium - a Pictorial Atlas. M itteilunge aus der Biologischen Bundesanstalt fur Land- und Forstwirtschaft. Berlin : Dahlem. K OMMEDAHL, T ., WINDELS, C. E . & STUCKER, R. E. (1979) . Occurrence of Fusarium spe cies in root s and stalks of sym ptomless corn plants during the growing season . Phy topath ology 69, 961-<)66. KOMMEDAHL, T . & W INDELS, C. E . (1981). Root , sta lk and ear infecting Fusarium species on corn in th e U SA. In Fusarium : Diseases, Biology and Taxonomy (ed. P . E . N elson , T. A. T ou ssoun & R. J. Cook), pp . 94-103. Univer sit y Park : Penn sylvani a St ate Univer sit y Press. KRIEK, N . P . J., MARASAS, W. F. 0 ., STEYN, P . S., VAN RENSBURG, S. J. & STEYN, M . (1977). Toxicity of a moniliformin-producing strain of Fusarium moniliform e var. subglutinans isolated from maize. Food Cosmetics Toxicology 15, 579-587. KUHLMAN, E. G . (1982). Var ieti es of Gibberella fu j ikuroi with anamorphs in Fusarium section L iseola. My cologia 74, 759-768.
(R eceived f or publication
2]
J uly
219
MARASAS, W. F . 0 ., THIEL, P. G ., RABIE, C. J., NELSON, P . E. & T OUSSOUN, T . A. (1986) . M on iliformin produ ct ion in Fusarium sectio n Li seola. My cologia 78 , 24 2- 24 7. MARIC, A. (1981). Fusarium diseases of whe at and corn in Eastern Europe and the Soviet. In Fusarium : Diseases, B iology and Ta xonomy (ed . P. E . Nel son , T . A. Toussoun & R . J. Cook ), pp . 77-93. U n iversity Park : Pennsylvania State University Press. NASH, S. N . & SNYDER, W . C. (1962 ). Quantitative estimations by plate counts of propagules of bean root rot Fusarium in field soils. Phy topath ology 52, 567-572 . NELSON, P . E ., TOUSSOUN, T . A. & MARASAS, W . F. O. (1983). Fusarium Sp ecies : An Ill ustrated Manual f or Id entifi cation. Univer sity Park: P enn sylvania State U niversity Press. RABIE, C . J., MARASAS, W . F . 0., THI EL, P . G ., L UBBEN, A. & VLEGGAAR, R . (1982). M on iliformin production and toxicity of different Fusarium species from Southern Afr ica. A pplied and Envi ronmental Microbiology 43, 517-5 2 1. THIEL, P. G ., MEYER, C. J. & MARASAS, W. F. O . (1982). Natural occurrence of moniliformin together with deoxyn ivalenol and zearal enone in Transkeian corn. J ournal of Agricultural and Food Chemistry 3° ,3°8-312 .
19 86
and in revised fo rm 1 June 1987)
9-2
Prim ed in Great Britain
FUSARIUM SPECIES OF THE LISEOLA SECTION ASSOCIATED WITH STALK AND EAR ROT OF MAIZE IN SOUTHERN ITALY, AND THEIR ABILITY TO PRODUCE MONILIFORMIN By A. LOGRIECO AND A. BOTTALICO Istituto tossine e micotossine da para ssiti vegetali del Consiglio Nazionale delle Ricerche, V ia G. Amendola 197/ F, 7 0126 Bari, Italy Fu sarium species of the Liseola section, isolated from infected maize (stalks, seeds ), and from soil after a maize crop in southern Italy, were identified as belonging to F. moniliforme and F . proliferatum . F. moniliform e was isolated more frequently from stalks and seeds than from soil, while F. proliferatum was mainly present in soil. Moniliformin (up to 1520 mg kg:") was produced by only some isolate s of F. proliferatum from seeds and soil.
According to the nomenclature of Booth (1971), both Fusarium moniliforme Sheldon and Fu sarium moniliforme var . subglutinans Wollenw. & Reink. have often been associated with stalk and ear rot of maize (Kommedahl & Windel s, 1981 ; Marie, 1981). Attempts to identify the Fusar ium isolates of the Lis eola section associated with fusar iosis in southern Ital y have led to th e recogn ition, together with F . moniliforme, of another morphologic group of isolates showing characteristics rather different from those reported for F . moniliform e var . subglutinans (Bottalico, Visconti & Solfr izzo, 1984). ' In recent taxonomic investigations of Fusarium species within the Lis eola section increasing importance has been placed on phial ide morphology and microcon idial arrangement, as well as ph ysiological Table
* Table
1.
characteristics . Such criteria have necessitated the recognition of other species (Burgess & Liddell, 1983; Nelson, T ou ssoun & Marasas, 1983) and /or varieties (Gerlach & Nirenberg, 1982; Kuhlman, 1982). This encouraged us to reinvestigate th e taxonomic featu res of the isolates from southern Italy, and to assay th eir capability to produce moniliformin. The production of this toxin by Fusarium isolates of the Liseola section is not universal (Bottalico et al., 1982; Rabie et al ., 1982 ; Marasas et al ., 1986 ). MATERIALS A ND METHODS
Samples were taken in 1984 from three different maize fields in Basilicata (south ern Ital y) wh ich
Per centage of maiz e sta lks inf ected with Fusarium species of the Liseola section
Field
N o. of hybrids examined
1
13
2
11
3
10
Percentage of stalk s infected *
Fusarium spp .
