CROP PROTECTION (1985) 4 (3), 337-345
Integrated m a n a g e m e n t o f Fusarium and Verticillium wilts o f cotton in China CHI-YI SHEN
Department of Plant Protection, Beijing Agricultural University, Beijing, China
Abstract. Fusarium and Verticillium wilts of cotton, which are widely distributed, generally occur concurrently and cause serious losses in cotton production in China. A general survey in 1982 showed that about 16% of Chinese cotton-growing regions were infested and could be demarcated into heavily, moderately and lightly infested regions. The estimated annual loss was about 100 000 tons of lint cotton. The tactics used for integrated management have been developed. Three biotypes of Fusarium oxysporum f. sp. vasinfectum have been identified. Different virulent strains have been found in both F. oxysporum f. sp. vasinfectum and Verticillium dahliae in different regions. Since 1951, 47 Fusarium-wilt-resistant and Verticilliumtolerant ciJltivars have been developed and grown in heavily infested regions. About 50% of the potential loss from cotton wilt diseases is saved annually. By using an organic solvent infusion (OSI) technique, fungicides such as carbendazim or ethylethene thiosulphonate can easily penetrate into dormant seeds; thus, a better disinfection of internal seed-borne pathogens is obtained. Seed coating treatment with a combined formulation of the systemic fungicides carbendazim and quintozene and the insecticide carbofuran provides a good integrated control of seed- and soil-borne diseases as well as of cotton aphids, thrips and soil insects at the seedling stage. More plant growth and yield of lint cotton have been obtained in comparison with the untreated control in field tests.
Introduction
Fusarium and Verticillium wilts of cotton cause an important yield loss in major cotton-producing countries all over the world. In recent years, numerous reports involving all aspects o f research work as well as reviews and synopses have been published (Anonymous, 1973; Erwin, 1977; She et al., 1978; Garber, 1980; Wilkins, 1981; Halloin, 1982; Kappleman 1982; Minton, 1982). Fusarium and Verticillium wilts were introduced into China probably with the importation o f G. hirsutum from the U S A as early as 1892. In 1936, the author reported and described these diseases from Nanking and Shanghai (Shen, 1936; Shen and Chow, 1936). At first, they occurred in limited areas, but after 1950 cotton wilts became widely distributed over nearly all the main cotton-growing 0261-2194/85/03/337~)9503.00
© 1985 Butterworth & Co (Publishers) Ltd
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Fusarium and Verticilliumwilts of cotton in China
regions and caused serious losses, especially in the irrigated, high-yield and continuous-cotton-cropping regions.A cotton-wilt disease survey made in 1982 indicated that about 16~o of our cotton-growing regions were infested and could be demarcated into heavily, moderately and lightly infested regions, with an estimated annual loss of about 100 000 tons of lint cotton. The tactics adopted for the integrated management of cotton wilts are: (1) to emphasize quarantine and seed disinfection to protect disease-free regions; (2) to develop resistant cultivars for heavily infested regions; (3) to use crop rotation, mainly with rice, and sanitation for moderately infested regions, and (4) to use soil disinfestation for isolated and lightly infested regions. As a result of the above-mentioned integrated management, about 50~o of the potential loss of lint cotton is saved. A national Cotton Wilt Coordination Research Committee (CWCRC) was organized in 1972 with the aim of promoting our research programme for their integrated control. The activities and results of research work are published in the form of annual reports, synopses and booklets. (CWCRC, 1973a, b, 1974, 1975, 1976a, b; Liin and Loo, 1982; Shen and Chen, 1982; Chen, 1983). This paper will deal with the studies of cotton wilt pathogens, their biotypes, the breeding of resistant cultivars and the methods used for seed disinfection and seed coating for integrated control. M a t e r i a l s and m e t h o d s Studies of cotton wilt pathogens and their biotypes
