Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/4/2005
Publication Date: 1/4/2005
Citation: Hutmacher, B., Davis, M.R., Ulloa, M., Wright, S., Munk, D.S., Vargas, R.N., Roberts, B.A., Marsh, B.H., Keeley, M.P., Kim, Y., Percy, R.G. 2005. Fusarium in acala and pima cotton: symptoms and disease development.. National Cotton Council Beltwide Cotton Conference. pp. 245-246.
Technical Abstract: Within the past several years, some differences have been noted in the situation with the fungal pathogen Fusarium oxysporum in Acala and Pima cotton in the San Joaquin Valley of California. Typically, earlier-recognized races of this organism found in California cotton only caused significant crop foliar damage and yield impacts under conditions where it was found in combination with susceptible varieties of cotton and at least moderate populations of root knot nematode. A race 4 isolate of Fusarium oxysporum has been identified in a small number of Pima and Acala cotton fields in recent years, and research to date has shown that this race can infect susceptible varieties, cause damage, and may reproduce inoculum under soil conditions that do not support significant root knot nematode populations. Research efforts to date have focused on evaluation of plant samples under field conditions to verify presence or absence of the pathogen, and initiation of variety screening programs under both greenhouse conditions with inoculated soil, and where possible, in two field sites where this race 4 has been confirmed. Three field screening trials have shown that susceptible Pima varieties are more severely affected in terms of foliar damage, plant stunting and stem vascular staining, but have also confirmed that Acala and non-Acala Upland varieties can be infected, albeit with plant damage. Significant varietal differences in susceptibility to the race 4 pathogen have been seen in both Pima and Acala entries.