During 2003-2004, the field triales were conducted to study side effects of 3 animal manures including cow, sheep and poultry on seedling diseases, Alternaria leaf spot and verticillium wilt with 11 treatments and 3 replications as randomized complet block in Karkandeh Agricultural Research Station with history of soil-borne diseases. The 9 treatments including of 10, 20 and 30 ton/ha. animal manures and two checks. The combined analysis of variance for cotton diseases, emergence, yield and yield components showed that, there were no significant differences among these traits. Mean comparisons of disease data revealed that, animal manures had significant effects on incidence and severity of cotton diseases. Treatments of poultry manure and cow or sheep manures had the least and most rate of seedling diseases, respectively. In addition, Alternaria leaf spot disease incidence and severity were at least in cow manure treatment in comparison with others. The high yield were obtained from 20 ton/ha. poultry manure and manure treatments were significantly different from checks. We have concluded that application of some semi-decayed or decayed animal manures could be useful in sustainable diseases management of cotton.

Cotton production using conservation tillage practices has increased in the past decade. Most studies involving reduced tillage have shown a reduction in plant populations, which has been attributed to seedling diseases. Although most of these studies have focused on no-till production, cotton planted in the mid-south is often planted using stale seedbeds. The objective of this research was to compare the effect of stale seedbed production and conventional tillage with and without in-furrow fungicides on the incidence and severity of seedling diseases. Tillage systems were established in the fall to focus on the effect of tillage on inoculum density and distribution and to minimize differences in the soil environment between tillage treatments. From 1998 to 2001, cotton was planted and seedling disease was evaluated by counting surviving plant populations, estimating stand uniformity, and conducting root and hypocotyl disease indices. Soil populations of Pythium spp. and Rhizoctonia spp. were also estimated. Plant populations were significantly different between tillage treatments in 1998 and between in-furrow treatments in 2000. Skip variables were not different in any year. Soil populations of Rhizoctonia spp. were highly variable and not significantly different among treatments in any year. Populations of Pythium spp. were higher in stale seedbed plots in 2000 and 2001. There were no differences in seed cotton yield in any year. In this study, stale seedbed production increased the incidence and severity of seedling diseases of cotton in only one of four years, but the disease was effectively managed with the application of in-furrow fungicides. These results indicate that the potential for an increase in seedling diseases associated with stale seedbed production is minimal and is not sufficient to overlook the potential benefits of this tillage system.

Farmers in Northern China were interviewed during the 2002 season concerning their knowledge, perceptions and practices on Bt cotton. Farmers have some awareness of insect pests in Bt cotton, especially on the resurgence of sucking pests such as red spider mites and aphids, but 60% of farmers overestimated damage by Helicoverpa armigera, the cotton bollworm in Bt cotton. Farmers' knowledge was very poor on the identification of diseases and natural enemies of pests in cotton. Farmers' knowledge and perceptions of Bt cotton were not significantly associated with their gender or formal education. All the farmers in the survey had adopted Bt cotton during the 5-year period since seed became commercially available in 1997. Their reasons for adoption were either; to save labour, to reduce pesticide applications, to obtain higher yields or to make cotton growing more profitable. Farmers used more than 7 varieties of Bt cotton and 29% of the seed used was home-retained. Pesticide was sprayed intensively on Bt cotton with an average of 12.7 applications per season. The results indicate that farmers were still over-utilising pesticides in the control of pests in Bt cotton. Farmers in small producer cotton systems need further training in the identification of pests, natural enemies, basic ecology and integrated pest management strategies to ensure sustainable production of Bt cotton.

In cotton (Gossypium hirsutum) the enzyme (+)-[delta]-cadinene synthase (CDNS) catalyzes the first committed step in the biosynthesis of cadinane-type sesquiterpenes, such as gossypol, that provide constitutive and inducible protection against pests and diseases. A cotton cDNA clone encoding CDNS (cdn1-C4) was isolated from developing embryos and functionally characterized. Southern analysis showed that CDNS genes belong to a large multigene family, of which five genomic clones were studied, including three pseudogenes and one gene that may represent another subfamily of CDNS. CDNS expression was shown to be induced in cotton infected with either the bacterial blight or verticillium wilt pathogens. Constructs for the constitutive or seed-specific antisense suppression of cdn1-C4 were introduced into cotton by Agrobacterium-mediated transformation. Gossypol levels were not reduced in the seeds of transformants with either construct, nor was the induction of CDNS expression affected in stems of the constitutive antisense plants infected with Verticillium dahliae Kleb. However, the induction of CDNS mRNA and protein in response to bacterial blight infection of cotyledons was completely blocked in the constitutive antisense plants. These results suggest that cdn1-C4 may be involved specifically in the bacterial blight response and that the CDNS multigene family comprises a complex set of genes differing in their temporal and spatial regulation and responsible for different branches of the cotton sesquiterpene pathway.