Biotypes of F. oxysporum f. sp. vasinfectum were studied in 1972 by isolating 47 strains of the pathogens from 14 provinces and inoculating them separately on differential hosts belonging to three species of cotton, i.e.G, barbadense (two cvs), G. hirsutum (four cvs) and G. arboreum (three cvs); however, for practical reasons, we did not use Glycine max and Nicotiana tabacum (as used by Armstrong and Armstrong (1960)), Inoculation was achieved by sowing acid-delinted seeds of differential hosts into soil which had been infested by mixing with a 2~o sand: corn: meal medium containing different strains of the pathogen. Eight seedlings were maintained in each container for disease rating and 10 replications were used. Experiments were maintained under conditions favourable for disease development. Data regarding infection type and disease index, as observed 3 weeks after germination of each differential host-pathogen strain complex, were used to separate the biotypes. This experiment was repeated in 1973, but using single-spore isolates; several other experiments on biotypes of the same pathogen in different provinces all confirmed the result (CWCRC, 1973c). The identification of the species of cotton Verticillium wilt in China was made during 1977-80 with single spore lines isolated in eight provinces. All strains were grown on PDA and plum agar medium but stored at different temperatures (20°C, 25°C, 30°C, and 33°C). The growth rate of the colonies and microsclerotia formation were compared. The criterion used to separate V. dahliae from V. alboatrum is that the former species forms microsclerotia and the fungal colony grows well at 28-30°C. All the strains so far examined are of 111.dahliae (Isaac, 1949; Schnathorst, 1973, Chang, et al., 1981). Within the biotypes, strains of F. oxysporum f. sp. vasinfectum and V. dahliae with different virulence (e.g. strong, medium and weak strains) have been isolated from different localities in China.
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Breeding wilt-resistant cultivars The breeding of Fusarium wilt-resistant cultivars was started in Szechuan Province by selecting individual resistant plants from cv. Delfos 531 in heavily infested fields, followed by strict screening of their progeny in disease nurseries infested with virulent strains of pathogens. The pure line pedigree Selection programme was continued, and in 1956 the first Fusarium-wilt-resistant cultivar, cv. 52-128, was developed. By using the same technique, the second Fusariumwilt-resistant cultivar, cv. 57-618, was developed in Szechuan from Deltapine 15 in 1961. However, both yield and lint quality of 52-128 and 57-681 were inferior to the original cultivar in non-infested fields. During the last 30 years, these two cultivars used as a source of resistance were crossed with other cultivars to improve their agronomic characters. A number of resistant cultivars providing better yield and lint quality have been developed and extended widely in China (Tan, Wen and Fu, 1983). Since 1975, the breeding of Fusarium-resistant and Verticillium-tolerant cultivars has been emphasized and the newly developed cultivars Shaanxi 1155 and Liaomiao 7 have acquired these desirable characters. Regional resistant-cultivar tests are made annually in heavily and uniformly infested fields in different provinces, to determine their resistance to local pathogenic strains, adaptability, yield and lint quality in comparison with the locally used cultivar, and in order to decide whether to extend them.
Seed disinfection and seed coating treatments The aim of using the organic solvent infusion (OSI) technique is to enhance deep penetration of systemic .fungicides such as carbendazim or ethylethene thiosulphonate (402; ETS)* for effective disinfection of internal seed-borne pathogens and also for avoiding germination of cotton seed after aqueous seed treatments. Organic solvents such as chloroform, acetone, dichloromethane, dichloroethane etc. were tested alone or in combination with the appropriate concentration of carbendazim or ETS to determine any phytotoxic effect on the germination of cotton seedlings and the =effectiveness of disinfection o f internal seed'borne pathogens. I4C-labelled carbendazim was used to test the penetration and translocation of carbendazim at the seedling stage. Seed coating treatments were a combined formulation of the systemic fungicides carbendazim or quintozene (pentachloronitrobenzene; PCNB) and the insecticide carbofuran (2, 3-dihydro-2, 2-dimethylbenzofuran-7-yl methylcarbamate); Laboratory experiments, field trials and extension work were carried out in 11 provinces of b o t h North and Central China, with different climatic conditions and prevalence o f diseases and insect pests, to determine the effectiveness of integrated control at the seedling stage. Plant growth and lint production of plants grown from treated seed were compared with that from the untreated control seed. Results and discussion
Biotypes ofFusarium oxysporum f. sp. vasinfectum Three biotypes of Fusarium wilt were identified with distinct pathogenicity on differential hosts and their distribution is shown in Table 1 (CWCRC, 1973c). *Synthesized and manufactured in China; no known IUPAC or CA name.