F. moniliform e
F . proliferatum
83'8 97'2 96 '0
47'6 78' 1 58'5
33'6 3'6
11'5
T en stalk cores, sampled in August after anthesis, were examined for each hybrid.
2.
Percentag e of maiz e seeds infected with Fusarium species of the Liseola section
FAO maturity class
N o. of samples examined
Fusarium spp.
F. monilif orme
F . proliferatum
200-300 400-500 600-700
15 19 19
4'1 21·8 5° '3
3'3 20'9 4 8'1
0'4 0'9 1'9
Percentage of seeds infected -
* On e hundred seeds were examined for each sample.
Fusarium spp. of the Liseola section
216
Table 3. Presence of Fu sarium species of the Li seola section in ma iz e fiel d soil, f rom th ree sites, in fo ur months Number of Fusarium colonies* Site -
Fusarium spp. F . moniliforme F . prolifer atum
-
Site
1
- -- -- - - -- -- -
April
May
June
38
42
40
4
16
Jul y 32
Site 3
2
- ----- -
Apr il
May
June
July
Apr il
M ay
Ju ne
Jul y
T otal
70 2 16
50 12 28
30 2 6
4
34
42
16
20
418 16 66
2
4
* Colonies grown on 10 agar-PCNB plate s, each inoculated with 1 ml 1 : 1000 diluted solution from 3 g of soil.
were planted with ten hybrids belonging to two different classes of FAD maturity (60<>-700 and 40<>-5 0 0 ) . In August, after anthesis, ten stalk cores (7 nun diam) were taken for each hybrid per field from the lowest internode of green stalks, using a tool similar to that described by Kommedahl et al, ( 1979) . The cores were brought to the labora tor y in small plastic bags , shaken in 1 % NaOCI for 30 s, placed on pentachloronitrobenzene (PCN B)-peptone-agar medium (N ash & Snyder, 1962), and incubated for 7 d at 23-25 "C . Fifty-three commercial seed samples of different hybrids, belonging to three FAD maturity classes, were examined (T able 2). One hundred seeds per sample were left for 12 h under running water, then surface treated with 0'5 % NaOCI for 1 min, cut in halves, and placed on PCNB medium for 5-7 d.
Three gram soil samples, obtained by combining three randomly selected samples (3- 15 em deep ), were collected for four months (April, May, June and July) from three different fields where maize was previously grown. Each soil sample was passed through a 2 mm sieve, then successively diluted with water to give a final dilution of 1 : 1000. Aliquots of one ml of final soil dilutions, mixed in a shaker for 30 s, were pipetted into Petri dishes ( 10 dishes per treatment) to which 15 ml of cool PCNB medium were added. Identification Fusarium colonies on PCNB medium were
subsequently transferred to potato-saccharoseagar med ium (P SA), and incubated for 7 d at about 24° under fluorescent lamps for 12 h d- 1 • Singlespore cultures of Fusarium species of the Liseola section were then obtained on PSA plates, and finally they were identified in accordance with the nomenclature of Nelson et al. (1983). Observations were made also using water-agar with sterile soil, or with sterile rice seed, or with sterile carnation leaf (Nelson et al., 1983 ), or using KCI media
prepared by adding 2, 4, 6 or 8 g of KCI to a litre of 1'5 % water-agar (Fisher et al., 1983). Moniliformin analysis
Moniliformin production on autoclaved seeds and analysis of the toxin in dried colonies were carried out using methods described in a previous report (Bottalico et al., 1982). Forty-three isolates of F . monil iform e from stalks (20) , seeds (22) and soil (1), and thirty-three isolates of F . proliferatum from stalks ( 18), seeds (8) and soil (7) were tested for moniliformin production. RESUL TS
On the basis of phialide morphology and microconidial arrangement, the Fusarium isolates of the Liseola section from maize stalks, seeds, and field soil were divided into two groups. One group was characterized by microconidia always borne in chains on monophialides (Figs 1-2), while the other group showed microconidia borne both in false heads and in chains , usually on polyphialides but sometimes also on monophialides (Figs 3-8). According to Nelson et al, (1983) they were identified as F . moniliforme Sheldon and F . proliferatum (Matsushima) Nirenberg, respectively. Some isolates of F . pro liferatum with clavate microconidia also produced some pyriform microconidia, but only on rice seeds and never on wateragar, or on other nutrient-poor media. As reported by Nelson et al. ( 1983), this characteristic was not constant, and the percentage of pyriform microconidia was usually very low (0'5- 1 %). On water-agar, the isolates of F . proliferatum generally produced many false heads and short chains, but the abundance and length of the chains was increased by decreasing th e water potential of the medium, and longer microconidial chains were formed on medium with 4 g I- I KCI. Isolates of F . proliferatum also produced thickened hyphae and conidia on different media. F. moniliforme was isolated more frequently than
A. Logrieco and A. Bottalico
6 r
J, ~
.