Recent reports have shown induction of resistance to Rhizoctonia root rot using nonpathogenic strains of binucleate Rhizoctonia spp. (np-BNR). This study evaluates the biocontrol ability of several np-BNR isolates against root and foliar diseases of cotton in greenhouse trials, provides evidence for induced systemic resistance (ISR) as a mechanism in this biocontrol, and compares the disease control provided by np-BNR with that provided by the chemical inducer benzothiadiazole (BTH). Pretreatment of cotton seedlings with np-BNR isolates provided good protection against pre- and post-emergence damping-off caused by a virulent strain of Rhizoctonia solani (AG-4). Seedling stand of protected cotton was significantly higher (P < 0.05) than that of nonprotected seedlings. Several np-BNR isolates significantly reduced disease severity. The combination of BTH and np-BNR provided significant protection against seedling rot and leaf spot in cotton; however, the degree of disease reduction was comparable to that obtained with np-BNR treatment alone. Significant reduction in leaf spot symptoms caused by Alternaria macrospora occurred on cotyledons pretreated with np-BNR or sprayed with BTH, and the np-BNR-treated seedlings had significantly less leaf spot than BTH-treated seedlings. The results demonstrate that np-BNR isolates can protect cotton from infections caused by both root and leaf pathogens and that disease control was superior to that observed with a chemical inducer.

Root-knot nematode [RKN] (Meloidogyne incognita) can increase the severity of Verticillium (V dahliae) and Fusarium (F oxysporum f.sp. vasinfectum) wilt diseases in cotton (Gossypium hirsutum). This study was conducted to determine some of the physiological responses caused by nematode invasion that might decrease resistance to vascular wilt diseases. The effect of RKN was investigated on spore germination and protein, carbohydrate and peroxidase content in the xylem fluids extracted from nematode-infected plants. Two cotton cultivars were used with different levels of resistance to both of the wilt pathogens. Spore germination was greater in the xylem fluids from nematode-infected plants than from nematode-free plants. The effect on spore germination was greater in the Fusarium-resistant cultivar (51%). Analysis of these fluids showed a decrease in total protein and carbohydrate levels for both wilt-resistant cultivars, and an increase in peroxidase concentration. Fluids from nematode-free plants of the Verticillium-resistant cultivar contained 46% more peroxidase than the Fusarium-resistant cultivar. The results provide further evidence that the effect of RKN on vascular wilt resistance is systemic and not only local. Changes in metabolites in the xylem pass from the root to the stem, accelerating disease development.

枯、黄萎病是世界棉花生产中的两大重要病害。传统育种缺乏抗源，几丁质酶和and#61538;-1,3-葡聚糖酶是植物防御体系中的两种防卫因子，两者之间存在协同增效作用。据此构建了4个单价和2个双价基因(分别定位于细胞内或细胞外)的植物表达载体，通过花粉管通道法转化棉花，经PCR和Southern杂交检测以及1996and#61566;2000年温室及病圃多代筛选鉴定，已培育出对枯、黄萎病抗性提高的转基因棉花株系。将抗病基因导入国产抗虫棉品种GK19中，还获得了兼抗病、虫的转基因优系。 | Fusarium and Verticillium wilt are two important diseases in cotton in the world. Traditional breeding method does not have resistance germplasm. Chitinase and and#61538;-1,3-glucanase are two factors with synogestic effects involved in the plant defense system. Based on this fact, a series of plant expression vectors either harboring chitinase gene or and#61538;-1,3-glucanase gene or both were constructed. The two genes are expected to be expressed and localized in vacuole or in extra-cellular space. The transformation of cotton was conducted by pollen-tube pathway method. Molecular analysis of transgenic cotton plants by polymerase chain reaction and Southern hybridization, and successive repeated selection of transgenic cotton lines in greenhouse and fungi-infected nurseries during the period of 1996-2000 demonstrated that the transgenic cotton lines with Fusarium wilt and Verticillium wilt resistance were obtained. Meanwhile, the above anti-fungal genes have been integrated into insect-resistant cotton variety GK19 which resulted in the development of transgenic lines resistant to both cotton boll worm as well as Fusarium and Verticillium wilt.

In order to have a better understanding of the behaviour of several commercial cotton varieties in relation to the main diseases in the cerrado vegetation area, 4 trials were conducted at COODETEC's experimental station in Primavera do Leste, state of Mato Grosso, during the 2003-2004 growing period: EGTRA (Trial on the degree of tolerance to Cotton rust Ramularia); EGTDA (Blue Disease); EGTRO ("Ramubse"), and EGTPC (Boll rot). Two plants were artificially inoculated with "Ramulose". For EGTRO and all other trials, infestation took place naturally. Each trial is composed of the materials to be tested: IPR 96, IPR 94-227, IAC 24, CD 405, DELTAOPAL, IAN 338, CD 408, CD 409, and CD 410, together with a susceptible and a resistant check variety. In the case of EGTDA, the initial stand of IAC 24 was significantly reduced, and IPR 94-227 was the most tolerating variety. For EGTPC, IAN 338 was the material that underwent the most intense rotting process, and CD 409 and IPR 96 were the most tolerant to rotting. For EGTRA, IPR 96 achieved the best mark. In the case of EGTRO, CD 410 was the material most sensitive to "Ramulose" and IPR 96 and CD 407 were the most tolerant varieties after the tolerant check variety BRS Antares. (Résumé d'auteur)