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Fusarium and Verticillium wilts of cotton in China
TABLE 1.
Biotypes of F. oxysporum f. sp. vasinfectum and their distribution Susceptibility on differential hosts*
Biotypes I
II
III
G. barbadense
G. hirsutum
+ + +,.+ +
+ + +, + +
+++,++
+++,++
+ + +, + +
--
G. a r b o r e u m +, +
Distribution
Yangtze River and Yellow River Mainly Yellow River, but Yangtze River also
--
Turfan region, Xinjiang Province
*Susceptibilityrated as follows: + + +, highlysusceptible, diseaseindex (DI) 50-100 + +, susceptible, DI 25-50 +, moderatelysusceptible, DI 10-25 +, weaklysusceptible, DI 0-1-10 - , immune,DI 0. Different virulent strains, classified as strong, moderate and weak, exist within the biotypes. For instance, the strains occurring in the disease nursery in Chinyang, Shaanxi Province, where the Shaanxi Provincial Cotton Breeding Institute is located, are the most virulent strains of biotype I. Thus, the resistant cultivars selected and developed by this Institute are highly resistant to nearly all the strains from other provinces. The identification of the species of Verticillium cotton wilt and its strains in China According to Isaac (1949) and Schnathorst (1973), the criterion used to separate V. dahliae from V. albo-atrum is the production of the microsclerotia and the growth of its colony at at 30°C (no growth above 33°C); the pathogens of Verticillium wilt so far studied in China therefore are V. dahliae. A few severe strains belonging to defoliation type T9 (USA) have been found in Kiangsu Province, whereas most of the strains commonly occurring in China are moderate or weak (Liu et al., 1983). Breeding resistant cultivars The leading Fusarium-wilt-resistant cultivars 52-128 and 57-681 were developed in Szechuan Province as stated above. Table 2 indicates the average disease index and yield increase in infested fields between the original cultivars and the cultivars developed after selection. However, in non-infested fields, yield and lint quality remain inferior to those of the original cultivar. The resistance of cvs 52-128 and 57-681 has been maintained for about 30 years and they are still being used as a good source of resistance in our breeding programmes (Tan et al., 1983). A number of Fusarium-resistant cultivars with
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TABLE 2. Disease index and yield of 52-128 and 57-681 in infested fields in comparison with the original cultivars Delfos 531 and Deltapine 15 Cotton cvs
Average disease index
Yield increase compared with original cv. (%)
52-128 Delfos 531 (original cv.)
12"8 (1953-57) 55"1 (1953-57)
+38-70%
57-681 Deltapine 15 (original cv.)
2.0 (1958-62)
+42.6-52%
26-0 (1958-62)
high yield and good fibre quality have been developed successfully: these include Shaanxi 4, 401,721, 5245 and CAAS 86-1. They have been widely extended in most of the heavily infested regions. The number of cotton-wilt-resistant cultivars obtained has been increased greatly during the last 30 years (Table 3) (Tang, 1982). Our experimental results so far suggest that Fusarium-wilt resistance is exhibited as a durable and adaptable partially dominant and maternally inherited factor (Tan et al., 1983). Since 1975, the emphasis of breeding programmes has been on the development of Fusarium-resistant and Verticillium-tolerant cultivars to meet the simultaneous occurrence of the two wilts in most cotton-growing regions. Shaanxi 1155 and Liaomiao 7 are newly developed cultivars with these properties. It has been indicated also that resistance to both wilts can be combined with high yield and good lint quality (Wang, 1980). Interspecies crosses between cultivars of G. barbadense and G. hirsutum have also given a promising degree of resistance to both wilts. When comparing Chinese wilt-resistant cultivars with those introduced from abroad, we have found in infested disease nurseries in China that the resistance of the Chinese cultivars is greater than that of the foreign introductions (Table 4) (Tang, 1982).