...
217
7 ~:
.,
•
~
r
.
-v.
'--- •
y
,
J
Figs 1-2. Fusarium moniliforme, simple phial ides bearing microconidia in chains (x 400). Figs 3-10. Fusarium proliferatum, phialides and polyphialides bearing microconidia in false heads and chains, x 100, Fig. 3; x 250, Figs 4-5; x 400, Figs 6-8; water-agar medium cultures without KCI (Fig. 9) or with 4 g I-I KCI (Fig. 10) and longer chains of microconidia (x 100). 9
MYC 90
Fusarium spp. of the Liseola section
218
Table 4. Production of moniliformin by Fu sarium species of the Liseola section isolated from maize in southern Italy* Fusarium isolates']
F. moniliforme
F. proliferatum
*
t
Sou rce Stalk Seed Soil Stalk Seed Soil
No . of isolates tested
N o . of toxin producing isolates
Amount of moniliformin produced (m g kg" )
3 3
221-1520 467-1213
20 22 1
18 8 7
Isolates were grown on autoclaved corn kernels at 25-2 7 °C for 3 weeks . Identified according to Nelson et al . ( 1983 ).
F. proliferatum, both from stalks from each of the three fields (T able 1) and from seeds of different FAO maturity classes (T able 2). In contrast, from soils the ratio was reversed, and F. moniliforme was not found at all in two fields (Table 3). None of the forty-three isolates of F . moniliform e from soil, seeds or stalks was able to produce moniliformin. This toxin was produced by 6 out of 33 isolates of F. proliferatum (up to 1520 mg of toxin per kg of dried colony). All the toxinproducing isolates were obtained from soil or seeds. Isolates from stalks failed to produce moniliformin (T able 4).
1979 ; Allen et al., 1981 ; Rabie et al ., 1982 ; Marasas et al., 1986). Such conflicting data may be related to the geographical or igin of the isolates, as well as to the use of different systems of naming isolates. The ability of F. proliferatum to produce moniliformin appears to be restricted to some isolates, and it is not clear why all isolates from stalks were negative . Marasas et al . (1986) found all strains of F. proliferatum were able to produce moniliformin, but they analysed onl y a few isolates from maize and did not specify their origin. It appears that further studies are necessary to assess the relationship between source and toxigenicity for isolates of th is species.
DISCUSSION
The authors are grateful to Mr V. Ricci and to Mr M. Solfrizzo for their competent technical assistance.
It appears that in southern Italy maize represents an important host for both F. moniliforme Sheldon and F. proliferatum (M atsushima) Nirenberg. However, F . moniliforme is more widely distributed in vegetative parts, while F . proliferatum is more frequently present in soil , and the thickened hyphae formed by F. proliferatum could represent soil survival structures. Some sim ilar taxonomic characteristic could lead to confusion of F. proliferatum with F. subglutinans (Wollenw. & Reink.) Nelson, Toussoun & Marasas, the latter being characterized by microconidia always borne in false heads on polyphialides. As a result of this investigation, we support Fisher et al. (19 83) , who recommend the use of KCI (4 g 1-1) in a wateragar medium for the improved identification of Fusarium species belonging to the section Liseola . Isolates of F. proliferatum, but not of F. moniliforme, were able to synthesize moniliformin . The negative results concerning F . moniliforme are in accordance with our previou s report (Bottalico et al., 1982) and those of others (K riek et al ., 1977; DeLucca et al., 1982; Thiel, Meyer & Marasas, 1982), but there are also reports of positive results (Cole et al., 1973; Burmeister, Ciegler & Vesonder,
REFERENCES ALLEN, N. K., BURMEISTER, H. R ., WEAVER, G. A. & MIROCHA, C. J. (1981). T oxicity of dietary and intravenously administered moniliformin to broiler chickens. Poultry Sc ience 60, 1415-141 7. BOOTH, C . (1971). Th e genu s Fusarium. Commonwealth M ycolog ical Institute, Kew. BOTTALlCO, A ., VISCONTI , A. & SOLFRIZZO, M . (1982). Production of moniliformin by Fusarium species, in Italy. Phytopathologia mediterranea 21 , 105-106. BURGESS, L. W . & LIDDELL, C . M . (1983). Lab oratory Manual f or Fusarium Research . Department of Plant Pathology and Agricultural Entomology, University of Sydney. BURMEISTER, H. R., CIEGLER, A . & VESONDER, R. F . (1979). Moniliformin, a metabolite of Fusarium monilif orme NRRL 6322 : purification and toxicity . Applied and Environmental M icrobiology 37, 11-13 · COLE, R. J., KIRKSEY, J. W ., CUTLER, H. G., DOUPNIK, B. L. & PECKHAM, J. C. (1973). Toxin from Fusarium moniliforme : effects on plants and animals. Sc ience 179,
1324-13 26. DELUCCA, A.
J., DUNN, J. J., CIEGLER,
A . & KUHLMAN,
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