Six family groups of upland cotton (Gossypium hirsutum L.), derived by backcrossing, were compared over multiple environments. Each group consisted of a different nonrecurrent parent (NRP), a cultivar from Africa with resistance to bacterial blight [caused by Xanthomonas campestris pv. malvacearum (Smith) Dye]; the same recurrent parent (RP), ‘Westburn 70’, susceptible to that disease; the F₄ of the cross between them; and the Bc₁F₄, Bc₂F₄, Bc₃F₄, and Bc₄F₄ generations. All entries were evaluated for lint yield, six fiber properties, and seven agronomic characters. Reactions to three diseases were also determined for the Bc₄F₄ and the RP in two environments per disease. The objectives of this study were to measure the degree and rate of recovery of RP traits through four backcross generations in upland cotton as well as to determine reactions to three diseases (including blight) in the Bc₄F₄ generation. Eighty-four sets of comparisons (six family groups by 14 traits) were possible in the portions of the study not involving diseases. The NRPs differed significantly from the RP in 69 of the 84. Among those 69 combinations, the number (and percentage) of significant differences from the RP in the F₄, Bc₁F₄, Bc₂F₄, Bc₃F₄, and Bc₄F₄ were 47 (68%), 35 (51%), 25 (36%), 25 (36%), and 14 (20%), respectively. No significant differences were detected in any family group between the Bc₄F₄ and the RP for lint yield, 2.5 and 50% span lengths, uniformity index, and pulled lint percentage. One or more such differences were found for micronaire, T₀ and T₁ fiber strengths, picked lint percentage, boll size, bur size, lint weight per boll, lint index, and seed index. Depending on the trait, three, four, and often more backcrosses were required to recover the RP traits. Several instances of transgressive segregation were noted mainly in the earlier backcross generations. The observed rate of recovery of RP traits was 96% of the theoretical rate. The only intentional selection in these materials was for bacterial blight resistance. As expected, the level of blight resistance in the Bc₄F₄ reflected that of its NRP. Also as expected, the level of tolerance to Verticillium wilt (caused by Verticillium dahliae Kleb.) and of resistance to the Fusarium wilt [caused by Fusarium oxysporum Schlect. f. sp. vasinfectum (Atk.) Snyd. & Hans.]–root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] complex in the Bc₄F₄ reflected that of the RP with three possible exceptions.

Six family groups of upland cotton (Gossypium hirsutum L.), derived by backcrossing, were compared over multiple environments. Each group consisted of a different nonrecurrent parent (NRP), a cultivar from Africa with resistance to bacterial blight [caused by Xanthomonas campestris pv. malvacearum (Smith) Dye]; the same recurrent parent (RP), 'Westburn 70', susceptible to that disease; the F4 of the cross between them; and the Bc1F4, Bc2F4, Bc3F4, and Bc4F4 generations. All entries were evaluated for lint yield, six fiber properties, and seven agronomic characters. Reactions to three diseases were also determined for the Bc4F4 and the RP in two environments per disease. The objectives of this study were to measure the degree and rate of recovery of RP traits through four backcross generations in upland cotton as well as to determine reactions to three diseases (including blight) in the Bc4F4 generation. Eighty-four sets of comparisons (six family groups by 14 traits) were possible in the portions of the study not involving diseases. The NRPs differed significantly from the RP in 69 of the 84. Among those 69 combinations, the number (and percentage) of significant differences from the RP in the F4, Bc1F4, Bc2F4, Bc3F4, and Bc4F4 were 47 (68%), 35 (51%), 25 (36%), 25 (36%), and 14 (20%), respectively. No significant differences were detected in any family group between the Bc4F4 and the RP for lint yield, 2.5 and 50% span lengths, uniformity index, and pulled lint percentage. One or more such differences were found for micronaire, T0 and T1 fiber strengths, picked lint percentage, boll size, bur size, lint weight per boll, lint index, and seed index. Depending on the trait, three, four, and often more backcrosses were required to recover the RP traits. Several instances of transgressive segregation were noted mainly in the earlier backcross generations. The observed rate of recovery of RP traits was 96% of the theoretical rate. The only intentional selection in these materials was for bacterial blight resistance. As expected, the level of blight resistance in the Bc4F4 reflected that of its NRP. Also as expected, the level of tolerance to Verticillium wilt (caused by Verticillium dahliae Kleb.) and of resistance to the Fusarium wilt [caused by Fusarium oxysporum Schlect. f. sp. vasinfectum (Atk.) Snyd. & Hans.]-root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] complex in the Bc4F4 reflected that of the RP with three possible exceptions.