TABLE 3. Numbers of Fusarium-wilt-resistant and Verticillium-tolerant cl)ltivars obtained during 1951-79 in China Total no. of Both Fusariumresistant and
Fusarium-
resistant and Period 1950-59 1960 1970-79 Total
Verticillium-
Fusarium-
Verticillium-
Verticillium-
tolerant cvs
resistant cvs
tolerant cvs
tolerant cvs
5 13 29 47
3 11 22 36
2 2 5 9
0 0 2 2
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Fusarium and Verticilliumwilts of cotton in China
TABLE 4. Comparison of the resistance of Fusarium- and Verticillium-wilt-resistant cultivars developed in China and those introduced from the USA Fusarium-* resistant cvs
Diseased plants (%)
Disease index (%)
Shaanxi 4 Shaanxi 401 86-1 SP21 (US)
8.1 8.1 3-2 50.0
4.7 6.7 2.2 36-2
Cooker 5110 (US)
52.6
40-8
Verticillium-** tolerant cvs
Laoyang 5 8010 8004 Deltapine 16 (US) Paymaster (US)
Diseased plants (%)
Disease index (%)
3.5 22.7 9.5 58"0
0"9 6.8 3.3 18"9
64.2
30.2
*Data collectedfrom the diseasenursery of the Institute of Plant Protection,ChineseAcademyof Agricultural Sciences(CAAS). **Data collectedfrom Handan RegionalExperiment Station.
Seed disinfection with the O S I technique
Internal infection of seeds was first demonstrated by Elliot (1923) who found up to 6~/o infection of cotton seeds from a wilted crop. In China there has been much evidence that long-distance transmission of Fusarium and Verticillium wilts is caused by the presence of seed-borne pathogens either on the seed surface or inside the seed coat (Chow and Zhow, 1958; Chen, Chen, Wong and Hu, 1980). Several methods of seed disinfection have been used in China (CWCRC, 1973b): 1. 2.
Soaking delinted cotton seeds in 0.5% fungicide (ETS) at 55-60°C for 30 min. Soaking cotton seeds in acidified 0-5% carbendazim with emulsifiable agents for 24 h or 0"3~o of free-flowing carbendazim powder for 14 h in cold water.
However, cotton seeds treated with aqueous fungicides must be sown immediately unless they are dried for storage: for this reason we treated cotton seeds with the OSI technique so that carbendazim or fungicide (ETS) might penetrate deeply and disinfect internal seed-borne pathogens (Harman and Nash, 1978; O'Neill et al., 1979). The results of the experiment with the OSI technique show that cotton seeds treated with certain combinations of fungicides in certain organic solvents such as 2% a.i. carbendazim W.P. in acetone, chloroform or dichloroethane for 4-6 h or 2 - 3 % fungicide ETS in acetone or dichloroethane for 4-6 h or 2% pure carbendazim in acetone for 8 h, will provide a successful control of internal seedborne Fusarium-wilt pathogens without any adverse effect on the germination of cotton seeds. Experiments with labelled carbendazim indicated that the action of organic solvents enabled carbendazim to reach the seed embryo by penetrating the seed coat, and that the labelled carbendazim translocated to the roots and young leaves after germination. This technique warrants further investigation for use in the quarantine service.
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Seed coating treatment for integrated control of seedling diseases and insect pests Seed coating treatment using a combined formulation of carbofuran, carbendazim or quintozene with 'stickers' (adhesive agents) gives successful control of seedling diseases caused by Rhizoctonia solani and Colletotrichum gossypii, as well as seedborne Fusarium and Verticillium. The control of cotton aphids, thrips and some of the soil insects can last for 40 days after seed emergence. After this stage, cotton aphids are controlled by natural enemies in the fields. Field trials and extension were conducted for 2 years in 11 provinces of North and Central China where climatic conditions and the prevalence of diseases and insect pests are varied. The results so far obtained were confirmed, as shown in Table 5. In addition, as a result of the seed coating treatment, plant growth and lint production have been increased by 10-20~o over the untreated control. Thus the seed-coating treatment can be regarded as effective, simple and economical; furthermore i t has no toxic effect on beneficial organisms and it avoids environmental pollution.
TABLE 5. Effectiveness of seed-coating treatment for integrated control of seedling diseases and insect pests Formulation (by weight)* 1 : 0.8 : 100# 1 : 0.5 : 100t Untreated control Formulation (by weight)**
Total no. of seedlings
Plants killed by disease (%)
Aphid infestation (%)
584 627 547
9.9 9.4 28.2
100
Seedling emergence (%)
Plants killed by disease (%)
Aphid infestation (%)
0 0
1:0"8 : - - : 100t I : 0"4 : 0"4 : 100~
75 74
19 4
0 0
Untreated control
76
31
38
*Experiment at Hebei Province **Experiment at Hubei Province tCarbofuran: carbendazim: seed ~Carbofuran: carbendazim: quintozene:seed
Acknowledgements
Thanks to the members of the Cotton Wilt Coordination Research Committee for offering their research reports. Thanks especially to Professor Dr F. Grossmann, Professor Dr F. Miiller, University of Hohenheim, FRG, and Mr Li, Jin-yun, BAU, for their collaborative research project on the Organic Solvent Infusion technique in treating cotton seeds for disinfection and also the phytopharmacological studies with I4C-labelled carbendazim done at the University of Hohenheim. Thanks to Mr Li, Jin-yun for his seed coating experimental and extension work in China.
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References ANONYMOUS (1973), Verticillium wilt of Cotton: Proceedings of a Work Conference, National Cotton Pathology Research Laboratory, College Station, Texas. Washington, DC: Agricultural Research Service, USDA. ARMSTRONG, G. M. and ARMSTRONG, J. K. (1960). American, Egyptian and Indian Cotton Wilt Fusaria: Their Pathogenicity and Relationship to Other Wilt Fusaria. United States Department of Agriculture Technical Bulletin 1219. Washington, DC: USDA. CHANG, S. C. LI, QING-JI, CHEN, JI-DI and YAO, YaoWEN (1981). Identification of the species of Verticillium wilt of cotton in China. Acta phytopathologica sinica 11(3), 13-18. CHEN, C. T., CHEN, S. S., WONG, Q. Y. and HU, H. X. (1980). Studies on Verticillium wilt pathogen borne inside cotton seed. Acta phytopathologica sinica 7(3), 159-164. CHEN, QI-YING (1983). Integrated Control of Cotton Wilts. Beijing, China: Science and Technology Literature Publication Co. CHOW, YUAN and ZHOW, D. (1958). Method used for examination and isolation of Verticillium wilt pathogens in cotton seeds. Acta phytopathologica sinica 4(2), 121-127. CWCRC (1973a). Annual Report (1973) of the Cotton Wilt Coordination Research Committee. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1973b). Studies on seed disinfection of cotton wilt. In: Annual Report (1973) of the Cotton Wilt Coordination Research Committee, pp. 69-73. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1973c). Research report on the biotypes of Fusarium cotton wilt in China, In: Annual Report (1973) of the Cotton Wilt Coordination Research Committee. pp. 42-55. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1974). Annual Report (797d) of the Cotton Wilt Coordination Research Committee. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1975). Annual Report (1975) of the Cotton Wilt Coordination Research Committee. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1976a). Annual Report (1976) of the Cotton Wilt Coordination Research Committee. Communication of the Research Institute of Plant Protection, Beijing, China. CWCRC (1976b). Fusarium and Verticillium Wilt of Cotton. Beijing, China: Agricultural Pubfication Co. ERWIN, D. C. (1977). Control of vascular pathogens. In: Antifungal Compounds, vol. 1, pp. 163-216 (ed. by M. R. Siegel and H. D. Sisler). New York and Basel: Marcel Dekker Inc. ELLIOT, J. A. (1923). Cotton wilt: a seed-borne disease. Journal of Agricultural Research 23; 387-393. GARBER, R. H. (1980). Report of Verticillium Wilt Committee, Cotton Disease Council. In: Proceedings of the Be#wide Cotton Research Conference New Orleans, Louisiana pp. 6-7, Washington, DC: AR-SEA, USDA. HALLOIN, J. M. (1982). Thirty years' summary of cotton disease loss estimates: crop years 1952-1981. In: Proceedings of the Beltwide Cotton Production Research Conference, Texas A & M University, p.3. HARMAN, G. E. and NASH, GLENDA (1978). Soaking Brassica seeds in fungicide solutions to eradicate seed-borne fungi: a comparison of aqueous and organic solvent infusion techniques. Plant Disease Reporter 62; 408412. ISAAC, I. (1949). Comparative studies of pathogenic isolates of Verticillium. Transactions of the British Mycological Society 32. 137-157. KAPPELMAN, A. J. (1982). Report of the Cotton Fusarium Wilt Committee, Cotton Disease Council 1983. In: Proceedings of the Beltwide Cotton Production Research Conference, Texas A & M University, pp. 4-5. LIU, JIA-YUN (1983). Different virulent strains of Verticillium dahliae in Jiangsu Province. Journal of Nanking Agricultural College 1, 37. Lf3N, J I N G - D I A N and LOO, C. L. (1982). Cotton Wilts and their Control. Shanghai, China: Shanghai Scientific & Technical Publication Co. MINTON, E. B. (1982). Report of Cotton Seed Treatment Committee. In: Proceedings of the Be#wide Cotton Production Research Conference, Texas A & M University, pp. 11-13. O'NEILL, N. R. PAPAVIZAS, G. C. and LEWIS, J. A. (1979). Infusion and transl0cation of systemic fungicides applied to seeds in acetone. Phytopathology 69, 690-694. SCHNATHORST, W. C. (1973). Nomenclature and physiology of Verticillium spp. with emphasis
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on V. albo-atrum versus V. dahliae controversy. In: Verticillium Wilt of Cotton: Proceedings of a Work Conference, National Cotton Pathology Research Laboratory, College Station, Texas, pp. 1-19. Washington, DC: Agricultural Research Service USDA. SHE, MEI-RE (1978). Quantitative analysis of fungicide 402. Organic Chemistry 4, 26-29. SHEN, CHI-YI (1936). Cotton Diseases in China. National Central Cotton Improvement Research Institute, Bulletin No. 1. Nanking, China: National Central Cotton Improvement Research Institute. SHEN, CHI-YI and CHEN, .Q:.Y. (1982). Advances in cotton wilt diseases research work in China. Scientia agriculturae sinica 1982, 1-7. SHEN, CHI-YI and CHOW, Y. T. (1936). A Survey of Cotton Diseases in China. National Central Cotton Improvement Research Institute, Bulletin No. 2. Nanking, China: National Central Cotton Improvement Research Institute. TAN, Y. J., WEN, X. H. and FU, J. K. (1983). A preliminary study on the genetics and stability of Fusarium resistance of cotton. Acta phytopathologica sinica 10, 33-39. TANG, LEN-WANG (1982). Advances in breeding cotton wilt resistant cultivar in China. Scientia agricultur ae sinica 1982(3), 16-22. WANG, Y. (1980). The development of cotton cultivars resistant to Fusarium and Verticillium wilts. Acta agronomica sinica 6, 28-33. WILKINS, G. M. (1981). Fusarium wilt-nematode complex and Verticillium wilt. In: Compendium of Cotton Diseases. 3340 Pilot Knob Road, St Paul, Minnesota, 55121, USA: American Phytopathologieal Society Inc. Accepted 8 October 1984